[aaronbee]

I've read older posts about this, but for the sake of my own understanding, I would like to ask a question to see if I understand it or missed something.

The thing is, I already have a plasma table, and for thousands of dollars more the people who built the table will gladly sell me an attachment to cut pipe, but I don't want to spend thousands of dollars more.

So, basically, if I bought another stepper motor identical to the one which currently drives the Y axis (across the table) and attached it to a chuck to hold the pipe which had a gear setup identical (same number of teeth, pitch, etc.) to the one currently used by the Y axis, wouldn't I be set? Actual design aside (like how to attach said chuck and additional motor to the table), in concept, I just unplug the Y leads and attach them to my new motor?

From there I tell sheet cam the material width is the circumference of the pipe and I'm done?. Send the g-code generated to mach 3 and cut whatever I want on this pipe?

Am I missing something? Am I making this way too simple in my head and there's something I haven't considered?

Basically, I just want to notch 2" pipe and I hate using those hole-saw-type notchers. I don't really have any desire to write my name in the side of the pipe, I just want to notch it and I found a coping calculator that gives me the curve I need. I can't see why that wouldn't work, but then again, that doesn't always mean much in reality.

Thanks.

[jcc3inc]

Sir,

If you think about it, rotating the pipe may not give you the shape you wany unless the pipe is quite thin. Witth thicker pipe, the holesaw cut will match the pipe to which you attach. With plasma and a rotated pipe, all the edges of the cut are perpendicular to the outside surdface of the pipe at the point where the cut is made. As an example, imagine a 2" pipe with a 1/2 inch wall thickness and visualize the finished cut; it will NOT match the required shape. The only way to plasna (or oxyfuel) cut for a good fit is to NOT rotate the pipe to be cut, but rather raise and lower the torch as required throughout the cut. Now the thickness changes so that presents more problems.

Thin wall pipe is no problem. And maybe you can adjust the cut, if need be, to accommodate the error if the wall thickness is small.

If you want to replace your table's long axis stepper to enable rotation, you will need to generate a gear ratio to match the pipe's OD.

Another approach would be to make a friction wheel of *exactly* the pitch diameter of the present drive pinion. Now resting a pipe (of ANY Diameter) on the friction drive will result in the same distance traveled as you require. For practical purposes, you will probably want to couple two wheels together (make a cradle of sorts) to better support the pipe. This kind of pipe support is commonly used when cutting various sizes of pipes.

If you want to discuss this further, you can contact me at jccinc-at-owc-dot-net

Regards,
Jack C.

[bogger44]

I've read older posts about this, but for the sake of my own understanding, I would like to ask a question to see if I understand it or missed something.

The thing is, I already have a plasma table, and for thousands of dollars more the people who built the table will gladly sell me an attachment to cut pipe, but I don't want to spend thousands of dollars more.

So, basically, if I bought another stepper motor identical to the one which currently drives the Y axis (across the table) and attached it to a chuck to hold the pipe which had a gear setup identical (same number of teeth, pitch, etc.) to the one currently used by the Y axis, wouldn't I be set? Actual design aside (like how to attach said chuck and additional motor to the table), in concept, I just unplug the Y leads and attach them to my new motor?

From there I tell sheet cam the material width is the circumference of the pipe and I'm done?. Send the g-code generated to mach 3 and cut whatever I want on this pipe?

Am I missing something? Am I making this way too simple in my head and there's something I haven't considered?

Basically, I just want to notch 2" pipe and I hate using those hole-saw-type notchers. I don't really have any desire to write my name in the side of the pipe, I just want to notch it and I found a coping calculator that gives me the curve I need. I can't see why that wouldn't work, but then again, that doesn't always mean much in reality.

Thanks.

Tom candcnc.com has a screen for pipe cutting I think that your idea will work fine just have it work like the ones you can but there are videos on thier operation. you will get some taper just like flat steel but it will be fine.

I also am building a pipe cutter I have a lathe chuck (from a machine shop, a couple hundred bucks they get sloppy a few thou. too many and they change them out after a while) with a 4" through hole. I cut a flange to bolt to the chuck and welded it to a 4" id 1/2" wall piece of pipe.

Basically the outer wall of the pipe will ride on bearings and the moter will drive off the outer wall. This way I can stick a 30' 3" piece of pipe through the chuck and cut it.


I'm building my own scribe will cost a couple hundred plus the air scribe 500.00 but I can't see paying 3000.00 for a kit.