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Converting a Grizzly G8689 Mini Mill to 3-axis CNC, Part 4:
Next up, the table itself!
Turns out there's just barely enough room under there to clear the ballnut, so now I just have to figure out how to mount it.
Looks like I can put it right about there, that should clear with minimal interference.
Now, the previous owner, whoever originally converted this thing, had
milled a couple slots in the saddle,
attaching simple slab mounts via
nothing more than setscrews. I didn't really want to mill too much more
so I tried to figure out a way to utilize the existing slot. After
some thought and a couple of corn dogs-
they're brain food, trust me- I
came up with a plan of attack.
I began by bandsawing a likely-looking size of 3/4" aluminum, and
squaring it up a bit in the mill.
The notches at the corners are
leftovers from the scrap I bandsawed it out of.
To fit it and use as much room in the slot as I could, I needed to round
the ends to match.
I have plenty of corner-rounding cutters, but not
one for a 5/16" radius, as the PO had used a 5/8" endmill.
have a machine that, with a little care, can generate nearly any radius
And with just a few minutes and a fine belt for fine-tuning, I got a good snug fit.
I was able to fine-tune the fit even more with a couple hand files, to
make sure it seated solidly at the bottom of the slot-
and you can see
here how it will line up with the proposed new ballnut location.
I knew I'd have plenty of room on one side, but wasn't sure about the
other, so I drilled and countersunk one hole to start with.
And then drilled and tapped the "long" side of the slot in the saddle to accept a 1/4"-20 bolt.
Setting the saddle upright in the mill, and helping hold the mount in
place with a clamp, I eyeballed
a good "right about 'thar" location and
started out by boring through with several sizes of endmill-
'step' of the edge of the casting would not be conducive to proper
After that, it was simply a matter of applying the boring head until,
probably by blind luck,
I managed a 0.0015" slip fit to the ballnut.
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