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@...]
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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