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Author Topic: Some starting advice for two steppers on one axis  (Read 13325 times)

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Offline stirling

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Re: Some starting advice for two steppers on one axis
« Reply #20 on: February 27, 2016, 08:04:08 AM »
Why not use current sinking then any BOB should do. Just go from the UC300 to one BOB and then from each BOB output to each pair of drivers.

As far as squaring is concerned - you could just drive the axes against the end stops for a moment.
Re: Some starting advice for two steppers on one axis
« Reply #21 on: February 28, 2016, 04:09:45 PM »
Yes, squaring will be needed.  The two xy tables will be carrying a single bar of some sort for the hall probe along a Z axis.

Picture a 12 in DIA tube, 6 ft. long with an X-Y table at each end that will position a bar in the tube.  A probe runs along the bar (Z axis)
to scan the inside of the tube, thus mapping the magnetic field.  Positioning on X, Y, and Z.

TheDude,
Re: Some starting advice for two steppers on one axis
« Reply #22 on: February 28, 2016, 04:17:35 PM »
Just thought up another squaring option that might work well.
If one was to put a simple SPST toggle switch on the PULSE line to one of the paired drives, isolate the signal to that drive while squaring with the other, then close the switch for normal operation.
A viable work around ?

Just thinkin",
Russ

This is an interesting idea..  I was thinking I would do this mechanically, but isolating them temporarily to adjust with Mach seems like a good idea.  As long as they would not jump when reenergized.

TheDude,

Offline stirling

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Re: Some starting advice for two steppers on one axis
« Reply #23 on: February 29, 2016, 04:36:23 AM »
Picture a 12 in DIA tube, 6 ft. long with an X-Y table at each end that will position a bar in the tube.  A probe runs along the bar (Z axis)
to scan the inside of the tube, thus mapping the magnetic field.  Positioning on X, Y, and Z.

Why do you need TWO XY tables for this?
Re: Some starting advice for two steppers on one axis
« Reply #24 on: February 29, 2016, 06:43:58 PM »
Positioning accuracy needs to be .002-.005in.
I cannot have sag along the Z axis, so I thought the best approach is to tie the Z axis bar on both ends for proper support.
I don't have much room for a driveshaft along the tube axis to drive the other end.

This is not the typical use of CNC for metal or wood working, but I proposed this idea as an acceptable positioning device to map the magnet bore tube since I have some experience with a HobbyCNC controller with my lathe in my home shop.

Any other ideas?
« Last Edit: February 29, 2016, 06:49:05 PM by thedude »
TheDude,
Re: Some starting advice for two steppers on one axis
« Reply #25 on: February 29, 2016, 07:05:01 PM »
I don't subscribe to an online pic posting site so I can't provide a sketch of the basic layout.  Does this site not let you post a pic from your local PC??
TheDude,

Offline ger21

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Re: Some starting advice for two steppers on one axis
« Reply #26 on: February 29, 2016, 07:15:41 PM »
Yes, click the Preview button and you'll then see options for attaching pics.
Gerry

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Re: Some starting advice for two steppers on one axis
« Reply #27 on: February 29, 2016, 07:36:56 PM »
Ok,  giving it a shot.  A crude sketch of what I'm going to do.
TheDude,
Re: Some starting advice for two steppers on one axis
« Reply #28 on: February 29, 2016, 07:37:34 PM »
It worked,, !! thanks ger21 !!!
TheDude,

Offline stirling

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Re: Some starting advice for two steppers on one axis
« Reply #29 on: March 01, 2016, 04:07:24 AM »
Your labeling is probably guided by your familiarity with lathes. But if you swap the labeling for X and Z you have a standard XYZ gantry layout. Two slaved motors for Y and single X and Z. Sorry - I don't see a problem here. All pretty bog standard stuff. What am I missing?