Assembly troubleshooting

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Sometimes there are issues with assembling your ShapeOko whether it be something that got overlooked, or maybe it is something that is a common issue that people need help on, either way this is the place to go. If you don't see your issue then go to the forums and ask your question there.

Squaring the machine

I.C. shared his methodology for squaring a machine in a forum post. See also Calibration and Squaring the Machine.

User Max Metz noted in the forum post Tensioning the machine...

Tensioning the machine...

(A)s one does up the bolts to secure the Makerslide to the end and motor plates the tension is critical if everything is to stay square. Over tighten just one bolt and the Makerslide twists in the small tolerance between hole and bolt, I noticed this earlier when assembling the x axis, ideally a small tension wrench would make things a lot easier.

The inexpensive way I did it was to fit spring washers (also known as lock washers) between two flat washers to all 8 bolts on the x and y axis, tightening each until the spring washer just closed, then I tightened the bolts diagonally 1/8th of a turn on each axis until the machine began to twist - then I backed each bolt a little. This squared the machine without any twist.

Bolting it down (ShapeOko 1 style endplates)

If the machine isn't square due to bowed plates, cvoinescu noted in Re: Squaring and V-Wheels, "You can adjust at least 1/8" when you bolt the frame to the spoil board. You pretty much have to bolt it down anyway." It is important to ensure that the carriages are able to travel smoothly for their entire distance.



Check all wiring for continuity and a good connection through the entire range of motion of the machine.

If things don't seem to be working, post in the forums for help including:

  • What you did;
  • What happened;
  • What you expected to happen.[1]

Random operation difficulties may be caused by a poor quality USB cable.[2] A cable w/ at least one ferrite bead is strongly recommended.


Identifying the port for the Arduino

The name allocated to the Arduino depends on the device itself, e.g., 'Arduino Uno', or 'USB Serial Port'.

The simplest way to tell which port the Arduino is using, if it is not labelled as "Arduino Uno (COMxx)" is:

  1. Open Device Manager without the Arduino connected
  2. Click on and expand Ports (if listed)
  3. Plug in your Arduino
  4. After a second or two, the port associated with your Arduino will pop up in the listing <-- This is the one you use.[3]

Alternately, load your communication/control program w/o the Arduino attached, check the Com port drop-down and make note of the options, quit, attach the Arduino, re-start the Com port program and use the new entry.

Driver Software

Lengthy post discussing issues w/ loading the driver for an Arduino in Windows: Solution Found: Reload Driver! Plus: full history.

Stepper Drivers

Stepper drivers are fragile. Never power on a driver connected to a motor that does not have a secure connection throughout the entire possible range of motion. If you do, the driver chip can be damaged or destroyed. Some of the TI driver chips are fairly resistant to this, but it is a good idea not to try. Pololu chips will be killed instantly, but can more easily be replaced. TI chips are soldered directly to the controller board.[4]

(Most? All?) Stepper drivers will overheat, especially at the voltages required to more a gantry laden with a spindle, indicated by missed steps resulting in distorted appearance. If your print is compressed or distorted in one or both axes, try cooling the steppers using heat sinks/pipes, a fan or a combination.


Power supply makes noise (chirps), motors don't move

The polarity of the wires from the power supply to the gShield is reversed.[5]

Motors make noise but don't move

It was noted in motors just whine but don't spin, "I built a stock shapeoko but when I would issue a GRBL command the motors would twitch (slight motion) but then just whine for an appropriate amount of time (x=1000 is 10 times longer than x=100) and then twitch again and turn off....I guess as I was going through the instructions it did not register to me that there is a step "potentially change the initial GRBL settings" since apparently they were much too high. [EDIT: in particular $0, $1 and $2 were wrong)"

See Grbl Configuration (or Assembly step 15 Verifying Settings for a v1).

Motors vibrate but don't move

A wrongly swapped pair of wires can cause a stepper motor to vibrate, rather than move. Stepper motors vibrating

Each motor has two pairs of wires (e.g., red and blue are one pair, and green and black are the other pair), each pair connected to a winding (coil). Each driver has two so-called H-bridges, each of them designed to drive a winding. If you accidentally wire a motor with one wire of a pair into one H-bridge and the other wire into the other one, it won't work, but it may still make noise and vibrate. Also, if one wire isn't connected properly, so that only one coil is powered, the motor may vibrate and not move at all (or may move slightly in a random direction).[6]

This can also be caused by insufficient current.

