so i haven't air arc'd much, i run a pipe pro and wondering what kind of amps you run for 1/4 carbons, also air pressure? thanks regards shannon.
weaver
1/4" is a pretty big electrode it will take @300+ Amps and all the air you can. For air you will need to maintain at least 80 PSI which will require a rig capable of over 25 cfm if you are doing any serious gouging.
Here is a link to Thermadyne/arcair pdf on Air Carbon Arc Guide.
http://www.thermadyne.com/arcair_pdfs/89_250_008.pdfoh and don't forget the leather sleeves and ear plugs.
Good Luck
Marshall
By Blaster 
Date 02-21-2010 19:50
Edited 02-21-2010 19:53
Wacco is right on.
I use mostly 5/16" and 3/8" - 3/8" is my favorite.
I usually start at ~300 for 1/4", ~400 for 5/16", and ~500 for 3/8".
If the machine has a dig control, I usually max that out too.
If you are moving slow and steady and the electrode shorts out, more amps are needed. If the end of the electrode glows red hot excessively, and periodically a 1/2" - 1" piece of the end just blows right off the electrode, the current is too high.
The air arc is not too sensitive to amperage level. The big deal is having the air holes lined up exactly in line with the electrode, and using a technique that keeps the air holes directly behind the direction of travel. You can't go too slow, but if it feels like you are pushing the electrode through wet cement, you are going too fast and will almost certainly leave carbon and oxidized metal behind, stuck in the gouge.
I like to travel at a speed that results in a rapid "pop" "pop" "pop" rather than a continuous "shooooooooosh", at least on the final cuts to ensure a very clean gouge that is free of carbon and oxides.
Also, lower current levels for a given electrode are useful when you are cutting one member off of another (or a bolt head, whatever), and it is important to not nick into the piece that is being saved.
Why not size down to a 3/16" carbon rod and knock it back 10 or 15 amps from all out. It'll be considerably easier on the machine and the job will still get done.
Shannon,
I would offer one comment that I do not consider a 'correction' or 'criticism' to what Marshall and Blaster have stated.
There is always a difference between something that will work best, and something that will get you by. Now be careful, we are not talking about welding and codes. We are talking about air-arc.
So, I have had to run less air than what Marshall stated on many occassions. His pressure and cfm flow are much more ideal, but you can get by at 60 psi and about 15 cfm when talking about 1/4" electrodes. When running 5/16 or 3/8 the higher pressure is much more important. You have to have enough to keep the molten metal blown out. When running lower air pressure you may find you have to run a little slower depending upon what you are used to. As stated by others, if you are really 'pushing' it then you are trying to go too fast considering your other variables and the results will be to reduce the quality of the entire job and/or add to costs because of additional cleanup, joint preparation, material contamination, etc.
The question of dropping to 3/16 can be very appropriate as well. There are many applications where those would work just fine and save wear and tear on the smaller machines.
The choices are always going to have several variables: machine capacity, air compressor rating, job being done, time/cost, etc.
And do be careful about burning up your machine working it at maximum for long periods of time. Some may take a lot of heavy loading, others may not.
Have a Great Day, Brent
You really need ear plugs. 300 should run 1/4 easy enough. I don't like the pop pop deal, I try to get a steady sound. that will give you a smooth cut, and keep your machine from humping.
