Thread: A Couple of Blade Grinding Jigs

I like that way of flatterning the backs.

But are you shore the result is flat......I know it have to be pretty close...... but whats stopped me from trying similar before, is the spongy velcro that holds the disks on........Does it slightly hill the blade at the corners ?.....uno, just a little daylight at the corners when rulers on .

Originally Posted by derekcohen

So the practice chisel seems to work quite well. But I couldn't proceed beyond this point. To my great frustration I only then discovered that the grinder's body projected beyond the 6" wheel and prevented the chisel body being ground in the opposite direction. I shall have to wait until I get a 8" wheel for the machine. So there we wait ..

You could unbolt your bench grinder and turn it around, so that it sits on the right of your tool rest. The grinding wheel will be running in the opposite direction but I don't this would be a problem

but whats stopped me from trying similar before, is the spongy velcro that holds the disks on........Does it slightly hill the blade at the corners ?..

Hi Jake

Very fair question. In fact, my concern about keeping the blade flat was the reason I avoided using the disk sander before. However, the dial indicator base is very substantial and holding the blade flat is quite easy. I make sure that the bevel area goes on last and comes off first. The scratch pattern tells me that I am getting an even grinding. If you want you can finish off with sandpaper on glass or a waterstone. The disk sander then will just do the donkey work.

Regards from Perth

Derek

Hi Derek.

Sounds like nothing to worry about then.

Thanks for sharing the ideas Derek. That magnetic board idea in the jigs looks clever too.

I might pinch that idea, if you don't mind. Can see how it would grip any thin blade easily too....like uno jointer and thickness blades. small blades too no doubt.

Maybe attach a small fence in behind the row of magnets though to keep the blade square....?

My normal jigs require a clamp that extends over both sides of the blade....make its difficult sometimes because the clamp has to be kept thin to stop it running foul of the grinder wheel......but with the magnets, it looks like I won't need support from the underside of the blade, which should give more clearance....and more options. Simplifys things.

Still amazes me how reliable those magnets look (still haven't had any experience with them).... are you shore there isn't a little play ? I mean, does the occation bump shift the blade about on those magnets....cause I can't have that happening in a grind. (if that makes sense)

Goodluck with your chisel.

Maybe attach a small fence in behind the row of magnets though to keep the blade square....?

Hi Jake

There is already a fence - that is what the thin steel plate is for. It is just thick enough to support the chisel edge and thin enough to go under the clamp (which has a limitation for thickness).

Still amazes me how reliable those magnets look (still haven't had any experience with them).... are you shore there isn't a little play ? I mean, does the occation bump shift the blade about on those magnets....cause I can't have that happening in a grind. (if that makes sense)

This is the first time I am using them. You can get them in several sizes. I would have prefered larger ones but these were at hand. The chisels I am grinding are narrow. If you are wanting to grind something wider and want the ultimate security, then consider clamps.

Regards from Perth

Derek

Originally Posted by derekcohen

Hi Jake

There is already a fence - that is what the thin steel plate is for. It is just thick enough to support the chisel edge and thin enough to go under the clamp (which has a limitation for thickness).

Sorry, my mistake. I should have looked closer.

Some good ideas Derek.

I made a slightly hollow ground sided chisel from a 6" triangular file. The sides were hollow ground by accident when I was grinding off the file teeth. Although the sides are not deliberately sharpened I have still sliced my fingers a couple of times with it. The chisel itself is quite hard and takes longer than usual to work up a burr but it stays sharp for a long time so it appears to be good steel.

Cheers
BobL

Good idea Derek, I have a couple of chisels I might try that back-flattening on...

Are you holding the mag base to the sander by hand or clamping it? I imagine that it could get fairly thrown around the workshop if things went awry. ?

woodbe.

Hi Woodbe

The dial gauge base is quite heavy and the magnetic force it exerts is high. Once attached, the blade is not going anywhere. It gives me the control to hold it against the disk manually. Just make sure that you approach the disk as if you were going to set the blade doiwn flat all in one go, but then set the tail end down first and the bevel end last. When you lift it up, remove the bevel end first.

Regards from Perth

Derek

Like the idea very much Derek.
Have seen pix of those dial gauges before but not sure what they are usually used for, where to get them and how much.
Thanks for a good idea.
Bob

You can probably get them at bunnies. Hare and Forbes sell them too.

http://www.hareandforbes.com.au/samp...orking/36.html

woodbe.

Great idea for hollow grinding the bevel edges on chisels, Derek I think I'll pinch that one - I find the bevel edges on chisels are often unsatisfactory. Thanks for sharing your idea

Cheers

Paul

Damn, now I will have to get a disk sander combo :mad:.

Great ideas Derek, and thanks for sharing them

Hey Derek,

I've got a Makita (planer) blade sharpener that is fantastic for flattening the backs of blades. See HERE
Because it's a water stone the finish is remarkable without the effort of a stationary stone. The only problem you might (will) encounter is practice. You need a little practice to be able to get an even mirror finish.
Without downward pressure on the blade, it actually aquaplanes and doesn't grind any of the blade. This is very handy when you come to pull the blade off the stone for inspection, just reduce pressure until the blade aquaplanes & then remove as you describe. The original unit comes with a 1000 grit stone & there is an optional 6000 grit stone that is available.