Through Cut Too Shallow

Hi!
This is literally the first time I turned my machine on. I cut https://www.inventables.com/projects/calibration-test-pattern in 3/4 MDF. Everything was great, except the through cut (.75") only cut at .64". Any advice?

Thanks,
Travis

Did you zero the Z-Axis to the top of the material?

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Brandon Parker

I did. All the other cuts were great. It was just the cut that was supposed to go through that was shallow.

Did you change the outline’s depth-of-cut to match the thickness of the material you are using?

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Brandon Parker

I did. And I verified that the cut depth was set to .75. it’s strange!

Also, thanks for helping!

What endmill?
You most likely lost steps on your Z.
One way to know is when the carve is finished, if you jog to 1" above the surface, is it exactly 1" above the surface?

Hi Neil, I’m using the 1/8" straight cut bit that comes in the super pack. I’ll run the cut again and check the Z there. It’s just weird because all of the other depths were very precise. Maybe I’ve got the bit too far into the collet?

Does it have one of those ring stops? As long as you have enough cutter to reach, that shouldn’t be a problem. If you’ve only got 1/2" of cutting edge, that might be a problem.
I’d try an upcut bit for the profile cut. You’ll get a better chip evacuation.

I’ve got it all the way up to the stop ring. It looks like there should be an inch of cutter. I was using the flat bottom cutter to make sure I could get all the right measurements. Thanks for sticking with me.

I see now that I have a spiral upcut bit that will leave a flat bottom hole. I’ll give that a shot as well.

Travis,
If you are going to do as NeilFerreri1 suggests, make sure to take into account that when the carve finishes the Z-Axis will be at the Safety Height that was set for the carve. Typically this is 0.15" as default in Easel. When a carve finishes the bit should be that high above the piece, and moving the Z-Axis up 1" should place it 1" plus Safety Height above the Z Height at which you zeroed it.

Another super-simple thing to check is the set screws on the Z-Axis pulley; make sure they are tight.

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Brandon Parker

Hi Brandon and Neil,
Thanks for the advice! I did take into account the safety height (measured that first, kicked it up an inch and measured the distance and then reversed that process). It’s accurate there. I reran the cut with the spiral upcut bit and it cut through in some places and not others. The picture shows that it was mostly the left-hand side that got cut all the way through. I’m wondering if it’s just a variation in the material thickness? or the waste-board that I have underneath it (1/8 plywood)? When I cut MDF with my track saw, I usually wind up with little sections that I’ve got to peel off/break off.
Thanks,
Travis

I also checked and everything is square. Maybe it was uneven clamping pressure.

So, third try didn’t go through and the left side is about .748 but the right side is about .723. I’ve also got the dust shoe attached. Think that might have an impact? I measured the distance between the board and the bit all the way across the axis and it’s the same at every point.

Tightened my belts and had a run that had consistent, flat bottoms and a consistent depth through the cut that was supposed to cut through, but didn’t get there. I set my depth to .757 and the cut was .75 deep. Apparently my material is a little thicker than .75.

Managed to get it through! I rounded up to .76 and that did the trick. Tiny bit of a groove in my plywood wasteboard, but that’s what it’s for! Thanks for all your help guys.

One more update. My first real project (a tool holder) failed to cut all the way through. It made it through on the left-hand side, but not the right. I’ve check the distances between the bit and the waste-board as closely as I can and I can’t find a difference. I also checked the level across the entire board and on the x-axis.

I also made the same cut with deeper depths (.765, .77) and the depth of the cut didn’t change at all.

I’m lost.

  • Add a thin sacrifiscal layer of MDF or similar to your spoil board
  • Make a “skim cut” of this surface using a large 3/4" flat wood bit, this will make Z parallell to the cut surface

The try the following work flow:

  • Jog the bit down to it touch the new cut surface, jog it up the same distance as the thickness of your material + an arbitrary amount. Say material is 1/2" so the total distance is 1/2" + added value
    Use this Z-position as your Z-zero and set design cut depth = 1/2" + added value
    This will ensure that the total depth carved = all the way to the surface. Any discrepancy will now be due to lack of stiffness/rigidity (or lost steps)