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# Building basics, checks, maintenance

This guide only fits for Trikarus or Hangprinters which make use of RepRapFirmware and closed loop motors with implemented torque mode feature. If you have no closed loop motors, no torque mode or if you run Marlin those procedures are different (other ways of measuring anchor points, coordinate system buildup, G-Codes, ...). So please check if the firmware (fork) you use has the according features. Ignoring will result in strange results or just zero results. The guide tries to focus on the core parts which are ceiling module, effector, print platform and anchors. The short answer for what you have to do: get everything level (especially the horizontal direction), free of tilts and tighten the lines. Driven by concept a real Hangprinter might not have the fancy regular frame Trikarus has. It's not easy to say how long the procedure described at this page takes. Take hours into account! Only setting up the frame will take 40 - 60 minutes. Inserting all the components and fixing them has a lot of frustration potential.

You have to do an intense calibration after mounting your anchors in the room / frame because the firmware needs to know the XYZ position of each anchor. There are 4 general anchor points for 4 axes ABCD in total. Because there are 9 lines in total there are 9 places where the lines need to be fixed (knots) and tuned. An uncalibrated Hangprinter will never reach the targeted coordinates properly. Either it will try to move too far out of the volume (which is not possible) or it just will never reach the maximum possible volume - depending on the values you measured and entered. A bad calibrated printer will behave just not as exspected. For example if you set the effector to home position and let it move to some XY with keeping Z coordinate constant it may happen that the effector still lifts up or down, which means it does not keep the Z level constant. That means that you cannot print anything.

# General overview

Please have a look at Typical Hangprinter problems to have an overview of bad things which can happen with Hangprinters in general.

The following illustration shows the general concept of Trikarus, reduced to some core components.

Non-firmware-related constants of Trikarus

• $//$ (effective height of the D line ceiling anchors)
• $//$ (height where mover will "sit" in the three arm pockets (usually for parking or transport fixation)
• $//$ (height from effective effector D line entries to nozzle tip)
• $//$ (height of the arm borders - remember that the effector can not properly move if it is countersunk into the arms)
• $//$ (value bounded by the developed print platform) see also RepRapFirmware and calculations or thumb formula for recommended print diameter)

Unknown variables of Trikarus to find out by measuring and calibrating

• $//$ (maximum printing height - required for slicing. This will vary according to your frame size)
• $//$ (maximum printing diameter - required for slicing. This will vary according to your frame size)
• $//$ (A anchor point)
• $//$ (B anchor point)
• $//$ (C anchor point)
•  $//$ (D anchor point)
• $//$ (the axis offset between the nozzle axis and effector axis)

Notes on the scheme above

1. only 1 of 3 drives ABC with one line shown
2. only 1 of 3 lines of D drive shown
3. only 1 of 3 stopping arms / drive fixations shown
4. only 1 of 3 line tuners shown
5. belonging to the height difference between your print platform and your ABC anchors the Z height per anchor might be a positive or negative value each. All anchors have a unique Z value because the floor / bottom frame will not be exactly horizontal. The six bottom anchors settle the pivot points ABC.
6. $//$ is machine specific value which requires to set $//$ size correctly in firmware and slicer profile (remember: usually Hangprinters do not have any limit switch. Trikarus tries to implement a height switch for  $//$ but it's experimental). Note that $//$ is the height of the profile pocket where effector will sit in. The effector cannot move if it is caged, so you will have to reduce height effectively by this value. Additionally it makes sense to add some buffer (safety distance) between mover and $//$. You should use some value $// 5 mm\end{array} //]]>$
7. $//$ depends on the calibration itself. For example if a +50 mm move in Z direction only moves +40 mm, $//$ and therefore $//$ and $//$ will be horribly wrong
8. $//$ needs to be be tested for each new room / frame because larger anchor distances mean larger print diameter
9. pivot point $//$ can be measured manully with a laser distance meter (measure the total height from bed to ceiling plate and subtract $//$) or just calculate it by

10. pivot points $//$, $//$$//$ can be measured with linear ruler or similar

11. $//$ is where the top side of print bed including print surface (like blue tape) is
12.  $//$ is a required value for offset between nozzle axis and effector axis to define the tool position
13. Basically there are different axes which could be the Z axis of the origin coordinate system, for example the axis of the nozzle, the center of the effector triangle, the center of the print platform (if it has some kind of center - maybe your print platform is just some random piece of wood) or the center of your ceiling plate (center of the triangle which is formed by the three D lines) or the middle of your frame. We use the ceiling axis as origin axis. The ceiling axis can be understood as some kind of "root axis" because it's spawned by the center of the three D lines. And as we already did some pre-matching adjustments while setting up the machine, we can say roughly that nozzle axis, effector axis, ceiling axis and bed axis and frame axis are aligned on each other.
14. the coordinate system (origin X0 Y0 Z0) is where the nozzle tip touches the print bed. It is aligned as shown in the following image (X axis perpendicular to to the line the A anchors form, B and C are kind of mirrored each other to Y axis). Another description: A lines are always parallel to Y axis (X- quarters). B anchor points are in X+/Y+ quarter and C anchor points are in X-/Y+ quarter.
15. for calibration and verification purposes there are different types of anchor coordinates. There are pivot points A, B and C anchor coordinates, as well as explicite A1/A2, B1/B2 and C1/C2 anchor coordinates. The explicite A1/A2, B1/B2 and C1/C2 anchor coordinates can be used for print volume verification OpenSCAD tool.

Note that in this drawing the print platform is not centered perfectly like you will have in a real world situation too. The image also shows the effector at some random position to better clarify for the parallelism of each line pair A, B and C.

