Detail pass starts out correct then goes off path

Hi everyone. I’ve been using my X-Carve 1000 for over 3 years and have had pretty good luck, but I am experiencing something new.

I make a lot of cribbage boards and I make the cuts in several stages. After cutting the pegging holes, I cut an MSU design in the center of the board using both roughing and detail passes.
I’m carving into red oak, using a Birch Plywood for the material and no changes to feed or speed.
The roughing cut uses a 1/8” double fluted straight cut end mill and the detail bit uses a 1/32” fishtail spiral bit.
Between each carve, I home the machine (using the stops for X and Y), change the bit and re-zero the Z with the probe.
When starting the detail pass, I pause the machine as it lowers to begin the carve and ensure that it is in the correct position, then un-pause the carve and let it begin.
The first part of the detailed looks great, but then it starts to very slightly off path (negative on the Y axis).

I’ll try to attach a photo so you can see the result.

Any thoughts on what is going on?

Thanks for any assistance,

Brian

Look closely at the GO GREEN letters, then in the helmet things start to go off path and the GO WHITE is even further off.

Thanks,

Brian

Question 1: is it reproducible or happened only once?

Question 2: if it is reproducible does it always behave like this or randomly shifts the Y?

If only happened once, I would say that your material has moved.

Vilmos,

It has happened 3 times.

I am going to try another but change the detail bit to the 1/16" bit and see what happens.

Brian

When you do the bit change do you follow the inventables procedure and home aftet bit swap? Or do you not home, but have the steppers set to lock with $1 and the dip switch Change?

I have set the steppers to lock, but like most of you I find that tightening the collet securely means that changing the bit requires more torque than the steppers can prevent, so movement happens sometimes.

So, I always set the M-5 Post assemblies to the X and Y home positions and use that same position as my work home for these cuts.

Again, looking at the cuts, the words GO GREEN are just what I wanted, but by the time the carve gets to GO WHITE, I’m off by 1/16" so, something is not working right.

Brian,

when changing cutters are you using two wrenches’ or one?

Ok, so no material. By logic, it is not the bit change. That would add a constant XY offset.

What I am thinking is that your two Y-axes (Y1 and Y2) don’t move together. So one of them is behind the other (say Y1 moves 10 mm, Y2 moves only 9.5 mm) which causes a tilt and that causes a changing offset. Check the belts, make a mark, then move Y like 500 mm and measure the distances travelled by both axes. Do it like 5 times. Even if off 1 mm, that will cause this. It can be that something gets under the gears maybe that causing one of them to slip… or one of them just became loose? Maybe too tight?

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I see what you mean there. It could have skipped a tooth, but woth that tiny bit id expect the bit to break b4 the belt skips… unless theres some small part (like the little lines) that drive the machine left just a tad further than its can travel, and that makes it loose a steps, after the go green is carved…
Can you share the easel project?
Go to project>share > change it to unlisted and copy that link… we can’t mess up your original copy via the link :wink:

I will try measuring the two Y axis. Thanks for the thought.

I don’t think they are loose, but I will check.

Here is a copy that anyone can access.

One other item for consideration, my photo zoomed in on the problem areas, but the cribbage peg holes are done in a single carve with the 1/8" bit and no issues there.

I am starting to think that it might simply be the material (feed and speed), or the 1/32" bit.

So, I am am going to try using a 1/16" bit instead next time.

Ok, let us know. Just one thing to be sure about.

(I do surface analysis when I measure molecules on the surface (e.g. drug candidate in dosed animal tissue) and I have a similar system: XYZZ, i.e. on the Z axis there is a tool that can also move along the Z-axis. We scan the workpiece to be analyzed with a scanner (optical image) and then put it on the holder. During the scan, it can have yaw. The holder can have a yaw, a roll and a pitch. The goal is to move the tool down 100 um above a surface spot (Z) that you selected from the optical image (XY)… It is all math. just saying that very small rotations along some axes can cause issues/deviations in the XY plane.)

Small chance, but who knows.

I think it’s just an issue with slight variances that occur when one homes after completing a carve… maybe

I tested the two Y axis and they seem to be in sync (they returned to the same position after moving them around a bit)

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Then I am out of ideas, sorry :frowning:

Just one, the I have the Dewalt 611 Trim Router.

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Well that just might be your issue most likely, your “Z” carriage (as your facing the front of your machine) is moving to the left enough to overcut the project in the second pass. try using two wrenches to relive pressure and possible movement in and/or gantry.

Seth, I did not have the steppers locked with the dip switches. Thank you for that tip. I do have them now and I’m sure that will help.

I’m also going to take the advice of those of you who recommended marking the homing position with a bit to ensure that I am indeed back at the same starting point.

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Seth,

Thank you for that detailed analysis. Watching your video, I think you might be right.

I appreciate the effort you went to in order to help me out. I’ll let you know.

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Thanks. I don’t know if I can with the Dewalt 611.

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you sure can, it’s flat wrench

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