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JasonW
01-31-2002, 02:32 AM
How hard would it be to make a tube bending die similar to the ones sold by Pro-tools? I was thinking of a tube dies with a CLR of around 7", capable of bending 2 "x .125 round tube. I have a "decent" offshore lathe: 12" (17" over gap)x 36", gear head construction with a 2 HP motor.50-1500 RPM. I would assume the blank would start out with a say, 15 " dia. I can get the die blank casted cheap. Was thinking of a 3/4"-1"x4" cylinder like protrusion in the center of one side of the blank. I was thinking of turning between centers, and attaching the dog to the protrusion. The protrusion would then be hacked off when the lathe work is complete. Is this project possible? I have only had the lathe for about a month, and am still learning.

halfnut
01-31-2002, 10:40 AM
There is a big problem, lathe is not big enough. 15 inch diameter in 12" lathe, I know it has a gap bed. The part can swing in the gap, but how are you going to get the tool to the work?

I turned some bending rolls last night, 120mm at center of radius, for 32mm tubing, actualy 1 1/4, small diameter 88mm. I used a radius cutter we had built in shop, worked good. The radius cutter could be hung sideways off toolpost, with the compound all the way back, swung over a bit, one might get there.

Lot of forces cutting chunks this big, how slow does your machine go, what kind of material. With HHS tooling at 100sfpm I figure 26rpm.

Might have to find a bigger horse.

kap pullen
01-31-2002, 12:38 PM
halfnut,
Been there, done that too.
Turning, backfacing, and grooving oversized plates with a boring bar off the back of the tool post ain't the best place to be.
But it can be done.

Lotta stress on the compound and slide.
It's only cast iron, can't take any whoopses with all that overhang.

How bout three plates bolted togather? Don't know if the pipe contacts the whole radius when bending. Maybe could use partial radius in the center plate.

my two cents worth,

kapullen

halfnut
01-31-2002, 01:13 PM
Kap,

I remember cutting threads on the end of a shaft which was hanging off end of old Lodge and Shipley one time. Had about a 3" sq bar bolted to compound, slot milled for cutter. That old 18" L&S was a horse, had something secure to bolt that long bar to.

I figured out how a threading dial works on that job, I couldn't engage it, needed to get that carriage as far to the end as posible. Figured out the Chalking the gear method of picking up right spot on leadscrew with halfnut. I chalked the chuck and watched the feedslot in leadscrew, carriage parked in same spot every time, worked good, got the job done. It was 5tpi, would have been much easier iffin it had been 4tpi, just glad it weren't 4 1/2 tpi.

This old Lodge and Shipley with it's 18" chuck is what Jason needs for this job.

kap pullen
01-31-2002, 02:48 PM
yea,
That 18" lodge would do the trick.

I had to make an L shaped bar to turn the stub ends on a new holand bailer shaft one time. had to take off tailstock, and the thread dial to get that far out.
Monarch 16 x 54".

Was a bearing fit in a recess so couldn't get a mike on it. Had to use dial calipers.
Guess it worked,he never came back, or paid me for the job.

We all get funnys now and then.

Do you like that night work?
Quit my last job over that.

kapullen