On 2011-09-06, wrote:
Conversion uses ubiquitous 5/8" ballscrews and ballnuts. However,
there should be enough off the beaten path that the hobbyist/
enthusiast may find interesting. A pictorial summary can be found
here;

http://www.pbase.com/eldata/d300_x2cnc

Interesting and well documented -- within the limitations which
the web site put on your own added text. I mean who cares about the
camera (a nice one) or the EXIF data when you are documenting a project
like this -- but you live with what the web site will allow. :-)

A question and a suggestion to follow -- both related to turning
the ends of the ball screws:

1) Was it truly necessary to anneal the ends of the screws? I
believe that they are only case hardened, so after a first
heavy cut to get under the case, you should be fine. (Perhaps
with the insert tooling you were using, you could not take that
heavy a cut. I've used that style of insert tooling, and have
long since abandoned them for the more industrial style with a
carbide anvil under the inserts among other things.

2) Looking at the photo showing the teeth of the chuck jaw lining
up with and resting on the crests of the ball screw thread, I
suspect that the other two chuck jaws would be touching at
non-optimum places, so what I would probably do (if I did not
have collets large enough for the task), I would have taken some
aluminum, mounted it in the chuck and marked the point in the
middle of the #1 jaw, then bored it to barely clear the ball
screw, then removed it from the chuck and slit it at a point
midway between two chuck jaws (probably 180 degrees opposite the
marking for the #1 jaw), then put it back in the chuck (using
the mark to put it in the same position), so it would act as a
reasonable collet and be less likely to damage the crests or
flanks of the ball threads.


Good job, anyway.
DoN.

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