[jgramlich]

I'm kludging together a plasma torch, some rollers and a steel frame to make a machine that can cut 42" OD (or smaller) steel pipe. The machine will not only cut but it will have the potential to bevel the cut (i.e. for welding two pieces of pipe together).

I'm sort of working on a design that has an electric motor attached to what amounts to a small tire via a chain drive to rotate the pipe. Right now I'm guessing a 5hp, 220VAC 3 phase motor. I'll have to check against another machine that does a similar job, but with a saw blade (and no beveling).

The wall thickness of the pipe will be around 1/2" or less, so I'm not worried about the plasma, but I'm trying to keep this as simple as possible, both for operation and maintenance. I've got somewhere between $1000-2000 USD for controls and the motor.

What I'd like to do is literally have a "volume" knob where a user will set the volume to the wall thickness of the pipe...so there will be settings for 1/8", 3/16", 1/4", 3/8", 1/2", 5/8" and 3/4"...faster for 1/8", slower for 3/4".

Is a VFD a good solution for this project? I can set the knob to deliver signals to the vfd based on the settings, and perhaps use a microcontroller to do it digitally if necessary...but I'd rather do it analog. Keeping it simple, stupid and all that rot.

Thoughts?

[langwadt]

I'm kludging together a plasma torch, some rollers and a steel frame to make a machine that can cut 42" OD (or smaller) steel pipe. The machine will not only cut but it will have the potential to bevel the cut (i.e. for welding two pieces of pipe together).

I'm sort of working on a design that has an electric motor attached to what amounts to a small tire via a chain drive to rotate the pipe. Right now I'm guessing a 5hp, 220VAC 3 phase motor. I'll have to check against another machine that does a similar job, but with a saw blade (and no beveling).

The wall thickness of the pipe will be around 1/2" or less, so I'm not worried about the plasma, but I'm trying to keep this as simple as possible, both for operation and maintenance. I've got somewhere between $1000-2000 USD for controls and the motor.

What I'd like to do is literally have a "volume" knob where a user will set the volume to the wall thickness of the pipe...so there will be settings for 1/8", 3/16", 1/4", 3/8", 1/2", 5/8" and 3/4"...faster for 1/8", slower for 3/4".

Is a VFD a good solution for this project? I can set the knob to deliver signals to the vfd based on the settings, and perhaps use a microcontroller to do it digitally if necessary...but I'd rather do it analog. Keeping it simple, stupid and all that rot.

Thoughts?

the ones I've seen the wheels aren't driven, instead a chain that goes around
the pipe also go on a driven sprocket so it both holds the cutter on the pipe and drives it, so the wheels could just be big bearings

I guess you could use a vfd and a gear motor, but it is probably overkill
and 5hp sounds crazy how fast do you need to go?

how about something real simple for a start, cannibalize an accu drill replace the trigger with a potmeter and an on switch

[jgramlich]

It doesn't have to go very fast...probably no more than 40 inches per minute of surface travel....but the pipes are big. 20' thru 40' sections of 42" OD pipe of 1/2" thickness...might way a couple of thousand pounds possibly. Need the torque more than the speed.

[langwadt]

It doesn't have to go very fast...probably no more than 40 inches per minute of surface travel....but the pipes are big. 20' thru 40' sections of 42" OD pipe of 1/2" thickness...might way a couple of thousand pounds possibly. Need the torque more than the speed.

I see what you mean, you want to rotate the pipe. What I had in mind was to have the pipe stationary and just have the cutter "roll" around it

a lot less hassle moving the cutter around than a few thousand pounds of pipe

something like this: [ame=http://www.youtube.com/watch?v=VtQAPf681Ho]Plasma pipe cutting with PMX1650 with AMCO chain pipe cutter - YouTube[/ame]

[keebler303]

If you choose to use a VFD, the ones I use (Baldor) allow setting up to 8 speeds which are switch selectable. You could of course just use a potentiometer for the analog speed control but you won't have specific, determined setpoints. A potentiometer would allow the user to tweak the speed if desired. If you want just a button to push (or selector switch) for each thickness, the preset speeds setup may be the way to go.

Matt

[Al_The_Man]

For the speed and method shown in the video, I would think that VFD would not be all that feasible?
I would tend to go with a DC motor and a gearbox of some kind.
Using a KB/Baldor DC controller.
There are Cyclo or Planetary G.B's that are available, ebay etc that would do the trick.
A bonus would be a motor and drive that takes a tach.
Al.

[jgramlich]

It's got to be able to cut smaller than 42" as well...probably down to 8 or 12 inch pipe. Another thing I want it to do is bevel cuts...probably at 45 degrees...basically to create a gap for welding two pipes together.

[langwadt]

It's got to be able to cut smaller than 42" as well...probably down to 8 or 12 inch pipe. Another thing I want it to do is bevel cuts...probably at 45 degrees...basically to create a gap for welding two pipes together.

for smaller pipe just use a shorter chain, for bevel cuts angle the cutter illustrated here;

[ame=http://www.youtube.com/watch?v=OaLW7y0w3FE]How to cut steel pipe with an oxy-fuel pipe cutting machine. - YouTube[/ame]

[Al_The_Man]

Looks like it may be easy to duplicate using ordinary roller link chain?
A chain length could be pre-made for every dia. used.
Once the chain is connected a tensioner could be used.
Al.

[langwadt]

Looks like it may be easy to duplicate using ordinary roller link chain?
A chain length could be pre-made for every dia. used.
Once the chain is connected a tensioner could be used.
Al.

yeh something like a cannibalized roller skate or four big ball bearings and
a few lengths of bike chain

the video shows how tensioning is done by pushing the wheels against the pipe

[Joe Jones]

You want to cut 3/4" tubing on an angle for welding, and you want to rotate a multi-ton pipe in sync with a plasma cutter.

First, what plasma cutting machine are you currently using? What torch? A hand torch or a machine torch?

It is possible to make the cutter you seek, using a simple PlasmaCam 4x4 machine that is heavily modified for this purpose. I would love to tackle the project!

As for rotating the pipe, the motors on the PlasmaCam table obviously cannot rotate a pipe that weighs many tons, but I am sure there are ways to translate the movement of a small motor into a matching movement of a larger motor.

This would be fun to put together! Where are you located?

Joe

[Al_The_Man]

This would be fun to put together! Where are you located?

Joe

Legacy thread from 8 Years ago!
Maybe solved it by now!