# Required tools for building and calibrating

1. computer with network access and all required software stuff → Used Software / Firmware stack
2. grease gun (for sure with grease inside )
3. set of metric hex keys (standard sizes from 2 up to 10 mm) - this is really important
4. set of open jaw wrenches - this is really important
5. adjustable jaw wrench (there are a lot of parts which have a hexagon socket to keep fixed)
6. pipe wrench
7. rubber hammer
8. marking
1. permanent marker - thick
2. permanent marker - thin
3. masking tape (for temporary markings at the floor and elsewhere)
4. elektronic labeleling device (if you don't label your things it will be your death)
9. spare parts
1. screws
2. fireline
3. other components which might belong to Hangprinter
10. measurement things
1. tape measure
2. carpenter's rule
3. caliper
4. multimeter
5. cross spirit level (used for the print platform)
6. regular long shape bubble level (used for the base frame - don't use a crappy lightweight one and check if the spirit levels are correctly adjusted inside their housing)
7. laser distance meter- this is really important
8. marble or ball (for checking levelness of the ground)
11. cutter knife
12. thermal paste
13. tweezers (for picking up the lines or pulling out SD cards from Raspi / Duet)
14. piece of cloth (for cleaning and handling a really hot nozzle)
15. screw driver cross recess - rough

16. screw driver cross recess - fine

17. screw driver single recess - fine (for screwing down the terminals of Duet and Smart Stepper)

18. a ladder to reach the top of the frame - this is really important
19. roller or squeegee (for applying blue tape)

Other highly recommended stuff

2. much much much much much time. It's not something you just do on the side while being in a hurry.
3. endurance
4. quiet people who don't bug you

# Transporting Trikarus and pre-preparations

## Effector fixation and bottom anchor line wiring

• lock the aluminum beams with three velcro strips at the arms. Note that the velcro clips are only for transportation and not for daily use! Using them for regular parking of the effector is not very handy. Brakes for each drive would be a better idea for this job.

• mount complete line system at the ceiling module including the 6 bottom anchors. This reduces installation complexity a lot because you do not need to to the fuzzy work above your shoulders.
• While mounting the anchors ensure that all lines are put correctly in the ceramic inlets and bearing slots
• Ensure correct placement of the felted parts which prevent the lines to fall off from the lines but also check out if the bearings still can move smoothy. If the bearings cannot rotate properly the friction will get much higher which is bad for the movement system

## Handling

The ceiling module has 2 handles on the top side and two handles on the bottom side. Additionally it has 3 ring bolts for other purpose fixation. While transportation ensure that the effector looks to the sky because it's not constructed to withstand 16 kg of weight.

# Build steps for Trikarus

## General

1. Find the required tools and all necessary individual parts carefully before assembling! Better to pack too much than not enough!
2. At least 3 people are required to set it up. It has been proven that there is a great danger that the frame will tip over or that the helping hands will not be enough to hand over individual parts.

3. Please check out all the frame parts. They are labeled with "A", "A1", "A2", "B", "B1", "B2", "C", "C1", "C2" to mark which frame part joins the other part. This is important for tolerances and for things like wiring of power management, network cables, USB webcam and PTFE tubing. They also mark the positions of the anchors/coordinate system that way.

# I. Assembly steps frame with ceiling module

1. Before assembling the frame, it should be ensured that all tolerances have been manufactured so that no moving parts seize. In our case there were tolerance problems, so that some parts had to be easily machined with a rubber hammer and the prepared nylon sliding washers could not be inserted at all points.
2. Before the frame is assembled, all individual assemblies must also have been prepared accordingly (pre-assembly).

## Spread parts on the floor

Spread out according to the rough arrangement on a flat place with sufficient free area around it (10 m² would be good!)

## (Re)grease stainless steel bushes / fitting screws

So that the dowel screw connections (swivel joints) do not squeak, do not rust and go easier, they should all be lubricated. Use a grease gun to distribute some grease in the stainless steel bushings or on the fitting bolts. If necessary, spread with a brush.

## Join the hexagon

1. First of all, the large hexagon is put together from the three prepared fork bases and the three belonging straight connector (fork top) profiles
2. After that, all profiles must first be aligned with each other
3. Then profiles can be screwed together (countersunk screws ISO 10642 M3 x 16 mm)

## Place the feet under the frame

Place 6x frame feet under the frame and screw in the 6x socket head screws ISO 4762 clockwise until the cylinder heads are at least smooth / flush with the 40 mm steel profile. Do not screw them down yet. Please also double check that you use screws which have thread from bottom to top (full thread screws). The feet shall have no configured distance to the beams yet. They are getting adjusted after building and placing the frame assembly. They are used to adjust the levelness of the ceiling module later. The feet should be put under the frame before it get's heavy due to installation of all the required components. Remember that the whole printer weighs several kilograms. The assembled frame can be lifted by one or two persons if you want to put the feet under it later but that's not really recommended. If you need more distance you can use the provided spacers.

## Move the frame to it's final target position

Please think of the place where Trikarus will stand. It needs stable ground. The flatter the better.

Please take a spirit level to check the levelness of your ground. You can also let roll a small ball or marble over the floor (maybe the marble does not roll because your ground is too soft or it's just really even). Then you have a first view where you will need to adjust your frame feet screws later. At the exhibition place where Trikarus was first installed the ground is not even. It has a small deviation.

## Screw on the fork top profiles

Screw on the 3 upper fork parts (straight profiles) and fold each into the inside of the frame as shown.

Required for each join:

• 2x huge washer made of TPE
• 1x fitting screw
• 1x disc spring
• 1x lock nut
• 1x lock nut cap made of PETG

If the fitting bolts seize, they can be easily hammered in with a rubber hammer. Normally they thread correctly through the stainless steel cylinder then.

Since the frame is symmetrical, it doesn't matter where the emergency stop switch is attached!

