I Thought I Knew How to Use a Torch

I thought I knew what I was doing but I'm not so sure.

MCL

Never Never crank up acetylene past 15. Not exactly sure where the explosin point is but 15 psi is in the danger zone

I've got a big cutting tourch hooked up to some fairly large tanks and like to run 10 acetylene and 50 or 60 for O2 to really cut through stuff.

When gas welding I like to the two to be balanced and with a small tip like it in the single PSI numbers - 5&5 sounds right.

Flame and cone patterns are what I'm looking for and are more important than an exact psi as long as it's not too far off.

It only takes a second to show you the correct patterns but real difficult to describe - picture is worth a 1,000 words. I'd recomend that you get a gas welding and cutting book that has pictures of the correct flame and cone patterns.

I've always heard in cutting you use 5x as much O2 as acetylene with welding almost even.

good luck

Lets start with basics since your discription of your problem is vague.

Acetylene set to 5psi, that'll cut 1-1/2" material
Oxygen set to 30psi.

Mixing body, two valves where the hose connects, one acetylene, one oxygen. The oxygen valve should be fully open with a cutting head attached.

Cutting head, Near the cutting lever is a oxygen valve.

Set pre-heat cutting flame by turning on acetylene valve on mixing body then turn on oxygen valve near the cutting lever to set pre-heat flame.

Depress cutting lever to cut.

If you still can not cut mild steel fairly clean post back being very discriptive of your problems.

See the below info to set preheat flame, tip cleaning and general torch info:

UpDated 03/26/05:

A trick I use for accurate free hand cutting is using a sanding disc to knock off the heavy scale and then use a scratch awl for my lines. The line is very thin so it makes following lines very easy.

Another is to stop cutting when you feel your hands or torch get out of balance. When that happens, stop and reposition the torch then continue cutting.

The cleanest cut comes from a clean tip. After you clean all the orifice bores in the tip, fire up the torch and set flame for cutting, then depress the cutting lever and observe the flame.

There should be a long very "uniform" inner flame cutting cone. If that inner cone is not "very" uniform then your cut will be ragged just like the flame cone is and the back of the metal will have slag. Reclean the center orifice until it's very uniform.

A cut with a clean tip will have a very smooth cut surface with very little (if any) slag on the backside of the cut. If either one of these is not present reclean the tip.

The center bore orifice can get deformed and the tip needs replaced or cut off. It's really important to hold the cleaning file straight in the bore hole and just removing enough material to clean the bore to make the tip last a long time.

I've never used a new tip that was clean enough for cutting right out of the box.

To expand on my thoughts:

Altough theres many different tip sizes, I have a found a No3 makes for a all around good cutting tip as it will cut upto 1-1/2" or 18ga sheet metal depending on the preheat setting.

Another consideration is as the tip size becomes smaller so does the orifice size and it becomes a bare to clean them ity bity holes. If using an automatic cutting machine then changing tip size would be a production benefit.

Setting the proper neutral preheat flame, the orifice holes around the center cutting orifice, can be observed by the tip of the inner flame cone. A neutral flame has a blue colored flame outer sheild with a light blue to white inner cone flame that is slightly rounded at the cone tip. A oxidizing flame (too much oxygen) has a sharp pointed very white inner cone. A reducing flame (not enough oxygen) would have a very round to a ragged thrid inner cone.

I have found 5psi acetylene and 30psi Oxygen while cutting to be a good all around setting for upto 50ft of 1/4" hose. Your final pressure setting is regulated by the needle valve adjustments on the mixing body.

For brazing or welding a size #0 tip works well with 5psi Acetylene and 20psi Oxygen. Again the needle valves on the mixing body sets the final pressure needed at the tip.

I also use the above settings to preheat 2" round bar without any problems using the #0 size tip or the rose bud tip.

The advantage to using a rose bud tip is that it expands the flame temperature over a wider area vs using a #0 size tip. I very seldom use my rose bud tip. Preheating with LP saves some expensive gas then finish heating with Qxy/Acet.

Never run Acetylene above 15psi for any reason! T_Bone

There is no way to determine what the flow is by adjusting valves on the torch. The preheat valve on a combo cutting torch is the only valve that you should adjust. That adjustment is to set the flame tips on the cutting tip.

This is the way I was taught and it has always worked for me. If you still have a question, just ask. Someone on here will have the correct answer.

Good Luck!

Is the tip damaged or clogged at all? It should make a symmetrical star type pattern when you bring the tip down do a piece of metal. If the star shape is lopside or missing some "legs" then all of the preheat holes are not clean enough.

I expect it's one of two things: Your tip needs cleaning, or your flame isn't adjusted correctly. Mine seems to cut better when the flame is just a bit on the rich side of neutral.

Lotta folks here with WAY more experience than me (like, just about everybody...) but I adjust for a good, sharp flame and then "soften" it with just a touch more acetylene, and it cuts like a big dawg.

You have probably reformed the center passage from repeated cleaning. It doesn't take much to go from a nice new tip to one that doesn't work as well.