# Bended straight cuts

Today I cut this part. The outcome did not match my expectations: One of those long lines should be straight and the part itself should not be tilted. Any idea, what went wrong?

CAM: Kiri:Moto worked fine for other machines today…

tilting like that is almost always the result of the chain skipping on one side .

curves are the natural way that errors show up on the maslow, but since you have other cuts that are straight, you had the machine suitably calibrated at one point, but with the chain lengths not being correct, having it result in extra curves is to be expected.

I expected someting like this. It’s still strange, that all passes followed the same path (4 cycles with a step down of 4mm).

Unless you were having skips happen during the cut, all movements after the initial skip will have the same error in placement.

Think of it in terms of the math used, this is not the actual match just super simplified.

The system wants to goto position A. The system knows that to determine what position it is at it multiplies what link motor 1 is on by what link motor 2 is on to get the X, and divides to get the Y.

Your system believes it is on chain 4 and 3, giving it a position of 12,1.3 or A. In reality it is on chains 5 and 3, meaning its position is actually 15,1.6 C.

It wants to go to position B which is 20,1.25 so it tries to move to 5,4, releasing each chain by 1 link. instead it is on chain 6,4 resulting in it moving to 24,1.5 D.

In this example it should have moved from 12,1.3 to 20,1.5, instead it actually moved from 15,1.6 to 24,1.5.

So when it comes around the 4th time to make that move from position A to B it will again find itself starting at C and moving to D.

If at some point between the 1st and 4th path another chain skips the positioning of the system will be offset by that skip from then on, compounding, or correcting (if it skips back) the path of the cuts.

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Thanks @digitydogs for your explanations. I think I got it.
In this case the skip happened before that cut. And during the cut no more skips occurred.
I could reset the chain lenght and I’m good to go. Right?

Yep reset your chains and youll be back to proper cuts

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