## Mount gas pressure springs

The 3 gas springs help to move the head plate module vertically more easily

Required for each join fork:

• 2x washer made of PE
• 1x collar screw
• 1x lock nut
• 1x lock nut cap made of PETG

The fork joints can then be folded back to the starting position (as in the previous step)

## Hook in the upper part of the frame (upper hexagon) and screw together

This step requires at least 3 people. 2 people have to hold the upper heaxgon while the third person makes the screw connections. Another cheat will be to put europallets below the hexagon.

The first connection can still be made by two people (one person is holding, one person is screwing)

For each fork required:

• 2x huge washer made of TPE
• 1x fitting screw
• 1x disc spring
• 1x lock nut
• 1x lock nut cap made of PETG

If the fitting bolts seize, they can be easily hammered in with a rubber hammer. Normally they thread correctly through the stainless steel cylinder then.

## Put the LAN cable into one of the forks (except the fork with the emergency halt button)

To have a local LAN access in case Wifi fails you have a wired fallback connection which can be hidden completely in the fork. Put the cable inside the beam and connect it to the router. Please use only flat style LAN cable because the frame will cut thicker cords (only rare space between top hexagon and fork pivot). Use the magnetic beam end cap to hide the cable if not used.

The photo shows Trikarus in an already installed state so please do not wonder!

## Wire up the USB Webcam

Avoid climbing up to the roof by connecting the USB webcam before lifting the ceiling module to the maximum frame height.

## Mounting and fixating the ceiling module

At first please install the felts between the top hexagon feets and the polycarbonate plate. This avoids scratching your material.

You cannot insert the module from downside. The ceiling module has to be inserted from the top side. Use the two handles on the top side to lay in. Insert the ceiling module so that the power supply has the shortest distance to the fork with the emergency halt cable.

The photo shows a state where Europallets where put below the top hexagon. Reason for this are some instabilties with our current frame construction (gas springs lost huge amount of their gas)

## Wiring the emergency stop button

After installing the frame with head plate, the electrical connection between the emergency stop switch and the power supply must be created. There are two cable openings provided on the housing of the power supply. These still have to be wired.

The emergency button is not a decorative element. It is used frequently - especially while adjusting basics!

## Wiring up the ground wire

The following installation is not really professional yet but it does the job

## Connect the power cord to the printer

Connect the C14 power cord to the switching power supply, plug the other end into a socket and press the toggle switch. The internal relay should now have a red lighting LED and the power supply should turn on.

If your power socket (source power) is not on the ceiling, the electricity must be routed from the floor. To do this, the power cable must be laid on the machine frame.

Check all electronics before extending the printer to the top.

## Extend the frame to the top

This step requires special attention.

• The frame must be extended slowly and with patience as evenly as possible
• Before moving out, it makes sense to place one person per fork corner. At each corner, some body weight should be shifted to the floor frame so that it receives additional support.
• Caution, risk of bending if the frame feet have already been unscrewed and you tap on the frame parts!

the left photo shows just some test

## Fix the fork joints

To fix the forks (prevents the folding movement), a countersunk screw ISO 10642 is screwed in for each fork.

## Attach quick releases

Install 3x quick releases and use them to stiffen the frame. These angle adjustments help to prevent the frame from tilting or wobbling due to different manufacturing tolerances a bit.

It may be necessary to open and move the quick releases several times. By leveling the frame, it is possible that the curvy elongated holes move slightly

## Check frame stability

Check whether the frame wobbles very much. If yes: retighten all neccesarry screw connections (fitting screws) and check feet if they all touch the ground. There are 6 frame feet, 12 bolt connections, three quick releases and three fixation screws for the forks. All of them should have good contact. It's impossible to get the frame absolute non-wobbling. While running the printer this should not be the problem because no one ever should touch the frame or lines while printing. When shaking the frame it takes ~ 10 seconds until vibrations are gone.

## Ceiling plate leveling

Before leveling the ceiling module you should check the general levelness of your ground (if not already done while placing the frame in the room). The fine leveling steps will be done later.

Take a spirit level and level the frame by configuring the height of the six adjustable yellow feet. You can put the level at the top surfaces of the three long connection beams between the fork corners. Adjust one feet per corner to adjust the frame like a triangle. The three remaining feet should hover due to missing contact with the ground now. If your frame is level you can adjust those remaining feet simply by screwing down until they get safe contact with the ground. Now the frame should be stable.

Ideally, the ceiling plate is now level too, provided the frame has been correctly leveled by adjusting feet and the frame tolerances are ideal. However, there is likely to be a discrepancy, even after having a level ground and a level frame. To check this we take another spirit level on the ceiling plate. Remaining angles can be corrected afterwards by placing a little felt between the ceiling module and the three welded support plates of the hexagon frame part or just by re-adjusting the feet screws on the frame bottom. You will also see (later) if your ceiling module is leveled well if your effector will sit in the three arms correctly at maximum Z because the installed Z endstop should trigger if everything is horizontal. If there is a gap between one or more arms and the effector, the ceiling plate is not level and/or the effector is not level too.

## Mount the six bottom anchors

This step is only for installation purpose. The calibration is complex and will be done later.

• Pull down the lines from ABC drives to lower the anchors until you can screw them down to the frame corners. You will have to pull down A1/A2, B1/B2 and C1/C2 pair-wise. If you only pull one anchor (one line) than the other line of the spool will de-spool
• ensure that all felt fixators are installed properly without blocking the bearings. A smooth movement is required
• check for collisions between ceramic inlets and the V bearings. Sometimes the inlets are pushed in too deeply into the base frame roller block. If thats the case push them into their correct fitting position again

• check all lines if there are any twistings between bottom anchors and effector. Each twist will lead to failing movement system

If there is power on the Smart Steppers and they are enabled they will not move when you try to pull the lines. To pull the lines you need to disable the Smart Steppers either by sending M84 command or by turning off the PSU power in the meantime. Another trick would be to push the reset button on the Smart Stepper LCD. Then you have around 5 seconds time to pull lines until it returns into previous control mode (sPID/pPID/torque).

