Frustration at its Worst

If you’re still losing position, check the two grubscrews that hold the toothed Pulley onto the motor shaft are tight.

These can randomly slip under load causing odd losses in position…


Yeah this can be frustrating as the shifting is a symptom with a tone of possible causes.

Short answer “Something” is slipping. As opposes to a software error.

The fact that it shifts mid print means it is slippage as opposed to all of the print being mis-sized which would be a step calibration. You should do one anyway, as it is an issue, it just probably won’t fix this.

Do you have a Stock Spindle? SERIOUSLY consider upgrading it. Apparently if your stock spindle is developing a fault it starts to put out a lot of signal noise that can make you steppers move when they should not. Isolating it is maddening as it is random and erratic.

Belt tension. Double check it, triple check it. The belts loosen up after a bit of use. Pluck the belt like a string. it should twang not thud. I have no idea what pitch is right. I kept tightening and plucking until the pitch started to go up just a bit.

Check you eccentric nuts. So may people have had them loosen. Locktight is your friend.
Check your pullies and idlers. Again things seem to looses up after initial use. all the vibration I guess.

Give your pots a bump. Just a bit and see if that helps.

Test slower feed rates.

If you try to carve to fast the RPMS will drop and things start to drag. If you want to cut faster you need to upgrade to a stronger spindle.
Also the stock spindle bearings apparently don’t take side loads well? So lower is your friend.

Watch the print to see when the shift happens.
Mine was occurring on rapid moves, moving the spindle form one cut area to another, not during cutting. So for me it was a slipping belt issue. A belt retune and all was good

My surface is flat, I have the Inventables wasteboard. I made image bigger to use a 1/8 bit, slowed the rates down, and even bumped up the pot another tiny turn. (clockwise)

And yes stock spindle is what I have. Not sure how interferance works, but I use LED lighting in my shop, which runs off my solar panels, but my machine, computer and monitor (and A/C) run on electric power as normal, not sure if that even matters but figure I throw it in there.

And now here is my results. So I am trying guys, it only seems a left and right issue? My wheels are nice and roll when I push the spindle side to side, the belt is tight and makes a twang noise (haha). Again I am so frustrated, this is driving me crazy.

You could try putting a sharpie on the spindle mount, and let the program draw your pattern on paper. If the problem is with software, or interference in the stepper cables, then you would see the left/right shift in the drawing. If the problem is mechanical, then this would probably work perfectly, and you wouldn’t see an issue until you put a lot of force on the spindle.

When I have had the x belt slip, it has been obvious. The tension in the belt was much lower after the slip. This meant is was slipping at the belt clamp. If the pull on the motor is slipping you wouldn’t see this. You might want to check the X pulley to make sure the grub is in, and tightened against the flat of the motor shaft.

Finally, you might try increasing or decreasing the voltage trim pot for the X axis. It could be too high, causing a thermal shutdown of the MOSFET, resulting in lost steps. Or it could be too low, in which case the motor doesn’t have enough torque to counter the force of the wood pushing back on the spindle/bit, and causing it to slip.

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This is where the problem lies with me? I do not know if my wheels are too tight, or too loose, or my belt is too tight or too loose? I wish there was a way to video conference and show someone my machine in realtime, maybe it would be obvious tto a pro. But to a beginner, this makes no sense. :frowning:

Sorry I am not understanding what you mean by make sure my grub is in? All my nuts and such are tight

When mine was slipping it was obvious. made a horrible noise and shifted 4"

This is tricky because it is so subtle a slip. :frowning:

I think running the carve with the spindle off is you best bet.
It will isolate any possible motor signal nose and let you hear the other components.
Run it normal and listen.
Run it fast and listen.
See if it makes any strange sounds if/when the slip occurs.

Too much stepper current (pot to high) Temp over heat pauses / stutters sound weird.
So do under current stepper slips (pot too low) kind of a thunk

I recommend some calibration cuts.
Grids, Circles and Squares so you can measure and see exactly which axis are off and in what way.

There is a video at the ends of the instructions on adjust the machine.
You might want to review that to see how tight the v-wheels should be.


There are several of us to get together on Saturday evenings and video talk about machines. Both stock and modified machines. You are more than welcome to join us and talk about the problems you are having with your machine.
Here is a link to the thread that started it all. Anyone interested in a weekly Inventables Google+ Hangout?


