Thread: Sharpening old razor blades

KMS Tools sold a big bar of CrOx/AlOx. The carrier matrix is a very hard wax of some sort that smells nice.
I know it's a mix as I found a number of pin-head sized white globs of AlOx.

DO NOT use a nice handsaw to cut the bar to give away a piece of it.
I might just as well have been sawing sandpaper or a rock.
It's still good enough to cut soapstone so it's a permanent part of my stone tool kit now.

I bought a bar of the Veritas mix. The first thing I noticed was a lot more wax and softer wax at that (cheap filler).
Not used it much yet. Maybe the softer wax will make it easier to spread in my box card strop materials.

The 10X magnifier is good enough in a strong LED light to show me the bright reflections off damaged bits of the tool edge.
Big? Start with 600. Small? Start with 800. Up through 1,000 then 1,200, then 1,500 then hone.
Leonard Lee's pictures indicate that I've done enough.
Inspection shows no reflections then I know I've got a carving sharp edge again. Test in wood.
I never carve hair so that's a waste of time test.

For my purposes, it's just a Yes/No situation to be worked on. The exact nature of the edge is of little concern.
I'm carving very soft western red cedar and yellow cedar so the tool edges have to be pretty slick.
I'd probably use more magnification if the device fell into my lap. But for the past 15+ years, I'm good.

Originally Posted by Ben Dono

I thought one of the advantages of Veritas over the industrial sized chrome blocks is that Veritas is a dual grit. The AlOx cuts fast but crushes down quickly and then the chrome oxide takes over. Do you know of any other brands in the industrial sizes that are comparable to Veritas? I'm keen for a cheaper option as I tend to give a lot of it away as samples.

Oh, and one more question mate. Are the 10X magnifiers powerful enough or would you go with a 60x or 100x?
Cheers mate and all the best from OZ,
Ben

Couple of things here on the compounds - the veritas compound doesn't have anything that crushes down in it. Even calcined alumina is still really hard, but if you want a finer finish out of it, use it on a softer substrate (hard leather or wood) and the alumina won't "Dig deep". I'll provide some picture to show the difference with 3 micron alumina from autosol.

R-V mentions the sticks feeling soft, and it's true, they do feel softer, but they are not less abrasive dense that I can tell - the compound is softer because someone specified that as a customer. If they aren't applying well, add a drop of mineral oil to the substrate and then "color" on the oil drop with any fat/wax based stick and you'll be fine. Most sticks are harder so that they don't just rub apart in a warming high speed wheel.

As far as cutting these things, use a worn out coping saw or hacksaw blade - you can cut through them easily and since the blade is already dull, abrading the tips is no big deal.

I sold hard japanese stones for a while and sometimes they arrive broken. The broken ones become nagura. But how to cut them is something to solve. A coping saw or hacksaw blade will cut them easily even though they're about 15-20% aluminum oxide and 55-60% silica (like a sandstone or hone slate). Of course, the blades will continue to get more rounded, but it doesn't matter. I could cut a half dozen stones into pieces with a used hacksaw blade and maybe half of that with a no-longer-sharp coping saw blade.

Originally Posted by Robson Valley

It's still good enough to cut soapstone so it's a permanent part of my stone tool kit now.

Same as I've found - the fine abrasives will work the point right off of the teeth, but once they're a little rounded, they still cut stones and abrasive sticks well.

Agree on functional edge expectation. Despite being a dilweed who takes pictures of edges all over the place, I don't have a loupe or anything in my shop, but 10x would be fine if I had bad eyesight or needed just a little help. It's enough to see a stripe of unfinished work at an edge, or damage.

Originally Posted by Ben Dono

I thought one of the advantages of Veritas over the industrial sized chrome blocks is that Veritas is a dual grit. The AlOx cuts fast but crushes down quickly and then the chrome oxide takes over. Do you know of any other brands in the industrial sizes that are comparable to Veritas? I'm keen for a cheaper option as I tend to give a lot of it away as samples.

Oh, and one more question mate. Are the 10X magnifiers powerful enough or would you go with a 60x or 100x?
Cheers mate and all the best from OZ,
Ben

My comment here on larger bars -here in the states, there's a lot of industrial supply and there are several companies making buffing bars - you're really looking for buffing supplies for alternatives.

Typically here, a kilogram bar of compound is the same price as the 6oz veritas bar.

The veritas bars (formax microfine sold by other retailers here) are soft and easier to spread on (still need a drop of oil to do it well), but they break down too fast to be ideal for a powered buff. That doesn't matter to you if you're not using a powered buff, but explains why what you're likely to find in general is harder bars. See comment on drop of oil - they still work fine if you add that drop, the hard bars will "write" off their wax in to the oil no problem. If they seem to hard at first, ignore it.

Make sure anything that you buy has alumina in it - there are some ultra fine bars that are iron oxide only, or coarser silica - they're not usually for ferrous metals. You want bars advertised as being for steel or stainless steel. That is exactly what the formax/veritas bars are typically described as "for stainless". industry recognized white and gold as alumina bars for steel and stainless steel as fine, rouge colored bars for softer metals, and green bars as being for stainless (even though most are mostly alumina as it's much cheaper than graded chrome ox - and it's better for our purposes).

These are hard surface white scratches from a 1kg bar marked "kocour" here and listed as 2 micron calcined alumina - https://i.imgur.com/Y9nu8SA.jpg

These are same hard surface but with the LV bar (https://i.imgur.com/NoGfvvH.jpg)

Oops, the LV bar looks more aggressive than a 2 micron buffing bar (it is, the big particles in it do disproportional work, but on a softer surface it will work well)

The white compound above comes in a 3 pound bar for $12.18US here. This starts to make you wonder why you'd want to buy buffing compounds from woodworking suppliers - I agree. They're not very competitive on it, and we have luck here with industrial supply because manufacturers go through these large bars at a high rate, which means they become a cost-competitive commodity.


(I can't find both of my autsol pictures to compare so here's two with very aggressive 5 micron compound)
hard surface:
https://i.imgur.com/64xvJSq.jpg

soft surface:
https://i.imgur.com/NDjGaAV.jpg

Note the soft surface picture compared to the LV on hard surface - use of the coarse stuff on wood is finer (and faster) than the use of LV stuff on corian or metal plate like lapidary would do.

The LV stuff should leave a very fine surface if it's, too, used on soft wood.

Look up online buffing supply or polishing supplies and tell them you want a 2 micron buffing bar with alumina, though, if you want the same thing or better for much cheaper (I was wrong about the KG above - all of these big bars are sold in 48 ounce bars here at the same price as 6oz of stuff from a woodworking supplier).

Here's the green 1 micron bar from industrial supply here (on a hard surface).
https://i.imgur.com/mRnALwa.jpg

Note that the average is even finer than the 2 micron, but on a hard corian surface, the odd big particle still leaves unsightly scratches. For woodworking, this size of abrasive is meaningless - it won't notch an edge or leave any visible scratch on a surface.

These compounds can have such variable particles because a buff will never be strong enough to push the large particles hard into the steel like a corian lap can.