## Mount the filament tube end piece

Take some fishing line and knot it below the D motor. The tubing should end at the same height level like the transport fixation arms.

## Let Smarty Mac Skydriver climb up to the top

He's a "magni"-tude guy and watches the emergency exit.

## The base frame with ceiling module is fully assembled

To maintain the position, the frame corners on the floor can be additionally secured with markings using some tape. This step is particularly important if Trikarus would be installed in the room without the fixed frame.

## Extra: sanity check of frame dimension

Do some sanity checks of the frame. This is optional because Hangprinters normally do not have a frame. But for better precision we try to measure all we can to find error sources quickly and in early states. In a Hangprinter without frame this is not relevant but for Trikarus exhibition frame we can use the benefits of this. The better the frame dimension are regular the easier it will be to adjust anchors later because the smaller the resulting angle deviations are. If the three verticals of the truncated triangle (hexagon style frame) are the same length this would be a perfect result. I remeasured all six frame bottom part lengths and the three distances between fork and the parallel connector beam on the opposite side, for each. So in total we get 9 measurements.

OverviewMeasurements of Trikarus frame

$//$

$//$

$//$

$//$

$//$

$//$

$//$

$//$

## Adjust the webcam view to get a nice overview of the printer build volume

This image shows an already finished setup of Trikarus

## Mark the center of the frame

This step is a little bit dirty because we work on unknown ground (yet unknown grade of levelness)

We need the middle of the frame to (re)adjust the laser pointers for later usage. We use some magnetic line winders to create temporary helper lines between each anchor fork (take the center which is exacty below the guitar tuner) and it's parallel frame connector beam (take the half of it's length. That gives 800 mm).

Take some tape and put a marking on the ground.

To work out good calibration we make use of the three laser pointers at the ceiling module. But they are really sensible. We have to adjust their focus. To do this rotate the body of the laser pointers until the dot looks good. Additionally we need to adjust the position where the spots hit the ground. The angle of the pointers can be adjusted using the set screws. We make use of the template sheet with 570 mm circle and the three target markings. We use a 570 mm circle because the laser alignment has exactly the same size on the ceiling plate. Due to uknown ground levelness slight deviations may occure on the template (laser pointers could point slightly to different target position). Those can be fixed or reduced later.

# II. Setup steps for the effector (mover)

## Wire up the retraction cable management system

Trikarus uses a very thick main cable with a lot more weight. To compensate the weight effect we wire up a self retracting dyneema cable system (see V2 Silent VR Cables by KIWI).

1. Wire up the six retraction cable units
1. Put the first unit next to the B anchor where the main cable leaves the ceiling plate and attach it to the main cable. Keep around 50 cm distance between the mounting point and the ceiling plate
2. Attach all other units to the main cable and leave 50 cm space between each mounting point. Follow the winding direction of the main cable
3. The last unit will be attached at the mounting point of the really first unit because one retraction cable unit can only handle a maximum of 180 cm elongation
2. zero out the small silent stoppers - we do not need them
3. rotate the rubber fixations at the main cable until the face inward. This reduces possible effect of collisions with the movement system

## De-spool unrequired D line amounts

The effector is mounted by three lines, which are all on the same spool (D spool). Due to different winding, the height or the tilt angle (or the horizontality) of the effector can always change somewhat. It's a good idea to have some more line on the spools to have some backup but too much line is bad for the movement system. For this reason, the followup calibration should be done with as maximum as possible despooled lines. To have maximum quality of the behaviour of spooling up /down lines while printing, its good to leave only the amount of line on spool wich is required to keep Hangprinter fully operational in it's build volume.

1. Move effector down (Z direction)

By sending an according move command the D-axis is going to lower the effector towards the floor. Move it until it hovers a few centimeters above the floor. Note that the ABC lines are dropping down to the bottom because they are not handled automatically by the drives. We do not perform classical XYZ movements in this step. We only move the D drive down. The ABC lines will loose tension while down movement until they are nearly flat on the ground. Please have close look that the lines do not jam with other elements like maintenance tools. In regular printing mode that might also be the print platform which could lead to line jammings. If the effector is moved in the wrong direction, the configuration should be checked. The direction of rotation of the motors can be changed in one of the following three ways: config.g in RepRap firmware, physical wiring of the phases or configuration in the Smart Stepper firmware. You can also pull the effector manually without any GCode movement. Then you will need to power down the machine or power off the D drive Smart Stepper or set the D drive Smart Stepper into "torque 1" mode.

G0 H2 D-250 F500 ; repeat until the effector is at the desired height - 250 mm each. It does not yet matter if the moved height is not exactly what you entered as long as your effector moves down to the floor until it hovers some centimeters above
2. Pull all the line trough them while spooling down D drive. The effector should be kept at the bottom of on of the frame corners all the time. So you simulate the maximum possible required D length in normal printing operation circumstances. Leave at least two full windings on the D spool to have some good grip (less force on the blank knots).
3. When done re-tie the guitar tuner trimloks for knotting. Put the unrequired segment of line into the little line reservoirs (magnetic winders).

## Equalizing the D line lengths (fine tuning)

Doing this step the effector is not level yet but you configure one of the hard requirements: lines D1 = D2 = D3. You will reach the condition that ceiling plate and effector are parallel to each other. But because the effector tilts around itself around Z axis we have make them parallel without dangling line and without any horizontal shifting first. So we need to wind up the effector back to top again until it sits in the three brackets (transportation arm fixations).

The effector needs to sit in the arms really tight. We use clockwise turning at the guitar tuners to tighten and counter-clockwise turning to losen the lines. Clockwise turning means when viewing at the guitar tuner's tuning wing points to your face (same rule is used for bottom anchors!). We are now going to "tune" all lines that they have same tension. We can check this by "playing" them like guitar strings. If they all sound equal then the tension is the same. Please not that the limit switch might create an extra offset between effector and fixation arm which should be nulled before doing this step.

