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Old 20-06-2012, 11:40 PM
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Nico13 (Ken)
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Nico13 is offline
 
Join Date: Jul 2009
Location: Geelong region.
Posts: 947
Quote:
Originally Posted by alistairsam View Post
Nice work Nico,
Would you have a link to the controller and The stepper?
I like the simplicity and smoothness, should do the job well.
Is that a 7.5 deg stepper with a gearbox?

Just a suggestion
I'm a fan of micro stepping and I think you could get finer movement with a 1/16th controllerlike the allegro A4988 stepper controller, a 555, and your encoder switch with a 1.8 deg motor like this one
http://www.robotgear.com.au/Product.aspx/Details/459
This is the controller
http://www.robotgear.com.au/Product.aspx/Details/561

This video is a test of 1/32 micro stepping with a different controller where I'm sending a train of 6400 pulses for one rev. So one manual step pulse would yield very small movement and you could have one pulse per encoder tick.
http://m.youtube.com/watch?v=53tgJ4pwn1w

I know micro stepping yields lower torque, but current is adjustable and torque should be ample for a focuser.
I'll be making one with a simple lcd display that shows the number of steps.
Just need to think of a home position routine.

Yep love the idea of micro stepping as well and the stuff you linked to looks the bees knees.
The bits I'm using will do the job although not a small step size, 5.6 deg I think it was, the gear reduction solves that issue but with the slight dissadvantage of a small amount of backlash in the gear set, not significant enough to cause a problem at my level of imageing though.
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