Cutting AMP the same on 18g as .250

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subisquared
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Cutting AMP the same on 18g as .250

Post by subisquared » Tue Aug 06, 2019 9:12 pm

I got a question... Ive been using my wright cnc plasma table now for about a year now. i have a powermax45 plasma cutter. Should I be turning down my amp dial on my plasma unit? i just leave it at 45. my torch hight i rarely adjust, most of the time its set at 88.
Turn down the plasma dial to lets say 30 then turn up the torch hight? i think the hypertherm book says i should be around 120volt on my torch hight on 18g. it lifts so high if i set my torch hight at that it wont even cut


id just like some input.. leave it and keep doing what im doing???

subisquared
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Tue Aug 06, 2019 9:32 pm

oh yeah, I'm running air flow on my plasma cutter at the 2 green lights.. i believe its 110psi?

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djreiswig
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Re: Cutting AMP the same on 18g as .250

Post by djreiswig » Tue Aug 06, 2019 10:18 pm

Are you adjusting your feedrate up when you cut thinner material? You should be able to leave your amps at 45, and follow the Hypertherm cut charts in the manual for the volts. Try some straight line test cuts with THC off. Start by verifying the correct cut height and then see what the volts read when you cut a straight line at the correct speed. The volts need to be whatever it takes to maintain the correct cut height. It may or may not match the cut charts.
If you slow the feedrate the volts will climb as the metal melts away making a wider kerf. As the volts climb, the thc will adjust down to try and lower the volts.
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Thu Aug 08, 2019 12:42 pm

Test cut this morning
1/4” steel
THC was disconnect
Voltage reading was average of 84volts on a 15” long cut
Plasma was set at 45 (all the way up)

Sheetcam settings for 1/4”
48ipm
Pierce hight .15”
Cut hight. .06”

The powermax 45 manual is saying I should be around 120.. so raise the cut hight up? Then i won’t be at the recommended .06” like the book and sheetcam.


By all means, I’ve figured out how to use it as it’s been, but never feel it’s been 100% dialed in.

subisquared
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Thu Aug 08, 2019 12:49 pm

Just changed it to .15 cut hight, that raise the voltage upto 96. Now I know going higher and higher will make the cut width wider.
Gonna stop here until someone gives me some feedback. Thanks I appreciate the help

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Ironken
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Re: Cutting AMP the same on 18g as .250

Post by Ironken » Thu Aug 08, 2019 1:33 pm

Personally, on my equipment, the Hypertherm chart is within a few volts of being correct when I perform straight line test cuts and I have edited the cut charts within Sheetcam and my JD2 MAD machine.

I don't know where on your machine or how you use the voltage info you gather from your test cuts as I'm not familiar with your setup.

Here's how I do test cuts.......

Use the Hyp cut chart to determine the speed for the material and consumables you are using (bear in mind with finecut consumables the amperage may not be 45 on thinner material).

Say Im testing 1/4" mild steel. Hyp says 48ipm and 130v with a pierce height of .150 and a cut height of .060. I will disable thc, set the feed at 48ipm, cut height at .060. I will dry run (no torch) and allow the machine to touch off and begin movement then pause the "cut". I will slide .060 of feeler gauges between the torch and plate to verify it is running at .060.

Now I reset the program and enable the torch disable the THC and let it pierce and cut at the recommended settings. Observe the VOLTAGE during this cut once the arc has time to stabilize. It may fluctuate some, I just go with an average and that will now be your corrected voltage. You would enter this value wherever your mechine has this info or into Sheetcam.

For whatever reason (grounding, sun spots, Russia, gremlins) the voltage listed in the Hyp charts may not be exactly correct for your machine and you may need to play with it.

Also.....NEVER coil your leads, especially the work lead. It can and will make your THC go ape shit.....I speak from experience and yes it can make your torch try to cut in mid air.

As a side note, the 2 green lights do not indicate air pressure on your 45xp. You can get into the menu and see the air pressure display. There should be no reason to adjust your cut pressure. Just make sure you are getting sufficient air pressure at the inlet of your machine.

You may know all of this crap but, I wanted to make sure we were on the same page so maybe one of us can get you making sparks.
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Re: Cutting AMP the same on 18g as .250

Post by djreiswig » Thu Aug 08, 2019 3:17 pm

What is your voltage divider set at? Your control may be looking for a different ratio.
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Thu Aug 08, 2019 7:15 pm

I’m using a Proma THC unit.

Here’s how I’m getting my readings.
-Proma thc is on, plugged into the cpc port on my hyp45 but disconnected from my wrightcnc built control unit.
-my test file is 15” long, just my normal settings in sheetcam. (Settings I posted above in my last post)
-using mach3 to cut the file. (Clicking torch hight button on otherwise if it’s off, it will just go down turn on and sit in one spot) It will go down and touch the metal then lift to cut hight.

I set my cut hight to .020 my Proma unit will show 109volts on a cut-straight line while it’s live.

I gotta read and reread the info you guys have posted up. I feel you guys are hot on the trail of my issues. Sounds like it’s not at the correct hight while cutting to get the correct voltage. Just need to figure out how to adjust it.