## Validate distance between nozzle tip and ceiling plate

While the effector is in top position it's good idea to validate some measurements. Move the effector to maximum Z position and take a ruler to measure the distance from nozzle tip to ceiling plate. This should give nearly or exactly the same values as the pre-set constants from theory: $//$

We measure this again by hand because it's useful and because it can change if you do something with the nozzle (changing to another for example).

## Remove effector tilt around Z axis and finalize frame levelness

The final horizontal alignment takes place using the three bubble levels installed on the effector, the three laser dots from the ceiling module and the machine frame.

There is a poisonous tilt around the Z axis. Omit self-twising misalignments which may come frome a effector which is idling perfectly horizontally but twists (around Z axis) by unequally created forces from effector's center of mass or unequal line lengths at the bottom anchors (if installed already). Due to the doubled lines this problem is reduced but still possible. Trikarus effector twists a lot because the extruder unit is heavy. The nozzle is in the center of the effector but the mass is not. You can see this in the photos. However, the self-rotation of the effector has bad influence on the line equality for the anchor line pairs ABC and the self-tilt also makes it impossible to get a horizontal level effector and therefore no level ceiling plate. So this step is really import. In short: the three D lines must be totally vertical.

1. move effector to the ground
2. put some foam pieces below the effector corners so it cannot hover freely. We want to adjust it's rotation while using the laser dots. In case the lasers were correctly preconfigured and the laser screws on the effector have correct distance, the laser light will hit the surface of the screw heads. You need to screw out the effector corner screws until they match with the laser spots. The positive effect using the laser pointers is that they project the light also directly below the screws so they appear on the ground or print platform. We can always use the laser lights to put back the effector to X0 Y0 - even at higher Z positions. This can be really helpful for resurrecting failed prints.
3. adjust the ceiling plate guitar tuners again until the effector spirit levels are fine

## Adjust $//$ to align effector axis and nozzle axis (zeroing out offsets)

The center of the effector is not the same as the center axis of the nozzle. There might be an XY offset between those two vertical axes or you can eliminate that offset by adjusting your hotend installation on effector. If your effector has two or more tools (extruders or whatever) use the effector axis instead of nozzle axis to do later alignments. For calibration of the machine it's essential to do the best on eradicating misalignments or redundant / unrequired measurements. To eliminate possible issues it's best practice to match nozzle axis with effector axis (Trikarus is a single tool machine). The Aero Extruder mounting assembly is designed to be reconfigured. If this was not already done while assembling the effector, you should it do while setting up the printer environment. The following drawings show the orientation of the effector in the coordinate system, the A1/A2, B1/B2, C1/C2 pivot points and the offset of the nozzle. A well placed nozzle can reduce errors which can appear on slack lines while printing (self-rotation around Z axis). Note that this step is not required for finding the origin on the print platform. To place the effector into origin we use the laser pointer spots instead only.

## Get the maximum movable Z height

For creating a good slicer profile it's recommended to read the maximum movable Z height for the effector. This depends on the frame or room where the Hangprinter is mounted, and it depends on the configured height of the print platform (honoring platform additions like tapes or sprays). Please have a look at the drawing in general overview.

1. To find out the maximum Z height just lower the effector until the nozzle tip touches the print bed in origo (if that's not already the case).

2. Null the Z value

G92 X0 Y0 Z0
3. Raise the effector to the ceiling. Moving into maximum will raise the encoder error because tension will build up if the effector stucks. That's exactly what we want in this case.

G0 H2 D250 ;repeat until effector stops moving and Smart Steppers react on torque overload.
4. Interprete the values correctly:

1. read the encoder values of the D axis Smart Stepper
1. geterror()
2. readpos() - this needs to be recalculated by line buildup compensation and spool radius
2. read the recent Z value from current position

M114 ;read current position
3. compare with M114 value and readpos() value. You may also use a laser distance meter to check rough value.

## Fine adjustments of ABC lines orientation and de-spooling of unrequired line segments

To have maximum quality of spooling up lines while printing, its good to have only the amount of line on spool wich is required to keep Hangprinter fully operational in it's build volume. To do this release the guitar tuners and pull all the line trough it while spooling down and while effector is at the bottom (print platform). When done re-tie the guitar tuner trimloks. This step is the same like D lines which already happened while building up. Put the unrequired piece of line into the little line winders (reservoirs). Do this step while the print head (nozzle) is touching the origin X0 Y0 Z0

• the position of the six ABC anchors must be adjusted so that the following requirements are met
• the anchor pairs A1 + A2, B1 + B2 and C1 + C2 are each parallel to the effector
• line pairs have same length (A1=A2, B1=B2, C1=C2). The line lengths per anchor pair have to match exactly as much as possible. The anchors can be rotated and moved losening or tightening the screws at the frame. We can use the laser pointers illuminating the horizontal effector screws to validate that the effector is still in un-tilted position while we adjust the line lengths.
• each anchor pivot point pair has to have the same Z coordinate. For example if A1 Z coordinate is lower or higher than A2 Z coordinate this will mean that the line length of A1 ≠ A2. If the floor and/or frame parts are bumpy/uneven you will have to ensure "clean" Z height per anchor the mechanical way first. See also What is a Hangprinter and how does it work?
• you can use tape and helper lines to perform measurements and temporary markings

This step is required to get matching line lengths by knotting the lines in the guitar tuners and adjusting the position of the anchors. Using the guitar tuner's tune function does not help to apply proper tension for each drive because every time the drive loses power it will lose it's torque. We use the tuners basically just for quick knotting of the lines. For having more secure knots we can apply some windings on the shafts of the tuners. We use clockwise turning to tighten and counter-clockwise turning to losen the lines - same way like already done at the ceiling module. Put remaining line on the magnetic line winders.

