the daily grind

[matthew]

Bummer. Have successfully spoiled the mirror finished blade of my HNT Gordon smoother.

Previous owner had problems sharpening tool steel and for some reason put a slight back-bevel on the blade. Well not really a bevel, more just rounding the back edge a bit near the edge. This I don't want.

So i set to on a piece of plate glass and some PEP valve grinding paste I found in the shed. Plane blade went a nice even grey colour with a shiny rim, my aim obviously was to get rid of the shiny (untouched) rim. Then a scary sharp finish.

after sweating on it for half an hour without a lot of progress I washed off the grinding paste, dried the blade and went to bed.

BUT in morning I find the blade covered in fine red rust and consequently thousands of tiny pits in the back of the blade. Overnight the blade must have picked up some residual moisture. FFFFFFFFFFFFFFFFFFFFFFFFFFFFF ok I'll not be foulmouthed here.

yes I should have oiled the blade after grinding. stupid me.

So I set to tonight to grind back to the shiny metal again. But its taking ages. feels like it will never be the same again. any suggestions? What grinding paste should I be using?

[kiwigeo]

I use an 80 grit carborundum powder on a glass plate to rough dress backs of my blades. The stuff is available from Carbatec. I then work the back of the blade on Japanese water stones..800 through to 5000 grit.

http://www.carbatec.com.au/veritas-lapping-kit_c19953

[matthew]

well i popped out and got a Veritas kit.

And spent the last three hours learning to lap with "free-grit". Amazing, after all this time, never done it before.

Things I learned

1. Rust is a powerful enemy. The mirror-smooth HSS blade is covered in not-so-microscopic pits after being ground flat using a water based paste and wiped clean and dry (I thought) but not oiled. And left on a dry bench overnight. I think the roughness from grinding dramatically increased the metal surface area and wiping the moisture off wasn't enough. then the chemical action starts and WHOA ruined.
2. marine plywood is a better lapping base than glass because it holds the grit better. And is a lot quieter to use and doesn't annoy the neighbours so much.
3. Glass is flatter though
4. WD40 is a good lubricant
5. Don't even THINK of moving from 80 grit until the pits are gone. check with the optivisor!
6. MUCH easier to hold a blade and apply more force if glued to a wooden block with double-sided tape.
7. Rust is a powerful bugger.

And after all that I STILL haven't managed to get rid of all the pits .... Aaaaaargh! Patience needed!

PS: 8. Focus' Hamburger Concerto is good lapping music

[Kim]

Things I learned
4. WD40 is a good lubricant

That it is, but spray degreaser from SuperCheap Autos is only $1.99 for an even larger can than WD40 and works just as well. Wait for 20% off store wide days and then load up with a carton

Cheers

Kim

[charangohabsburg]

Kim, needing that much oil: are you a full-time blade lapper?

and wiped clean and dry (I thought) but not oiled. And left on a dry bench overnight

Did you lay the blade with it's mirror face down?

I ask because I have a japanese kitchen knive which starts rusting (within few minutes) on the lower side when laid down on the dry kitchen table (wood) and just wiped "dry". I have it to get the knive "air dried" for at least 10 minutes (will not use mineral oil on a kitchen knive). Once learned that I also stopped using oil on my plane blades and chisels and never had a problem since then (except when picking up the phone while sharpening tool blades... ).

This is my "drying set up" :

2011_A80_8834-1.jpg (128.77 KiB) Viewed 6903 times

Oh well, of course the Veritas blades are hard to get rusty, but the japanese knive will really provide more than the daily Fe-dose needed for a well balanced nutrition when getting rusty.
... and yes, sharpening still happens in my kitchen even if since having begun with lutherie some 10 years ago I have "banned" (the rest of) it to the former dining table...).

If your blade was well vented through the night, please let me know, and I will oil my blades again.

Hoping for a fast and not too painful recovery of the shiny side of your fine plane blade!

[matthew]

Markus I don't remember; I ground the back of the blade with a water lubricant, got fed up with it being so slow, wiped it carefully dry and put the blade on my bandsaw table (plywood) and I forget whether side up or down. Big sinking feeling next morning!

[charangohabsburg]

Yes, I imagine how bad this made you feel. Some of the most excellent steels don't forgive anything Probably I should be more careful and go back wiping my dry (or "dry" ) blades with an oily cloth before storing them.

[kiwigeo]

For rough working a blade I use a diamond stone....good for flattening japanese water stones as well.