PDA

View Full Version : Stoning?



jdf001
02-08-2014, 11:08 AM
Hello I have heard that one can clean surfaces on the mill and vise using an aluminum oxide India stone. I was wondering what grit stone one would use for this.
Thank you for your help!

awerby
02-08-2014, 03:46 PM
Don't do that. These are (or should be) precision-ground surfaces that need to be exactly flat. An abrasive stone like that will remove some of the steel and make the flat surfaces irregular, so they'd never work right again. If you need to clean light corrosion or staining from your mill and vise, some WD-40 and steel wool should do the job.

There is an operation called "lapping" that's done with abrasives, but it's not cleaning; it's done to make irregular surfaces flatter. But that needs to be done very carefully, since if you do it wrong you can ruin your machine.

Andrew Werby
www.computersculpture.com

lsfoils
02-08-2014, 09:52 PM
Greetings,

I will disagree with awerby on this. When done properly, stoning reduces the harmful effects of scratches, dings and burs. Any bearing surface with these untreated features is not accurately flat. Some will only be revealed to the naked eye by stoning. You can measure this effect with an indicator and the effect will definitely create problems for doing accurate work. Yes, it is important to choose the correct stone. I use: Slip stones 7145 9242 MSC. It is a soft India stone that costs about $11. Make sure to keep it clean! I use a cheep diamond sharpening pad & WD40 for this and it quickly removes metal that loads up in the stone. As far as removing too much of the surface, I think if you get too vigorous, you could harm the flatness. So make sure to stone the whole table, not just one area. This is regular practice before mounting a vise in most of the shops I've worked in. And make sure to stone the bottom of the vise, too. Hope this helps. - Doug

Geof
02-08-2014, 10:42 PM
Let me stick my foot in the water....you are both correct and incorrect, sort of. Stoning the table to knock down the ridges that get pushed up around dings and scratches will not materially affect the overall flatness of the table but it will remove localized high spots that can seriously affect fixtures, vises, etc bolted onto the table surface.

But stoning the entire table surface to clean is not necessary: as awerby says use steel wool, or Scotchbrite for light corrosion and staining and do not try to clean a corroded or stained surface all the way down to pristine appearance. That does remove material and over a long period can affect accuracy.

lsfoils
02-09-2014, 07:49 AM
Hi Geof,

Eloquent. But scotchbrite should not be used, according to the guy who taught me (a while back, ugh!) I do like to use this stuff: Grizzly.com (http://www.grizzly.com/outlet/Sandflex-60-Grit/G1808) (or finer, down to 120 grit a while ago). Less likely to load the surface with abrasive. I was told scothbrite will. Been using the sandflex stuff for years and it removes the black stuff. You can see the pit left behind by the action of staining, even with the naked eye. But the black is gone and the scratches left must be viewed with a loop (10x or better), not so with scotchbrite, of just about any mesh that I've used. I use the SB for engine turning and cleaning up grinding marks after welding. Works great! - Doug

lsfoils
02-09-2014, 08:12 AM
Ah, cleaning is the operative word in the OP's post. Missed that. But, the sandflex still stands as the best I've used for that purpose.

mountaindew
02-09-2014, 08:47 AM
I recently found the need to stone the precision ground t slot face also. Vise keys set more accurately.
I don't put much pressure when stoning a surface. lightly stone is key word for me, then hand clean all surfaces before setting fixtures.
This is on my procedure list to avoid problems from burs, nicks and lifted edges. "It helps and a required step imho"
I have a few kinds of stones and just for grins I use an old k2 ski edge stone for the small t slot face and normal good quality flat one for table.

Hope this helps
Lane