The lines cannot tear simply by tensioning them (49.9 kg per rope pulling force necessary). Rather, the stepper motors lose steps beforehand or the closed loop stepper motor drivers give way (maximum holding force exceeded).  The maximum holding force for the used Stepper Motors MT-1705HS200AE by Motech Motors are 8.2 kg.
This step needs to be done when Smart Steppers are enabled/active with simple PID mode. Do not put them in torque mode for this step. Otherwise it may happen that you will need to catch moving lines or to fix messed up lines from de-spooled drives because torque mode without knotted lines results in endless turning drives.

The guitar tuner acts like a knot between the line pairs. If the lines de-spool unequally it will mean uneven forces. While printing you might figure out that there are lines which have completely no tension.

• floss each line pair A1+A2, B1+B2 and C1+C2 in the related guitar tensioning mechanism (use the small trim lock scew to fix them - marked with red circle in the following photo)
• "play" the two lines <A or B or C>1 and <A or B or C> 2 like guitar strings and listen to them. Or try to use a guitar tuner. The frequency or "the sound" of both strings should be the same. Then they have the same length!
• Put remaining line on the magnetic line winders

Notes on the knot:

Ideally for ABC drives you would have one long line each which is fed through the motion system parts. But most Hangprinters including Trikarus include multiple coils. So for example there is not one A line an A1 and an A2 line. While the printer moves it always will happen that one of the line's tension drops to zero. This could be reduced if the knot between A1 and A2 could float (moving freely) because the tension would better normalize between then. The tension per spool changes due to unequal line buildup even if A1 and A2 are on the same spool with the same motor. It would not help to knot A1 and A2 separately. It would just give some better handling for (un)mounting the lines.

## Clean up the spool winding quality (fixing line salad at the drives / optimize line buildup)

Before we continue with final measurements we re-adjust the lines on spools. Previously they were put on the spools by hand. Now we can use our electronics to make the best winding we can get. Additionally it may happen (often) that you lose lines because lines get slack while printing and the winding fails. It often causes manual troubleshooting at the drives. Then you need to climp up to the ceiling and fix it.

To adjust or fix problems easily

1. smoothen the failed drives using /opt/sms_modes/sms_smooth_*.sh scripts
2. unwind the spool completely by hand. If you have luck you must not climb
3. let the spool wind up again using /opt/sms_modes/sms_torque_*.sh while keeping the lines in your hand. This way the drive will perfectly spool up (important to have best line buildup)

## Calibrate the IMU (MPU 9250) at the effector

Once installed and leveled physically the IMU should be nulled to have some clean reference output for correct monitoring and calibrating tasks.

# TODO

## Move the effector back to the top

Now the effector should be moved up to the maximum height so that there is enough space to set up the printing platform. This can be done by

• GCode

G0 H2 D250 F500 ; repeat until the effector is at the desired height - but at least about 2 meters above the floor.
• or with torque zup mode (/opt/sms_modes/sms_zup.sh).

# III. Setup steps for printing platform

The print platform consists of 3 equal segment pieces which are small enough to be put into the back of a regular car (for transport). To keep it as simple as possible it has a form of an easy shape to produce with a plunge saw or cutting or milling machine. This is a lower cost but solid and plane solution. It's also not too heavy but heavy enough to keep in place. Other possible materials are regular wood, Multiplex, CDF, MDF, HPL-F, flagstone, glass, aluminum, circuit board, PET plate, PEI plate or Firepanel. Ideally you choose a material with low flammability.

## Preparing the print platform (apply adhesion promoter)

Trikarus uses an IR probe for Z level sensing. Usually they have high precision when used with opaque bed surfaces, medium or low with transparent surfaces. Transparent surfaces (glass, PEI etc.) must be backed with a matt black surface and must not be coated with glue, hairspray etc. The platform is opaque and can be masked with blue tape for example. You may also use other trivial "standard" products like classic hair spray or glue stick, or more specialized stuff like 3DLac or Magigoo. There are a lot of different materials and adhesion types possible. In our case we use 19 mm thick chipboard with blue painter's tape on it (to give a cooler look, to better peel off the printed parts and to protect the bare surface). You need about 0.31 m² of tape per segment and per side to wrap it. So in total you have 6 * 0.31 m² = 1.86 m² (upside and downside) surfaces to cover. On a regular tape roll there are about 2.4 m² so you will need more than the half of a tape rolls. Use a roller or squeegee to apply the tape.

Trikarus platform shapeUnfinished tape maskingA finished print platform look

Print platform position and orientation - centering print bed axis (if there is one) and nozzle axis (alignment)

If your print bed is some random piece of platform (for an example of a random platform like Torbjørn does look the following photo) with no regular or symmetric shape you cannot really align some axis. But you can mark the point where nozzle tip on print platform is in X0, Y0, Z0. Some of the following steps cannot be applied to a such a platform.

## Connect platform parts

Similar to the base frame, the printing platform can be connected with screws. It consists of individual parts so that it is easier to transport by car and by human. The platform frame is built directly into the printer frame already set up.

1. Clamp straight profiles into the corners and screw together
2. Place platform feet underneath

3. Insert short straight profiles on the side lugs of the long straight profiles and insert them in the center cross

## Align the print platform and leveling

The platform should be located in the middle. We can make use of the three lasers which point on the surface of the middle beams. We also also make use of the premarked center point and put the center feet of the print platform on it. Adjust all four screws until the platform is level over complete beam surface structure.

## Place the 5-point polygon platform segments on the frame and check levelness again

• Place 3x platform elements. Everything should attach flatly and nothing should wobble
• If individual segments wobble or have an uneven surface tilt, small pieces of tape can be put at the bottom site to compensate for this

• configure the horizontal six platform adjusters to fixate the platform from all sides (prevent lateral displacement)

• re-adjust the platform orientation according to the laser spots and the circular template sheet. The middle is formed by the three inner bed segment edges
• If the platform was levelled correctly and if the ceiling module is really horizontally the laser dots should perfectly match the markings on the PETG template.

