Re: New Mini mill/drill

Hi Edward,
I own the Grizzly mini-mill and can answer some of your questions.
The mill has a #3 Morse taper and comes with one 3/8" and one 1/2"
collet that uses an also provided M12 drawbar. I prefer using end
mill holders with 3'8-16 thread for which I made my own drawbar.
Don't worry about the toolholders falling out. As a matter of fact
most people have problems getting them out when they are changing
tools, because they tightened the drawbar with a wrench instead of
just hand tightening it. I would never use a Morse taper without a
drawbar in a mill, though.
The Harbor freight mini-mill is practically identical, but uses R8
tooling. The JT33 that is mentioned is just an R8 to JT33 arbor for
the drill chuck. R8 holders are a little easier to get, but that
doesn't mean that you would be happy with a 3" boring head on one of
these little mills. As far as I know the Harbor Freight mini-mills
are still on the boat. Nobody has actually received one, yet.
Potential for CNC conversion: X and Y are pretty easy. I've started
on the X drive using a servo motor with a 16:1 double belt reduction
and the stock acme screw. Gives plenty of torque and enough speed,
16IPM, considering the small working envelope of the machine. I
bought the Geckodrive 320 servo motor driver to use with it.
The Z-axis is a different story, as it uses a rack and pinion drive
which would have to be replaced. Since that makes it less usefull as
a drill I will probably stick with a 2D system and would not
recommend these mills if you want to do engraving.
Klaus

--- In CAD_CAM_EDM_DRO@y..., Edward Rupp <edwardrupp@n...> wrote:
> Hi folks,
>
> I've been looking at a new mini mill/drill machine that Harbor
Freight
> (item 44991-0ARA) and Grizzly (G8689) are selling. It looks like a
> great candidate for a CNC conversion. Has any one had experience
with
> this model?
>
> The machine looks identacl from both mail order catalogs. However
> Harbor Freight clams their machine has a R8 taper spindle, and
> confusedly says it comes with a JT33 chuck taper. The Grizzly
catalog
> says only a M3 taper.
> I'm wary of using a morse taper for milling. In my drill press the
> chuck is held in by probity a M3 taper. It falls out if I have a
drill
> chatter or the drill sticks in the work. Seems to me a mill with a
> morse taper would be worthless.
>
> Any thought on the spindle suitability?
>
>
>
> Thanks a bunch.
>
> Edward Rupp