Flattening a plane sole on a cinder block???

[Harold Burrell]

OK...don't shoot me...I've never done it. I'm just wondering if anyone has.

[Jim Koepke]

Doubtful, assuming you mean successfully.

jtk

[Josh Pelletier]

I haven't and I would venture to say that it can't bedone. That being said, I am inexperienced in the Neanderthal ways of the woodshop but it just doesn't make sense to me that it would work.

[Bill Houghton]

Cinder blocks make lousy planes - too much friction on the wood, hard to grip, and way heavy.

But if you meant using one as a stone to abrade the iron - well, you can give it a try. I wouldn't expect it to work too well, but I could be wrong. Don't start with your best Bedrock plane.

I've flattened a sharpening stone on a cinder block, and it worked amazingly well; and the cinder block was still flat and ready to take on another stone when I was finished.

[John Coloccia]

Cinderblocks are actually pretty darn flat.

[Tony Shea]

They may be flat, and might be able to abrade waterstones and other stones but I would think it would be real slow going on a metal sole. If the block was able to abrade the metal I would think it would dull up very quickly and abrade just about nothing after ten minutes or less. Another factor is whether or not we are talking about real cinder blocks of yester year or cinder blocks made of concrete.

[John Coloccia]

Why wouldn't you just lay a piece of sandpaper down? I thought the point was to find something reasonably flat. Maybe I misunderstood? You can certainly use a cinderblock to flatten a water stone, but you'll be rubbing for a good long while to flatten cast iron, I think.

[John T Barker]

Cinderblocks are actually pretty darn flat.

Compared to what?

[John Coloccia]

Compared to what?

A straight line.

[george wilson]

An excellent way to screw up your plane. The concrete will quickly wear down and you will be honing your plane into a convex sole.

[John Coloccia]

For shucks and giggles, toss a cinderblock on your mill tonight and tram it, George...or just toss a straight edge on it. I did it out of curiosity years ago when I first read about flattening stones on a cinderblock. I didn't record the exact results because honestly I never thought it would come up in casual conversation (LOL), but I do remember being impressed just how flat they really are.

[Jim Matthews]

I know Artie Shaw would dress his own mouthpieces on a cinderblock stoop at his house in New Haven.

His results were repeatably good, but that was a hard rubber versus concrete opposition.
I think the cast iron versus cinderblock would create a track from the leading edge of the sole.

Rather than use cinder block, I would suggest an offcut from a headstone maker.
They can get a long section pretty flat. As was previously suggested,
using the substrate directly will create wear.

How much, I couldn't say.

I don't know that this is actually necessary.
As I understood it, the geometry of the plane requires three points of contact (TMH)
be aligned, and coplanar, for the sole to do the job properly. Flattening the
entire sole seems excessive, on larger planes when examined under that light.

[Kevin Bourque]

I've tried this before.

I started by rubbing two 6x8x16 concrete blocks together to remove any boogers from the face of the blocks.
After 1 minute both faces were surprisingly smooth.
Then I drew a swervy pencil line on the blocks and rubbed them together again for about 15 seconds.
The lines were almost completely rubbed off.
I rubbed the blocks together for another 3 or 4 minutes using water as a lubricant.
I ran my framing square over the block and it was surprisingly flay in all directions and corner to corner.
I didn't use the concrete block to flatten a plane, rather I used it to flatten an old oil stone that had a serious belly in it.
I kept it wet at all times with a water hose and withing 10 minutes I had made some serious progress.
I forget exactly how long it took but when I was done the stone was flat.
I finished it up with various grades of wet/dry sandpaper.

[george wilson]

That's been done before,but it's not the same as trying to flatten a cast iron plane sole. I do not see how something like a cinder block,made of an easily worn material would remain flat enough to get the plane flatter than it was to begin with. And,what about larger particles in the block scarring the plane's sole?

[steven c newman]

Would it work for, say, a wood bodied plane, or even a Trans Plane? maybe keep a little Coffin smoother flat?