Plasma - decrease feedrate for cutting holes.

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rockcrawl

Plasma - decrease feedrate for cutting holes.

Post by rockcrawl »

Typically when cutting small holes with plasma the feedrate must be reduced to about 60% of the normal speed to improve cut quality. The THC should also be switched off to prevent the tip from diving due to the lower speed. It would be great to have an option to automatically reduce feedrate by a certain percentage when cutting holes under a certain size, and to send MACH THC on/off commands at the proper times.

The way I do it now is move all my holes to a different layer and use a separate operation for the holes.
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Les Newell
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Post by Les Newell »

To a certain extent this can be done in the post processor. Have a look at the MP1000-THC-scriber post. It probably does most of what you want.

Les
rockcrawl

Post by rockcrawl »

Great, can't wait to try it out. Thanks!
rockcrawl

Post by rockcrawl »

I ran a few tests and this seems to do the trick. Thanks again for the quick reply. I did find an error in the post, the following comment is incorrect or at least misleading:

Code: Select all

--Put your switch offset value here in MILLIMETRES
switchOffset = 1.5
With my units set to inches I have to enter this value in inches.

I also tried TNG for the first time. I cannot get lead-ins/outs and wiggle pierce to work, is that a limitation of an unlicensed version?
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Les Newell
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Post by Les Newell »

I'll fix the switch offset. it should be in millimetres.

Leadins/leadouts should work. Can yousend em a job file to look at.
rockcrawl

Post by rockcrawl »

Leadins/outs do work, I was using a newly configured tool and I had the length set to 0" :oops:

The MP1000-THC-scriber post file woks as expected for reducing feedrate on small arcs.

The THC on/off code is causing some problems. It inserts the thcon/thcoff command in the correct places, but it causes Mach to pause briefly for each command. This isn't really a problem for holes, but for a square where the offset toolpath generates small arcs on the corners, or any shape that is a combination of arcs and lines, it pauses twice at each corner. I think this is a limitation of Mach, stopping travel as it waits for the THC on/off macro to run. I'm using a one-line macro to use an M code to execute a button press, I don't know how to make it any simpler.

For now I've just left the thcon/thcoff commands nil. Has anyone been able to get this to work?
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Les Newell
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Post by Les Newell »

The THC on/off pause is a known problem in Mach. This is why I didn't really done much about it before.
albertstien3329

Post by albertstien3329 »

Hi, I go to open sheetcam and getting this message(This vcarve plugin has expired. You must install latest version to continue using it.) I tried updating, but it said no updates found. I am using windows 7 with sheetcam version 4.1.30 Any help greatly appreciated.
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Les Newell
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Post by Les Newell »

Is your clock set correctly? If your computer's clock is out you can get this message. If you don't use teh V carve plugin go to Options->plugin options->Vcarve2 and make sure 'Enabled' is turned off.
raniadoll

hello

Post by raniadoll »

I down loaded the PDF instruction book but it is confusing because it covers both milling and jet cutting and I only need the jet cutting part for plasma cnc and I am not sure which page to ignore and which is important.
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Les Newell
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Post by Les Newell »

Have a look at the training series from Arclight Dynamics http://arclightcnc.com/training.html. It starts about half way down the page.

By the way, it is better to start a new topic than try to re-use an old one. That way it is easier for people to search the archives.
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