[TheForge] learning to use a cutting torch properly

Thu May 29 02:25:01 2003

The torch mfgs are generally eager to send you material on how to use 
their stuff...also most older welding texts are helpful.
I'm opinionated on this (too) and will babble forth, right or wrong, way 
too long , about it.
1. Each tip size has a recommended pressure range..it makes a difference.
2. The tip size should change with the steel thickness to be cut..that's 
in the charts too...it also makes a diff.
3.Clean the tip orfaces very carefully. They need to be clean and they 
won't work well when reamed out rudely. Used tips become oversized, 
loose their internal tapers and develop trumpet shaped mouths...it 
doesn't take much tip distortion to cause a lousy cut. I keep my newest 
tips hidden and only bring them out when i need real precision.
4. Clean the surface of the steel of  any heavier scale, rust, dirt , 
clay etc. ( prissy, eh?)
5. As the metal thickness climbs, so does the oxy pressure. You need 
enough to blow all the way through. If the cut lines show a curve 
lagging behind the tip. either you are moving too fast or your oxy 
pressure is too low.
6. Travel speed is critical...too slow and the top of the cut melts; too 
fast and the  cut lags or doesn't even pierce all the way through. When 
the speed and everything are just right, the cut is straight, clean, and 
the slag comes free easily.
7 When you dont get all the way through right away, the steel boils in 
the cut and spits back on the tip, messing the tip up and overheating 
it. If you see that foam rising , raise the torch, back up to a  good 
part of the cut and slowly recut the bad spot. When the tip gets foamed 
on, stop and clean it.
8 Listen to the tip..it will tell you a lot.
Start cuts in thicker material going away from you...once the cut is 
started, but not all the way through, keep the tip moving away from the 
splash-back.
9 As the steel heats up from the cutting, and especially if cutting near 
other recent cuts, move faster.
10. Use a smooth cutting guide if possible, and drag the tip along it to 
get a straight line or a curve.
11 Like most welding, the distance from tip to work is critical.
12  Block the work up away from the bench so the dross can blow freely 
through the kerf..avoid bounce back.
13 Use a block or brick to rest your hands on and preferably another 
 for your elbows or forearms. Triangulate your grip with one hand as 
close to the tip as comfortable and the other back by the valves and 
your elbows or forearms apart and braced securely. Pulling rather than 
pushing tends to be smoother and cutting  from one side to the other is 
even better.
14 during sustained heavy cutting, it may be necessary to dunk the tip 
in a bucket every now and then to prevent overheating.
15 Avoid cutting in a corner, depression or down a hole if at all 
possible...if you must, keep the tip cool.
16. The Henrob ( i have one) is an inferior cutting torch. If you like 
the economy of the single preheat, that is available  in a number of 
sizes from many mfg under the name of a sheet metal cutting tip or a 
plate cutting tip. The ones for my Smith torch are a " drag type tip" 
and features a face that rides right on the metal to keep the distance 
perfect. It has one preheat flame  and an oxy jet. I've seen a Victor 
that had 2 preheats so one could cut either direction without revolving 
the torch around. These tips cut like a plasma cutter in kerf size and   
easy slag  removal if you get the travel speed right..slower than  a 
plasma though.
For thicker material , the Henrob ( formerly Dillon) torches just don't 
cut it.  You can cut several inches thick steel with a decent medium 
sized torch.

Next time I'll tell you what I think about this subject.....I should add 
( he said wavering) that I've never taken any instruction in any of this 
stuff and really don't know what I'm doing..So don't believe any of 
it.........Pete

Paul Hewitt wrote:

>I have never seen a good torch reference.
>
>two things are key
>
>1 the flame must be neutral
>
>2 size your flame for your material bigger is not better unless you have 2
>or 3" thick steel.
>
>Neutral flame adjustment
>
>Set your regulators to 7 PSI acetylene and 15 PSI oxygen.  Some people will
>tell yopu thats high on the gas side but thats what we use in the shop and
>it works the best.
>
>For thin material 1/8 or less, open the aceytlene and strike a flame adjust
>it so that the flame is about 8 to 9 incehs long, then turn on the ogygen
>till the flame turns blue.   Next depress the cutting lever and while
>holding it down adjust the flame till all of the light blue cones turn to a
>bright blue, play with this a few times if you have not already, as a
>hissing or oxidizing flame leaves a messy cut.
>
>Chances are also that much of the torch work you see is now plasma cut,
>while you can get fancy with a toirck, the cleanup end of things is always
>more time consuming.
>
>
>
>----- Original Message -----
>From: "Gladish Family" <[email protected]>
>To: <[email protected]>
>Sent: Wednesday, May 28, 2003 10:30 AM
>Subject: [TheForge] learning to use a cutting torch properly
>
>
>  
>
>>Would anyone please recommend an online reference or tutorial that teaches
>>how to really set up and use a cutting torch, in depth?
>>I've been using one all these years, and recently have been looking at
>>    
>>
>some
>  
>
>>really nice cutting work- it's one thing to be able to use a torch, and
>>another to use it well...
>>No luck this time with the search engine.
>>Thanks,
>>Andy G.
>>
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>
>_______________________________________________
>http://mailman.qth.net/mailman/listinfo/theforge
>theforge mail list group photo site is
>http://www.photoaccess.com
>Login:  [email protected]
>password:  anvil
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