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View Full Version : Cheap plasma-flame cutter gantry, your ideals?



ibewgypsie
05-31-2005, 06:15 PM
Using roller drawer slides, boxed together in a 90 degree cross slide arrangement. total gantry axis weight should be less than two pounds. Motors can be any small available one putting out 125 oz torque.

Using steppers, wave drive (cheap rascal)

Using browning xl gear pulleys attached to a motorcycle type cable drive (removing weight from moving structure.) Motors are stationary.

I recently played with a 2d router mounted on just such a arrangement. If it will work for a router it will work for plasma cutter.

HOW accurrate will it be? any bets? You could feel "no play in the router and it was used"


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David Cofer, Of:
Tunnel Hill, North Georgia

plm
05-31-2005, 09:36 PM
ibewgypsie,

Sounds like a plan. If it worked for the router, then it should work even better for cutting with fire - usually don’t need near the rigidity in the gantry system as you would for a router. Any plans for controlling the Z axis? Or, will it be fixed?

Never thought much of the combo gantry machines that claim they can be used for either routing or plasma/laser/torch. Seems like to be rigid and massive enough to do routing, you would be giving up performance that could be obtained with a lighter gantry in non-contact fire cutting – seems like the accel/vel/deaccel profile can be a lot more aggressive and probably cheaper to obtain. Evidently, your light router design seemed to work okay in routing, so I guess I need to rethink my logic.

Good luck with the project and keep us updated – I too have been thinking about building a gantry system for thin 2D stuff.

plm

wierdscience
05-31-2005, 10:06 PM
How about just a simple pantograph with steppers at the joints?

I don't think it would take much to run a torch around,probably more power needed to flex the cables/hoses.Rotating joints for the gas(s) and slip rings for the current.

Nah,never work...

Mike Burdick
05-31-2005, 11:34 PM
If I were making one I'd us a single arm with one stepper at the start and one in the middle. This way there are three sides open for ease of material placement and the arm arrangement can cut a pretty large workpiece in a very compact footprint. The arm can be raised and lowered if needed. For storage, just fold it up against the wall.

The arm also has the benefit of almost frictionless movement since the joints can be made from standard ball bearings which will require very little stepper motor torque.

I made an oxy/propane cutting torch like this. Works great.
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[This message has been edited by Mike Burdick (edited 05-31-2005).]

hammerhead74000
06-01-2005, 09:18 AM
For a small machine, that should work fine. I wouldn't do it on the Y axis, though - I would mount the motor stationary, and use a timing belt to drive it, and only use the cable drive for the X axis (assuming you have the axis slides mounted in the manner of a knee mill - the X rides on the Y).

P.s. I think you are already aware of it, but for our other readers: your plasma cutter must be electronics-compatible, i.e., not the high-frequency starting type; otherwise it's gonna' emit a lot of electro-magnetic interferience, and will crash the computer, among other things. Hypertherm, off the top of my head, makes some that are CNC compatible.

fixxit
06-01-2005, 09:26 AM
There is a website that has tons of ideas about, and pictures of homebuilt CNC routers, flame cutters, hot wire foam cutters, etc.

www.cnczone.com (http://www.cnczone.com)

There is enough material there to keep you browsing for days.
Click on the "forums" link at the top left side of the opening page.

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457863656C73696F72202100


[This message has been edited by fixxit (edited 06-01-2005).]

ibewgypsie
06-01-2005, 10:25 AM
Hammer:

I have already had the plasma cutter mounted on a arm off my cnc bridgeport. No problems.

The monitor did look funny a time or two, but I got magnets around it so it looks funny at times anyways. (my x-arcade joystick box is mounted to a magnet and stuck the the head)

I am just looking for a near-throwaway way to build one with the type tiny motors I see on a line tracer rig. 50 oz or so.. can be ran by single stepper ic chips. Ie, $1.5o per axis. The chips also have 2 bit, step/direction.

I do like the ideal of a barrel mounted post-pantograph.. keeping it cutting square is one problem. I'll sketch some more.

Ideal right now is the same as I had before to make a very light square frame to hang on a barrel, or take loose and sit onto a sheet of metal on 4 feet like a apollo lander. (except magnetic feet)

I bought some tight ball bearing drawer slides off ebay, they are in shipment. If worse case scenario? I will build some drawers and a toolchest.. HA.. nothing lost.

Last one I built cost ><$200, this one I want to cost less than $50.

They just came in UPS>
http://img.photobucket.com/albums/v85/ibewgypsie/Dscn0925.jpg

Ball bearing drawer slides.. brand Accu-ride from ebay. $20 for 4 pair of 20" slides.

They are "tight" and move freely. MUST have opposing sides to hold stress. At full extension I can not feel any movement up and down. They are 100 pound slides.

I think, 2 125 oz motors will power them. I am hunting some aluminum 3/4" angle now.

If I become angry, throw these into the corner? I can always build a machine tool chest. Personally? I think they will tote a flame cutter for a while before retiring.

[This message has been edited by ibewgypsie (edited 06-02-2005).]