Burnishing card scrapers

[glzahn]

Thanks for all the great info. I'll be using my card scrapers more often now that I know how to burnish them correctly.

[handi]

Just buy a burnishing tool. They are not expensive and the hardened steel works exactly as it should.

It is also highly useful for finishing mitered joints. Rather than sanding them, just run the burnishing tool down the joint slightly rolling the points together.

Ralph

[mike4244]

In my post I said a kitchen steel would work, I stand corrected. I did not realize there are very fine serrations on a steel until I looked at ours.If someone wanted to make burnishers it quite easy.
Put a handle on 3/8" drill rod.Enco has oil hardening drill rod 3/8" x 36" for under $5.00.Better yet but more expensive is A-1 which is air hardening for around $12.00 for 3/8" x 36"
If you harden the steel,may not have to, might be hard enough the way it comes,air hardened steel is easy to work with.Cut to length first,about 10" long should do.Heat til the rod is cherry red,let it cool without water or oil.When it is cool,several hours then polish it up.
Scotch brite pad should do it.Make a handle and epoxy it .
Another advantage to air hardened steel is heat rarely distorts the metal,water and oil hardening steel may distort.
mike

[kscott]

I guess it depends on the steel. Mine has striations ALMOST all the way to the handle but there's a 3/4" section near the handle which is smooth. That would be the most convenient spot for it.
JMHO
YMMV
Ken

[Howard Acheson]

Not to be a wise-butt, but why go to all that trouble when you can buy a real burnisher for relatively little. One advantage of a real burnisher is that is is well hardened and, just as important, it is real smooth. Smoothness is important to ensure that galling does not occur when using the burnisher.

[arnman]

Howard,

I have limited experience with scrapers, but I used your method on my scrapers. I have the Lee Valley oval burnisher and Lie-Nielsen scrapers.

By drawing out the burr (with the scraper resting on a flat surface), two very fine knife edges were produced on the edge. When I used the burnisher to roll them over (with the scraper held in a vice), the two fine knife edges scratched up the burnisher. I was not pushing down that hard.

It may be bad technique on my part.

In any case, I will be getting a carbide burnisher instead. I don't think the Lee Valley oval burnisher is hard enough.

[mike4244]

Your burnisher is defective if it scratches with use. Possibly never heat hardened.You may be able to save it if you want. Wrap a wet rag around the wood handle or remove the handle if possible.
Then heat the oval with a propane or Mapp Gas torch til the first 4" or so are cherry red.It should be non-magnetic then.Remove torch and let it cool.Polish out the scratches with emery paper,then Scotch Brite til it is bright.Unless you know what type of tool steel is used I would not bother quenching.I am not sure but will guess it is A-1 air cooled steel.I say this because of the small diameter of the oval,A-1 is least prone to heat warp.
Should be very hard,no need to temper.You won't scratch the burnisher any more.
mike

[Bibliophile 13]

Howard Acheson said:

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Not to be a wise-butt, but why go to all that trouble when you can buy a real burnisher for relatively little. One advantage of a real burnisher is that is is well hardened and, just as important, it is real smooth. Smoothness is important to ensure that galling does not occur when using the burnisher.

---

It's a good recommendation. Plus, a burnisher with a good handle is a lot easier to use than something not designed to be gripped (router bit shank, valve stem, etc.). If you're just learning to sharpen a scraper, you don't need the distraction of an uncomfortable grip.

I have, however, found that one burnisher I bought wasn't quite hard enough for some of the harder scrapers I had. (They were scratching up the burnisher's surface.) I switched to carbide and haven't had problems since. My burnisher is a broken carbide drill bit epoxied into a handle (shank end out) I made for it. Works like a charm.

[Howard Acheson]

With a good hard metal burnisher, you do not have to apply much pressure. Sometimes I apply a little paste wax to the blade edge.

I don't think I have ever had a problem rolling a hook edge. If the burnisher you have is hardened steel you should not be damaging the burnisher. Scrapers are not generally hardened steel so they should not damage your burnisher.

[Rob Young]

Howard Acheson said:

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With a good hard metal burnisher, you do not have to apply much pressure. Sometimes I apply a little paste wax to the blade edge.

I don't think I have ever had a problem rolling a hook edge. If the burnisher you have is hardened steel you should not be damaging the burnisher. Scrapers are not generally hardened steel so they should not damage your burnisher.

---

I usually have my bottle of 50:50 mineral oil & kerosene on the bench next to the oil stone, so a little on the fingers then transfer to the burnisher. Works great!

I have a Crown burnisher (frequently reported as "too soft"). I find it doesn't take much pressure at all to roll a burr on any card scraper I have. Recently picked up the ones from LN which are supposed to be Rockwell 49-51. The rest of mine I have no idea what they are supposed to be except that they are all over the map, especially the ones from old saw plates.

Hard to describe the pressure I apply but really, no more than one my use to push open a stiff door. Certainly not enough that I feel compelled to hold the scraper in a vice. I hold the card scraper in my left hand, the burnisher in the right and draw out/over the burr. I find a long burnisher works better for me than a little short one.