Need a torch lesson

I have gotten pretty good at heating up stuck bolts, etc. to get rusty equipment apart-but I am can not seem to get anything to cut (like lock collars).

I am now replacing 6 augers in my combine and have 6 "practice" pieces where I can cut off lock collars with no penalty for accidentally getting into the shaft-so good opportunity to learn.

1) How do I get my torch hot enough to cut and not just heat?
2) Any other tips?

Any input appreciated.

Paul

There are a couple of things I didn't see anybody mention, so I will. The valve on your tank of oxygen needs to be opened all the way or it will leak around the valve stem. It has two valve seats, one for fully closed (obviously) and another one for fully open. The valve on the acetylene bottle is normally opened less than one full turn so that you can get it closed in a hurry should the need arise.

A number of people have explained what to do with the oxygen handles on the torch body. This is easy enough to follow if you have a cutting torch with two oxygen handles but might be confusing if your torch has only one---they come both ways. The basic idea is that if you have a torch with two oxygen handles, you open one all the way and use the torch as if it had only one oxygen handle.

Dave (135 Fan) mentions that it's wasteful to set the gas pressures too high. I'll add that it also diverts attention from the issues that are truly important---clean tip, steady hand (practice, and more practice), correct travel speed. People waste time trying to get the gas pressures just right when they should be working on their technique. Except at the extremes, the gas pressure is not that much of an issue.

All the best, Stan

Awesome info-just what I was looking for.

Here are a couple of T_Bone's postings from the archives of this forum:

GAS SETTINGS FOR CUTTING
Posted by T_Bone on March 02, 2002 at 10:28:03 from (207.173.149.126): In Reply to: Re: Re: Cutting Torch Question posted by Gregg on March 02, 2002 at 04:43:24: Hi Gregg, I use two settings for all my cutting and brazing.
Cutting 40oxy/5acetylene
Brazing 20oxy/5acetylene Acetylene is set with gas flow on at the mixing chamber and gives about 7psi at the regulator when shut off. I control all final pressures with the mixing chamber. The reason for the above pressure settings is on the job with a 100ft of hose stretched out I never had to readjust my regulators. You might want to do a search on this forum as cutting/brazing has been talked about a lot this past couple months. Glad we could help.
T_Bone

GAS SETTINGS FOR CUTTING AND WELDING
Posted by T_Bone on January 24, 2002 at 16:36:44 from (207.173.149.113):
In Reply to: Re: Re: Re: Is Gas Welding Practical? posted by Tim Briggs on January 24, 2002 at 13:43:46:

Hi Tim,

Congrats Tim as you have just learned a great lesson, live with-in your means...fooled you huh? LOL Franz done give away my secrets :) Now that your wanting to learn, I'll Tell you anything I know to steer you in the correct direction. When I made the statement it doesn't matter what cylinder you have , as you'll never be close to over drawing any acetylene cylinder. Why? Too many welders think that you need to turn up the pressure to achieve a god like weld. ha ha it was a mistake...good I meant...I'm in a very good mood today so bear with me... The opposite is true. For my example with Branden on a 1" plate test, I would use 5psi of acetylene and 20psi oxygen with a #3 tip, just so I could have the speed to whoop him as normally I would use a #0 or a #00 tip but notice I didn't say anything about upping the gas pressure on act or oxy as it's not needed. Why?
I use two gas pressure settings for all my cutting and welding needs:
There's three gas valves located on the torch, two on the mixing chamber (the part of the torch closest to the gas supply hoses) one oxygen valve and one acetylene valve and there used for controlling preheat. The third valve is on a cutting chamber is up forward of the other two valves is for setting th oxygen mix of the preheat flame. If you had a welding/brazing tip on the torch, just the two valves on the mixing chamber would be used and if the cutting head is attached then the oxygen valve on the mixing chamber is set too wide open and the oxygen is controlled by the most forward oxygen valve and sets the preheat for cutting.

