Cutting Torch Guide Metal

[supergrumpy]

years ago I knew a really good welder, he used some sort of special metal strip as a guide when torch cutting

metal was light like magnesium but would not burn in the torch flame, he turned flame on it and it just sat there, looked to be sawn off something not purchased

if he was still above ground I would ask him, what was it????

 

[formenwhogrow]

Tungsten?

 

[oldhousehugger25]

We used copper slugs as a backup when welding sheet metal. It acts as a heat sink and also molten steel solidifies so quickly that it doesn't stick. Could the guide have been copper?
John

 

[bjb in TX from Ne]

It wasn't magnesium, magnesium will begin burning if exposed to that kind of heat.

 

[Puddles]

I carried one of these, (square on the bottom, not the circle burner) in my welding bucket for about 25 years. It takes years but the magnets do get weak. I Thick they’re made by Clean Weld. They have a copper blade; works well with an O/A torch! Years ago I was partnered with a guy who thought my burning square would help him carbon arc a straight line! He bought me a new blade! :wink:

 

[NCWayne]

It was probably copper but if the piece is just being used as a guide it really shouldn"t matter what material it is since the flame isn"t concentrated on it long enough to hurt anything. Personally I"ve used everything from copper to aluminium to plain steel and have never had a problem with any of it.

 

[T_Bone]

Hi supergrumpy,

I'm with Wyane, I use anything that's pretty straight, usually CR angle iron for the smooth face, with clamps or light tacks on one side.

If'n your really wanting a smooth cut, add a slip on roller/ball bearing on the high tip body.

T_Bone

 

[Butch(OH)]

At the risk of sounding like an smart arse I have never seen what I concidered to be a good torch man use a straight edge when cutting. Cutting straight with a torch is 75% technique 25% practice and 25% equipment IMO.

I could show you in 15 seconds the technique but would take me 2 pages to explain here in total. Basicaly you hold the torch at the rear, and only the rear, Top hand holding the torch and running the burn valve and bottom hand holding the top hand plus forming a rest on the work. This allows the torch to move side to side and fore and aft thus you can stay straight swinging sideways. Depending in the length of the torch tube you can cut 12-18" without moving your resting position You always cut side to side, not towards or away from your body. To make 90 degree cuts you need a torch with a 90 degree head so the handle doesnt have to be 12" off the work. You need a mark you can see that isnt 1/4" wide, sharpened soapstone on cleaned metal. Cleaned, aka ground, metal also cuts a LOT better and cleaner than even lightly rusted. All this being said you need to cut some metal to be decent at it. I get little pratice these days since moving into the front office but I can still cut a straight line,,, most of the time, LOL. The straight edges we have in the shop are made of a copper or brass like metal. The problem with all of them on a long cut is they warm up on one side, and warp. Thus your nice looking 4" long cut is actualy a very large arc, I have seen 1/2" on 4 foot!! Most of the time any cut over a couple feet the track machine is used these days but that doesnt help you with your problem. Good luck.

 

[trucker40]

In the shop where I worked they used steel plate about 4 inches wide different lengths and an inch thick,or a clean piece of angle iron or flat plate.One old man had a thick piece of brass about a foot long.On the ones they used a lot they welded a big bolt right in the center so they could grab that and move it without burning their hand.A piece of plate heavy enough and you dont need to clamp it down.It will set there and you can burn a line that looks like a robot burner did it even if you barely can use a torch,just watch the sparks on the bottom side,if they stop slow down to where you still see them going through again and it works every time.Just like anything else it takes practice.

 

[PJH]

My favorite straightedge is a 2' piece of railroad rail. It stays where I put it without clamps, won't distort, top of rail makes a nice place to slide my left hand while the tip of the torch rides on the bottom flange of the rail. I also have a couple shorter pieces for smaller cuts.

Not something you'd see a professional use, but then I'm not a professional.

I can make some nice cuts with it.

Paul

 

[Puddles]

Butch (OH) I agree with you to a certain extent! Me, I’m just short of being a hack with a torch, oh I can cut nice when I take my time to setup correctly. I’ve worked with some guys who are just awesome with a torch, two in particular I swear they can cut free hand better than I could cut with a tractor torch! But guess what? Both of these guys used straight edges majority of the time! Why? Because it is much faster, faster to setup and start, don’t have to be near as comfortable to make a fantastic cut, and actual travel speed is much faster with a straight edge. :wink:

 

[fixerupper]

I tried to take a pic of my straightedge, but the camera is in a bad mood so I'll try to describe it.

