Crazy one motor two screw idea, can it work?

[rlrhett]

I was looking at the Keeling site and realized that his motors all can have the shaft come out both sides. It occurred to me that if you mounted the motor parallel to the y axis and coupled some drill rod to each end you might be able to drive a dual lead screw x-axis without having to do belts like the Solysvaya machine.

One first obvious question would be, how would you make the 90 degree turn? If the shaft from the motor is aligned in the y direction, how do you turn screws aligned in the x direction?

Ideas?

[Switcher]

One first obvious question would be, how would you make the 90 degree turn? If the shaft from the motor is aligned in the y direction, how do you turn screws aligned in the x direction?

Belts?


.

[BigMike4u]

Somethig like a worm drive gear box. It would have to be a pretty good drive to prevent backlash.

Mike

[rlrhett]

Originally Posted by BigMike4u Somethig like a worm drive gear box. It would have to be a pretty good drive to prevent backlash. Mike

Does such a thing exist? Is it expensive? Is there a no-backlash version? Anyone have actual experience with them? Where would one get that?

[BigMike4u]

Heres one. They have a free catalog/

http://www.sdp-si.com/

Mike

[rlrhett]

Thanks. But, at over $100 per piece that is not really what I am looking for.

Does anyone have any actual experience trying to do this for a DIY machine? Is there a clever DIY solution that would make sense on a DIY machine? If not, never mind. But it seems likely someone has tackled this problem before. Is it simply unfeasible? No one out there done this?

[jcc3inc]

Sirs,

Why not use rack and pinion as the long axis drive? Use (2) gear racks, one each side!

At one time we made a small plasma machine (3 and 4 feet wide) where we used a single cross shaft having drive pinions on each end; these pinions were engaged into gear racks set onto the table with the teeth pointing UP on left and right sides. The drive motor was attached to one end of the cross shaft, and the cross shaft stiffness was increased via a tube (driveshaft approach).

It worked well; both sides of the carriage obviously moved in sync. The disadvantage was that the rack teeth pointing up tended to collect dirt.

There's a good simple solution.

Regards,
Jack C.

[rlrhett]

Originally Posted by jcc3inc Sirs, Why not use rack and pinion as the long axis drive? Use (2) gear racks, one each side! At one time we made a small plasma machine (3 and 4 feet wide) where we used a single cross shaft having drive pinions on each end; these pinions were engaged into gear racks set onto the table with the teeth pointing UP on left and right sides. The drive motor was attached to one end of the cross shaft, and the cross shaft stiffness was increased via a tube (driveshaft approach). It worked well; both sides of the carriage obviously moved in sync. The disadvantage was that the rack teeth pointing up tended to collect dirt. There's a good simple solution. Regards, Jack C.

Now that's thinking. That would be a great application for rack and pinion. Was the motor traveling WITH the gantry, or were the pinion gears fixed? Having just a little trouble visualizing.

Thanks!

[jeffmorris]

If using the motor to drive two pinions, one on each side driving rack gear, the motor has to be mounted on the gantry and travel with the gantry. I built an experimental CNC machine using rack and pinions using parts from Vex Robotics but the plastic gears were not good. I would replace the plastic gears with metal gears but I may not get metal gears that match the plastic gears exactly or can be installed on 1/2-inch hole spacing on the steel parts. For example there's a 36-tooth plastic gear that's 1-1/2 inches in diameter. I need to get a 36-tooth metal gear that's 1-1/2 inches in diameter. The plastic rack gear has 8 teeth per inch.

[billyinks]

If you wanted to stick with leadscrews, you could use a right angle drill adapter, something like this... http://www.harborfreight.com/cpi/cta...emnumber=92188