Large CNC Foam Cutter

[damae]

Originally Posted by cnccutter ...My buddy at work does the welding, cost me a dozen donuts...

Nice to have talented friends like that! I may think of going the air cylinder route eventually... sounds like a slick solution.

[esawyja]

I also use the air cylinder setup, check it out at http://www.poly-cor.com
look at the CNC page

[Mcyoda]

Originally Posted by Mac T. Knife I just got back from looking at the Megaplotter machines, sold by Demand Foam, and Original foam. They are using a timing belt system,,, the belt looks similar to "zip" ties. They are using steel guide rods embedded in the aluminum frame, and shielded bearings in a "V" configuration.

Can you use timing for vertical or Z-axis, will the weight of that axis push it down. Since belt has no holding torque, I was thinking is have to be screw.

[Mcyoda]

Originally Posted by esawyja I also use the air cylinder setup, check it out at http://www.poly-cor.com look at the CNC page

Can you share with me how the setup the air cylinder to control tension. May be a few photos. How is the tension control by the volume and pressure of the air?

Thanks

[blackbeard52]

Since belt has no holding torque, I was thinking is have to be screw.

Actually the belt is controlled by probably a stepper motor which has holding torque and since there is really no weight involved in the head it shouldn't be a problem. I have seen springs used to control tension on many foam cutters.. The air cylinder idea is intriguing must be a low pressure cylinder to prevent breaking the wire at high temps.

Bob

[Mcyoda]

Originally Posted by blackbeard52 Actually the belt is controlled by probably a stepper motor which has holding torque and since there is really no weight involved in the head it shouldn't be a problem. I have seen springs used to control tension on many foam cutters.. The air cylinder idea is intriguing must be a low pressure cylinder to prevent breaking the wire at high temps. Bob

Bob, you are right on stepper motor when is powered there is torque but I check the Demand Products that the Large CNC is control by servo motor. I was thinking that servo motor has no torque during idle. May be I am wrong on this I haven't own servo motor.

[blackbeard52]

Yes it does....about the only difference is the control and positioning is more accurate with a servo. And more expensive.... maybe overkill for a foamy.

Bob