Re: mini-mill converson data

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<davemucha@j...> wrote:

> Hi,
>
> I am looking for data on converting a mini-mill to steppers.
>
> can anyone offer some links ? or recomendations on stepper sizes ?
>
> I was thinking of starting with some NEM34's 150 in-oz because I

have

> them and could always swap out for larger units.
>
> Also, what is the best way to automate the Z axis ?
>
> Dave

Dave,
I just finished the conversion on a "Grizzly" type with the R-8
spindle. A ball screw for the Z-axis is the only way to go. I am
running a 180oz NEMA 23 with a 2:1 pulley ratio. Direct drive on the
X&Y axis'. Rapid rates are 24 IPM--Z and @13 IPM X&Y.(until I ball
screw them as well)(would also improve with higher voltage drives)
Not finished fine tuning EMC yet so they might get even better! I did
a jig for work with it: 1st piece:50 holes .035 DIA, 5/16" THK 6061,
w/ 2 .187 dowel holes 2nd piece: 50 holes .024 DIA, 1/8" THK O-1
flat ground, w/ 2 .187 dowel holes. I used solid carbide "circuit
board" drills with the spindle running flat out, no broken drills
even with the "slow" spindle speed. Had to "peck" .015" deltas
through the O-1. Both pieces line up perfect. I will be going to
market with the retro kit soon if you are interested? Just waiting
for another saddle to arrive so I can finish the ball screws for the
X&Y.
Good Luck with your upgrade it yields a nice little cnc for small
parts.
Ken