wet sanding on a surface plate

[ninefinger]

Hi all,

I'm trying to do some wet sanding using 400 and 600 wet/dry paper on a piece of flat granite (floor tile). The issue I have is the sandpaper keeps curling up on me, and then I catch it with a sharp corner of what I'm sanding and rip it. Does anybody have some simple trick to keep it flat? I thought that water between the paper and the plate would be enough but that is not the case. Or is it a case of "cheap" sandpaper?

Thanks,

Mike

 

[Lew Hartswick]

Or is it a case of "cheap" sandpaper?
Thanks,
Mike

Either that or you're putting too much pressure on the work.
And PLEASE don't do that on a real "Surface Plate".
...Lew...

 

[petertha]

FWIW I do something similar but just using a piece of plate glass. The trick is not to traverse the edge of the paper with your work piece... which kind of limits you to the standard 8.5 x 11" sheet area if thats what you bought.

In terms of the 'sticking down' business, Ive used 3M spray adhesive. Not the permanent stuff but the (hmmm whats the prt number now..). I think they call it 'tack' or 'frisket' or 'positionable'..something like that. Anyway, its lower strength. To remove is pretty easy, just lift a corner & wash some acetone in there & it comes off. I use this trick all the time in wood modeling for accurate parts. I make a cad template, it can be scale & very detailed, laser printed on standard paper, spray adhesive & press it down on the plywood, cut it with scroll saw, locate holes, finish to edges.. you get the picture. Then wick acetone into the paper & it peels right off. Next best thing to laser cutting! ;D

Thinking about this some more, you might be able to butt 2 pieces of we/dry togther on plate glass for larger area. Or better yet a micro-gap. Give it try & let me know.

 

[1Kenny]

I also use plate glass, 3/8" thick along with the sticky back aluminum oxide paper. Had the glass cut for one end of my tool box in the 80s and its still good today.

Kenny

 

[Stan]

Lew: Does this damage a granite surface plate?

 

[ausdier]

What about just putting a bulldog clip on each corner?

 

[Lew Hartswick]

Lew: Does this damage a granite surface plate?

I suppose it won't for the average "home machinist", but I just hate to see a precision
instrument used for some "hacking" sort of job. Like screwdrivers to open a paint can
or pliers for a hammer or etc.
The potential exists to damage a surface plate when it's being used for something
like that from dropping the work.
The right tool for the job if at all possible.
...Lew...

 

[Captain Jerry]

I'm sure you have all heard the story of the newbie who went to the tool room clerk and asked for a "wrench". The clerk thought he would explain thinks he is helping the newbie so he says " You need to be more precise. Do you want an end wrench, a box wrench, a socket wrench, or pipe wrench, and what size." The newbie's answer is " I don't care what kind but I want a big one to whack a cold chisel with."

Jerry

 

[Tin Falcon]

well lew I guess one of the shops I worked in was just abusive to tools . We had 1 small black granite surface plate that was used exclusivity for wet sanding . The cast Iron table top was use on the rare occasion on needed a surface plate.
I ocasionaly will place a piece of silica carbide paper on mine and oil sand.
probably the best advice is a small cheap one for sanding or a granite floor tile and keep the bigger better one in good shap. I would not use a good brand name precision surface plate for a sanding block but a cheap small import one yes.
Tin

 

[Stan]

I suppose it won't for the average "home machinist",

The average home machinist doesn't have all the specialized tools that the commercial shop uses. Even the ones that have surface grinders may not have the ability to grind aluminum so have to improvise.

Since I have used a surface plate with wet&dry to flatten and polish a lot of aluminum. I wondered if I had ruined it for it's intended use. I use as much care to not drop the work piece for either use.

I also use a cup wheel on my mill to surface grind which is not an approved use, but it does work.

 

[ShopShoe]

I use glass for the finer grades. When I am working up to the finer grades or at other times a made a jig for holding the sandpaper.

First of all, I was inspired by Frank Hoose's lapping plate as shown here:

http://www.mini-lathe.com/Lapping/Lapping.htm

Not wanting to buy the 1/2-in. Plate, and wanting a faster way to change the sandpaper, I Used a thinner sheet of aluminum mounted to a piece of particle board and some aluminum bars with toggle clamps:

Once again, I use the glass for the "best" work, but use this as I work to the point where I want to use the glass.

--ShopShoe

 

[Swifty]

For general use for things like this, I use a steel plate about 14" square x 1.25 thick which has been ground top and bottom on a large surface grinder.

Paul.

 

[ninefinger]

ShopShoe:

I really like your solution - it lets me use the cheap grade silicone carbide paper and not have it curl up. The other solution I like is buying the adhesive backed paper and sticking it down.

I think I'll source some adhesive backed paper as I'm almost out of the cheap hardware store stuff right now but I'll start scrounging material to make a liquid proof variant of shopshoes (maybe a plastic cutting board with granite tile or glass plate top..)

As for a real surface plate - if/when I do get one I won't be using it for sanding / lapping. My high school and college teachers would lap me with it if they found I was doing something like that with a surface plate :hDe:

Thanks guys - great advice as always on this site....

Mike

 

[hobby]

I have 2 of those imported surface plates, back when they were $15.00 each.

I use my surface plate as a flat reference for marking and guaging workpieces, but I use that same surface plate for prick punching workpieces, and assembling and pounding workpioeces together, as well as sanding, I also use it to rub aluminum parts directly on it without sandpaper, to give it a sheen, its my goto worksurface, for precision work as well as rough work.

If this was the sonly surface plate I had, THEN it would be used ONLY for precision work, and kept covered up during nonuse.

But other one is still under a cover under my workbench, with no mars on it watsoever.