## Mark the platform position

The print platform is heavy enough that it will not change it's position until you bump it with your feet but its better to fixate it. To maintain the the position, the frame corners on the floor can be additionally secured with markings using some tape or other templates.

# IV. Configuring the movement system and final adjustments

## Dragging around the effector and measurements of ABCD lines (line lengths and anchor coordinates)

Getting measurements of the anchors feels a little bit strange because you do not measure absolute XYZ coordinates like in a regular coordinate system. It's more like a "fused system". You measure the values of a XYZ vectors for each anchor (they are called "anchor points").  This step is highly important. Using a laser distance meter we can measure the line lengths between the effector and the anchor points ABCD. You can only get useful measurements with tightened lines. Please do this step in regular torque mode (/opt/sms_modes/sms_torque.sh). This step also can help to re-adjust anchors in case the print result should fail later on (due to happened changes in position of anchors or the leveling of the effector or levelness of ceiling plate). In this step we measure anchor coordinates XYZ and line lengths to validate those anchor coordinates. At least measurements for three of the six ABC lines are required. But it's better to take all six values to check against for each line pair. This will help you to eliminate other existing adjusting errors. By measuring all six bottom anchors we can see the rotation error around Z axis.

It's enough to measure with zero digits after comma because we will never get it more precise. Pre-defined anchor coordinate values and line lengths from theory do not help in practical use. We use the real situation and are going to measure the printer how it was built and configured physically. Note that there are small deviations for all anchors because i used ceramic inlets with inner diameter is 3 mm. Remember that lines are only 0.5 mm thick. So there is 2.5 mm of possible tolerance per inlet. Try to perform measurements using the center of the inlets. The following drawings show what we need to measure.

Exhaustive drawing for measurents for ABC anchorsSimplified drawing (what the firmware actually understands)

Exhaustive drawing for measurents for D anchor

## Measuring anchor coordinates

There are two differet ways on how to measure ABC XYZ coordinates. The preferred way is to measure everything relative to the print platform (which was made horizontal before). The second best way is to measure everything from ground (which may not be level). Using both methods we can determine the error of the ground. For this step we need tape measurement, caliper, laser distance meter, some temporary lines and tape and a lot of time and calm hands.

 XY coordinate measurements (tape measurement) A1 Vector A2 Vector B1 Vector B2 Vector C1 Vector C2 Vector X 0.00 mm 0.00 mm 1010.00 mm 1008.00 mm -1015.00 mm -1017.00 mm Y -1166.00 mm -1166.00 mm 585.00 mm 579.00 mm 578.00 mm 585.00 mm Line length to in origin measurements (laser distance meter) line length measured A1 1166.00 mm A2 1168.00 mm B1 1166.00 mm B2 1167.00 mm C1 1169.00 mm C2 1170.00 mm Way 1: Z coordinate measurements and calculated line lengths - measurements using print platform only Offset laser pointer to print platform 20.00 mm anchor Δ effector - print platform Δ anchor - laser dot Δ anchor - print platform Δ effector - anchor = Z coordinate calculated line length deviation A1 -29.60 mm -28.47 mm -8.47 mm -21.13 mm 1166.19 mm -0.19 mm A2 -30.38 mm -28.18 mm -8.18 mm -22.20 mm 1166.21 mm 1.79 mm B1 -29.55 mm -24.29 mm -4.29 mm -25.26 mm 1167.46 mm -1.46 mm B2 -31.00 mm -23.72 mm -3.72 mm -27.28 mm 1162.78 mm 4.22 mm C1 -31.53 mm -22.98 mm -2.98 mm -28.55 mm 1168.39 mm 0.61 mm C2 -30.27 mm -23.54 mm -3.54 mm -26.73 mm 1173.55 mm -3.55 mm Way 2: Z coordinate measurements and calculated line lengths - measurements using ground anchor Δ effector - print platform Δ print platform - ground Δ anchor - ground Σ effector - ground Δ effector - anchor = Z coordinate calculated line length deviation A1 29.60 mm 74.00 mm 68.79 mm 103.60 mm -34.81 mm 1166.52 mm -0.52 mm A2 30.38 mm 71.87 mm 68.68 mm 102.25 mm -33.57 mm 1166.48 mm 1.52 mm B1 29.55 mm 69.50 mm 72.76 mm 99.05 mm -26.29 mm 1167.48 mm -1.48 mm B2 31.00 mm 70.87 mm 76.28 mm 101.87 mm -25.59 mm 1162.74 mm 4.26 mm C1 31.53 mm 73.82 mm 74.13 mm 105.35 mm -31.22 mm 1168.45 mm 0.55 mm C2 30.27 mm 74.87 mm 74.80 mm 105.14 mm -30.34 mm 1173.64 mm -3.64 mm

$//$, $//$$//$

While ABC coordinates are hard to get the D coordinates are really easy. We just take the average of D1, D2 and D3.

1. $//$
2. $//$
3. $//$

$//$

## Measuring line lengths

The following values i got for a first measure sequence.

• $//$
• $//$
• $//$
• $//$
• $//$
• $//$

It does not make sense to measure D again because D line length matches D anchor coordinates!

## Validate the anchor coordinates

After getting anchor coordinate values and line lengths compare those values by calculating theoretical line lengths using formula $//$:

$//$ (in case of $//$)

$//$

$//$

$//$ ( $//$ is not a fixed value because it depends on the print platform adjustment. The better the ceiling plate and bed were configured to be level, the more homogenious the measurements D1, D2 and D3 are.)