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Re: Cutting AMP the same on 18g as .250

Post by djreiswig » Thu Aug 08, 2019 9:27 pm

Not familiar with the Proma THC, or the 45xp but my 65 has a voltage divider board that you can select different ratios. I think 50:1 is the default, so that may not correspond with what your THC is looking for. Or does the Proma use raw volts?
It doesn't really matter what the volts are as long as you determine what gives you a consistent correct cut height. The volts can be different depending on how your system is designed. All that matters is maintaining the correct cut height. As you have discovered, the volt reading will go up as the arc gap increases. If your cut height is too high, lower your volt setting. That will cause the torch to move down. Pretty simple once you figure it out.

Reread your post. After touchoff your torch should go to pierce height not cut height. After the pierce it should lower to cut height. It's hard on consumables to pierce at cut height.
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Re: Cutting AMP the same on 18g as .250

Post by Ironken » Fri Aug 09, 2019 8:18 am

Again, not understanding the Proma THC......I can only suggest that .020 is too small of a cut height unless you are cutting SS. As djreiswig mentioned, be sure that the torch goes to pierce height for the set pierce delay time then moves to cut height and proceeds with the cut. I think you are saying that the THC is not active while you are making your test cuts, and that is the correct way to get your voltage reading from your test cuts as long as your torch is at the .060 recommended cut height during the test cut.
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Re: Cutting AMP the same on 18g as .250

Post by acourtjester » Fri Aug 09, 2019 10:58 am

I had 2 Proma THC units (had both replaced by seller) the problem I had was what you are stating unable to cut reliably. This also was using different plasma units. the Proma seem to work better using the raw voltage input, but not as good as other brands of THC. I have had reliably cutting using a CandCNC DTHC-IV and a Price AVHC 10. The thing to understand is the start is to be a pierce height (0.160 about) and then pierce happens, then delay if needed, then torch drops to cut height (0.060). Then start the cutting operation after a short delay the THC takes control until the end of the cutting operation to maintain the correct cut height. The cut height is set by the voltage on the THC and the THC is to maintain the height buy moving the torch up and down to track that voltage. There is also a tolerance set on the THC as to how far it varies from the set voltage before it move. If this it to small it will bob up/down, to large and the cut may be irregular.
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Re: Cutting AMP the same on 18g as .250

Post by robertspark » Fri Aug 09, 2019 11:27 am

The proma is very slow to respond (i.e. if you are cutting fast.... it wont keep up)

this is due to the use of mechanical relays inside of it to provide THC UP and THC DN signals..... plus it has a 2Volt (minimum) deadband / hysteresis where it will not correct

(last page)
https://www.proma-elektronika.com/downl ... 150_en.pdf

suggest sell it on and pick up something else recommended by the others previous.

the factory default is 8V
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subisquared
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Thu Aug 15, 2019 5:04 pm

I'm still playing around with dialing this in. Just wanted to update you guys and let you know I'm still here. Not disappearing after 1 question.
Ill have an update with info and what i find out in a few days.
I appreciate all the help so far!!

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Re: Cutting AMP the same on 18g as .250

Post by jimcolt » Mon Sep 02, 2019 2:17 pm

1. a 45 amp nozzle produces its best energy density when operated at 45 amps. The specs in the cut chart generally are dialed in at full nozzle amperage. At 45 amps you will get the widest dross free speed interval (from the point where "low speed dross" forms to the point where "high speed dross" forms. Run the nozzle lower amperage and the DFI gets narrower, run at higher amps and the nozzle will wear very rapidly. The best performance in terms of cut quality and consumable parts life is right at the book specs for pierce height, pierce delay, cut amperage, cut height and cut speed.
2. Arc voltage listed in the Hypertherm cut charts is developed on lab grade equipment. The voltages are correct when cutting at exactly book specs with new consumables. If you are cutting at book specs with new consumables and your height control reads 30 volts different....then you probably have a height control that is not calibrated correctly. This doesn't really matter (the voltage) as long as the voltage you are setting is achieving and maintaining the physical cut height listed in the Hypertherm cut charts.
3. As the consumables (especially the electrode) wear, you must increase the arc voltage in order to maintain the cut height. Typically, near the end of the useable life (a pit depth of .060") of a Powermax electrode you will need to set the height control preset voltage about 12 to 15 volts higher than with a new electrode in order to maintain the correct cut height (best cut quality). Better height control systems do this automatically at the beginning of each cut cycle by sampling the arc voltage at a known height and speed (commonly called voltage sampling). Plasma operators that use voltage sampling style height controls generally have no issues with height related cut quality issues. Voltage sampling has been used on almost all high end industrial plasma systems for over 20 years. There are a few manufacturers in the light industrial market that use voltage sampling.....there should be more! Jim Colt

subisquared
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Re: Cutting AMP the same on 18g as .250

Post by subisquared » Sun Sep 15, 2019 9:37 pm

Thanks jim! All your info is great, I think you nailed it in paragraph 2. I am almost 30 volts lower than the book.
Just leave it? I’m getting great cuts and minimum dross. Or what do I adjust to get those numbers up in voltage without the THC lifting the head up..

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