So I've found myself working on a project that needs two flat flats that are parallel to each other and my usual trick isn't working well. Usually I just use my "poor mans/redneck surface grinder" which is nothing fancier than scrap granite counter top with sandpaper stuck down with elmers spray glue. However this time I'm having some difficulty holding the piece consistantly flat and I'm developing a rounded/rolled flat. That said, I thought I'd ask what do others like myself who cannot afford a surface grinder do to get consistent flats. I know I could go to the machine shop but that'll cost too much for the occasional one off piece. Short of that suggestion I'm all ears.

Back in the day it was files and scrapers. If you can fix the object, and alighn it, two parallel, hardend bars in plane will act as filling guides (have to be harder than a file) tho a set off runners and a backing ( say two boards, a peice of plywood and hot glue to fix the object) might work, as long as the sand paper is narrower than the sand paper.  

In my shop, one of the tools I use every day, is a 6" x 48" belt sander.

They are relatively inexpensive, and extremely versatile.

While I do have an old belt drive surface grinder, I really don't use it much.

Obviously, a lot would depend on the tolerances required by the job.

 

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Sorry for the long delay, today was a little hectic.

Charles, that's such a simple suggestion but sounds like it might be just the ticket. I'll give it a shot tomorrow if I have time.

SmoothBore, there really are no specifics required by this particular project. I got about 1/32" off and when I tried to reduce that I got further off in the other direction. I have been looking at various grinders and I'm thinking about one of those with a belt on top and a disc on the side. But I obviously need to find one that I can either put a shield over the motor to keep metal dust out or find one with a sealed motor. I used to use a belt sander but it didn't like the metal fragments getting in the motor very much.

One thing that has worked for me in the past is use of an inexpensive circular bubble level.  Get one side flat, flip, place level on second side and grind to suit.  Charles' idea is better, but if you don't have indexed guides of tungsten or hardened steel this can do pretty well.

I make flat mated cerfaces all the time, it's called a flat, level hoof mated to a horseshoe.

i had a gal try and convince me that you could do a better job with a rotary trimmer (for a wile they were trying to sell cattle hoof grinders as the new thing) I told her that I was sure she could do a competent job trimming a hoof, but as all machinned serfaces had been filed and scraped prior to the advent of the bridport mill and Blanchard grinder I would stick to a rasp. Then I am her to fit a shoe...

look at the old shop class exercises in filing.

2 flat and parelel, then 4 then 8 then 6...

I find that it helps to put guide rails on each side of the piece being sanded.  A drop of super glue will hold some steel bars in place on the granite countertop, then you glue a handle on the top of your piece being sanded.  Said handle rides on the rails to prevent tipping.