Inventables Community Forum

Problems cutting into wasteboard

I was having trouble last year with full-thickness carves going into the wasteboard, which I chalked up to the previous two years’ worth of damage making them unlevel. I bought a new board this summer, but the very first carve, even using the smallest thickness measurement that I got from the caliper, cut at least a mm into the waste board. Is there any sort of vertical alignment that I can do?

Is the new board skimmed or at any level heigh adjusted relative to Z?

Assuming your Z don’t loose steps, have you calibrated the steps per millimeter (or inch)?
If you command Z to jog 1" is the actual movement = 1"?

If the board is skimmed, steps/mm is right and no steps are lost there is no reason why it should dig into the board.

I have a skimmed board and when I carve material that vary slightly in thickness (thickness is rarely uniform throughout the piece) first “zero” on the board, then jog the bit to a known height (say 13mm if I use 12mm thick stock) and carve down to 13mm depth.

@JoshuaGates. I often will put a sacrificial board under my workpiece. Usually foam or 1/4” hardboard. This protects my wasteboard

I use furniture back sheet. Cut bigger holes to screw clamps. It’s exactly 3mm thickness. It’s very cheap and last for long.

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I thought of having another, more sacrificial layer, but doesn’t that screw up the functioning of tabs?

Not if you’re only off by 1mm.

@JoshuaGates The above are great solutions for protecting your wasteboard, but have you checked the depth of cut? If you create a pocket 1mm deep, is it 1mm deep?

Gotcha

Yeah, that’s a good question. I’ll check that out.

A good test is to create a round pocket, say 1mm deep. And inside it, create a series of smaller pockets that get progressively deeper.

I think it’s going to be difficult checking that with only 1mm sample size. Maybe do 10mm and see how far you’re off there.

I do always advise to cut deeper than the stock thickness, and use a sacrificial layer if you want to keep your bed in decent shape.

@xfredericox The reason I said 1mm is that it can be done in one pass on the Carvey. I’d be trying to rule out an issue with the “smart” clamp. Steps per mm shouldn’t be an issue.

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IF it turns out to be a consistent problem with depth, you can contact Inventables support and have them apply a fix factor to your machine. You would want to do a series of depth tests, zero’ing each time, to see if there is a consistent error. Take that error measurement and let support know.

Finally got some time to mess with this. I cut channels .1, .15, .2, and .3" deep into this piece. All were measured to be accurate, within .01" (and equally often high and low).

, but the gouge in my wasteboard is more like .03". Any ideas?

jg

If the machine is cutting the correct depth and you’re going that far into the wasteboard, could just be the measurement of your stock. Maybe your clamp pressure is uneven?

I thought that maybe it was stock measurement, but I’m using the same digital calipers to measure that that I’m using for the test above. The clamp is a possibility. Would that be enough to make that big of a difference?

Is the cut into the wasteboard consistent across the board?

Yes, it seems to be

Sounds like the smart clamp offset need a make-over?

That’s what I originally thought, but he’s getting a good cut depth. If the machine is cutting the correct depth, and your stock is the correct thickness, you wouldn’t get a .03" over cut. Can you try measuring the stock thickness after you clamp? Measure right by the “smart” clamp with the depth part of the calipers.
How long have you had the Carvey?