Jointer knives 7/64 vs 1/8 thick

[Michael Beardsley]

I recently bought an old used Geetech CT-150 6 inch jointer. I cleaned it up and it works great but one of the blades has a significant chip in it.

I ordered a new set of knives from Global Tooling out in Oregon and when I went to replace them last night I learned that the new ones are just a little thicker than the existing. The new ones are 1/8 and the old ones are 7/64. I can barely get them started into the cutter head, but I'm worried about pounding on the new blades (and cutting myself) trying to force them in. I can't seem to find anywhere on the internet 7/64 thick knives/blades.

Any tricks? Am I out of luck?

[Jim Becker]

Can we assume that you have the cleaned out completely? I wouldn't suggest forcing them for sure...not only is there the injury potential that you mention, but such a tight fit may also compromise your ability to adjust the knife height.

[Myk Rian]

Do not use anything but what the manufacturer calls for.

[Andrew Hughes]

How about sending the chipped knifes for sharpening.Then track down another set.
If they are too thick your may not be able to tighten them.

[Michael Beardsley]

That's the trouble... I don't know what the manufacturer calls for. The "manual" that came with it is super generic. Maybe an outcome of Geetech being a manufacturer for multiple brands back in the day? Sunhill I know was one of them.

Does anyone know where I can find knives that are 7/64 thick? I am not coming up with anything. I must not be entering the right things into the search engines.

[Wade Lippman]

They are heavier than the machine was designed for. I wouldn't want to be near something that was heavier than the design called for when it is spinning that fast.

[Mel Fulks]

Only similar thing I've seen ,and I'm sure others here too, is the big machines used to be made for 5/32 " thick knives. All the newer ones seem to be made for 1/8. I would call one of the full service old suppliers ,maybe Schmidt , and see what they know and what they sell.

[Michael Beardsley]

I just called Global Tooling to see what their thoughts were. They do have 6 1/8" long blades that are 3/32 thick. I don't know if the extra 1/8" length is similarly detrimental -- looks like there's more than enough room. At least the 3/32 thick knives would be 1/64 thinner rather than thicker and they'd slip into the head and be able to be tightened.

Thoughts from the more experienced?

[Mel Fulks]

Sounds like same thing only different, I would use those. But don't buy " HSS " insist on real M-2 .or T-1 HSS ,well worth the litte extra money. Everybody seems to push the cheap stuff rather than lose a sale to a competitor. Never seen a little difference in knife length make any difference, many are sold that are a tad short and you just stagger them. Just make sure there is clearance.

[John Donhowe]

Okay, I'm going to jump in as a contrarian. The blades from Global are 1/64" thicker. Given the density of steel, by my calculations that additional thickness for three knives adds 4.6 grams to the mass of the cutter head, which, if 2 inches in diameter and 6 inches long, has a weight of about 2500 grams.

So, the new knives add less than 0.2% (2/1000) mass to the cutter. I seriously doubt that safety margin is so tight that the cutter is likely to disintegrate or spin off pieces because of that slight increase in weight.

I agree with Jim in suggesting that you clean out the cutter head slots, as well as the gibs/wedges and lock screws. I suspect that the tightness could be due to there being crud/dust buildup on the threads of the lock screws, preventing them from going into the wedges any further to allow additional width.

When I bought my Ridgid jointer, as well as a previous Sears jointer off CL (both with a generic blade holding design) I cleaned up all the cutter head parts, and have never had any problems with tightness with either one- there's easily more than 1/64" extra room without forcing the locking screws.

If you can get it so that you can fit 1/8" thick knives, I's say go with them- they're a lot easier to find, and probably a lot cheaper, than 7/64" knives. Just my $ .02

[Tom M King]

Woodworkers Supply used to have the thinner knives. I'm not sure if they still do or not now. Personally, I wouldn't worry about that extra thickness either. You might have to thin down a wrench to tighten with though. I had to do that with an old Delta that I've been running 1/8" knives on for 40 years that was designed for thinner knives.

[Matt Day]

I tend to agree with John, and would likely use them. Tough to tell for sure without really seeing everything though. 1/64 is not much of a difference.

[Tom M King]

Found these: http://www.americannationalknife.com/2To7.asp

3/32 should work if 1/8 just won't go

[Myk Rian]

Blades 1/8" wider are ok to use, especially when setting them to the rabbeting ledge.

[Michael Beardsley]

Thanks for all the advice! Global Tooling was really nice on the phone and happy to give me an RMA so I can get a refund on the knives I can't use.

I did carefully clean out the cutter head and the lock bar (or whatever its proper name is) and all the bolts and the 2 springs. 1/64 is barely any difference, but when everything is well milled metal, there's no room for error. I have swapped the old blade back and forth a number of times just to make sure I'm not crazy and it slips right in when the new 1/8" thick ones won't.

I did think about grinding down the heads of the locking bolts, but ordering 3/32" blades seems like a less error prone solution. I just can't find reference to 7/64 anywhere on the net.