RE: [CAD_CAM_EDM_DRO] Improving accuracy on mini-mill? (lapping?)

If you plan to lap it, why don't you just strip down your machine of all
useable parts and throw the rest away. Then retrofit another mill. If you
lap it you can't control what you are doing. So why waste your time.

There is only one way to true it in you shop. Scrape the ways. A good
scraping tool and prussian blue, (artist oil paint will work). You can make
your own tools, if you can silver solder, or braize with brass. Weld a
piece of carbide to the end of a 3/8" or 1/2" rod, sharpen it into a
scraping profile on a green wheel. You can also use an old file. It's all
in the sharpening. There are books that will help you do this, do a Google
search or look at EBAy. Ask around maybe you can find someone with the
experience to do it for you, or teach you. I would recommend finding a
piece of equipment that is worn worn and not useable and practice on that.
Then go to your machine.

Scraping is becoming a lost art.

Good luck

Bruce

-------Original Message-------

From: CAD_CAM_EDM_DRO@yahoogroups.com
Date: 03/22/05 14:38:49
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@...]
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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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.

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