Motors Spin in Wrong Direction

If your motors spin the wrong direction, you can correct this by re-configuring Grbl, or by reversing the connections. Note that it is very important to disconnect the power to the motor drivers before doing this, as having the driver powered up while there is no motor connected can damage or destroy the driver or instead. Forum discussion here: Draws images fine but the Y axis is inverted. Wiring diagrams here.

Any one of these changes will reverse the direction:

  • swap the two wires of the first pair;
  • swap the two wires of the second pair;
  • swap the two pairs between them.[7]

See for more information on wiring up stepper motors.


If files are drawn correctly save for scale, or have an asymmetric distortion, Grbl will need to have its configuration adjusted per: Grbl Configuration

Motors make loud/unpleasant noises when moving

One possible cause is current is too high.

Power Supply

It is recommended to use a power supply that can supply at least 4A, preferably at 24V (although almost anything between 12V and 36V will do). If your power supply cannot provide enough current, the motors may not function properly. It is also important to make sure that there is heavy enough wire coming out of the supply, as it can heat up if it is too fine.


Flexible coupler will not fit on motor shaft or threaded rod

  1. make sure the screws are all the way loose on your coupler
  2. Start from a slight angle and try to rock the coupler onto the motor shaft
  3. make sure there are no burrs on the inside of the coupler
  4. With some finesse, use a straight blade screwdriver to slightly open up the coupler end[8]

Delrin nut does not move smoothly on threaded rod

The Delrin nut is made using a tapered M8-1.25 tap --- if the tap isn't run all the way to the bottom, or if the threaded rod is at the larger end of the specification it will be too tight for the motor to turn easily.

  • Try running the the nut up and down the rod by temporarily attaching the threaded rod to a motor using the flexible coupler (or try using a drill)
  • If the Delrin nut is still not smooth after running it up and down the screw several times, file a small angled flat on the end of the screw. Put the nut in the freezer for a few minutes, then run the screw through the nut again. It should run much smoother.
  • Or, if one has access to an M8-1.25 tap, run it through the threads.

One person has reported success lubricating their nut / rod w/ WD-40 300052 Specialist Dirt and Dust Resistant Dry Lube PTFE Spray.[9]

Delrin nut too wide


Created by: User:JCPhlux

Assembly Issue: Delrin nut too wide

Assembly Step Reference: Assembly step 6 Assembly step 13

Parts: SM-M08 Delrin lead nut

Forum Link: click here


When mounting your Delrin lead nut it should have a gap on both side so that it can move freely in the channel between the v rails of the z axis Makerslide.

Some of the Delrin lead nuts were cut at 40mm exactly which is the width of Makerslide channel and this will cause binding between the lead nut and Makerslide.

Below is an example of what it should look like.

File:Delrin nut spacing.png


To correct this issue you can either cut, grind, or sand the lead nut.

Do not worry if it does not look perfect as all that matters is that it can move freely in the channel between the v rails of the z axis Makerslide. The important measure is the distance between the mount holes and the hole for the lead screw, the outside dimensions do not matter as long as they fit into the channel of the Makerslide rail.

M8 Nuts not tapped straight

There have been some instances of nuts not being tapped squarely, resulting in the threaded rod being canted.[10] Re-arrange the nuts, or if necessary source replacements.

Motor Misalignment

Created by:

Assembly Issue: Z-axis binds when running

Assembly Step Reference: Assembly step 15

Parts: SM-ZA02

Forum Link:



The z-axis usually binds because the motor is misaligned. The easiest way to fix this is to loosen the motor mount and the motor a little, then nudge the motor while running the z-axis up and down until it runs smoothly and without binding. Take note of that position, then keep pushing the motor the same way until it starts binding again. Position the motor between those two positions, and make sure it still runs smoothly. Tighten everything down carefully, making sure nothing changes position. The z-axis should then run without binding.

Motor Moves Erratically

Forum Link: Z-Axis making noise, running unevenly


Z-axis does not move smoothly, may not move at all for a short range move..


