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View Full Version : Gear box for a CNC Plasma table?



Black Forest
12-23-2012, 06:23 AM
Any reason why these gearboxs wouldn't be really good for a CNC plasma table to reduce the motors down instead of using a timing type belt and pulleys? Seems they would reduce the bulk on the gantry and be one less thing to worry about. They are available in 5:1 or 10:1 ratio. Expensive maybe but seems quite fool proof.

http://www.automationtechnologiesinc.com/products-page/cnc-gear-box/51-planetary-gearbox-for-automation-systems-4-thousand-rpm

BigJohnT
12-23-2012, 07:53 AM
Looks good to me, just depends on the overall design of the axis drive. You need to take into consideration the fastest cutting speed you want to go. When I designed mine I looked at the cut charts in my Hypertherm manual and saw that the fastest speed listed was 666IPM but I figured I'd never cut that fast so a more realistic target was 500IPM which was the fastest optimum travel speed for any material and nozzle. Next I looked at the torque/rpm curve charts for the motors I was considering (AutomationDirect.com) to see what RPM at what voltage the motors would do. I already had chosen the G203v drive with a max of 80v and after all my calculations chose a 65v power supply. Now that I had the IPM I wanted to achieve and the RPM of the motor only some simple math was left to figure out what ratio I needed. My top two methods of driving the X and Y axis was a gear rack or a belt drive. For some unknown reason I chose a belt drive of which I've made a couple of modifications along the way. Some photos of a friends plasma table that used a gear drive here (http://linuxcnc.org/index.php/english/forum/30-cnc-machines/25901-diy-cnc-plasma-table-lots-of-pictures). The Z axis I used acme threaded rod which is plenty accurate for a Z axis with a THC. The other important thing is making a floating torch holder with a switch for touching off to the material.

I think I'm wandering off course...

John

macona
12-23-2012, 08:45 AM
Those should be fine.