Help - Zeroing Finish Pass on 3D Piece

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johnelle
Posts: 45
Joined: Thu May 25, 2017 7:23 pm
Model of CNC Machine: Shapeoko 3
Location: Groton MA, USA

Help - Zeroing Finish Pass on 3D Piece

Post by johnelle »

I just started the roughing pass on a 3d plaque that is going to mill away the first 1/3 of a 3/4 inch pine board. Now I am in a panic because my original zero point is sawdust and I am confused about whether I rezero the tool for the 2nd (finish) pass on the (rough) surface or do I have to reconstruct my original height? I suppose I can set a piece of scrap along side the zero since its the very lower left.

I know its a bit newbie but since this thing runs almost all day I am hoping somebody can save me before I ruin things.

Inchlaggan
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Joined: Thu Jun 04, 2015 3:59 pm
Model of CNC Machine: Stepcraft 420

Re: Help - Zeroing Finish Pass on 3D Piece

Post by Inchlaggan »

Scrap is fine, you can set Z zero ALONE anywhere on the bed. Replace the tool, jog X and Y over the scrap, jog Z down until it touches the surface, set Z zero- nothing else, then GOTO XYZ 0 and finish your plaque.
The other solution (too late if you have started the roughing cut) is to set Z zero on the bed when you created the toolpaths.

johnelle
Posts: 45
Joined: Thu May 25, 2017 7:23 pm
Model of CNC Machine: Shapeoko 3
Location: Groton MA, USA

Re: Help - Zeroing Finish Pass on 3D Piece

Post by johnelle »

Just to clarify. I have to Z zero to the original material height?

Inchlaggan
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Joined: Thu Jun 04, 2015 3:59 pm
Model of CNC Machine: Stepcraft 420

Re: Help - Zeroing Finish Pass on 3D Piece

Post by Inchlaggan »

Yes. A piece of the same stock will do. There may be an error as a result of the original stock not being an exact thickness over the entire surface, but it should be small.
This suggestion is on the basis that you have already begun the job and started the roughing cut.
If not, set Z zero to the bed before you create the toolpaths. Any variation in the stock thickness is dealt with on the roughing cut, but this is still not perfect.
VERY best practice is to mill the stock flat before the roughing cut, that is for perfectionists only!

4DThinker
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Re: Help - Zeroing Finish Pass on 3D Piece

Post by 4DThinker »

If you know the thickness you told VCarve your board was, then when zeroing out Z for your finish pass simply use the bed surface. Don't enter zero though. Use -(thickness).

4D

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FixitMike
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Re: Help - Zeroing Finish Pass on 3D Piece

Post by FixitMike »

4DThinker wrote:If you know the thickness you told VCarve your board was, then when zeroing out Z for your finish pass simply use the bed surface. Don't enter zero though. Use -(thickness). 4D
Be sure to enter a negative thickness! Otherwise your software will think Z0 is below the bed.
Good judgement comes from experience.
Experience comes from bad judgement.

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