Feed speed and/or acceleration is too high. Try a setting about 10% of what it is currently and see if it makes a difference. If that makes it better start going back up until you find a good speed.

Adjusting Scale

If your machined parts look correct but are too small, adjust your GRBL settings! I had to double the standard y/x values $0 and $1 to 87.480mm/step. Now everything is just great.

Check out Grbl Configuration

ShapeOko 3

When assembling the SO3, there are a couple of notable things to be aware of:

placement of the extrusion which is tapped for the controller
X-axis gantry for the SO3
left Y-axis for the XL and XXL
what seems to be a ferrite bead on the power cord is actually a switch
when plugged in and switched on, the power supply should have a green light, and the control board should have a blue light
when the USB cable is plugged in, additional lights on the control board should signal to indicate communication
Reversed Y-axis movement (Hello World is mirrored top-to-bottom)
power down and swap the Y-axis motor leads on the board
Z-axis movement is reversed
This can be caused by having the plate on upside down --- the pulleys should go to the left
jerky or hesitant movement
check the pulley set screws:
machine will not complete homing
ensure that all switches work (when pressed they should light up the controller on the board), and that at the end of travel they trigger on an appropriate part of the hardware (some users have adjusted switch plate placement using washers), and that the switches are connected to the correct places


Suggested process for tuning the Shapeoko:

With power off slowly roll the gantry while trying to hold each V-wheel in turn --- if the wheel can be stopped, tighten from turning then turn the nut to tighten engage the wheel using the eccentric nut while holding the bolt in position.

Once assembled and powered up, gently apply pressure to the gantries testing for any movement, and then tightening and adjusting to prevent out-of-plane movement.


Z axis tension, etc. Should it be adjusted such that the springs always return the Z fully to the top? [11]

  • Z-axis carriage moves smoothly along the entire length of travel
  • all wheels turn / make contact as the carriage moves
  • no wiggle or play (the Z-axis extrusions _must_ be as parallel as is possible)


Do the PEM nuts all face the bottom? Will the PEM nuts be sitting on the table when the frame is completed? Is there on the M5 x 16mm screws used in this process or are there more hardwired?

  • Correct, the PEM nuts are one the bottom / underneath (and support the machine on the table until one adds rubber bumpers). The bolts don’t have washers or anything else, just connect things.

Travel direction and reversal

Please disable homing, and then verify that the travel direction is as desired:

  • X +/positive moves should be toward the right, -/negative moves should be to the left
  • Y +/positive moves should be away from you, -/negative moves towards you
  • Z +/positive should raise the spindle, -/negative should lower it

If one (or more) of those is/are backwards, there are a couple of ways to reverse things, some mechanical, some electronic, one which is a bit of both, and also flipping bits in Grbl.


  • you can reverse the Z-axis by flipping the Z-axis spindle carriage plate over --- the static pulley should be on the left from the front


  • the Y-axis can be reversed by powering down and then swapping the connectors for the two motors on the controller

Electronic: any axis may be reversed by doing one of the following

  • swap either the left-most or right-most pair of wires
  • swap the left-most and the right-most pairs of wires (preserving their order)
  • reverse the order of all four wires

(all the possibilities are covered in case a wire is wired oddly --- you can set it right by making it match the others per the above if need be --- be careful to ensure that the Y-axis continues to be counter-rotating so that the two motors will move in unison on their opposite plates).

Or, one can just swap an axis using the invert bit in Grbl:

  • connect to the machine
  • bring up the MDI pane
  • bring up the Log window (tap "L" to do this)
  • switch back to the MDI
  • send $$ to the machine from the MDI
  • The invert bit is $3 --- take note of what it is and add or subtract 1, 2, or 4 depending on which axis you wish to reverse:
X = 1
Y = 2
Z = 4

changing the number so as to stay between 0--7 --- there's a table with all the possible combinations here: Grbl#Grbl0.9 Once you have the machine moving in the right direction, then homing should just work once you re-enable it.

First though, you can verify the various switches by depressing them --- there's a light on the new controller boards which wil light up when a switch is depressed. Use that to verify that each switch is good --- also ensure that mechanically the machine will engage each switch, then make certain that the machine stops as it reaches each axis --- if it fails to for an axis, power down and ensure the switch is still good and plugged into the proper connector (it's especially easy to have X and Y reversed).