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Old 05-22-2019, 06:42 AM
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Default Oxy/Fuel cutting 3/4" plate needs preheated ?

https://www.youtube.com/watch?v=vEWSpJ3oJa0

FF to 8:10

I dunno, I just start cutting.....

And when did 3/4" plate become known as "thick" ?
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Old 05-22-2019, 06:59 AM
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Yup me too
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Old 05-22-2019, 07:57 AM
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I do preheat 3/4" and thicker plate... If it is something I need a smoother cut line and don't want to do a ton of grinding prep...

But if I am just looking for a severance cut the I won't bother to preheat the material... It does seem to make enough difference when cutting with O/A
even when using propane cutting.
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Old 05-22-2019, 09:26 AM
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I never preheat. I find the smoothness of cut is all about consistency of speed, distance from surface, and the correct sized tip for the job.

If you don't jerk and wallow and tilt the torch tip at right angles to the direction of cut it comes out nice. That is hard for some to do because age is stealing our skills.
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Old 05-22-2019, 10:46 AM
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Quote:
Originally Posted by Ironman View Post

If you don't jerk and wallow and tilt the torch tip at right angles to the direction of cut it comes out nice. That is hard for some to do because age is stealing our skills.

That and plasma cutters. I rarely cut with a torch anymore. With the cnc machine, I rarely cut anything by hand anymore.
When I was building a regulator station I watched an older welder cut an 8” vertical pipe bevel by hand with a torch. It came out as nice as a machine beveler. There was no fuss about it either, just measured, drew it around with soapstone and cut it. Twas impressive.
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Old 05-22-2019, 11:16 AM
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It’s all perspective. Most of the folks that those videos are really targeted to, probably will handle 3/8” plate max most of the time. 3/4” plate and the proper equipment to work it is not commonplace in home garages.


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Old 05-22-2019, 01:32 PM
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Quote:
Originally Posted by Ironman View Post
I never preheat. I find the smoothness of cut is all about consistency of speed, distance from surface, and the correct sized tip for the job.

If you don't jerk and wallow and tilt the torch tip at right angles to the direction of cut it comes out nice. That is hard for some to do because age is stealing our skills.
Yeah, same here. Once I had the layout done it was just start at the edge and go...

If I had neglected the mill scale removal option, running the torch up and down the lines to preheat would often times pop the scale off and with it the soapstone layout.

Piercing is a different color horse. I could pierce 3/4 preety easy, with only a little preheat. 1" plate took a bit more warming but I could pierce that easy enough too...
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Old 05-22-2019, 02:52 PM
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Quote:
Originally Posted by TEK View Post
Yeah, same here. Once I had the layout done it was just start at the edge and go...

If I had neglected the mill scale removal option, running the torch up and down the lines to preheat would often times pop the scale off and with it the soapstone layout.

Piercing is a different color horse. I could pierce 3/4 preety easy, with only a little preheat. 1" plate took a bit more warming but I could pierce that easy enough too...
Once years back I had to pierce and burn a 2" hole in 1 1/2" plate to make room for a hydraulic hose in the head of a log loader when there wasn't enough room for a normal torch so I had to use a straight torch, after setting myself on fire a few times I made it threw and found it is hard to follow a line with a straight torch but I whittled it out
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Old 05-23-2019, 04:10 AM
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"after setting myself on fire a few times I made it threw and found it is hard to follow a line with a straight torch but I whittled it out"


Haha, the things we do for fun...
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Old 05-23-2019, 04:37 AM
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I guess maybe I should have said I preheat because all I have is a victor jr. so no not the proper torch for cutting thicker metals but if I have to plow through thick metal I will pre-drill a hole with the drill and start from there after preheating but I can cut fairly clean up to 3/8" with the V, jr. but prefer to cut with the plasma or band saw whenever I can or it allows...
But I don't find much need for using it for cutting anymore more for heating now than anything.
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