[badassdevil]

I am looking for some help i am trying to get rid of the whip on my z lead screw it is 1800 mm long and 12mm in diameter any ideas how i can lose the bad whip i am thinking of using m16 or m18 screw

[diycnc]

i would go with 25mm with 10mm lead minumum, it will still whip but at a higher rpm

look up on ebay LinearMotionBearings they have decnetly priced screws.

[BillTodd]

my z lead screw it is 1800 mm long and 12mm in diameter

That's a serious Z axis

12mm seems a little light for a screw of that length it has a core of only about 10mm.

One option (other than increasing the diameter of the screw) is to re-engineer the axis so the screw is stationary and taut between mounts, while the nut rotates (i.e. the nut is mounted, with the drive motor, on the gantry)

[Matt Adams]

How fast do you want to spin, and what is the pitch of the screw?

The 25mm diameter screw with 10mm lead recommended above is rated for 362 inches per minute. Is that enough?

1" diameter with a 1/2" lead gets you up to 468 i.p.m.

[badassdevil]

i got confused it should be the x axis lol funny considering i am a cnc machinist for a living

[badassdevil]

thanks for all the help guys i have re designed it so the nut rotates rather than the screw

[BillTodd]

thanks for all the help guys i have re designed it so the nut rotates rather than the screw

Pictures - or it didn't happen....!

[svenakela]

thanks for all the help guys i have re designed it so the nut rotates rather than the screw

Very good idea, I use rotating nuts myself and they are very well performing. I can "pre-tension" the screw and even though my screws are as long as yours (but thicker though, 16 and 20 mm) I have no problem driving my axis at 15-20 meters per minute, that's about 600-800 IPM.

Pictures not needed, I have videos.

[ame="http://www.youtube.com/watch?v=NkFSWTjDHjA"]YouTube - 20090416012[/ame]

[ame="http://www.youtube.com/watch?v=Ejed_tbt4Ho"]YouTube - 20090416010[/ame]

[peter.blais]

Looks like this thread is sorted- FWIW though, all the big screw manufacturers provide equations for predicting whip in their data sheets. A quick run through of those would prevent nasty surprises, and could probably be *roughly* used with other no name brand screws as well, for hobby use.

[badassdevil]

the system in your vids is very simular to mine and it works just great length is no longer and issue so in my opinion a better system

[BillTodd]

the system in your vids is very simular to mine and it works just great length is no longer and issue so in my opinion a better system

Come on then, where are the pictures ?????

[jurban]

Are there any commercial/stock rotating nut ball screws? The examples I've found here look custom or at least partially fabricated. I'd rather spend the money on that part instead of the time.

[Mike Everman]

Are there any commercial/stock rotating nut ball screws? The examples I've found here look custom or at least partially fabricated. I'd rather spend the money on that part instead of the time.

Well, there's two styles, belt driven and motor-integrated. Both require very nice rotary bearing sets. Thk, hiwin, nb, I think all make a belt driven nut. they are all ground ballscrews and all quite expensive.

Bosch Rexroth makes motor integrated types in sizes larger than NEMA34. My company makes NEMA23 size in both 16mm and 20mm ballscrew diameters, with leads from 5mm to 40mm. That last one will do 2.5m/sec. Mine are not exactly budget minded either, having very nice spindle bearing sets and zero backlash ballscrews.