little circles

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martyop
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25 Sep 2012 23:24 #24623 by martyop

little circles was created by martyop

I am milling 5 mm circles and 2.5 mm pockets about 1 mm into polycarbonate with a taig mill and EMC2. I drew the part in cambam and wrote the gcode out from there. The cutter is 0.8 mm, spinning fast and it doesn't look like it s deflecting. I'm feeding very very slowly, 10 mm/minute.
The little circles look sort of like lemons tilted so the ends are at 30 and 210 degrees.

What's up with that?
Thanks,
Marty

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andypugh
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25 Sep 2012 23:32 #24624 by andypugh

Replied by andypugh on topic Re:little circles

martyop wrote:

The little circles look sort of like lemons tilted so the ends are at 30 and 210 degrees.

Is it possibly a backlash problem?
I assume they don't look like lemons on the Axis preview?

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BigJohnT
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26 Sep 2012 10:33 - 26 Sep 2012 10:36 #24633 by BigJohnT

Replied by BigJohnT on topic Re:little circles

Can you attach your G code and a close up photo of the hole?

Slow feed in plastics usually will just melt the plastic and not cut cleanly. I would suggest a larger single flute end mill for the job.

John

Last edit: 26 Sep 2012 10:36 by BigJohnT.

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martyop
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01 Oct 2012 20:52 #24833 by martyop

Replied by martyop on topic Re:little circles

Your assumption is correct. Maybe backlash is the problem.
Thanks,
Marty

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andypugh
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01 Oct 2012 21:01 #24834 by andypugh

Replied by andypugh on topic Re:little circles

martyop wrote:

Your assumption is correct. Maybe backlash is the problem.

Does the mill use ballscrews or ordinarily leadscrews?
I think that some folk have found that there is a big improvement to me had with the Taig mills by paying attention to the thrust bearings.

Backlash compensation might help, but is rarely an ideal or complete solution.
www.linuxcnc.org/docs/2.4/html/config_in...b:%5BAXIS%5D-section
Sections BACKLASH and COMP_FILE

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martyop
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01 Oct 2012 21:01 #24835 by martyop

