Inventables Community Forum

New Driver problems with v-bit

Hi Inventables-

We are having problems since updating the driver. Our v-carve bit carves were working perfectly prior to updating. Immediately after the update we are having the following problems:

  • Over carving in the corners (going past the corner)
  • chatter in the curves
  • problems where letters are close together

Below are pictures of the problems. I would appreciate your advice,

David Kutina
Technology Education
West Seneca East Senior High School

Xcarve 2Xcarve 3Xcarve 1

Looks like you may be setting your zero too low.
Did you observe the chatter as it carved? Is the area with the “chatter” a smooth curve or does it have a lot of nodes?
Can you share the Easel project?

Hi @DavidKutina1,
Could you please share the Easel project with us so we can investigate this further? Also information on what type of wood was this carved in would be helpful.
Thanks!
Kacper

Here is the project.

It was carved in poplar. The area with the chatter is a smooth curve. It seemed like the machine was chattering on purpose, not like it was overloading.

Is your bit still sharp?
Is your machine tight, V wheels and end plates?

Bit has some use but is still sharp. The machine is definitely tight, no play anywhere. I see where the chatter could be caused by loose wheels or end plates or a dull bit, or a feed rate that is too high. But the with the other mistakes not so much. The machine is very consistent in the mistakes it is making. The inside corners especially are very precisely wrong, if you see what I mean. Also the area where the letters are close together (see the C and O in the picture) appear to be calculated wrong.

Is there a way to roll back the driver so I can eliminate that as a possibility? Easel seemed to require the upgrade before it would allow us to continue.

I ran another pass in MDF to see what it would do. It made the same errors again. To clarify further, the corners are fine until the finishing pass. Here is a photo after the depth has been machined but before the corners are detailed:

before 1

and then after the last pass. It’s tough to see in the MDF but the corners look fine until the last ‘touch up’ pass.

after 1

after 2

The jagged ‘stepping’ on the curves is definitely happening because the machine is somehow making tiny movements. You can hear it making a different sound when it cuts the curves and the router starts shimmying or vibrating.

Any thoughts on this? Inventables?

I think I’m seeing this issue as well. Have you been able to resolve the issue or are you still seeing it?

Nope. No resolution yet.

Dog bone effect due to bit going a little deeper than the design account for.
The pointy end of the bit is rarely truly a point, there will be a small flat spot. During Z-zeroing the bit is allowed to go deeper, causing the plunge geometry to be flawed.

Another possible partial component:

Also, minute stock thickness or Z variations can cause these issues.

Have you tried a different sender? I like CNCjs
This would rule out some things.
In the corners, I’m sticking with the thought that zero is too low. The chattering might be a serial communication issue. Try a different sender, then a different USB cable. Make sure you close most things on the computer controlling the machine.

+1, and system flexing. When carving the forces are sideways while plunging its axial “only”.
The smaller the letters the more pronounced any discrepancy will be.

So, Still having the problems. In the photos below I made ABSOLUTELY sure that the zero point was correct, the board was flat, the machine is tight and running smoothly. It does seem to be MUCH worse with the V-Bit than other bits. I tried running the machine and ‘air cutting’ the same pattern. I can HEAR the machine chatter when it does the curves that show up as problem areas on the actual carve.
Again these are new problems that happened as soon as we upgraded the driver. Is it possible to roll the driver back to a previous version and try that?

1

2534

I still think your machine is not tight.
Check all V wheels, end plates on the X and the Y riser plates.
Also the spindle.

1 Like

The “dog bone” result in corners/90deg edges come from the bit travelling too deep vs designed.
Most V-bits dont form an infinite fine point at the tip, but a various degree of flat spot. If Z is zeroed with a V-bit with a flat spot, the bit will ride lower than intended (= wider carve at material top)

V-bit

Another possibility is:

  • Z-axis that is floating / isnt rigid or otherwise precise enough
  • Material surfcace not parallell in height relative to Z over the whole area

I went through the entire machine and tightened everything again. Some parts had loosened some so I am sure tightening those helped. I re-checked the machine for square. Re-installed the driver. Checked the connections at the stepper motors and the controller. Used a brand new 90 degree bit and set the zero with the probe. Planed the board with our planer to get it as flat as I can.

The result is better (see photo), but not crisp. Still getting the dogbone and there is some definite wandering on the long straight runs. Maybe this is the best I can expect?

1b1a

Dogbone require fine-tuned machine and full Z-control to eliminate.
Wandering is not to be expected, something isnt tight
Better, but no - Not the best you can expect.

Hi @DavidKutina1
Could you share the second project with me please? I would like to run a couple of tests.

Also can you tell me what kind of wood are you carving on?
Thanks,
Kacper

I was getting the exact same problem on pine. It would finish the entire carve and at the very end it would go to each corner and push the v-bit down to create the problem you see in the first set of pictures. I just did a carve however on oak and it ran just fine. To reiterate its not the bed being unlevel as what are the odds that on each carve it becomes unlevel or the bit loose only at the corners.I am not seeing this issue now however. If the machine wasnt tight it wouldnt be restricted to the corners like it is.