making sure this is the rite plasma cutter for me

[ziptie007]

Ok I have been lurking on here for a while and I can say there is great info and some good guys on here. So now to what i'm looking to do. I'm going to be cutting 1/2 mild steel 80% of the time and thinner stuff the other 20% of the time. I will NEVER cut past 1/2 mild steel, I would also like to be able to use the plasma cutter for manual cutting so a hand style is a must. I'll worry about the table setup as money comes in so expect more posts from me. lol

I'm looking at the hypertherm powermax 600 or 1000 ????
or the thermal dynamics cutmaster 52 or 82 ????

Any recomendations from some of the experianced guys on here would help me out a ton.

[Torchhead]

If you want to cut 1/2" with minimal bevel and slag you need to think bigger. You can only pierce about 50% of the rated cut depth and the duty cycle will make you end up waiting more than you cut!..

The 1000 is a 60A unit and to do quality cuts (versus just hacking your way through the steel) an 80 to 100 Amp unit will give you straighter cut sides and better duty cycle. If you 80/20 mix was reversed (lots more thin than thick) the smaller unist would be fine.

TOM CAUDLE
www.CandCNC.com

[ziptie007]

Tom,

So your saying the hypertherm model 1250 then which is a 80 amp unit? The 1250's price is about the max in my budget has in it so i guess that could be the one i will get. Also with the 1250 what would be about the thinest mild steel I could cut?

Also with the thermal dynamics units the 151 has a 82/94 amp rating. I guess that could be another option. But from my reading it does seem like the hypertherm's on here are more popular.

Also one more question for anyone. How decent is a 3/8 hole going to look when I cut it on this 1/2 plate??? A guy I know just cuts out the flange with no holes then uses a drill press to do the bolt holes. I was thinking because that might be either because the cut quality wasnt there or because his plasma cutter wasnt strong enough.

Sorry for the newbie questions but thats what I am.


But on the brighter side I'm going to pick up a used plasma cam unit this weekend... yaaaa 4 me

[jimcolt]

The Hypertherm Powermax 1250 can use the FineCut consumables to produce the best cut quality on thin materials....you can cut 26 gauge or thinner if your machine can control the height and maintain adequate speeds.

You ask about cutting 3/8" holes in 1/2" plate. Using an air plasma and a hobby class cutting machine (PlasmaCam), here's what to expect for holes:

1. Height control is critical....you must pierce at 1.5 to 2 times the recomended cut height, then the THC must index down to the cut height while it is still on the lead in kerf. If the PlasmaCam is the newer DHC model and it is set up correctly...it can do this. If the height is not maintained correctly...the hole will not be round on the bottom.
2. Cut speed....rule of thumb: holes under 1" diameter should be cut at approx 60% of the speed that the rest of the part is cut at. This is to minimize taper that is caused by the lag in the arc angle.....and this slower speed will produce some easy to remove, low speed dross. The PlasmaCam software cannot change speeds automatically on different cut features...this will have to be done manually.
3.hole design.....and adequate lead in to allow the height control to pierce at pierce height...then index to cut height as listed above, with an overburn (stay on the hole radius past 360 degrees)....and you will get best hole quality. With the Plasma Cam software you do not have a lot of control of the design of holes.

If everything is done as listed above...you could get a hole that is round ....but expect about .100" smaller diameter on the bottom.....or a tapered hole. Since you will be using an air plasma...the cut edges of the hole will have a nitride hardening, caused by the 80% nitrogen content in the air that is used as the plasma gas...so you will rapidly wear drills or reamers if you intend to drill these plasma cut holes to improve their quality.

You can make very nice, small holes with industrial (read expensive) high definition or high performance oxygen plasma systems mounted on precision cutting machines....I have a cut sample on my desk of a 5/16" plasma cut hole in 3/8" steel that was tapped with a 3/8"-16 tap. Don't expect that kind of quality with an air plasma on an entry level machine!

As your hole sizes get bigger...the quality will improve. On 1/2" plate you can get pretty good hole quality with 5/8" and 3/4" diameters.

Jim Colt

[ziptie007]

thanx for all that info. I'm definetly going to have a nice learning curve ahead. But I'm pretty excited. Like anything new it seems a little over whelming at first but after some seat time its not that bad. Plus I got all you nice guys on here at cnc zone to help me out. Great info and thanx again. I'm thinking in the next few weeks that I'll have a couple of my 1st pieces cut.

The plasma cam unit I'm getting does not have the THC on it. But as I get more experienced I'm going to either get a newer plasma cam or torchmate set up. for now the price is rite and I have to get some jig plates cut.

[jimcolt]

Ziptie,

You must be getting one of the older 98-Z model PlasmaCam's......I have owned one for over 7 years. It actually has a THC....it's just not an arc voltage type. It has the ability to locate the top of the plate using some spring loaded limit switches....then it retracts to an operator set pierce height....then once the pierce is complete it does a controlled "drag" on the plate much like drag cutting by hand. Once you master it...it works pretty well! I have cut a lot of material on tat machine.

Jim Colt

[ziptie007]

Jim,

Glad to hear you have some good experience with that table. I'll be sure to keep your user name jotted down if I have some questions for ya. LOL. I do have another one for now. The thinnest gauge I will be cutting is 16g, do you have any ideas on what I should set the 1250 plasma cutter at? Also does the psi from the aircompressor change when cutting different thicknesses and material???

[Normsthename]

The thinnest gauge I will be cutting is 16g, do you have any ideas on what I should set the 1250 plasma cutter at?

I cut 16swg 95% of the time, mainly Stainless Steel.
I use the recommended Hypertherm cut speed of 3810mm (150") / min using finecut consumables and the amperage set at 40 amps.

As Jimcolt said above you need to cut the holes slower, but on my machine I have the acceleration set low (Heavy Gantry) so it never gets upto speed on small holes and it cuts them very well.
The smallest hole I cut in 16swg Stainless Steel is 5.5mm (7/32") and it comes out nice and round

Andy

[ziptie007]

I'm sure when I get the machine all setup I'll spend some time and just practice cutting 3/8 holes in the 1/2 sheet and see what settings look the best. The one flange I plan on cutting I'd a t4 turbo inlet flange and that only has 4x 3/8 bolt holes. But the small block ford header flange has 8x 3/8 holes in it. That may prove to be a littler or atleast time consuming. I'm glad to get some good info on here with mr being so new. Thanx guys!!!

[Normsthename]

Initially I would undercut the 3/8" holes and then open them out.
I would cut them at 11/32"
Once you have seen what the machine is capable of, perhaps you will then decide to cut them full size and not bother with the drilling process.

I do this on a couple of important holes in my Stainless Steel parts, and it is very easy to open the holes out on a drill press

Andy

[Big John T]

ziptie007,
I own a Hypertherm 1250 and would not get any smaller machine for 1/2". I also would not buy any other brand for a low end plasma table. It comes ready for CNC you just need the cable for the torch start to your control. I've had mine for a few years and love it.

John

[ziptie007]

john,

Thanx for that info. It looks like I definetly have a winner then. I'm just waiting for my incomevtax checkbto come in. It was suppose to be in by today but no check. Hummm. At least I have the money for the table. But then again one item needs the other. I do have a question for ya. Where do I get the cable for the trigger? Is it something I have to buy or can I make it? Thanx