I want to build a plasma cutter

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02 May 2013 09:12 #33508 by btvpimill
I am looking for suggestions for the cutter itself - torch, power supply, whatever else I need. I don't need to cut thick stuff 1/4" and under mostly. eventually I would like to add a rotary axis for cutting square tube.

Any suggestions?

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02 May 2013 18:56 - 02 May 2013 18:57 #33520 by BigJohnT
I use Hypertherm 1250, I'm not sure what the current models are but I'd go with Hypertherm. Some rig up the hand torch but if your going to be cutting much you want the machine torch so make sure the model you chose has that option. You also want a model that has arc ok output and torch start input.

Here is the plasma cutter table I built.

www.gnipsel.com/shop/plasma/plasma.xhtml

John
Last edit: 02 May 2013 18:57 by BigJohnT.

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02 May 2013 19:17 #33521 by btvpimill
Thanks John, Looked through hat you have on your plasma page. Is the water bed just for catching the slag, or do you under water cut?

I have a hand cutter that is about 15 years old - an old thermal dynamics model. I think it has been discontuined. :( it only has prolly 10 hours on it and the manual shows a machine head option. I checked with my welding supply and they were like good luck finding a machine head. Guess I will take a look and see if it has the I/O you are talking about.

Sure would be nice to use that instead of getting a new $2,000 or so cutter.

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02 May 2013 19:36 #33522 by BigJohnT
Lots of guys just rig up something to pull the switch on the hand torch. To be totally honest my first cuts had an assistant holding the trigger on the torch, so very crude indeed. If you have the I/O from the plasma that's great, if not you can work around that. I didn't even have a torch height control for the longest time and just carefully set my sheets in and made sure they were level.

Design the water table in from the get go, that is a mistake I made and had to add it on later. You want the water to be within a 1/4" of the top of the slats at a minimum. I don't cut underwater but you can in most cases. It is better to have the option to raise the water to the base of the material and not use it than not be able to. If you can cut outside with a big fan blowing the dust and crap away you can get away without the water table. The water table does reduce the dust and crap by 95% or more at 1/4" below the material.

Have you decided what kind of drive system your going to use for the gantry?

John
The following user(s) said Thank You: btvpimill

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02 May 2013 19:52 #33523 by btvpimill
Looking through my manual for it, I see there is a "Ok to move" connection and the connection to start (same as trigger on gun). They offer an "interface cable" as an option, but I am sure that can't be gotten so I will be happy to just hack in :)

Great advice on the water table!!

Gantry/drives/more has not been determined as yet

what kind of speeds do I need to acheive?

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02 May 2013 20:15 #33524 by BigJohnT
Your manual should have cut charts in it if not you can look in a similar Hypertherm manual for starting speeds. I built mine with 500 IPM in mind but rarely if ever cut material that thin.

John

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02 May 2013 20:27 #33525 by btvpimill
Just thought of this, I also have a PUMA 760 6 axis arm. it only has 80 hours on it (I got it from a universaty in DC). I have had it running before with the factory controls, but they are TERRIBLE!!!!! Maybe I just need to convert that to LinuxCNC then fashion a way to hold the torch. Build a table and volia!

I think it has a 4 foot reach radius, so I may be a little limited in how big a part I could cut, but to get me up and running (and put that PUMA to good use) maybe it is worth a go?

Then my out of pocket would be interface cards and sweat.

Guess I better go surching for any PUMA retro's on here.

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02 May 2013 23:11 #33534 by andypugh

Just thought of this, I also have a PUMA 760 6 axis arm. it only has 80 hours on it (I got it from a universaty in DC). I have had it running before with the factory controls, but they are TERRIBLE!!!!! Maybe I just need to convert that to LinuxCNC then fashion a way to hold the torch. Build a table and volia!.


That sounds like it could be great fun. And solves your 4-axis problem too.

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02 May 2013 23:20 #33536 by BigJohnT
That could give you the ability to cut bevels as well...

John

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03 May 2013 00:01 #33538 by btvpimill
Well for all the right reasons, I guess its time to retro that PUMA.

I am a bit busy now, but this is clearly the way to go - even if it doesn't work out for the plasma. As soon as I get the signals sorted, I will be looking for MESA cards to interface to it I think. So while I know I have read WAY too many posts telling others what works with what, when(if) I get to that stage I will be asking too :)

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