Changing material thickness

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Ade
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Changing material thickness

Post by Ade »

Hi Everyone! I am doing a project with my son to help him add to his wooden track collection and get introduced to the cnc. I made a curved track but when I go back to change the material thickness (or any kind of change for that matter), it throws the tool path off for the track grooves. I assume you can change the material thickness on the fly either from the design side or the tool path side (?) It only seems to be happening to this particular file. I can make changes to the straight tracks, recalculate the tool paths and everything is coming out fine. Can someone tell me what I am doing wrong? Thanks in advance! Attached is the file.
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Wood Tracks.crv
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Ade
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Re: Changing material thickness

Post by Ade »

Okay, I just tried opening this file up in version 9 (instead of 9.5), and I can make changes all day long and everything holds just fine. Maybe a bug in the new version?

garylmast
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Re: Changing material thickness

Post by garylmast »

I don't know about V-Carve and modeling, but how I modeled in Aspire, was I made two components, the base (add) and the tracks (substract). You then can adjust the height on either component.

Gary
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adze_cnc
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Re: Changing material thickness

Post by adze_cnc »

If you change the curves from beziers to arcs it works just fine in 9.509.

It could be the straight lines of the curves are something like 0.2489 inches which is less than twice the bit diameter.

Ade
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Re: Changing material thickness

Post by Ade »

The problem is that if I bring this file into 9.5 just as it is, it works just fine. It's only when I go to change something about this file in 9.5 like material thickness, or Z height settings, or even the file name itself that the pocketing goes weird. I didn't have this issue in version 9 at all. It ran whether it was arcs or beziers and I could change anything I wanted to. There must be something I'm not seeing here...

ger21
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Re: Changing material thickness

Post by ger21 »

Send the file to Vectric...
Gerry - http://www.thecncwoodworker.com

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adze_cnc
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Re: Changing material thickness

Post by adze_cnc »

...and mention my comment above so they have more information....

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Mark
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Re: Changing material thickness

Post by Mark »

Hello Ade.

I realize that this particular toolpath may have worked in V9.0 and does not in V9.5,
but it just as easily be the other way around.

As adze_cnc hinted at in his reply, it is a matter of mathematical tolerancing that is the cause of the problem.

With the pocket toolpath in your file, you are attempting toolpath pocket inside a closed vector.
With a 0.25" tool. It is not always easy to measure the exact points between two curves,
but if you measure the top end points of both vectors that you have selected for your pockets,
you will see that one is 0.249" and the other 0.2499" In other words, both smaller than the diameter of the
tool that you wish to go inside these vectors.
If you think about it, this should not work at all.
We do make some attempts to allow pocket toolpaths to work, if we can reasonably assume that the programmer
Is trying to slot with the tool, however there have to be limits to this, otherwise, toolpaths can just be wrong.

Perhaps the best way of machining this toolpath , would be to just draw a centerline vector down the center
of where you currently have your closed vectors and instead of using a pocket toolpath, using a profile toolpath (on the single open vector).

Alternatively, if using a pocket toolpath, you need to specify a tool that will fully fit inside the selection.
If you edit the diameter of your tool to be 0.245" that should work fine.

I hope that this helps.

Cheers,

Mark.

Ade
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Re: Changing material thickness

Post by Ade »

Thanks, Mark! That really helped!

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adze_cnc
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Re: Changing material thickness

Post by adze_cnc »

If you lack a smaller cutter (or can't use one) telling the software that the cutter's diameter is 0.248" (say) works well too. Sure the size of the pocket is going to be off by 4/1,000 of an inch but usually the diameter of a human hair is an acceptable error size.

Steven

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