I took a 24" tool magnet, like the one you bolt to the wall to stick tools to and bolted a 1-1/2" X 1-1/2"X 24" angle iron to it using 2" standoffs to keep the angle iron 2" away from the magnet. The angle iron is the straight edge the torch follows and the magnet holds it in place. I just plop it down in the general area I want to cut and tap it around until it's in the right spot. It's not perfect and doesn't work for every job, but it's kind of handy for cutting sheets or something like that.

It's also handy for picking up nuts and bolts, even when you don't want to. Jim

 

[T_Bone]

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!

I strongly urge you too research more information for your safety.

T_Bone

 

[T_Bone]

From the archives:

Theres nothing finner than a Victor 100 torch. Small body for great hand control and less hand fatigue. A with a 3/16"x25ft hose works well for shop use. The torch is rated for 1-1/2" cutting or brazing 1/2" plate. Great quality and will last a very long time.

You won't use too many tips, No3 cutting tip and a No0 brazing tip, for 99% of work in a commercial/home shop. A small rosebud is nice but not used all that much. All other tip sizes will most likely stay in the drawer.

The small portable tanks are of no use for the commercial/home shops. These tanks are for carrying up on the roof for small jobs.

A 200cft Oxy, 100cft Acet, tank size works very well for a commercial/home shop. The last (owner)cylinders I bought were $165eh then exchange when empty. Be sure and check your local gas supplier for cost of both cylinders and the Victor torch sets.

Nothing wrong with other brands other than the large mixing body size is like using a club that causes hand fatigue and ragged cuts/welding.

T_Bone

 

[chvet73]

I took T-Bone's advice on the Victor 100 several years ago. Never used my big Victor since. Guess I should sell the big one sometime. But I have a hard time selling tools and don't have any trouble buying more of them.

 

[tiresntracks]

That's funny, I did just the opposite. I quit using my 100 several years ago when I bought a 315C with a 2460 torch. I like it way better. I guess everyone's different.

 

[supergrumpy]

I appreciate the comments, thank you

have 3 Victor 100's plus bigger Victor, big one is out being rebuilt after being loaned, welding shop says they are the best to have

haven't worked with thick metal in some time so have been reading my welding book, been thru it 3 times and find new stuff every time I read it, now for some practice

large tanks for the shop plus small ones for dragging out to the woods

this old timer made the cut edge look like hacksaw did it and he made it look easy

 

[Anonymous-0]

Curve-o-mark makes an aluminum alloy magnetic cutting guide 24 inches long but additional sections can be bolted to it up to 6 ft. long. It's a little pricey but works awesome. Anything straight can work for a guide. Comparing a good torch cut to a hacksaw is an insult. I have made freehand cuts using a straight edge that were as nice as the original edge of the the steel. I can do pretty good freehand cuts but it takes lots of practice and very steady hands. My biggest problem is that I'm concentrating so much on being steady that I sometimes forget to breath while arcing my wrists side to side. To do really nice cuts you need the following, a proper size clean tip for the thickness you are cutting, the right gas pressures; 5 acetylene and 30 oxygen is a good general starting point, a comfortable position to work where the hoses aren't going to hook on anything or pull down on your hand, steady even speed and freedom to move the torch without interference. Often times I like to loop the hoses over my shoulder and leave enough slack so that I'm not pulling on the hoses. When you lay out your cut make a single fine line with a sharpened soapstone. A 1/4" wide line is useless. When following the line, cut on the side of the line and not down the middle. You want your piece to be the proper size after cutting not smaller due to the kerf width. Sometimes a fire brick or another piece of metal is nice to rest your steadying hand on so it doesn't get burn't. If I want to do real high quality cuts I won't wear a glove on my torch/trigger hand. With acetylene a 6 preheat hole is best. For straight cuts align the preheat holes so 1 is on the front of the line and 1 is on the rear. For bevel cuts have the preheat holes on either side of the line. Thicker steel will cut much nicer when preheated by running the torch over it first before cutting. A lot of people think that plasma is the be all end all of cutting but on steel it is much easier to get a good freehand cut with an O/A unit. Torch make is a personal choice. Dave