Re: [CAD_CAM_EDM_DRO] Re: Modifying an X-Y table - ACME - for fun and learning

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>
>>Chances are that the epoxy will fill those little gaps and lock the
>>part solid. Very solid. Even release agents do not always allow
>>the epoxy to be released from the gaps and pits and scratches.
>>

Warning received and understood. Thank you. I think a "coating" type
of release coat is an appropaite way to proceed.

>I have done this with success. You have to warm the screw to about 50°C, dip
>it in JUST-molten parafin (candle-wax is fine), and rotate it slowly
>horizontally (in a lathe set at 40 RPM would be ideal, for example). Then you can
>

I can do this with little problem. How thick a coat should I aim for?

Anyway, time for a little bit of an update.

Spent some quality time with the vise this evening, and took it
completely apart. I found one part was installed backwards (installing
it properly improved its performance considerably) and I took the time
to adjust the ways for optimal performance. It works quite smoothly,
now...in fact, surprisingly so. However, while taking it apart, I found
something curious. The two nuts are of decidedly different designs, and
have distinctly different problems.

The lower nut is of a removable type, and seems to have extremely little
backlash when fitted to the screw. So little that I can't see it with
the naked eye, or feel it when engaging it by hand. BUT, it's mounted
as a cylindrical nut in a receiving hole, held in by friction, and this
hole has a rather sloppy fit. It lets the nut move quite freely..
Assuming that what someone told me is correct, and the markings on the
gauge are in .001" increments, the backlash afforded by the *mounting
system* is around .02", or nearly 2/3 of a turn! I have a few ideas of
how to improve this fit, and consequently minimize the backlash
considerably. A trip to the hardware store, tomorrow, should solve a
few problems...and make a noticable improvement.

The "upper" nut is a different story. It's integral to the castings,
and can't be removed, reinforced, or otherwise improved without
modification. But, it's fit is not too horrible -- the backlash is only
about half of the other axis, and with a little "doctoring" it should be
almost acceptable. I have some JBWeld, and intend to try to "paint it
on" the nut, to improve the fit. This nut, unlike the other one, is
securely fastened to the vise.

Regardless, knowing where and what the problem is, is the key to fixing
it...

>However, I found later, when using store-bought ACME screw-stock, if you
>"make a tap" out of a length of that, you can TAP a "nut" made of Delrin, and that
>works super! One must INVENT as one goes along! That's part of the fun,
>no?!!!
>

It's part of the reason for this project! This is a hobby...it should
be fun!

If I do this right, it'll not only be fun, but it'll be useful, too.
Best of both worlds!

-- Chuck Knight