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
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
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.
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.
(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 in one or both axes, try a fan.
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)"
If your motors spin the wrong direction, you can reverse 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. Forum discussion here: Draws images fine but the Y axis is inverted.
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.
Delrin nut too wide
Created by: User:JCPhlux
Assembly Issue: Delrin nut too wide
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.
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.
Assembly Issue: Z-axis binds when running
Assembly Step Reference: Assembly step 15
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.