CUTTING:
1) I use a #3 cutting tip with pressure set at Oxygen 40psi and 7psi acetylene. Don't matter if I'm cutting 24ga or 1" plate I use the same tip and pressure settings. How about them dingle berries on the back side of the cut? I don't have any when I'm done if I done my homework!!! Why? Damn given-up more trade secrets but hey I have nothing better to do. I told you that I was in a good mood :)
What causes the dingle berries? A very CLEAN center hole in the cutting tip along with the correct speed controls the dingle berries! Period!!! Reread this as that�s the secret to cutting very well without slag on the back side!
On a cutting tip you have two types of mixed gas discharge holes. The outside gas holes are for base metal preheat and a center blow hole for discharging the base metal you just preheated. So with that I've have just explained how clean is clean for the center blow hole? Glad you asked!
After cleaning the center tip hole, fire the torch up with a little act/oxy mix. I hate those black carbon fluffies that fly around when you have too much acetylene. :) Set the acetylene too keep the flame, without oxygen, in touch with the cutting head tip. If there is a air gap between base of the acetylene flame and the tip, then you have too much acetylene. The next step id too set the oxygen. Oxygen is set by turning the green knob on the mixing chamber: LMAO
Oxygen mix is correct when then the heating flame is just cone shaped with a "rounded cone" top to the flame tip. Reread this as it's important. A sharp point cone is too much oxygen added and is called an oxidizing flame! Anotherwords too much oxygen. An that you don't want!
Now that you have the preheat set correct it's time to set the cutting flame, the center hole gas mix. The forward gas valve controls oxygen on the cutting head. Next depress the cutting lever. That is what blows the preheated metal away and cuts the metal. This "center" flame cone should have very clean lines on the cone edge extending out to the end of the flame cone. If the edges of the cone are ragged looking or the center cone is very short, then the tip center hole needs cleaned once again, thus repeating the test for a clean center flame hole. It may take you several tries of cleaning the center tip hole to get the flame cone correct but that is the first secret to burning a slag free base metal underside.
2) The second influence on cutting a slag free cut, is the cutting speed that the torch is moved forward for a given amount of base metal preheat BTU. Although this travel speed is important, it's much more important to pay attention to the cleanness of the center blow hole when free hand cutting. Automated Machine travel cutting will tolorate a more dirty cutting hole than hand cutting.

GAS WELDING:
1) I use 20psi Oxygen and 7 psi Acetylene. Pressures are set with torch valves OFF! Same with cutting pressures. The only reason I drop the oxygen pressure while brazing/welding is to keep from blowing my flame mix out if I bump the oxygen control valve. The same procedures are used for setting the welding flame as setting the preheat cutting flame. Pay close attention to the cone. A nice rounded cone flame tip is what your wanting. Notice that I never raised my acetylene pressure for either cutting or welding thus it never over draws the acetylene cylinder size. I also use these pressure settings for the acetylene "B" tanks and never over draw them.
I buy the largest cylinder size for cost effectiveness and so I don't have run and get them filled all the time. That�s the only reason though. Get what ever size you feel you can handle weight wise as they do get heavy to lift if you don't know how to lift them.
I'm sure I have forgot something so e-mail me if you like as I don't post my e-mail addy for spam concerns.
[email protected]

T_Bone

...and a great one on cutting with propane by Mark KW. Mark KW doesn't post on this forum any more, which is a real loss. He was one of the best.

