Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: LesC on March 15, 2013, 10:19:19 AM

Title: What Ratio Do I use
Post by: LesC on March 15, 2013, 10:19:19 AM

Hi,

just wondering if I employ a couple of stepper motors for my X,Y,Z axis how do I go about sizing them , any tips welcome.

What is the normal reduction ratio you guys use on the tooth belt stage, I am guessing about 5:1. Ultimately this should give me my resolution right ?


regards   Les C

Title: Re: What Ratio Do I use
Post by: JohnHaine on March 15, 2013, 10:59:35 AM

5:1 would be very high!  Sizing will depend on the machine - what are you trying to drive?  My small Denford mill has a 2:1 reduction and is quite happy with small type 23 steppers.  My Myford lathe has a larger, still type 23 stepper, but direct drive on the X-slide and I think 2:1 on the leadscrew IIRC. 

Better resolution comes from using microstepping on the drivers.  On the mill, the screw pitch is 5mm, so one full step is 5/(2x200) = .0125 mm.  Then I use 8 microsteps per step, so the theoretical resolution is .0125/8 = ~1.6 micron.

Title: Re: What Ratio Do I use
Post by: Chaoticone on March 15, 2013, 11:07:07 AM

Resolution can also be changed with gearing.  You will just need to do some math and a lot of thinking to figure out the best motor,gears,drive for you.  Oriental motor has a pretty good utility to help you figure out what you need.  I would defiantly do the math my self.

Brett

Title: Re: What Ratio Do I use
Post by: stirling on March 15, 2013, 11:33:56 AM

Quote from: JohnHaine on March 15, 2013, 10:59:35 AM

Better resolution comes from using microstepping on the drivers.

Hmmmmm - let's just say - debateable  :)

Ian

Title: Re: What Ratio Do I use
Post by: JohnHaine on March 15, 2013, 12:03:08 PM

...up to a point!