CPR PPR recomendation

[wcarrothers]

Getting along with the building of my 4x8

But was wondering about which incoders I should get for my servo motors. My mill conversion used the same 5 turns per inch screws that the router mill used but steped it down by 1/2 with the pully. That used a 250 CPR (1000 PPR quad) incoder

I was going to start out direct driving my z and x to the 5 turns per inch screws and I was wondering since I will not be gearing those down if I should use a 500 CPR (2000 ppr quad) incoder with it rather then the 250. Or rather reasons for doing one over the other..

Hopefully I will have some part pictures to post of the build up soon... Things have been a little slow..

b.

[wcarrothers]

Here is a little more detail on what I'm doing:

I'll be using 1100oz motors.. Hopefully they will be in soon..

To start I"m planning on direct driving the z and y ball screws that are .2 pitch (or 5 rotation per inch movement)

And the X will start with a rack gear that will have ~3.14" per turn movement gear down through a 10:1 planetary (so it would be something like .314" movement per turn of the motor.

Don't know if I will need to gear either of those down more.... But was thinking the mill conversion was a 2:1 reduction with the .2 pitch screws and used the 250cpr's and since I was not gearing the router mill down the same I was wondering if 500cpr's would be what I should go with?

Thanks again...

b.

[wcarrothers]

Incase anyone wants to know.. Dan from camtronics got back with me and suggested I do 500 CPR's for z and y to give resoloution of .0001 and then 250 cpr for the x that would give .00031

So that is what I'll end up doing.

b.