CUTTING WITH PROPANE
Posted by Mark Kw on May 27, 2001 at 06:12:59 from (216.37.229.149):
In Reply to: Cutting torch kit posted by Steve in CT on May 24, 2001 at 10:09:03:
A couple things on this one; first, most all Generico stuff is interchangeable with Victor, from tips to valve seats and regulator diaphragms. I've been using Generico regulators for about 7 or 8 years now on a daily basis with no problems yet.
I don't like acetylene very much and prefer to use LP for 99% of everything I do. If you want to use LP, you need to know a few things. First, you must use type "T" hoses with LP. The normal hoses used with acetylene will become soft and blow out after time exposure to LP gas. Anchor brand hoses are cheap and to be honest with you, they are the best I have ever used, remaining pliable in extreme cold is their biggest plus for me. Next, you need a torch specifically designed for use with LP or it will not work properly. The Harris type "F" is designed for use only with LP/MAPP gas and is the only one I have found that will mix the LP/O2 to give a proper burn at the tip. One of these will run you about $140 with a #2 cutting tip. The best part of the Harris design is that the rosebud tips screw right onto the cutting torch tip threads so there is no changing handles. Using LP takes some getting used to because setting the flame for different uses is slightly different from that of acetylene. For cutting, you need to use an oxidizing flame (very short light blue pre heat cone). LP cuts much faster, thicker and cleaner than acet once you have the proper torch/tip combo and get the feel of how to set it. One of the biggest plus sides to using LP is that you don't get the popping and blow backs when cutting dirty/rusty steel like acetylene does.
LP does require slightly more O2 than does acetylene but the end result is that you get much more cutting power for the same amount of O2 as with acetylene fuel gas. LP is also much safer too. Acetylene can self ignite when in gas form in the hoses/regulator if the gas pressure gets over 21 psi, LP will not even if the line gets full bottle pressure because of a regulator failure or operator error.
The myth that LP takes longer to pre heat or start cutting comes from those people who either used the wrong torch or the wrong flame setting. Too much gas at the tip will cause you to have a cold pre heat flame. Too much O2 will cause also cause a cold flame and make the cutting very slow and sloppy. In most cases of guys complaining about LP not being as good as acetylene come from them trying to use equipment that is not designed for LP use. The Victor and Smith adapter tips for use with LP on a torch handle designed for use with acetylene will not produce a proper LP/O2 mix and the flame and performance will suffer greatly. Properly set, I can hold a cut with LP on my Harris torch 2" to 6" from the work piece where with acetylene you will loose the cut when the tip gets 1/4" or more from the work piece.
The kerf of the cut from LP is also much easier to clean especially when cutting rusty steel. In most cases, I can cut heavy thick rusted steel with LP and do all the cleaning easily and quickly with a chipping hammer. Grinding is rarely ever required even if MIG welding the steel with solid wire. When done properly, the cuts from LP are confused with those made by plasma cutters.
For all the heavy duty cutting I do, I have yet to need an LP tip bigger than #2 and as a matter of fact, I don't even own any other size tips for it except for the rose buds. Adjusting the O2 pressure will control the thickness of the steel you cut while maintaining the same pre heat flame size and setting. I have made cuts on steel 10" thick that were clean and smooth with a standard #2 cutting tip but using 80 to 90 psi of O2 pressure. Yes, you do use more O2 but you are not using any more fuel gas for the heavier cutting as you need to do with acetylene. You save time because you don't need to constantly change tip sizes for changing material thicknesses. I rarely change O2 pressure settings because the cut valve on the Harris torches allows you to feather the O2 cutting pressure at the handle. This takes some practice but is a real time saver once mastered.
Now as for the tanks. A 20 pound LP tank will last for about 20-30 of the biggest O2 tanks known as the 292 size (the ones that are 10" in diameter and stand 5' high). A 3 or 5 pound LP tank is sufficient for any DIY'er uses unless you are running a large rose bud tip for long periods of time. You can buy the medium sized O2 tanks from most any gas supplier for about $150. What you need to ask BEFORE you buy: 1- will they exchange the empty for a full one or only fill your tank? 2- If they will only fill your tank, how long is the turn around time (time you wait to get the tank back)? 3- Are they going to charge you for the hydro test on the tank when it comes due (most run about $35)? Just FYI, most gas suppliers will exchange your tank if purchased from them and not charge for hydro testing and will offer you a transfer or buy back option if you move from their service area because some suppliers will confiscate tanks that are not branded with their name while other don't care or will do a dealer swap. You don't want to shell out $150 for a tank, move away from the area only to have to purchase another tank at the new location.
Some words of advice. Don't slack on price and size of the equipment. Get yourself a 16" Harris torch, the big heavy duty two stage Generico regulators, Anchor brand type "T" 50' twin hoses in 1/4" ID diameter and either Harris, Goss or NTT LP tips. If you decide to go with acetylene, get the heavy duty two stage regulators, 1/4" ID twin hoses and the Generico acetylene torches are fine with either Generico or Victor tips. Don't limit yourself to smaller hoses or a light duty torch because you will regret it down the road. The cost difference between going heavy duty and light duty for the entire set-up will be less than $100 and well worth the extra start up cost when you do not become limited by the size of the equipment.
As for me, the only things I use acetylene for is flame spray build-up using powdered metals and some very special cast iron welding where I need to add carbon in order to get a proper weld process. I brass and silver braze, solder and cut with the same #2 cutting tip. It takes time to get used to it and learning how to set the flame and gas pressures to get the tip to do what you want but once the learning curve is over, you save more time than you can imagine and don't need to have pile of specialized equipment to get the same type and amount of work done. If you have any specific questions, feel free to email me directly.

I cut at 90 degrees to the shaft and across the nut or collar, instead of in line with it and I make cuts on either side. This just leaves two quarters on each side that are easy to remove. Keep a hammer on hand to whack the remaining slugs loose.

Once you get the hang the hang of it, you'll save WD-40 and cheater bars for other things. On a bolt over about 3/4" I can usually leave bolt threads useable with minumum cleanup (wire brush addn maybe a bit of a tri file).

I'm on a project that requires some cutting and was not having much success. Bought a new larger tip and the dealer looked up the o2 and acteyelene pressures for it.(different tips take different pressures) New tip did not do much better. Happened to look at the upper oxygen valve on my Harris torch and it said to open the other o2 valve all the way before adjusting the upper valve. Did that and adjusted for neutal flame like glennester said and the torch cut like crazy. One of those "when all else fails, read the directions" things.

Also suggest you check out some books from the local library on welding and look for guidance. Good luck. Oh, be careful when cutting those collars and don't cut into the shaft.

KEH