piercing with oxy torch

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Old 11-01-05, 12:55 PM
peteetah
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Angry piercing with oxy torch

I am having a problem with popping when trying to pierce 3/4" steel. I assume it's from being too close to the piece with the torch tip, but when I move farther away, it won't preheat to cut. I have cut the piece successfully from the edge, but can't pierce. I am using a #2 tip, at 35 oxy and 3 for acetylene. Is this too thick too pierce a hole? Help!! Need to finish my wood splitter before snow!!
 
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Old 11-01-05, 03:53 PM
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I haven't tried to pierce 3/4" steel yet.
I would try 7 psi on acetylene if your tank is not to small.

Why don't you drill a hole first ?
 
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Old 11-01-05, 06:19 PM
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peteetah,

What I have done is to preheat well and start the cut at a bit of an angle to allow the sparks to blow to the side a bit and then bring the torch vertical as the surface melts.
Piercing is a spark intensive operation at the best of times and you have to be very carefull of yourself and what is around you.
The smaller the diameter you are trying to achieve the more difficult it becomes.

Predrilling a starter hole is a very good idea because it gives the molten material somewhere to go.

What shape and size are you trying to open up?
 
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Old 11-03-05, 01:18 PM
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I am piercing to a 5/8" diameter bolt, so I would say the hole needs to be 3/4". I do have the large acetylene tank. I would asume that once pierced, the edges of the hole would be easier to preheat and cut, just like the edges of this piece which I have already cut in half! (no problem) I just can't seem to pierce without the popping, which I assume is from being too close to the piece, yet can't preheat if I don't get closer. I do have a drill press. (floor model) Would that be easier? I assumed a 5/8" hole thru 3/4" steel would take an eternity.
 
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Old 11-03-05, 02:06 PM
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Since you are having a problem getting the metal hot enough to pierce (which is understandable) just drill an 1/8" hole in the plate and use it for a starting place for your cut. This will give the metal a place to exit instead of blowing back at you.
 
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Old 11-03-05, 03:58 PM
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I do a bit of metal working but I would choose drilling over burning any day.
Welders who do this all day long have the skill to make a very clean hole but for even advanced amateurs, burning holes for bolts is a crude operation.
I was able to pick up a 9/16"- 1" import bit set for not too much money and I have been getting good service out of them.
If you lube the bits and don't press too hard they will last a hobbiest a long time.
 
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Old 11-03-05, 06:08 PM
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oxy= 40
acc=07

light torch with ACC and adjust until flame leaves tip (small space between end of tip and start of flame...now turn back till flame rejoins tip end...now adjust OX untill you have no feathering.....preheat back of plate for 30 seconds or so...now move to side your mark is on..like stated above (almost) heat with the tip as far from the plate as the blue flame is long and straight at the metal...only when you are ready to cu do you then turn the tip jsut slightly to allow the molten metal to blow out slightly sideways until you blow through

i am not sure what a number 2 tip is unless you state the torch brand...i use a victor and use a 100-1 tip for plate that thick
 
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Old 11-03-05, 11:10 PM
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If your trying to remove a rusted 5/8" bolt.
I would heat it to cherry red then it should unscrew while red hot.

Or drill a 1/8" hole (1500 rpm) thru then use the larger 5/8" drill (400 rpm) it should take less then 2 minutes with the larger drill.
You may need to grind the bolt flat so you can start your drill.

The popping is either your over heating the tip or its collecting dirt from the material
A higher pressure on the acetylene can help push the heat and dirt away from the tip.
 
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Old 11-04-05, 07:31 AM
peteetah
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Thanks, everybody. I will use the drill press to drill out my holes. I have used my torch for all my holes, and you are right, they aren't beautiful. Must admit that I have used the drill press only for wood, seemed that it was easier and faster to burn thru the metal What kind of bit do I need to drill this?
 
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Old 11-04-05, 02:16 PM
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Drill bits.
look at the link.
Be sure that they are made from high speed steel.
You will see HS or HSS stamped on the shank of the drill.

Cobalt bits are good but cost more. used for material that is hard to cut like stainless steel.
The cobalt brills have a thicker web and can be hard to start with out first center punching deeply.

Most of the time a drill bit will catch and try to spin the part as it breaks thru the other side.
the part may also try to lift up.
So use clamps.

Drill bits can shatter use safety glasses.

If your making a lot of holes. drill the holes that you heated last.
some times the slag or something may chip the drill bit.

http://doityourself.com/store/highspeedsteel.htm
 
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Old 11-04-05, 08:57 PM
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peteetah,

When drilling, the manufacturer of the bit will have a recommended speed but here is a handy little chart in PDF format when you don't have this info.
Print and hang it on your shop wall.

Remember to use a lubricant and go easy and your bits will last a long time.

Speed chart link
 
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