Don’t know if this is the same problem I had but I would strongly suggest you call Inventables support and get them on board with this. Mine ended up being the spindle as there is an inherent problem with the spindle and the best solution , suggested by Inventables, is to go with the DeWalt 611 router and your troubles should go away. Now in their defense, they are aware of this problem and have corrected it but the replacement units won’t be in for some time. They seem to be offering some sort of compensation for the price of the spindle.

Inventables knows of my problems, but it is one email a day, and at this rate it could take a week or longer to actually figure out the problem. I am tempted to buy a Dewalt, but then I am out more money, and if that does not fix problem, back to a non working unit I sit. I am using Surface Pro 2 for my computer, running on 8.1 now, but soon to upgrade to 10.

I thank you for the Saturday video gathering, sorry to say my weekends are full due to going to shows each weekend. I do have off next weekend if it is not working by then (which at this point I see no solution) I might jump in and say hi to you all.

I have seen the video on adjustments, and I have adjusted my wheels according this this. And I might try the pen thing, but not too sure how to set the depth without ruining (or crushing) the marker?

call the help line. email is slow

Others have mention this, and it did in fact turn out to be the source of my problem: Noise from the spindle motor can make its way back into the g-shield circuit and cause it to send additional step pulses to the stepper motors. (It appears that the noise filtering on this setup is not that great.)

And the amount of noise from the spindle can change not only from spindle speed but also from brush wear. In my case, everything was fine for a couple of weeks, and then the noise issues suddenly appeared.

To test this, you can raise up your z-axis so that it is not in the material and with no job running, turn on the spindle with your g-code sender and just watch it for a couple of minutes. If this is the issue, you will see random steps in one or more of the stepper motors as long as the spindle is running. You can then turn off the spindle and see that the random steps no longer occur.

When I had this problem, I didn’t even try to solve it directly, because noise issues can be difficult, if not impossible, to resolve. (It’s more of a design issue.) So, I opted to replace the OEM spindle with a Dewalt 611, as suggested above.

Replacing the spindle did cure this problem for me.

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How can I learn about adjusting the “pots”? I know nothing about this or even where they are. Thank you, Mike Rags

On the g shield there are 3 white blocks with what look like phillips head screws on them these are the “pots” or potentiometers. One for each axis.

Very slight adjustments are all you should make until the desired result is achieved since they are fragile and only have about 270 degrees of total rotation ALMOST NO “FORCE” IS NEEDED.

in making adjustments,for example turn the pot in for the axis in question from 12:00 to the 1:00 position and try the axis again.

Really simple but intimidating if you have never done this sort of thiing before. It’s a learning experience.

Set the depths of cut to 1 mm, and set the depth per pass to 0.01 mm ( this will be rounded to 0.0). This way your Z will stay the same and the cut will go on “forever” and your pen wont be crushed.

I was having the same problems till I realized DUST! A small amount of dust on the rails or v rollers will throw the x carve off track. Clean the wheels and rails off and set up good dust collection. Mine hasn’t gone off track since I realized the importance of the machine staying clean.
Hope this helps

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I’ve also noted that there is some kind of grey residue building up on the wheels, and I’ve tried to remove it. But since I can carve (with a pen) perfectly UNTIL I turn on the spindle. Then it starts creeping. The spindle is to be sent back.

There is NO possibility is problem is dust. Disconnect the spindle, DUCT TAPE a sharpie to the thing and draw it on paper. I am pretty sure it is that D$#% spindle.

Russ, I know that this is an older post, but I didn’t see a solution in this thread, and I wanted to mention that I had this issue at one point, and I discovered that the default spindle that is connected to the PWM port on the controller was feeding electrical noise back into the controller, causing the controller to randomly inject extra pulses into both the X and Y axes stepper motors. Mine started after the spindle brushes started to wear just a bit after a few weeks of usage.

You can test this by turning on the spindle without a job running and watching it for a minute or two. When mine was having this issue, you could see the spindle slowly ticking in one direction or the other on each axis, and you could see that the stepper motors were in fact turning little by little without any g-code input.

My solution, which may not be terribly convenient for you, was to disconnect that spindle and replace it with a Dewalt DW660, which plugs strait into a wall socket instead of your controller. Since I did this over a year ago, I have never once had my router go off track like that.