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Pitting on Underside of holes

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Charlie10
Posts: 3
Joined: Tue Apr 24, 2018 9:12 am

Pitting on Underside of holes

Postby Charlie10 » Tue Apr 24, 2018 10:01 am

Hole quality is one of the main issues I've been fighting on our new plasma table. The biggest problem is that I keep getting these pits or dimples on the underside of holes. I've gotten it to be less frequent/ pronounced by experimenting with different entry and exit methods, but I haven't gotten rid of it completely. Not very visually appealing.
Holes have also been cutting about .025'' undersize, but not profiles. I've addressed that at the moment by just programming the holes that much larger.
I'm running a Shopsabre Sidekick with a Hypertherm 45XP and fine cut consumables. Enroute 6 toolpathing. Cutting mostly 11 ga steel, .08 and .06 aluminum.
Any help solving this would be appreciated.
plas holes pic.jpg

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weldguy
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Re: Pitting on Underside of holes

Postby weldguy » Tue Apr 24, 2018 10:10 am

What style of lead in are you using?

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SeanP
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Re: Pitting on Underside of holes

Postby SeanP » Tue Apr 24, 2018 10:31 am

It's when the slug drops out and the arc is looking for metal, it cant be stopped altogether with leadout/in, the only real way I have found is to have the torch turn off before it reaches the end of the cut, that's possible with sheetcam, sorry not sure about your software.
Powermax 45 with Duramax torch.
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Charlie10
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Joined: Tue Apr 24, 2018 9:12 am

Re: Pitting on Underside of holes

Postby Charlie10 » Tue Apr 24, 2018 12:08 pm

The best luck I've had is arcing in and out on a radius slightly smaller than that of the hole. I've read that you should not have a lead-out on holes and use an overburn, but the pitting has been the worst when I've tried that way.
Thanks. I'm not sure if its possible to turn the torch off before, or how to do so if it is. But I'll look into it.

SSCNC
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Joined: Wed Oct 26, 2011 9:09 am

Re: Pitting on Underside of holes

Postby SSCNC » Wed Apr 25, 2018 8:34 am

Contact our support team, we will be glad to work with you on improving your results.

motoguy
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Location: Central MO, USA

Re: Pitting on Underside of holes

Postby motoguy » Wed Apr 25, 2018 5:13 pm

I used to arc in/out on holes as well. I found they look much better with perpendicular lead in, no lead out, just a slight overcut (depending on thickness, something like .06 for 3/16), and disable the torch before end of cut (I disable .03 when I have a .06 overcut).
Bulltear 6x12 w/ Proton Z axis & watertable
CommandCNC/Linux w/ Ohmic & HyT options
Hypertherm Powermax 85 w/ machine torch
Solidworks, Coreldraw X7, Inkscape, Sheetcam

FazQuaz
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Joined: Tue Apr 18, 2017 11:14 am

Re: Pitting on Underside of holes

Postby FazQuaz » Wed Apr 25, 2018 11:39 pm

Motoguy,
How are you disabling the torch before the end of the cut as mentioned above?

CGT80
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Joined: Tue Sep 26, 2017 12:25 am

Re: Pitting on Underside of holes

Postby CGT80 » Thu Apr 26, 2018 12:40 am

Tag, as I have the same problem and also use fine cut and sheetcam.

ScottF
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Joined: Wed Nov 29, 2017 10:48 pm
Location: Colorado

Re: Pitting on Underside of holes

Postby ScottF » Thu Apr 26, 2018 8:20 am

In WinCNC you can edit the early off for the torch. I have done this and have been pleased with the results.
I don't have all the answers but I do have a lot of opinions....


ShopSabre Sidekick 8 with water table
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motoguy
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Re: Pitting on Underside of holes

Postby motoguy » Thu Apr 26, 2018 8:43 am

FazQuaz wrote:Motoguy,
How are you disabling the torch before the end of the cut as mentioned above?


With CommandCNC (Linux) I create a rule with the M62 P2 (Torch off before end) code. Then I apply it just like any other cut rule.
Bulltear 6x12 w/ Proton Z axis & watertable
CommandCNC/Linux w/ Ohmic & HyT options
Hypertherm Powermax 85 w/ machine torch
Solidworks, Coreldraw X7, Inkscape, Sheetcam

Charlie10
Posts: 3
Joined: Tue Apr 24, 2018 9:12 am

Re: Pitting on Underside of holes

Postby Charlie10 » Thu May 03, 2018 1:55 pm

plas hole test.jpg
An update on my results and findings. I called the guys at Shopsabre, who have been helpful any time I've had questions. The gentleman there directed me to the early torch-off setting and increased the auto-slow for arcs setting to slow my feed on holes. Turning the torch off early definitely made the difference. On all the lead-in/ lead-out variations I tried I now get practically no pitting. Although I've still had the best results arcing in and making a slight arc out. If I stay right on the hole radius on exit as has been suggested, I still get a slight mark on the edge. The slow for arcs setting is a mixed bag because it made my holes a little more true to size, but it also slows for arcs on the profile of the part. Obviously that causes noticeably more dross and increases run time. That seems like a shortcoming of WinCNC, that you can't slow the feed for only holes. Much happier with my results though, as you can see on the test piece.

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