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John Stevenson
12-27-2004, 07:13 AM
Prompted by Darin's post called Ground it Myself here's a couple of jigs I did some while ago when I was making tool holders.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/partingtooljig.jpg

Once the long blades out of commercial planer have had a few regrings they are useless and usually throw away.
These are solid HSS, some have a 5% cobalt edge strip that's still intact.
I grind these into pieces long enough to make parting tool blades.
First op is they go on the jig at the right on the top face and have a 5 degree taper ground on to give 2.5 degree side clearance when in the holder.
The keep plate for this operation isn't shown.

Next operation is to put the blade in the side jig and grind a 10 degree angle on the bottom to sit in the slot on the holder.
Last operation is to use the second jig to grind a 30 degree taper on the top to suit the holder.
You may want to alter the top and bottom angles to suit your holders but the idea is generic and just one scrap 36" planer blade will make at least 8 or 9 parting tool blades.

More than enough for a bad day http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif

Given the price of blades just one or two long scrap blades will be enough for most people for life.
Last set I did, I ground about four 3' blades up in a morning and got a shed load of blades.

John S.

aboard_epsilon
12-27-2004, 09:12 AM
Good post John.
but you or wierdscience do not say, if it makes any difference with the jigs orientation on the magnet .
should the blade be ground running down the magnet or across the magnet.
I would have thought running down, but wierdscience's picture shows it across.
all the best..mark

Michael Az
12-27-2004, 10:17 AM
Good idea and nice work John.
Michael

John Stevenson
12-27-2004, 03:14 PM
Mark,
In my case it doesn't matter as all the faces are clearance faces.
the cutting edge is applied by hand on a bench grinder afterwards.

John S.

Spin Doctor
12-27-2004, 06:08 PM
John we used to grind all the blades for the carpenter shop with jigs like that. And we always ground them with the jig at a slight angle to the slide and with coolant. Finish honed the cutting edges.

wierdscience
12-27-2004, 11:04 PM
John,are you part Scottish? http://bbs.homeshopmachinist.net//rolleyes.gif or have you been hanging around Alistair to long? http://bbs.homeshopmachinist.net//biggrin.gif

Good idea,now I know what to do with my old ones when they get to narrow.

Mark,the ones I ground are with the wheel turning into the cutting edge like you would sharpen a chiesil.
[This message has been edited by wierdscience (edited 12-27-2004).]

[This message has been edited by wierdscience (edited 12-27-2004).]