Replied by martyop on topic Re:little circles

( Pocket1 )
G17
M3 S1000
G0 X0.19896 Y-0.0672
G0 Z0.1
G1 F10.0 Z-0.4
G2 F50.0 X-0.105 Y-0.18187 I-0.19896 J0.0672
G2 X-0.19896 Y-0.0672 I0.105 J0.18187
G3 X-0.22427 Y0.0 I-0.98531 J-0.3328
G3 X-0.19896 Y0.0672 I-0.96 J0.4
G2 X-0.105 Y0.18187 I0.19896 J-0.0672
G2 X0.19896 Y0.0672 I0.105 J-0.18187
G3 X0.22427 Y0.0 I0.98531 J0.3328
G3 X0.19896 Y-0.0672 I0.96 J-0.4
G1 F10.0 X0.50213 Y-0.1696
G2 F50.0 X-0.265 Y-0.45899 I-0.50213 J0.1696
G2 X-0.50213 Y-0.1696 I0.265 J0.45899
G3 X-0.58561 Y0.0 I-0.68214 J-0.2304
G3 X-0.50213 Y0.1696 I-0.59867 J0.4
G2 X-0.265 Y0.45899 I0.50213 J-0.1696
G2 X0.50213 Y0.1696 I0.265 J-0.45899
G3 X0.58561 Y0.0 I0.68214 J0.2304
G3 X0.50213 Y-0.1696 I0.59867 J-0.4
G1 F10.0 X0.8053 Y-0.272
G2 F50.0 X-0.425 Y-0.73612 I-0.8053 J0.272
G2 X-0.8053 Y-0.272 I0.425 J0.73612
G3 X-1.18427 Y0.0 I-0.37897 J-0.128
G1 X-1.65
G1 X-1.18427
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G2 X-0.425 Y0.73612 I0.8053 J-0.272
G2 X0.8053 Y0.272 I0.425 J-0.73612
G3 X1.18427 Y0.0 I0.37897 J0.128
G1 X1.64872
G1 X1.18427
G3 X0.8053 Y-0.272 I0.0 J-0.4
G0 Z1.0
G0 X0.19896 Y-0.0672
G0 Z-0.3
G1 F10.0 Z-0.8
G2 F50.0 X-0.105 Y-0.18187 I-0.19896 J0.0672
G2 X-0.19896 Y-0.0672 I0.105 J0.18187
G3 X-0.22427 Y0.0 I-0.98531 J-0.3328
G3 X-0.19896 Y0.0672 I-0.96 J0.4
G2 X-0.105 Y0.18187 I0.19896 J-0.0672
G2 X0.19896 Y0.0672 I0.105 J-0.18187
G3 X0.22427 Y0.0 I0.98531 J0.3328
G3 X0.19896 Y-0.0672 I0.96 J-0.4
G1 F10.0 X0.50213 Y-0.1696
G2 F50.0 X-0.265 Y-0.45899 I-0.50213 J0.1696
G2 X-0.50213 Y-0.1696 I0.265 J0.45899
G3 X-0.58561 Y0.0 I-0.68214 J-0.2304
G3 X-0.50213 Y0.1696 I-0.59867 J0.4
G2 X-0.265 Y0.45899 I0.50213 J-0.1696
G2 X0.50213 Y0.1696 I0.265 J-0.45899
G3 X0.58561 Y0.0 I0.68214 J0.2304
G3 X0.50213 Y-0.1696 I0.59867 J-0.4
G1 F10.0 X0.8053 Y-0.272
G2 F50.0 X-0.425 Y-0.73612 I-0.8053 J0.272
G2 X-0.8053 Y-0.272 I0.425 J0.73612
G3 X-1.18427 Y0.0 I-0.37897 J-0.128
G1 X-1.65
G1 X-1.18427
G3 X-0.8053 Y0.272 I0.0 J0.4
G2 X-0.425 Y0.73612 I0.8053 J-0.272
G2 X0.8053 Y0.272 I0.425 J-0.73612
G3 X1.18427 Y0.0 I0.37897 J0.128
G1 X1.64872
G1 X1.18427
G3 X0.8053 Y-0.272 I0.0 J-0.4
G0 Z1.0
G0 X0.19896 Y-0.0672
G0 Z-0.7
G1 F10.0 Z-1.2
G2 F50.0 X-0.105 Y-0.18187 I-0.19896 J0.0672
G2 X-0.19896 Y-0.0672 I0.105 J0.18187
G3 X-0.22427 Y0.0 I-0.98531 J-0.3328
G3 X-0.19896 Y0.0672 I-0.96 J0.4
G2 X-0.105 Y0.18187 I0.19896 J-0.0672
G2 X0.19896 Y0.0672 I0.105 J-0.18187
G3 X0.22427 Y0.0 I0.98531 J0.3328
G3 X0.19896 Y-0.0672 I0.96 J-0.4
G1 F10.0 X0.50213 Y-0.1696
G2 F50.0 X-0.265 Y-0.45899 I-0.50213 J0.1696
G2 X-0.50213 Y-0.1696 I0.265 J0.45899
G3 X-0.58561 Y0.0 I-0.68214 J-0.2304
G3 X-0.50213 Y0.1696 I-0.59867 J0.4
G2 X-0.265 Y0.45899 I0.50213 J-0.1696
G2 X0.50213 Y0.1696 I0.265 J-0.45899
G3 X0.58561 Y0.0 I0.68214 J0.2304
G3 X0.50213 Y-0.1696 I0.59867 J-0.4
G1 F10.0 X0.8053 Y-0.272
G2 F50.0 X-0.425 Y-0.73612 I-0.8053 J0.272
G2 X-0.8053 Y-0.272 I0.425 J0.73612
G3 X-1.18427 Y0.0 I-0.37897 J-0.128
G1 X-1.65
G1 X-1.18427
G3 X-0.8053 Y0.272 I0.0 J0.4
G2 X-0.425 Y0.73612 I0.8053 J-0.272
G2 X0.8053 Y0.272 I0.425 J-0.73612
G3 X1.18427 Y0.0 I0.37897 J0.128
G1 X1.64872
G1 X1.18427
G3 X0.8053 Y-0.272 I0.0 J-0.4
G0 Z1.0
G0 X0.19896 Y-0.0672
G0 Z-1.1
G1 F10.0 Z-1.3
G2 F50.0 X-0.105 Y-0.18187 I-0.19896 J0.0672
G2 X-0.19896 Y-0.0672 I0.105 J0.18187
G3 X-0.22427 Y0.0 I-0.98531 J-0.3328
G3 X-0.19896 Y0.0672 I-0.96 J0.4
G2 X-0.105 Y0.18187 I0.19896 J-0.0672
G2 X0.19896 Y0.0672 I0.105 J-0.18187
G3 X0.22427 Y0.0 I0.98531 J0.3328
G3 X0.19896 Y-0.0672 I0.96 J-0.4
G1 F10.0 X0.50213 Y-0.1696
G2 F50.0 X-0.265 Y-0.45899 I-0.50213 J0.1696
G2 X-0.50213 Y-0.1696 I0.265 J0.45899
G3 X-0.58561 Y0.0 I-0.68214 J-0.2304
G3 X-0.50213 Y0.1696 I-0.59867 J0.4
G2 X-0.265 Y0.45899 I0.50213 J-0.1696
G2 X0.50213 Y0.1696 I0.265 J-0.45899
G3 X0.58561 Y0.0 I0.68214 J0.2304
G3 X0.50213 Y-0.1696 I0.59867 J-0.4
G1 F10.0 X0.8053 Y-0.272
G2 F50.0 X-0.425 Y-0.73612 I-0.8053 J0.272
G2 X-0.8053 Y-0.272 I0.425 J0.73612
G3 X-1.18427 Y0.0 I-0.37897 J-0.128
G1 X-1.65
G1 X-1.18427
G3 X-0.8053 Y0.272 I0.0 J0.4
G2 X-0.425 Y0.73612 I0.8053 J-0.272
G2 X0.8053 Y0.272 I0.425 J-0.73612
G3 X1.18427 Y0.0 I0.37897 J0.128
G1 X1.64872
G1 X1.18427
G3 X0.8053 Y-0.272 I0.0 J-0.4
G0 Z1.0
G0 X0.19896 Y-0.0672
G0 Z-1.2
G1 F10.0 Z-1.5
G2 F50.0 X-0.105 Y-0.18187 I-0.19896 J0.0672
G2 X-0.19896 Y-0.0672 I0.105 J0.18187
G3 X-0.22427 Y0.0 I-0.98531 J-0.3328
G3 X-0.19896 Y0.0672 I-0.96 J0.4
G2 X-0.105 Y0.18187 I0.19896 J-0.0672
G2 X0.19896 Y0.0672 I0.105 J-0.18187
G3 X0.22427 Y0.0 I0.98531 J0.3328
G3 X0.19896 Y-0.0672 I0.96 J-0.4
G1 F10.0 X0.50213 Y-0.1696
G2 F50.0 X-0.265 Y-0.45899 I-0.50213 J0.1696
G2 X-0.50213 Y-0.1696 I0.265 J0.45899
G3 X-0.58561 Y0.0 I-0.68214 J-0.2304
G3 X-0.50213 Y0.1696 I-0.59867 J0.4
G2 X-0.265 Y0.45899 I0.50213 J-0.1696
G2 X0.50213 Y0.1696 I0.265 J-0.45899
G3 X0.58561 Y0.0 I0.68214 J0.2304
G3 X0.50213 Y-0.1696 I0.59867 J-0.4
G1 F10.0 X0.8053 Y-0.272
G2 F50.0 X-0.425 Y-0.73612 I-0.8053 J0.272
G2 X-0.8053 Y-0.272 I0.425 J0.73612
G3 X-1.18427 Y0.0 I-0.37897 J-0.128
G1 X-1.65
G1 X-1.18427
G3 X-0.8053 Y0.272 I0.0 J0.4
G2 X-0.425 Y0.73612 I0.8053 J-0.272
G2 X0.8053 Y0.272 I0.425 J-0.73612
G3 X1.18427 Y0.0 I0.37897 J0.128
G1 X1.64872
G1 X1.18427
G3 X0.8053 Y-0.272 I0.0 J-0.4

