Thread: Nobody can sharpen my 3/8" jointer blades - what to do?

I have hand sharpened 6" jointer blades going sideways on an oil stone, but that was a set that were already sharp-ish and just needed a touch up. It was slow, and I needed ot be careful, but it worked.

Originally Posted by petersemple

I have hand sharpened 6" jointer blades going sideways on an oil stone, but that was a set that were already sharp-ish and just needed a touch up. It was slow, and I needed ot be careful, but it worked.

I would give it a go if they had an edge, but I think I would be there for 6 months starting from blanks. It is very frustrating that nobody can sharpen them, I might have to make inquiries overseas.

Thanks
Col

You would not be able to sharpen them on a wet grinder anyway. You would need to establish a bevel on a high speed grinder first.
I would make up a jig to grind the bevel on a high speed grinder and then use one of these to hone the edge.

You can grind knives in place in a jointer using a router. Remove the fence. You need to lock the cutterhead in place with the bevel of the knife parallel to the jointer bed. You will probably need to lower the tables. Put a cupped grinding stone in your router, a speed reducer is a good idea. Guide the router with a straight edge and set the depth of cut on the router to just touch the knife's bevel. Grind all of the knives equally. It has been a while since i did this but you get the idea. However you lock the cutterhead it must index in the same place for all of the knives. I must say that 3/8 seems pretty narrow. How deep is the slot that they go in? When new the knives should nearly bottom out and stick past the cutter head at least an 1/8th of an inch. I would base the knives more on the slot they go in than what someone had stuck in there, who knows where those knives came from.
Mike

Originally Posted by NCArcher

You would not be able to sharpen them on a wet grinder anyway. You would need to establish a bevel on a high speed grinder first.
I would make up a jig to grind the bevel on a high speed grinder and then use one of these to hone the edge.

Thanks I did not know a slow speed grinder wouldn't do the job.

Originally Posted by msiemsen

You can grind knives in place in a jointer using a router. Remove the fence. You need to lock the cutterhead in place with the bevel of the knife parallel to the jointer bed. You will probably need to lower the tables. Put a cupped grinding stone in your router, a speed reducer is a good idea. Guide the router with a straight edge and set the depth of cut on the router to just touch the knife's bevel. Grind all of the knives equally. It has been a while since i did this but you get the idea. However you lock the cutterhead it must index in the same place for all of the knives. I must say that 3/8 seems pretty narrow. How deep is the slot that they go in? When new the knives should nearly bottom out and stick past the cutter head at least an 1/8th of an inch. I would base the knives more on the slot they go in than what someone had stuck in there, who knows where those knives came from.
Mike

That is a very good idea - thanks. I don't what a cupped grinding stone is but I will google it in a moment.

With regards to how deep the blades go into the slot - they bottom out and are adjustable with grub screw, I would say that they would protrude 1/8", I am not 100% but will look at it when I get home from work. I will post a photo too out of interest too.

I did think that maybe they weren't the correct blades but I can find no info on the jointer anywhere. I thought of putting wider blades in it, but I am not sure whether the tables will come up high enough or there is enough clearance around the cutter head. I suppose there would be more centrifugal force generate as well which could put more stress on the bearings.

The jointer is made by Anglo Australian Engineering Company and the model is 'Exceller'.

I will try the router idea and see how I go.

Thanks guys

Col

some not very interesting photos of blade and spindle

Hi Colburge,

I think if you go to a jobbing machine shop as distinct from a sharpening shop they will be able to get hold of your blades in a pair magnetic angle clamps ( not sure if that is the correct terminology metal machinists please help) and then grind them on a precision cutter grinder or the like.


Old Pete

Going on your image showing the knife in the cutter block, it is back the front. The bevel should be on the left not the right as shown.

Originally Posted by Acco

Going on your image showing the knife in the cutter block, it is back the front. The bevel should be on the left not the right as shown.

thanks for that, I didn't notice and just threw it in for the photo.

Col

Originally Posted by old pete

Hi Colburge,

I think if you go to a jobbing machine shop as distinct from a sharpening shop they will be able to get hold of your blades in a pair magnetic angle clamps ( not sure if that is the correct terminology metal machinists please help) and then grind them on a precision cutter grinder or the like.


Old Pete

Thanks mate, I will look into it.

Col

Col

there's a good idea for sharpening jointer blades from Ashore in this thread
https://www.woodworkforums.com/f154/s...-blades-43559/

Originally Posted by ian

Col

there's a good idea for sharpening jointer blades from Ashore in this thread
https://www.woodworkforums.com/f154/s...-blades-43559/

Thanks Ian

I had thought about doing it on a drill press last night, but didn't know how I would hold them at the correct angle. Fitting them into a block and running it up against a fence might work and I think that is how I will go. I don't have a drill press though!

I have been waiting for an older floor standing drill press to come up 2nd hand but I think I will just bite the bullet and go to Carbatec tomorrow and get one, as they are on special for $295 down from $369.

thanks

Col

Another option may be this, if it'll grip your blades OK: click

Buy a piece of plate glass say around 10 mm thick from your local glazier and lay it on a thick piece of MDF. 15 and 5 micron 3M micro-finishing abrasive sheets are available in Aus here. Get some 40 m as well for badly chipped edges.

HTH

Originally Posted by rsser

Another option may be this, if it'll grip your blades OK: click

Buy a piece of plate glass say around 10 mm thick from your local glazier and lay it on a thick piece of MDF. 15 and 5 micron 3M micro-finishing abrasive sheets are available in Aus here. Get some 40 m as well for badly chipped edges.

HTH

Thanks for the link, someone else also posted the same one earlier on in the thread I think, I just don't know if the blades will have enough width to be held. I am going to Hare and Forbes tomorrow to pick up my new table saw, so I will take a blade and see if they have one to look at.

I had a go at making a prototype jig out of wood and sharpening one of the blades on the grinder which turned out pretty good, I then finished on glass and sandpaper. I am going to make a permanent jig out of mild steel at some stage. I am yet to set the blades properly in the jointer as it is not as easy as I first thought. I am buying a Dial indicator and base tomorrow and will use that to find TDC of the cutter head and go from there, it looks like the most accurate method.

Thanks for the input

Col