Re: [CAD_CAM_EDM_DRO] Sherline Z-axis ballscrew feed.

Dan,
I have been pondering the same thing as the Z axis slop is seriously
screwing up my engraving. There is a routine that lifts the tool at sharp
internal corners at the V tip angle to give the same radius as the tip
at the surface. With backlash all you get is a gouge. Ugly!
Replacing the stock nuts and leadscrews gets old fast.

I have contacted Jena-Tec, <www.jena-tec.com>, 888-453-6283 about their
miniature ball screw assembly p/n JTm3-08020 (300mm length, 2mm lead, 8mm dia,
nut diameter 16.5mm/0.650"). I believe this could be shoe horned in without
too much trouble. At least it's long enough to fit. Most others are too short.
I was told a price of $156.00 each, and the sales guy offered a loaner sample.
To date I have no sample and have not pursued it any further, but want to.
Would you do me/us a favor and try your end. It looks really good.
Also, I'm not sure this is a single start thread leadscrew.
I did not ask the quantity discount.
BTW, since my initial contact they have more choices now, SMALLER!. Maybe the
X and Y can be done as well??
RichD

"Statman Designs, LLC" wrote:

>
> I have a question for the group of experts here.
>
> How difficult would it be to create a Z-axis for the Sherline milling
> machines that used a zero-backlash ballscrew drive mechanism? I am not
> suggesting that you retro-fit a ball-screw to an existing Z-axis. The
> Z-axis simply bolts to the X-Y table and the spindle and motor assembly
> simply bolt to the Z-axis.
>
> How difficult would it be to completely replace the Z-axis with a ballscrew
> assembly and then re-mount the Sherline motor and spindle to the new Z-axis?
>
> It seems that this would be quite a worth while upgrade for the Sherline CNC
> system. The Z-axis is the weakest link in the ability to do repeatable work
> on the Sherline. There is no backlash adjustment mechanism and the spindle
> and motor do not weigh enough to always stay at the bottom of the leadscrew
> pitch. This can, and has, resulted in large jumps of the Z-axis downward as
> it settles to the bottom of the screw pitch.
>
> Daniel J. Statman, Statman Designs
> www.statmandesigns.com
> dan.statman@...