Torch or plasma

[NPloysa]

Whats the difference? Isn't a torch usually oxy/acetylene?



I will purchase if it's cheap, otherwise I will rent one. I want to cut 1/4"-1/2" plate and bar stock, also some tubular in the same wall thicknesses. I guess I could borrow one or use one of the TDR members' if they wanted to help me out



I have used a torch before but not too familiar with them.



Nick

 

[WDixon27]

plasma is real nice but to cut stuff over 1/4" quick and clean you need a fairly good sized unit small ones are around a grand and do a good job on 1/4 ($1500-2000 id guess unless a used one could be sorced), super clean cuts and it doesn't heat up the material much, you can almost put your hand on the cut seconds after the pass depending on the material being cut

 

[NPloysa]

So a torch would be cheaper but won't give me as clean of cuts, correct?

 

[BBRam]

So a torch would be cheaper but won't give me as clean of cuts, correct?

That is correct.

 

[AndyMan]

To put it in perspective:



oxy/acet rig $300

a "CHEAP" plasma cutter $1000



I'd love to have a plasma cutter, but as a hobbiest, there's NO WAY I could justify spending a grand on a plasma rig I'd only use once a month. IMHO, unless you're a fabricator that's using it several times a day, the torch would be just fine.

 

[NPloysa]

Ok, makes sense. The money I save in NOT getting a plasma I can buy in grinding wheels for my angle grinder Thanks for the help!



Nick

 

[GFritsch]

If you have not used a cutting torch before you should have an experienced person show you. Some guidelines:



1. Crack the gas only 1/4-1/2 turn at the tank. Gas should never be higher than 15 lbs, and 5 psi is usually fine.



2. Open the Oxygen tank and adjust to 25-30 psi. Make sure that oxygen is shut off at handle.



3. Light the gas and adjust for little smoke.



4. Open oxygen valve and adjust flame to small tip



5. Hold tip very close (but not touching) material until tip gets steel red hot and small sparks jump from metal. Open oxy lever and move in slow even path noting sparks from backside of metal. You can tell by sound if you are cutting through.





I am by no means an expert, although I have used a torch off and on over the years at work where a clean cut is not important. :-laf



Read up, or better yet have an experienced user help you to start. Good luck.



Hopefully some others will chime in and add to my post and correct me if my technique isn't completely correct.



Greg

 

[NPloysa]

I have used two different torches, once each. Its been a few years so yes I need more teaching and practice. The whole thing I was concerned with is the gas valving and pressures, etc. The torch has the handle with the lever. With the lever depressed in cutting mode, that is gas and oxy, with it let off it is just gas?

 

[ttbird]

there are two small valves on torch handle. One is gas the other is oxygen. Use these to valves to adjust flame on torch first. After that follow others advice. The long lever on torch increases the oxygen volume blowing the molten metal from your cut.

 

[JGrefenstette]

nick,

sounds like you got some good advise.

one thing that you may want to note of is that when you depress the oxy valve, you should notive about 5, 1/8 inch long, blue "teeth", (small flames) they are the last bit of flame closest to the tip. My techniuque has been to let these "teeth" just hardly touch the material, and give it a slite zig zag left to right as you slowy avdance forward. This zig zag will give you a slightly larger cut meaning less chance of rewelds occuring, when the molten puddles in the void and welds it back shut. also, the oxy valve is what i refer to as the "throttle" of the torch, it ads heat and intensifies the flame, the more pressure you give it, the hotter and quiker you will be able to cut.

And for 1/4 i usually give the torch a slight angle, just like pushing a bead when welding. This angle will help keep the cut blown clean.



And last i would where some kinda face or eye protection, not as much for shade, cause the torch aint that bright, but for "pops", when you got to quick or hit an air pocket and get a POP! it just pops molten metal around and scares you. SOme use shade #5 but i just use sun glasses. No big deal



Good luck

Jimmy

 

[nickleinonen]

With the lever depressed in cutting mode, that is gas and oxy, with it let off it is just gas?

you have oxy & acy in the preheat flame, and you add loads of oxy when you hit the trigger. .



if you get good with the torch, you can cut as clean as plasma [i still can't]. . i've got access to both at work [we have an esab powercut 1500 & ~10 oxy/acy sets] and most of the time i still use a torch... i will break out the plasma when i need to do some cutting when there is lots of oil/grease on the metal being cut [no preheat flame lighting up the grime] or when i need to cut cast iron [quicker than with torch] but a torch will give you better control when cutting cast iron

 

[Forrest Nearing]

I've got a torch... love it... but I really want a friggin' light saber of a plasma... you know, something that'll cut through a bank vault...

