Replacing jointer knives

[eyekode]

I have an old delta 37-220 (6" jointer) that apparently takes 6 1/8x 19/32 x 3/32 knives.

I ended up ordering the wrong size: 6 1/8 x 5/8 x 1/8.

So it is 1/32 too tall and 1/32 too thick. It didn't look too crazy so I installed them anyway. I ended up having to grind down my wrench to be able to fit in the now reduced sized clearance for the screws but they seem to fit.

I also noticed the angle on the new knives was lower.

Anybody think this will cause a problem?

Thanks!
Salem

[bob vaughan]

The problem and risk comes from the extra thickness of trying to get 1/8" knives in there. The lock bar (gib, shim, whatever) is backed so close to the hex head screws that only a ground skinny wrench will get in the slot. When a 5/16" wrench is ground that skinny, it has a tendency to spread over the flats before the proper torque can be applied. This means a possible risk of slinging a knife. When the old Delta jointers sling a knife its usually when an unfamiliar operator tries to put 1/8" knives in a used jointer that's new to them. There's no guarantee that a knife will come out, but the risk is higher. I've seen many of the older Delta machines that people are using 1/8" knives in them with no knife slinging, but once they realize the risk, few continue the practice.

1/8" carbide knives in Delta jointers are particularly insidious about coming out, I guess because they are so heavy and slick.

For a setting video, Google: bob vaughan + jointer

[eyekode]

Originally Posted by bob vaughan

The problem and risk comes from the extra thickness of trying to get 1/8" knives in there. The lock bar (gib, shim, whatever) is backed so close to the hex head screws that only a ground skinny wrench will get in the slot. When a 5/16" wrench is ground that skinny, it has a tendency to spread over the flats before the proper torque can be applied. This means a possible risk of slinging a knife. When the old Delta jointers sling a knife its usually when an unfamiliar operator tries to put 1/8" knives in a used jointer that's new to them. There's no guarantee that a knife will come out, but the risk is higher. I've seen many of the older Delta machines that people are using 1/8" knives in them with no knife slinging, but once they realize the risk, few continue the practice.

1/8" carbide knives in Delta jointers are particularly insidious about coming out, I guess because they are so heavy and slick.

For a setting video, Google: bob vaughan + jointer

Bob,
Thanks for the reply. This was my primary concern. I wasn't really concerned about the depth because they don't "bottom out" in the head.

I am however pretty sure the screws have good torque on them. The wrench I used was particularly porky to start with. It is still thicker than the head of the screw.

That being said I think I will swap them back out . Anyone need 6 1/8 x 5/8 x 1/8 knives for a steal?

[mxracer]

One other option for you is to take those knives to a machine shop and have them grind 1/32 off of the thickness. Obviously that depends on your proximity to a machine shop and the cost of grinding compared to new blades, but a good surface grinder and a good machinist and in about 20 min you'd have the right sized blades.

Dan