Re: Improving accuracy on mini-mill? (lapping?)

Hey,
All you will do is smooth everything out, and probably make worse
the convex/concave condition of the mating slides. A surface with a
small texture to it is a good thing as each pit holds oil for
lubrication.

The problem is that your X axis topslide is probably convex, so
that each end is up and only the middle is touching the base Y axis
slide. What you want are two mating flat surfaces. Then with light
gib pressure the table will be secure and won't rock. Of course this
also assumes the dovetails are square and parallel to eachother,
which they won't be.

Through careful inspection on a surface plate or other very flat
surface and your test indicator, you should be able to detect the
high/low spots. Bring the high spots down until the ways are
parallel with the face of the milling table. Do the same for the
base slide ways.

Better yet, you could buy some linear slides and build your own
X/Y axis using your existing CNC mill. Then you could use your mill
to rebuild your Z axis so that it is much beefier.

Best yet, use your mini-mill as is, have fun with it and save your
time/money/efforts for another, bigger/better machine.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Abby Katt" <cnc@a...> wrote:
> Roger,
>
> But I wasn't really thinking of using say.. 60 grit..
>
> I was thinking more of using something fine (ie 600 to 1200 grit),
to smooth
> out the bearing surface and gibs, so that I could reduce friction,
allowing
> me to tighten them more and gain better rigitity. If I used a small
enough
> grit size, wouldn't it just remove the current irregyularities from
the
> surface and even it out more, so that they still more or less
defined the
> same plane, but moved with less friction?
>
> I've heard of a few people using lapping.. Does anyone else have any
> experience here?
> A worthy-try, or a just plain bad idea?
>
> Thanks!
> Abby
>
>
>
>
> -----Original Message-----
> From: Roger Hampson [mailto:r_.hampson@t...]
> Sent: 22 March 2005 20:38
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: RE: [CAD_CAM_EDM_DRO] Improving accuracy on mini-mill?
(lapping?)
>
>
>
> As far as I can see two things will happen.
> 1 the application of abrasive compound will size the machine slide
ways
>
> And
>
> 2 ruin what would otherwise be a usable machine
>
> problem is that you have no method of lapping just the point you
need to, to
> bring back accuracy
>
> Roger
>
> -----Original Message-----
> From: Abby Katt [mailto:cnc@a...]
> Sent: 22 March 2005 20:30
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Improving accuracy on mini-mill?
(lapping?)
>
>
>
> Hmmm..
>
> I noticed that if I stick a DTI of my asian mini-mill so it's
probing offset
> to the middle of the table table/vs the column and then press on
the table
> at the extents, I can see the DTI needle move quite a lot! Aaah!
Now, since
> the cutting head is usually in the middle of the table, I guess
that the
> effect here is not so much, but still...
>
> So this makes me tighten up all the gibs, but the problem is that
when I do
> this, it makes it much harder to move the table (or impossible).
This leads
> me to ponder using some sort of lapping compound on the ways, and
then
> programming the mill to go back and forwards a few hundred times,
to smooth
> up the ways/gibmetal, so that I can then tighten the gibs more to
get a more
> rigid setup with less friction.
>
> Is it a good idea?
> What sort of lapping jive should I be using? Brasso? Valve grind
compound?
> 1200grit? 600? Peanut butter and toast? :)
>
> Is the lazy CNC way of having the mill do the work a good idea, or
> bad-science? Will it just make more sense to do it all by hand with
the old
> emery-cloth?
>
> Thanks guys!
> Abby
>
>
>
>
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reach it if
> you have trouble.
> http://www.metalworking.com/news_servers.html
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> http://groups.yahoo.com/group/jobshophomeshop I consider this to
be a
> sister site to the CCED group, as many of the same members are
there, for OT
> subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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