 

[Mhannink]

ok before we get all technical here i just want to say that gfritsch has the basics right and he's also right that you should have some one who knows more show you the ropes cause if your not careful you could be dead. i would follow his instructions they are how i go about cutting and im much more experienced. as for the technical part most of ya'll have it right except the part about the extra o2 when you hit the lever its not increasing the heat nor is it blowing the metal away it is actually burning the metal. it is in a sense a catalyst. its reacting w/ the metal and making it burn up and disappear. other then that its mostly all right. i wouldn't worry about that though till your more comfortable and familar with how it works. just basically remember to keep your regulated pressure down acetelyne is very unstable over 15psi. think old school dynamite. your o2 isnt near as important but should be around 20 to 25. on my setup i run 5psi acet. and 20psi o2. i can cut just about anythickness of metal it just takes longer the thicker it gets. fwiw i had an expert cut a railroad rail w/ only 3psi acet. and somewhere in the 10 to 15 psi o2(i forget that number exactly). it took him a while but he did cut it. well i hope that helps ya and i didnt confuse ya too much

 

[DJW]

Before turning on the Gas and especially the Oxygen at the Bottles, (Tanks?) it's a good thing to fully depressureize the Gauges, that is, turn the handle on the Gauges, the handle as you face the Dials, COUNTER CLOCKWISE and Stand to the Side, Never Facing the Gauges, or Popoff Valve, when you Slowly open the Oxygen Bottle valve.

 

[WDixon27]

i have a buddy that works for the city that was telling me about their plasmas, said they had some that would blaze through a man hole cover like ripping a sheet of cardboard Oo.

I've got a torch... love it... but I really want a friggin' light saber of a plasma... you know, something that'll cut through a bank vault...

 

[Steve St.Laurent]

Before turning on the Gas and especially the Oxygen at the Bottles, (Tanks?) it's a good thing to fully depressureize the Gauges, that is, turn the handle on the Gauges, the handle as you face the Dials, COUNTER CLOCKWISE and Stand to the Side, Never Facing the Gauges, or Popoff Valve, when you Slowly open the Oxygen Bottle valve.

I've always read that you should take the pressure off the springs in the regulators when it isn't in use. When I finish with any of my bottles I turn the bottle off and back the pressure off. With my OA torch I turn the bottles off, then open the acetyline on the torch until the gauges zero out, then close the acet and open the oxygen to purge the torch and lines of acetylene. Then close the oxy and then back off both regulators until there's no pressure on the springs. With my welders I just turn the bottles off and back the regulators off. What I've read is that if you leave the regulators cranked up the springs will weaken over time.



The other consideration for torch vs plasma is if your going to be doing stainless or aluminum then plasma is your only option - a torch won't work. Also, thinner materials plasma works a lot better - on thin materials you'll warp it with a torch. However, IMO a torch is pretty much a necessary item to have if your going to be doing much fabrication if for nothing else than straightening things. My torch gets used for that more than anything else. I can see the day that I'll have a plasma cutter in the shop as well.

 

[GHarman]

Whats the difference? Isn't a torch usually oxy/acetylene?



I will purchase if it's cheap, otherwise I will rent one. I want to cut 1/4"-1/2" plate and bar stock, also some tubular in the same wall thicknesses. I guess I could borrow one or use one of the TDR members' if they wanted to help me out



I have used a torch before but not too familiar with them.



Nick

Hey Neighbor, I live over in Gilpin Co. will be glad to stop over on the way to the Buffalo Creek Rifle range and give you a hand on the Oxy-Acetylene cutting. Let me know how I can get in touch, if your interested. GregH.

 

[Forrest Nearing]

call me redneck, but I just crack open the valves and go...

 

[GHarman]

call me redneck, but I just crack open the valves and go...

Hey Bud, I just wanted to weigh in on some safety here. Oxy-Acetylene is not your friend! It is like a Wolf that has gotten used to eating hand-outs at your house. Be aware of what you are doing. I started my welding career Oxy-Acetylene welding in 1970. There are posts here by knowledgable people, Please read them and learn. No disrespect intended. A couple of things that have not been mentioned, that are very important, SAFETY WIZE are; 1. Do NOT use more than 1/7 th of the remaining volume of your tank per hour. You will draw out the acetone and leave a BOMB for the guy that fills it. ( They are supposed to check them. ) Acetylene tanks, when empty are still heavy because they are filled with a CEMENTATIOUS substance that is porous. Then a quantity of acetone is then introduced that will absorb the Acetylene allowing the higher storage pressure in the bottle. If you store your Acetylene bottle in the prone position you will drain the acetone out of the bottle when you light up and cut or weld. Which one of us do you want to give CONDOLENCES to your FAMILY?! 2. Acetylene in its free state is EXPLOSIVE. Above 15# delivery pressure, the friction of the gas traveling through the hose will cause it to detonate like a string of DET-CORD. Your grinding sparks falling on a ACETYLENE hose will do the same thing. Dont stand on your hoses or wrap them around your neck, arm or leg! Use a short section of lighter hose (called Whips) from the main hose to the torch if you feel overweighted by the heavy hose attached to the torch. 3. Secure your bottles. A falling oxygen bottle can break off a valve and launch itself into a random pattern of death and distruction. 4. Use FLASHBACK arresters at your torch. Keep your hands for doing other nice things! There is alot more to talk about. Will write more later. GregH.

 

[nickleinonen]

fwiw i had an expert cut a railroad rail w/ only 3psi acet. and somewhere in the 10 to 15 psi o2(i forget that number exactly)

dang, low pressures. . i usually run ~10acy, ~50oxy... i don't want to take forever cutting through +1" plate. . the lower pressures just makes it easier to fine tune the flame from the valves on the torch