Anti Whip solution for long screws?

[martinw]

Dear erniebro,

It's probably worth having a similar type of arrangement where the lead screw passes through the moving gantry. For example, you could have a two leadnuts on the gantry spaced a few inches apart. The two could form an anti backlash system at the same time as keeping the screw in line.

BTW, I'm sure it's been done by loads of people..

Best wishes,

Martin

[One of Many]

I'd think it would be less work to start over with a larger screw than design a fix to doctor a problem. I have found the fix itself comes with its own set of problems.

I had an opportunity to see a very, very larger Thermwood 5 axis router with a very similar screw support design that supported the 2"+ x 30-40'(?) high helix ball screws. The screws were stationary and the servos ran with the gantry turning the nut. The bottom of the gantry structure had a cam shape where the servos were mounted. The screw supports had cam followers that rode on the cam shape to handle a reversal in direction without interference. I get the sense this worked for this application for 2 reasons. First, the screw did not turn and second, there is far more flat surface on the high helix ballscrew than a standard threaded rod.

The problem you may gain is wear from a screw cutting into the support surface.

DC

[Khalid]

erniebro thanks for explaining the concept..I am visualizing another idea..I will use C type half nut of teflon mounted with some retractable mechanism at the bottom of my Y-slide at a distance of 6" from my lead screw nut...As the fake nut arrived at the motor end plate it will automatically retract..as it goes back it will engage again...

Another idea is to mount the same in the middle of gantry, so when the nut mount plate come closer it retract and when it goes further it reengage...

Sorry for bad english