electronic lead screw

I did a bit of testing of the ELS.

To assess the maximum force available, I have a bucket of lead wheel weights as a dead weight. It is able to move against a 110 lb. force which is the capacity of the bucket. At 105 lbs. it balked at a feed rate of 3.5 mm/rev. which corresponds to 1040 rpm on the stepper but was happy with 3 mm/rev. or 890 rpm. At 110 lbs. the limit was 2.5 mm/rev or a stepper speed of 744 rpm.

I doubt seriously that I would ever be running that fast. Certainly not with metal. I will thread at 170 rpm for the spindle speed and the coarsest inch thread I can cut is 8 tpi which would be 510 rpm on the stepper motor. Even if I cut a metric 5 mm thread at 170 rpm, the stepper rpm would only be 800 rpm.
 
RJSakowski said:
I did a bit of testing of the ELS.

To assess the maximum force available, I have a bucket of lead wheel weights as a dead weight. It is able to move against a 110 lb. force which is the capacity of the bucket. At 105 lbs. it balked at a feed rate of 3.5 mm/rev. which corresponds to 1040 rpm on the stepper but was happy with 3 mm/rev. or 890 rpm. At 110 lbs. the limit was 2.5 mm/rev or a stepper speed of 744 rpm.

I doubt seriously that I would ever be running that fast. Certainly not with metal. I will thread at 170 rpm for the spindle speed and the coarsest inch thread I can cut is 8 tpi which would be 510 rpm on the stepper motor. Even if I cut a metric 5 mm thread at 170 rpm, the stepper rpm would only be 800 rpm.
Click to expand...
does this mean Briney Eye was led astray by an Eng book?
 
RJSakowski said:
I found this online calculator.
The calculations agree fairly well with what I observed earlier today.
Click to expand...
sorry re belated response,
Thankyou 4 the link, but re Torque(raise) = F*Dm/2*(L+u*PI*DM)/(PI*Dm-u*L) , Torque(lower)= F*Dm/2*(L-u*PI*DM)/(PI*Dm+u*L)
definitions, terms, not found.
plugged in values left coefficient at 0.1, "compute", got ans of "Torque Raise" 0.512, "lower" of -0.156 but i don't get what that means, no units, just 'select units' in parentheses.
 
Qtron said:
sorry re belated response,
Thankyou 4 the link, but re Torque(raise) = F*Dm/2*(L+u*PI*DM)/(PI*Dm-u*L) , Torque(lower)= F*Dm/2*(L-u*PI*DM)/(PI*Dm+u*L)
definitions, terms, not found.
plugged in values left coefficient at 0.1, "compute", got ans of "Torque Raise" 0.512, "lower" of -0.156 but i don't get what that means, no units, just 'select units' in parentheses.
Click to expand...
If you dig into the site, they are talking about a vertical lead screw so gravity is taken into account. Raising the load against gravity requires a driving (+) torque while lowering the load in a controlled fashion requires a braking (-) torque. For our purposes, we need only look at the torque required to raise the load.
 
RJSakowski said:
If you dig into the site, they are talking about a vertical lead screw so gravity is taken into account. Raising the load against gravity requires a driving (+) torque while lowering the load in a controlled fashion requires a braking (-) torque. For our purposes, we need only look at the torque required to raise the load.
Click to expand...
Thanks RJ.
BTW, & i normally wouldn't do this so freely, if U want a rotary divider WITH auto settable X table feed for automated cutting of gears, I can highly recommend Steve Ward's version, his webpage not updated yet, as the improved version just completed.
Very smart , comprehensive, & well written s/w, using a PIC.
I just today got it going with an auto-tuning stepper driver from Leadshine.
8000 microsteps soooo smooth!
Www.worldofward.com
 
RJSakowski said:
If you dig into the site, they are talking about a vertical lead screw so gravity is taken into account. Raising the load against gravity requires a driving (+) torque while lowering the load in a controlled fashion requires a braking (-) torque. For our purposes, we need only look at the torque required to raise the load.
Click to expand...
Hiya RJ hope ur OK, didnt hear back re Staves rotary table controller. (I didnt pay heaps for it!).
Am not his 'official' promoter, in case I gave that impression.
Finally Got cloughs els going, after long delay with led& key board delivery.:)
 
Qtron said:
Hiya RJ hope ur OK, didnt hear back re Staves rotary table controller. (I didnt pay heaps for it!).
Am not his 'official' promoter, in case I gave that impression.
Finally Got cloughs els going, after long delay with led& key board delivery.:)
Click to expand...
Things are fine here. Just settling finally into winter. I hope you are far enough away from the wild fires to not eat too much smoke and ash.

I probably wouldn't have an interest in the rotary divider. I already have a 6" 4th axis for my Tormach. It too is crazy smooth. I don't recall what the driver microstep setting is but it increments in .001º or .36 seconds of arc. My 12" RT is coarse by comparison at 5 second resolution.

I have designed a tool post for the Tormach so I can use it as a vertical CNC lathe. The working length is comparatively short but I can, in theory, turn lengths of around 6". Because of the R8 spindle, I wouldn't be able to run work through the spindle, a problem in common with the ER collet chucks. The Tormach also doesn't have the capability of synchronizing the spindle to the other axes so threading in that mode is out but I have threadmilling capability so I'm covered there. I also would need to get a small three or four jaw chuck to be able to turn work larger than the R8 collet capability.
Tormach Lathe Accessory.JPG


Glad to hear the ELS is finally working for you. I want to change out the LED's on mine for brighter ones but that isn't urgent. When I ordered the display board, I actually ordered two so I have a spare. I haven't ordered the LED's yet but it will be a quick fix when I finally get them in.

I did some threading using the ELS a week or so ago. A bunch of studs for fastening 1-2-3 blocks together. It sure was nice to be able to switch from feed to threading without messing with gears. It makes me wanting a VFD for the spindle though. Always another project.:rolleyes: Actually, next on the list is to finish work on the auto release for the half nuts. The design has been done for some time and parts have been acquired. I just need to cut some metal. My expectation is that it should be repeatable to within a few thousandths.
 
RJ, U've been busy! Thanks for sharing & posting the cad drawing too, very nice. Not sure re the need for a vertical lathe, horizontal seems more natural.
Tool post to be motorized?
Probably wont need 0.01° provided on Steves drive, let alone your precision quoted, except if driving a telescope!
Smoke has hit us again, but not as bad, rain has doused some of the fires, ~ 100 still burning tho.
Smoke has travelled around the world now. 9-13 miles up!
So thats why the 1-2-3 blocks are Swiss cheese.
(I had asked at a shop, but no answers).
I have a VSD, but not fitted yet. Pain changing belt position on the motor end of the lathe. Upper belt OK.
Just a thought re feeds vs threading, if u use the els to provide the faster feed mode, that would add to the wear of the leadscrew c/f using the built in auto feed already provided on the lathe.

I am quite interested as to how U auto release the ½ nuts, and integrate that with cloughs els.
Cheers,
 
You must log in or register to reply here.
Back
Top