CNC Plasma Cutter

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CNC Plasma Cutter

Post by DRobs86 » Wed Aug 26, 2015 11:55 pm

At some point down the road I would like to build a CNC plasma cutter. I know very little about plasma cutting to be honest. Just what capability does a 500 to 700 dollar plasma machine have? Harbor freight has a $650 machine from Chicago Welding that they claim can do 5/8" steel at 5IPM. How optimistic is that rating? Is there a rule of thumb in plasma cutting on the width to feedrate relationship? For instance, if it could cut 5/8" at 5 IPM could I cut 5/16" at 10 IPM? 1/16" at 50 IPM?

I know plasma requires some special CAM techniques. The Shapeoko wiki lists a few free programs that claim to be for laser or plasma machines. Has anyone ever used these? Are they any good? Building the machine would be expensive enough for me, so I'd hate to be into a CAM program for another several hundred plus dollars.

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Re: CNC Plasma Cutter

Post by DonaldE » Wed Mar 16, 2016 5:48 am

yeah i have used this but i was not satisfied with the end result, but i recommend you to build a machine i know it would be a bit expensive but it will you you an ease in long term

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Re: CNC Plasma Cutter

Post by Gamble » Wed Mar 16, 2016 4:07 pm

Everyone says building one is the best way to go. I didn't have the time and I got a good deal on mine so I just bought it
As far as plasma cutters go. There is a wide range.
The harbor freight plasma is actually pretty damn good.

Cheaper plasma cutters do not have blowback start. This means you have to touch the torch to the work, hit the trigger and lift off. Burns up consumables quick. But it also makes for a less expensive machine. For light hand use it's ok. I saw one person use it on a cnc plasma. Keep in mine for this you will need THC/zaxis or height control. Everyone calls it something different.

Other plasma cutters use HF High frequency start. Again for hand use they are ok. Not my preference at all. But HF will will bug out other electronics so I would steer clear away from ones that use HF like eastwood.

Generally what you will find is anything plasma the best of the best is hypertherm. Made in USA. Great support and great power. However a little pricey but for good reason. I started with a cheaper plasma. It worked great for about 1 year. Got some good cuts. Then upgraded to a 60amp cutter and that was also great. Still have it. but the gas solenoid crapped out. Finally bought a hypertherm and haven't looked back.

As far as speed on cuts go. It depends on the plasma and the table. My table is limited to only 150ipm. With newsoftware and upgrades ($3300) i can go up to 200ipm
My current cut speed is 120ipm. I'll be honest it's an ok speed. Sometimes I cut at 70ipm or 45ipm are painfully slow. Like do I really have to sit here for 3 minutes to cut that part lol :D

So as I cut right now (and settings vary a lot from person to person)
14g mild steel I cut at 120ipm
.090 aluminum = 120ipm
3/16 steel = 75ipm
3/8 steel = 25ipm

On the 60 amp cutter I did 1/2" steel at 25ipm with great results.

Keep in mind you will spend a lot of money on consumables. Cheaper plasma will burn through consumables quicker. Buy a good air compressor and air filter. lol I say this and I've had my cnc plasma table on a 29 gallon harbor freight compressor. Get a nice little laptop. Some software will set you back money.
Oh and the biggest expense is material. Keep that in mind. Small the machine the more it costs for material to have to pay someone to cut it to size. My friend buys a full 4'x8' sheet for the same price as I pay for two pieces of 2'x'2. So if you build one you build something that can handle a 4x8 or 5x10 sheet. It will save you money in the long run.
It's not uncommon for me to burn through $500 of material in a month on my busy months and I don't use it full time
CNC Plasma Table
Tig, Mig Welders

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Re: CNC Plasma Cutter

Post by DRobs86 » Sat Mar 19, 2016 3:11 am

Great info guys! Thanks.

I am curious about the results given by a plasma cutter. I understand that it wont be as good as a laser, but I talked to a guy who runs a CNC plasma cutter in a small industrial concern that cuts sheet that doesnt require any close fitment and he really talked lowly of its capabilities. I think I asked him if he could hold 0.01 inch with it and he was really hesitant to say that it would. He offered me the opportunity to come down, give him some files, and try some things out for a pretty low hourly rate, but said he just didnt think it would do it. I didnt get into the model he had or any specifications on his machine. I also asked him how it would run on aluminum and stainless and he talked like the stainless would blue terribly and that aluminum would not cut well.

Is this the general case or was he just running a bad machine?

Talk to me more about that harbor freight machine... Does it require touch off?

Also, having never actually plasma cut anything, I am curious what precautions need to be taken to protect rails and drive components. It looks like its easy to destroy your machine if you dont plan ahead.

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