Yikes, looks like it is a very fine pitch. Well, the only thing that
matters is the diameter and pitch. Your 6x1 makes me think
6 mm dia and 1 mm pitch. I have actually seen some like
that listed on eBay, so you ought to just search there and
see what comes up. The real problem is they are rarely made very
long as whip and stiffness become problems.
The seller on this one said it was C3, but after measuring its travel a
couple times it can't be any better than C7. Probably closer to C9. THK
does make one but, "Perforated poop masked crusader!!!" those things are
expensive. I think I'll just keep an open search on Ebay and see if any pop
up. In the mean time I think I'll explore other options for this
application. Wish I had room for 16mm. There are tons of those out there
at a reasonable price.
Which is a finer pitch than that used on the Compact-5/CNC, and
which is otherwise a similar length. I think that the Compact-5 uses
one of 8mm diameter, but I've never actually needed to measure it.
Agreed. Bridgeport, in their BOSS-3 through BOSS-6 machines,
even with a ball screw larger than one inch, and with the speed
limitations of their original stepper motor setup, did a trick to
minimize whip. The Y-axis is normally driven by rotating the screw, but
the X-axis has the screw rigidly mounted to the right end of the table,
and rotated the ball nut (in a pair of opposed bearings) instead. A very
good way around the whip problem, but perhaps not enough for stiffness
on a 6mm ball screw.
I am in the process of fitting this screw as a lead on the Z axis of a mini
mill. (Smaller than my Taig). I was hoping to finding something similar
for the X&Y, but I either can't find them or the price of a single lead
assembly is more than the whole machine. I had retrofit that machine from V
groove to Acme a while back, but the anti-backlash nuts I found for that
size are just to puny. Under light aluminum cutting loads the nuts give
constantly. Can't really use anything bigger in the space available. I
suppose I might be able to use 8mm, but that would be it, and I would have
to drill out the table and cross slide for clearance.
P.S. That nut is freaking hard. I tried to drill it out slightly so 6/32
mounting screws would go through easily, and I had to do it one drill size
at a time, and I still cooked two bits even while pouring oil on them while
cutting. If I find more of these they will get 4/40 screws for mounting.
Ouch! Even smaller than a Taig, that leadscrew sounds too
small for the task.
And expect that small a ball screw to flex under similar loads.
Note that Bridgeport had an interesting approach for the ball
screw for the Z-axis (spindle quill, not the knee jackscrew, which was
not motorized). This was in the old BOSS-3, and probably the same up
through the BOSS-8 (which had servo motors instead of the BOSS-3's
The quill bearing cartridge was built within a cylinder whose
outside was the ball screw, and the corresponding ball nut ran around it
in bearings and was turned by a timing belt. This meant that the force
applied by the ball nut was truly on axis.
It *should* be hard, given that the surface forms the ball race
in the ball nut.
I think that you will find that all the drills which you used
need at least resharpening, if not replacement.
It originally had 1/4" V-grooves with pinch sleeve nuts. I changed it to
1/4" Acme with acetal anti-backlash nuts. The V-groove had pretty poor
accuracy. The acme was very accurate, but the nuts flexed. I think the
ballscrew will be better than either.
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