Is there a good way to flatten the back of plane irons / chisels quickly? I have some old tools hanging around which were obviously sharpened on hollowed out stones, creating concave backs (center of blade will touch my stone, but the outside edges are raised up). I’ve tried the big green waterstone (220 grit), but it hollows out way too quickly. I’ve got an extra coarse diamond stone, but it is slow, too.
Any advice is appreciated. Thanks.
Replies
Beltsander
Take your plane irons to a local machine shop who has a surface grinder.
It will probably cost you about as much as buying another iron.
One of the reasons people give up on their tools, is they want them sharp right now, they first time they use them.
I usually work on them a bit now, and bit more later, and all of a sudden one day, they are sharp. It is then relatively easy to keep them that way.
TW,
I will cast a vote for the type of wet-dry sandpaper sold at NAPA auto parts. Both the 180 and 220 grit. On the one hand, it wears out easily but on the other hand it cuts very aggressively when sharp. It is made in Finland and called "Gator Grit." Just wet the front and back with WD-40, oil, whatever, and lay it down on a piece of MDF or smooth plywood, or any flat surface. As a matter of fact, as soon as I get done goofing off and wasting time on the computer here, I've got this newly-acquired E.A. Berg Eskiltuna bevel edge bench chisel which needs to be tuned up some time this week and it will probably see some "Gator Grit" time to flatten the back before moving on to the PSA film and other patented white-lab coat, top-secret sharpening methods that I employ (I could tell you but then I'd have to kill you). Good luck, Ed
My sympathies about the condition of your blades. Personally I'd stick with the course grit waterstone, courser the better. Let em soak till they stop bubbling, pause to flatten every couple of dozen strokes or so (it won't take long when done often) and keep at it till you get inside the ball park.
I'd prefer waterstones over a power tool method simply because they're guaranteed not to heat the blade at all, much less risk getting it hot enough to affect the temper.
PITA I know, but take solise in knowing you'll never need to repeat it on that particular blade..
Mike Wallace
Stay safe....Have fun
Mike,
How do you flatten your coarse water stone? I use an extra coarse diamond stone to flatten my 800, 1200, and 6000 grits, but I'm not sure what is best for the big green stone. I am in agreement about not heating up the blade. It's a tapered James Howarth blade which I'm planning on making a wood plane for. It's about 120 years old, and I'd prefer not to ruin the temper with my impatience.
Thanks to everyone for the advice. I will probably try every idea by the time I'm done with this one, save the machine shop, of course.
-Matt
I've a 150 grit flattening stone that makes light work of virtually anything. This one....
http://www.axminster.co.uk/product.asp?pf_id=32262&recno=3
its smaller than most of my bench stones but apparently it doesn't know that; it took some gouges left by a 3.8mm blade out of a 2000 grit stone in less than a minute...
messy... but effective...Mike Wallace
Stay safe....Have fun
Pretend you're flattening the sole of a hand plane and affix abrasive to a piece of float glass; a longer piece of glass (and abrasive) will yield longer strokes and more material removed per stroke.
Start with a more agressive grit, e.g., 80-grit, and work your way up through progressively finer grits, ensuring you have a consistent scratch pattern across the steel before going finer. Remember that the grading system for abrasives is not consistent among all abrasive media, i.e., 1,200-grit sandpaper is not the same as a 1,200-grit ceramic stone.
Use a vacuum cleaner with brush attachment, or a bench brush, to remove the swarf frequently while sanding, and make sure you remove all remnants of coarse grit when switching to a finer grit to avoid stray and unwanted scratches.
There's no reason, other than aesthetics or bragging rights, to flatten the entire back of a chisel or plane iron - concentrate on the part of the surface where the work will take place.
Good luck,
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
Edited 5/24/2005 8:33 pm ET by jazzdogg
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