Hooking up a 25:1 motor to a ballscrew Z axis

[steve4460]

Here is a nother question .
I have this ball screw driven Z axis and I would like to hook up a 25:1 asm98aa motor to it, the ball screw moves 1/4" per turn . What would be the numbers to enter to make this work?. Where do I set this up ?. I know that the motor might be overkill but that is the only one I have with the matching drive that works on the alpha controll board .
Thanks for the help .Pictures will follow when its done .

[dirk]

The Unit value would be: 200 (steps rev) x 25 (reducer) X 4(turns per inch = 20,000. This is very high. Your top speed on that axis using Alpha control will be 1 inch per second. If this is a second Z-axis you will have to activate the A axis in shopbot control software.
I'm curious as to which driver you are using that is compatible.
Any Step Direction driven driver should work with little modification. I have found that I had to use ground common instead of +5v common to drive Geckos off of Alpha Controller, which is the reverse of PRT controller. I also had to add a buffer to increase the sinking capacity as the controller has a max of 10ma and the driver needed 16ma. I do not have an alpha machine, but I’m testing driving Geckos using the signals straight from an Alpha controller. I am not familiar with the actual circuit board attached to controller of the Alpha and what signals are available on that board.

I relized that the unit Value posted above did not include microstepping, which would be 10 times the unit value of 20,000= 200,000. That would make your top speed 1/10 of an inch per second. It would be best to hook up an ungeared motor to that axis.

Dirk

[steve4460]

Hi Dirk
The drive that I am using is a Vextra asd30a-a.I have all the cables from shopbot , so that takes the guesswork out of that part . I also have a 10:1 motor , would that work better ?. So what would be the numbers for that one ?. Both of these motors have the # asm98aa they are just geard differend .I shur hope that this will work for a additional Z for my indexer.
Thanks for your help .
Ps: Your the one with that mega bot aren't you ?. How is that comming along?.

Stephan

[dirk]

Stephan
Yeah, I’m the one building the big bot. It’s progressing well, I started on the gantry today. If all goes well I’m hoping to be finished in 4 to 6 weeks.
I didn’t find the exact motor you specified on Oriental motors site. However I'm assuming it's an AS-series Alpha motor. Looking at the specs for the different geared AS-series motors a 25:1 motor has a max permissible rpm range of 0 to 120 rpm which translates to 120(rpm)/60(seconds)=2(rounds per second)/4(rounds per inch)=.5 inches sec top speed. The 10:1 reducer has a max permissible rpm of 300 which translates to 300(rpm)/60(seconds)=5(rounds per second)/4(rounds per inch) = 1.25 inches/second. The 25:1 would be great to turn the indexer. You could get by with the 10:1 on the Z. Are you set on using a ball screw? If you were to use Rack and pinion on your Z either motor would work extremely well. I didn't realize these were Alpha motors, so I think you can adjust the step resolution in the driver and wouldn't have problems with step frequency. How did you end up with these motors?
Dirk

[steve4460]

Hi Dirk

After reading your first reply I got to thinking that the slide with the ballscrew is a little big and heavy for what I was thinking of doing with it so I think I will go the rack and pinion gear way .
I got the 2 25:1 motors and drives from a guy in Texas of ebay .
One of the 25:1 motors is for the indexer .
Thanks again . I might actualy get to hook this all up this next weekend and then all the fun starts .Good luck with your bot too .

Thanks
Stephan