Thread: Planer knife grinder

Due to the narrow width of the blades it will be safer to mount the blades in a carrier.

You don't need a lot of power to sharpen them so the bench grinder is probably the most convenient way to go.

Just make sure in selecting a bench grinder that the blade can slide right across the front of the grinder.

All will depend on wether you want a hollow grrind or a flat grind, pro machines produce a flat grind, using a cup type wheel, the knives are held in a chuck of some kind i.e. clamped or magnetic and the grinder pases the length of the blade usualy with a flood coolant set up. I built my own some years ago unfortunatly I have nothing on paper just in my head. It sounds complicated but they realy are quit simple to build. I mounted the grinder using linear bearings.

Thanks for the replies guys. This is just what i am after.



I have contemplated mounting the knives in a carriage similar to the tormek setup. I am not too fussed about a concave grind, as the 10" stone won't hog them out too much. China, your idea sounds very good, and I am now leaning towards an overhead grinder setup. I have some 1" ground bar that may work well. I also have a few bits of P bronze, which would suit for bearings. The linear roller bearings that I have seen are way too expensive for this little project. I have access to a tool and cutter grinder for under $2000.00 with quite a few attachments, so I really can't justify too much expense for this, especially when time is taken in to consideration. Problem is I now have limited room left in the workshop, so I was hoping to make this grinder, with a small footprint, which the T & C grinder doesn't have.

I can make up a hardwood holder which would hold the knifes at 30 degrees, and grind two at once.

I will draw up a roughy sketch and post, so that this can be discussed some more.

Thanks again.

Fos

Makita used to make a flat circular stone wet grinder.Stones are only available in NZ and the good old USA. The design of the unit is so simple in a couple of days I will follow through with details and or photograph the one I have. The design is simplicity itself and easy to set up and use.
Have fun Peter

In an informative discussion in Woodwork Forum Groggy reply number 4 dated 18th March 2007 has a selection Makita that shows a pic of the machine I mentioned.The stones are available in NZ and the United States currently.

The unit can sharpen blades to 15 inch,flat plane.Easy to make a drive for the stone and a sliding holder for the blade using the two posts to acheive that.Easy to make the similar unit.You can go to the archives Patents Office with the Patent number and make a copy of the original specs for evaluation purposes of course.They do this free.

Another way to go.

Peter

That would be in this thread talking about the Makita 9820-2.

This is the rig I use. Not your normal grinder in that I can dial the rpms from 0 to 5000 or so via a Variable Frequency Drive. But you can see that it's pretty simple. I've done planer blades up to 15" without any problems. I don't have any carriage or anything just use my hands and light pressure. I just slide them by until they no longer are being ground. Bit of a touch up with a diamond file and there good to go. Takes about an hour to do three 15" blades. The heat build up is low as long as you keep a consistent movement.

Looking at the rest, the ledge allows you to maintain the same width; therefore keeping the blades in balance?

Nice idea. It also wouldn't matter that the wheel was square, or the rest is square to the wheel, provided you do a complete pass, and the same amount of passes on each blade.

Thanks mate I dont know much about the ways to display or transfer pics etc you have well done.

I have a mate who using an angled grinding wheel takes his large band saw blade and 1.5 mins later has sharpened it by eye,does it several times per blade and makes bandsawn boxes to die for cut by eye with exclusive timbers and a top price.

Very few people have the knack or ability,do admire the simplicity of the sharpening device pictured,thanks,heath robinson is alive and active.

Peter

Originally Posted by Groggy

Looking at the rest, the ledge allows you to maintain the same width; therefore keeping the blades in balance?

Nice idea. It also wouldn't matter that the wheel was square, or the rest is square to the wheel, provided you do a complete pass, and the same amount of passes on each blade.

correct the toolrest fence can be adjusted to take more off if needed.

Now that is a simple yet ingenious setup toad man.
The fact that it can be hinged down out of the way, so that the grinder can be used for all other purposes is a gem!

Is the wheel on the RHS leather faced?

Thanks for all of the replies guys.

Originally Posted by Fossil

Now that is a simple yet ingenious setup toad man.
The fact that it can be hinged down out of the way, so that the grinder can be used for all other purposes is a gem!

Is the wheel on the RHS leather faced?

Thanks for all of the replies guys.

It's an mdf wheel charged with white buffing compound

I was looking something up in an old textbook I've got and I came across a different approach for planer blades. He's got a jig that holds the blade at the correct angle (just a saw kerf in a block of wood. He's got a grinding wheel mounted in his drill press. There's a fence on the drill press table and he just sits the block on the table and rides it against the fence back and forth under the grinding wheel with the drill running. If you set the depth stop on the press, it would be similar to setting the depth of the fence on TA's gadget. You also have plenty of speeds on the drill to choose from.

Just another thought.

Originally Posted by silentC

I was looking something up in an old textbook I've got and I came across a different approach for planer blades. He's got a jig that holds the blade at the correct angle (just a saw kerf in a block of wood. He's got a grinding wheel mounted in his drill press. There's a fence on the drill press table and he just sits the block on the table and rides it against the fence back and forth under the grinding wheel with the drill running. If you set the depth stop on the press, it would be similar to setting the depth of the fence on TA's gadget. You also have plenty of speeds on the drill to choose from.

Just another thought.

Darren
What's the textbook called and/or who is the author?