X-Axis Motion Feel?

So, I’m kind of chasing down a chatter issue, and I see that a lot of people have seen the EXACT same issue, my unit is behaving precisely in sound and method like you see here:

But I don’t see that anyone has really posted much of a solution or approach to solving it. My problem is only when the cutter is moving parallel or very near directly along the X-axis, and appears to have become worse with time. The belts and V-wheels are all appropriately adjusted, and I can feel no major flex (outside of the normal range, anyway) on any of my axes. The bit is sharp, the motor set-screws are tight, and the same issue appears to be active regardless of climb or conventional milling, in both directions on the X. I do not appear to be losing steps, though, the finished product comes out fine. Just excessively chatter-marked, unless I take a couple very light finishing passes to clean it up. I only note this because I have now produced over 60 of the exact same piece, in the same materials, and the performance now is markedly different than it was in the earlier parts. I have to use a lighter cut than I did initially, and use more finishing passes.

All of which is combining to make me wonder if my X stepper is having a problem of some kind.

So, after all the rambling, my question for you guys: When you slide your X-carriage left and right by hand with the power off, do you feel a steady, smooth back-pressure from the motors? Sliding the gantry along the Y axis feels “smooth”, as does manually turning the Z-axis motor. When I slide my carriage back and forth, though, I feel “jerks” and hesitations, as though the motor isn’t resisting smoothly throughout the motion. Something doesn’t FEEL right there…

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I have the same issue where the motion on the x-axis is something like this:

It’s a regular pattern and it occurs at the same spots. It happens when I don’t have power connected, so I’m wondering what it could be. We all randomly chose which stepper goes on the x-axis, so it’s strange that this is the only place it occurs… it it could be this is the only place it’s noticeable.

That is EXACTLY what I am feeling. I’ve not noticed exactly where it happens, I should use some tape to mark spots and see if it does repeat!

I also would note that I’m running an X-Controller, so I don’t even have the same stepper drivers, etc. Very, very interesting! I think I might also pull the wires on my X-Axis stepper, and see how it feels running it without being connected.

I recently switched from the gShield driver to digital Leadshine drivers, but the issue wasn’t affected at all. It would have been an easier problem to solve it if were just the drivers. Hopefully someone has a solution.

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Now that’s very interesting! It makes me wonder if we’re dealing with a mechanical issue, or an electrical one. Or, perhaps, there’s no issue at all and I’m barking up an empty tree. But it just seems a bit coincidental that the only axis I have chatter on is the same axis that has a completely different feel to the motor.

Since it’s a periodic occurrence, it could be the stepper itself has some issue whenever it reaches the same position around its path, or possibly one or more of the vwheels has a flat spot. I’ll take a look and see if I can pin down what’s causing it.

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It seems the v-wheel is the issue, at least for me. The put a marker on one of the wheels and noticed the bump in the x-axis motion occurs when the v-wheel is in the exact same position each time it makes one revolution. I tested the motion of the x-axis after loosening the eccentric nuts one by one. There was a particular one (back right of gantry) that when loosened caused the x-axis motion to become smooth. I tightened the other eccentric nuts that I had just loosened, except for the “problem” v-wheel, and the x-axis motion is now smooth again.

I have my machine in an enclosure, so I’ll have to wait until the weekend to take it out and see what’s going on with the back v-wheel.


Now that is VERY interesting! I will have to do the same with mine, perhaps I have some gunk built up on one of my rear lower V-wheels that I can’t see? There’s no notable loading on the front ones, I use a toothbrush to clean them all off periodically, but I can’t really see the back ones so I have to do that by feel. Perhaps I’ve been less assiduous than I need to be back there. Either that, or there COULD be an actual flat spot on a wheel…

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I get the same smooth-bump-smooth on my X axis. I suspected it might be a small flat spot on one of the wheels that got put there when I was a little overzealous when adjusting wheel tension. Delrin is a relatively soft plastic when dealing with such a small load bearing area. That’s what I get for making it good’n’tight.

Very interesting to see that I’m not the only one with this going on! I’m curious, though, because the two Y-axis slides don’t seem to suffer the same way. Although I haven’t had to fiddle with them nearly as much keeping them tight, so that does make sense…

I can’t speak to mine right now, as I’m not at home, so I don’t know if I have the same issue. But to throw some speculation out there, is it possible that we (whoever is experiencing this problem) have nicked one or more of the x-axis wheels when sliding the x-carriage onto the makerslides during assembly? I could see the x-axis being more prone to this than the y-axis because of having to align two pieces of makerslide with two separate sets of wheels. The wheels could be a little soft, and the makerslide a bit sharp on those points… maybe… just speculating!

Possible, I suppose… I was exceedingly careful with mine for that reason. I think I am going to release the V-wheels one at a time, and see if that does result in that smoothing out. If so, I will remove that V-wheel entirely for a closer inspection!

This is very interesting, my X axis also has “Bumps” that I can feel if I slowly push the carriage across the X axis. It feels just like there is a flat spot on the vwheel.

As anyone measured how far apart the bumps are? Are the vwheels about an inch in diameter? If so then the bumps should be about three inches apart

Now I feel compelled to check this on mine when I get home tonight.

I put a little marker on one of the v-wheels and saw the bumps occurred when the marker was in the same position as the gantry moved along the x-axis.

I noticed that when my machine has sat idle for a while the plastic wheels get a very small flat spot which causes a bump, this seems to resolve itself as I use it. however I am getting irregular motion at slow feed rates such as 150mm/min which easel recommends for aluminium , does anyone else have this issue?

We had a very similar problem. After months of it, finally figured it out by taking our X-Carve into Inventables. They determined that the pulley wheel was slipping on the flat part of the motor shaft. It wasn’t enough to come totally loose, just enough to rock back and forth. Easy fix after months of struggling. Hopefully this helps.

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I had not thought about there being any slop in the pulley. Interesting… I will check that out.

I think it would be helpful if the assembly instructions indicated to seat one of the setscrews on the pulley shaft’s flat part. I’ve read of a few instances now where this omission has caused issues.