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martyop
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01 Oct 2012 21:11 #24836 by martyop

Replied by martyop on topic Re:little circles

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martyop
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01 Oct 2012 21:15 #24837 by martyop

Replied by martyop on topic Re:little circles

Ordinary lead screws. I'll check the backlash doc that you mentioned.
Are there ball screw kits for the Taig?

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btvpimill
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01 Oct 2012 22:37 #24843 by btvpimill

Replied by btvpimill on topic Re:little circles

Throwing in my 2 cents here. Looking at the picture of your part, looks like cutter deflection to me. Notice when you enter the little "holes" on either side, the part appears gouged on the bottom or the right side and the top on the left side? also the big center hole shows the same type stuff. This happens because at that point in the cut, the tool is trying to take a full cutter wide cut, so it bends away from the left cutter edge.

Backlash would show as flats on each reversal of a screw and it doesn't really look like that is the issue.

I suggest you go with Johns idea and use a bigger mill. Or get a finish pass in there if its not already. If it is, then it needs to be bigger.

You could reverse the direction of cut, it may help.

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BigJohnT
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01 Oct 2012 23:36 - 01 Oct 2012 23:39 #24846 by BigJohnT

Replied by BigJohnT on topic Re:little circles

You definitely have mechanical issues. In addition to that cambam is not generating circles but moving in and out of the pockets. Sometimes you have to draw a complete circle in your Cam software and tell it to cut that.

I assume that both programs are the same... btw it is much nicer to attach your G code to a message rather than include it in your message unless it is real short... makes reading easier not having to scroll a zillion miles to the top after scrolling to the bottom.

John

Last edit: 01 Oct 2012 23:39 by BigJohnT.

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