Screw drives and linear rails and wood dust

[peteeng]

Hi Gerry - No its the correct technical term although whipping is used a lot. Its in all the text books. whipping, whirling and critical speed all same...Peter

[wizard]

I think your friend is pointing out a real issue. How bad it will be depends upon the type of dust you produce.

In any event good maintenance prevents a huge problem from developing. Periodic greasing or oil lube is a must. The last thing you want to have happen is bearing tunnels gumming up causing a bearing to drag. Once this happens you can see some nasty wear as the balls drag instead of rolling. The carriages can actually lock up in extreme cases.

[Jandyman]

I'd like to work through the whip calculation posted above, but have a couple questions. First, how will I know the density? And what is "E"?

[peteeng]

Hi Jandy - Steels density is 7830kg/m3 which is in the example twice. Its symbol is rho or the funny "P". and steels modulus is E=205GPa. Which is in the example. Ho Ho Ho Keep making Peter

[machinedude]

I'd like to work through the whip calculation posted above, but have a couple questions. First, how will I know the density? And what is "E"?

this may be a little easier for you.

Metric Critical Speed Calculator | Nook Industries

[Jandyman]

Thanks! I had found that after I posted, and determined that running a 1610 ball screw over about 50" would be no problem with double bearing mounts at one end and single bearing at the other end. Doing a rapid at 300 ipm would require 750 rpm at the motor, which is apparently doable with the right motor and drivers, and it looks like I have the right motor. I learn so much on this forum!

[machinedude]

Thanks! I had found that after I posted, and determined that running a 1610 ball screw over about 50" would be no problem with double bearing mounts at one end and single bearing at the other end. Doing a rapid at 300 ipm would require 750 rpm at the motor, which is apparently doable with the right motor and drivers, and it looks like I have the right motor. I learn so much on this forum!

one thing to take note of is the torque speed curve of your motors the stepper motors tend to drop off in torque on the high end quite a bit. 750 is not near that so you should be ok as long as you are not under sized on your motors. it's an adventure and you do learn a lot by doing it yourself. even if it's what you should not do i'm guessing your running steppers i hope i was right? if you have servo's you have a ton of wiggle room they do well over a wide range of speed.

[Jandyman]

Yes I have steppers. I'm told here on the forum that as long as I have low inductance motors (I do), good drivers (GeckoDrive 450, so ??), and high voltage power supply (probably need to upgrade), then I should be good. Plus, I only need 300 IPM for rapids, no need to cut over 100 IPM.

And yes, the journey is part of the fun. No sane person would head down this path LOL.

[peteeng]

Hi Jandy - Welcome to the asylum. Peter

[machinedude]

And yes, the journey is part of the fun. No sane person would head down this path LOL.

think you hit the nail on the head on this