If they match well we are done and finally we can configure the K parameter of M666 which defines the coordinates for firmware. After entering them in config.g we need to reboot the controller. If not we need to remeasure.

M669 A0.0:-1166.00:-21.13 B1010.00:585.00:-25.26 C-1015.00:578.00:-28.55 D2617.33

## Testing to reach the entered ABC anchor coordinates

For Trikarus it's no problem to move to outer coordinates where A,B and C anchors are defined (XYZ). We might get large errors if the buildup compensation is not done well (slack lines) - i measured about 26 mm at A anchor before i calibrated the printer well - but we can just move the effector to the outermost fork anchors like shown in the photo:

We can make use of this extremity moves because if the effector is placed there we can have another visual check for line lengths (A1 = A2, B1 = B2, C1 = C2). If we find any error we can re-adjust the guitar tuner trimloks this way.

## Validation of line buildup compensation (M666 Q and R) for ABCD

The line buildup compensation algorithm is really important for exact movements and to prevent slack or overtightened lines of ABCD drives. It is not that important for small build volumes but if you want to print high, using your great build volume advantage, you need it. Because without compensation the error created by spooling up and down lines will be too large (see RepRapFirmware and calculations). This makes it impossible to get good print results and it will waste your expensive filament. We need to ensure to have well tensioned lines all over the build volume. This steps requires to have properly configured movement system (e.g. corrent micro stepping, transmission ratios between pulleys and gears, etc.). The buildup compensation factor is highly sensible and is the same for all four drives. While sourcing the parts of your Hangprinter you measured / modeled the spool radius from each drive (or at least from one drive), the coil width and line diameter and you precalculated a line buildup compensation factor. If you put your effector in origin and there is a lot of idling line on spools then you have to adjust the spool radii with the extra diameter which comes from the extra line. We need to perform this validation step after leveling the ceiling module / effector / frame and after measuring and entering the anchor point locations into firmware.

See RepRapFirmware and calculations for the calucation of the factors. There exist theoretical values but due to mechanical tolerances in line diameter, coil width and so on we get some corridor of possible numbers. Usually we will find more correct factors by manual experiments.

Checking the factors:

1. Enter the calculated factor Q and the theoretical radii (R) values in firmware config.g
2. reboot the controller (each time you change M666 settings you need to do this)
3. Place printer in origin and apply sPID mode. We use /opt/sms_modes/sms_prepare.sh which does a lot of steps like sPID mode, setting home position and resetting the error values of the Smart Steppers
4. Make ABC smooth using
1. /opt/sms_modes/sms_smooth_a.sh
2. /opt/sms_modes/sms_smooth_b.sh
3. /opt/sms_modes/sms_smooth_c.sh
5. Perform Z movements. Move slowly using F-Parameter in G0/G1 if you lose steps (check the error value on Smart Steppers). Maybe we need to adjust the motor currents before. See Smart Stepper - calibration and control modes (sPID mode, pPID mode and torque mode)

G1 Z<VALUE>; slowly raise up D axis to +Z coordinate
6. Measure the distance between the nozzle tip and print platform center using a laser distance meter. If the buildup was calculated and entered correctly (Q and R values of M666 command) there is +/- 0 mm deviation between targeted height and measured height. Note that we cannot use the position information of Smart Stepper because they don't know anything about buildup compensation values. They only know about sent amount of step commands. The same is for error (we can only compare targeted steps with reached steps). You can even reach highly accurate XYZ coordinates at height of 2200 mm and higher. This was succesfully validated with Trikarus. Having deviations we need to adjust Q and R values and to remeasure Z until everything fits and the lines are tensioned all over their way - regardless of the Z coordinate. To validate if you found the correct line buildup value you will have a set of constraints:

1. targeted height = measured height. There should not exist any deviations Z coordinates at the ground level ( ~ 500 mm or less) and ceiling level (~ 2000 mm and higher)
2. no or less wobble: the ABC lines are not slack at higher Z coordinates (> 1000 mm). The effector still feels stiff when touching because the lines are just tight like yourself
3. the Smart Stepper error limit is not reached (trouble by force overloads)
1. note that it might be neccesary to recalibrate Smart Steppers if the default error is too high
2. effector will not "dance" if error value is below ~ 0.90 (tested)
7. Now place the effector to origin again and set all drives to sPID mode. Make some regular movements. Check if ABCD work well. If ABC drives create large forces at higher Z or the lines are just wobbling we need to adjust the radii.

If general machine calibration is bad, Smart Steppers have wrong calibration or tension gets too high due to misconfigured line buildup, the following video shows what can happen. The drives may get load and make some kind of cracking-noise sound and the effector starts to "dance" (it can happen while printing too the same way. It will make holes in your print surface or kick the print off the platform). The system can get overtightened and the servo motors try to fix the error by pulling back the lines.

# V. Setup steps filament feeder

The planned filament feeder is not ready yet so use ordinary spool mechanism (spool on two free rotatable rods)

# Place the feeder

Never place the filament inside the printer's moveable range because collisions can happen (painfully tested). It should be at some location far off the toolhead and the lines

# VI. Check the electronics

Check if all electronic parts act as exspected

• ceiling module
• UPS
• Power Supply
• Raspberry Pi
• Duet 2
• Relay LED spots and stripes
• Relay Power Supply
• Webcam
• Smart Steppers
• Gyro sensor
• LED stripe and LED spot
• Z limit switch
• Laser pointers
• effector
• IMU
• heater cartridge
• encoder
• extruder fan
• filament fan
• LED stripe
• z probe

# VII. Disassembly or emergency maintenance of the base frame (folding / dismantling)

## Uninstall the three quick releases

Otherwise the frame will block and cannot be pulled down to maintenance working height. If you forget those you will possibly destroy the threaded rods of the quick releases (tested painfully). So please do this first!

## The remaining things

The disassembly works the inverted order it was buildup except that you can skip adjusting steps

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