Planer knives problem for Grizzly 15" planer

[Phil Knuckles]

I have a mysterious problem with my 2003 Grizzly 1033 planer. When my knives become dull the handwheel turns backwards and the infeed table lowers.

So out go the Grizzly HSS knives and in go the 'recently sharpened' carbide tip knives made by Global Tooling. The infeed table still lowers. I called the sharpener, who is also a woodworker, and he says that he ground the knives with a 220 girt diamond wheel, and they where sharp.

So I take both sets of knives, HSS and carbide tipped, back to get re-sharpened. To our surprise, the HSS knives work great, but yet the carbide tipped knives cause the infeed table to lower.

Both sets of knives were sharpened at 35 degrees. The carbide tipped knives were bought new a few years ago. I have been setting knives in planers for over 10 years now. I checked the bed rollers and all is well. Both sets of knives are flat, straight, and look like new.

[Bruce Wrenn]

If your Grizzly is like my Delta, there is a height lock on one or more of the support posts. Try it, you may like it. Sounds like the knives are setting up a viberation that is causing hand wheel to turn.

[Jim Becker]

The problem makes sense if you think about it a little...as the knives get dull, rather than slicing into the wood, they begin to pound into it more and more. If you don't lock your table setting as Bruce references, that repeated shock will move the table down. The only reason your outfeed table isn't doing the same is likely because it IS locked in place.

[Jon Dieterlen]

Carbide and high speed steel have some different properties that are contributing to your problem. HSS knives are softer thus less brittle than carbide. This means hss can be sharpened to a sharper edge than carbide. As the edge of the carbide is sharpened, it becomes thin and breaks off before a razor sharp edge is formed. HSS on the other hand is less brittle and a very sharp edge can be achieved. What this means, is carbide starts out duller than HSS in the beginning. As the tool is used, the HSS will dull quicker because it is not as hard. I have never liked carbide for planer blades because they cannot be sharpened sharp enough. HSS is good short runs on a molder head/shaper head as it will give a finer finish. Any runs on a shaper or molder in excess of 2000' lin ft you should look at carbide tooling. I made the mistake of purchasing carbide knives for a planer many years ago. They used excess power to cut, and the edge ultimately broke after limited use. Never again!
Hope this helps

[fRED mCnEILL]

I had the same problem with my Grizzly 20 in planer. I posted the problem on here, Shiraz told me to contact the service guy at Grizzly. When I explained the bed moving problems he said immdiately"dull knives". I changed blades(HHS) and it works like a dream. Don't know about carbide blades though.

Fred Mc.

[Phil Knuckles]

I failed to mention that I do use the locking knobs on the side of planer. Although, when using new or sharp knives one shouldn't see a regression in the table height.

I tried locking the table, with sharp carbide knives, and it still lowered. Is there any way to sharpen these knives like new? I am taking them to get re-sharpened.

[Phil Knuckles]

Is it possible to get the knives re-sharpened like new? The cost of the knives new was approx. $180. I would hate to deem them useless at this point.:eek: