Coarse stone recommendations

[Ratbag]

I finally went to the hardware shop today and bought a 120 grit beltsander belt. Initially it was really good and was taking a lot of metal away, but it clogged up quickly.
I tried vacuuming it out which it did clean up, but it wasn't the same anymore and it started to take a long time to remove the metal.

I kept working on it and was able to sharpen up a vintage giant chisel that I wasn't able to sharpen previously. Last time I gave up because I couldn't flatten the back or take off enough from the front without spending hours and wearing out my diamond plates. Now it is decently sharp enough to be usable, but it pretty much wore out the grit on the beltsander belt that i bought and it still took me a couple of hours. Given the price of the belt sander belts are about $10 at my local hardware shop, I think if I use this method a lot it could end up becoming expensive if I do a lot of sharpening up old tools.

I have placed an order for a Sigma power ceramic stone #120 from Tools from Japan which I hope will work as good as the beltsander belt and hopefully without the clogging issue.

I'm starting to realize that buying used tools can seem cheap at first, but you will spend a lot of time and money to bring the blades to a decently sharp state.

Tim.

I've found that old black PVC waterpipe does an excellent job of cleaning out swarf from sanding belts. The only proviso I'd add is that it's best to use it sparingly & frequently, before clogging becomes severe.

Grits will vary between belts too. Silicon carbide & aluminium oxide have different cutting characteristics, but which is which I can't rightly remember.

DMT make a superb very coarse gritted lapping plate that performs well too. It's expensive, but at 12" x 3" it is the largest, and at <.0001" unifomity the flattest available.

[D.W.]

Norton coarse crystolon stone ( a new one, they get harder and less friable as they get old )

That'll be good for bevel work. It won't stay flat for back work, though.

For work flattening the back of something, I'd use a milled plate or an old plane sole charged with 100 grit diamond powder (should be about 25 cents a carat, and cost about a dollar per pitted iron to use...at most).