Carbide tipped vs solid carbide jointer knives?

[J.R. Rutter]

Any pros / cons to tip the scale either way?

I suppose that solid knives last longer, but I would hate to drop one!

[Jim Dunn]

I second that nightmare about dropping a solid carbide anything. I don't think the solid carbide blade would last any longer as it's only the edge that cuts anyway.

[Steve Clardy]

You can buy many sets of HSS blades compared to 1 set of carbide.
Carbide cost more to sharpen.

[Richard Wolf]

I'm with Steve, plus if you have a Tormek with the jointer planer jig you could sharpen your own. Please don't start another Tormek tread.

Richard

[Michael Ballent]

Unless you are working with high silica woods like ebony I do not think that the cost is justified. Although I have never heard of carbide tipped jointer knives either.

[lou sansone]

Unless you are working with high silica woods like ebony I do not think that the cost is justified. Although I have never heard of carbide tipped jointer knives either.

I agree with michael... also teak is another wood that will require carbide
lou

[Dev Emch]

No good solution here as there are many variables to consider.

First of all, solid carbide is very brittle and prone to cracking. This is esp. true in longer jointer blades. Anything solid carbide over 12 inches is a very bade idea as you install one knife and pull out two or more.

The better way to go is carbide tipped. You get the benifits of carbide without all the risk of cracking knives.

But HSS provides a sharper edge and can also be back beveled if needed. Also in larger, older industrial machines with knife grinders, they can also be honed. Nothing beats a set of in-place honed jointer knives! The shavings look like somthing off a Lie Nielsen wood plane being used by Deneb himself! HSS is also way cheaper.

But some woods are insanely hard on blades if you forgive the pun. Woods like teak and many others from the rain forest actually have a nasty habit of depositing silica on the inside surface of the cells. Its very thin but it greatly shortens the life of any cutlery being used. In this case, you have to run carbide or that other stuff offered by Freeborn... Tanalum is it?

Now a few years ago, my buddy Steve got a hold of a set of jointer knives and planer knives that were like nothing any of us had ever seen. They were tipped with an M-42 steel alloy. The M-42 alloy is most often used to make steel cutting tools for the metalworking industry and I have used M-42 to cut metal. It cuts anealed and semi hard chrome molly steel like BUTTA! My buddy was able to finish the interior of two homes done in oak without so much as a touch up on these knives.

But they were hard to make as the M-42 had to be brazed onto the backer strip and many larger machines use a thin knife or a 1/8 inch thick knife. This makes it hard to make as the brazing leaves the knives heat warped. So these knives were to hard to make and eventually were discontinued.

But most carbide tip knives are made this way and that may explain why they cost so much.

Hope this helps a bit and good luck...

[Chris Giles]

I have solid carbide on my DJ20 and wouldn't go back to the steel. The steel knives were a little sharper I think, but only for a little while. Then the nicks and dull spots appear, and you have to find the sharp spots that remain, etc. Time to sharpen again. I like being able to feed anything thru with out worrying about hurting its feelings. Exotics, melamine, mdf, you name it. No problem, they stay plenty sharp. Going into my third year without sharpening! I didn't think they'd last this long.:)

[Ian Barley]

I use a lot of Iroko (like Teak - high silica). Carbide tipped knives last three times as long and cost three times as much to sharpen but I save by not having to stop production to change knines twice. I rate it as worth it. I would NOT buy solid carbide because of the risk of fracture.

[Dev Emch]

But keep in mind that some jointers have their own knife grinders and these frequently work only on steel. Some can do carbide.

The main advantage is that you rough install your knives and then use the grinder to grind the knives sharp. Once done, park the grinder head and then crank the honeing stone across the grinder bar while the jointer is running. This takes each knife down to the same height. Perfect. As the knives loose their keen edge, you just go over it once with the honeing jig. You can hone several times before you absolutely have to regrind.

This system produces a head where all knives are cutting. In general, one knife is always higher than the others so its producing the finishing cut. When all knives are cutting, your surface finish is killer. Also, your feed rates can go way up as well. The shavings are not chips anymore but look more like something from a hand plane.

[Jim Becker]

I also agree with Michael. The carbide knives, while harder and able to stand up longer under certain conditions, are also more brittle. HHS is more forgiving, easier to get sharpened (carbide requires special equipment) and a lot less money.

[tod evans]

fyi, tersa offers the m-42 blades for their heads and they are reversable..02 tod

[J.R. Rutter]

Thanks guys,

I run a lot of Braz. Cherry, which is very hard on steel. I've been grinding in place with the Tage Frid router setup that he described in his first book on joinery. Basically, you try to come close to a dedicated on-machine knife grinder does, using a router sled and cup grindstone from 1/4" flexshaft grinder. You index the cutterhead with a strip of aluminum mounted temporarily on the infeed table, and wedge the cutterhead lightly in place. It works quite well, and as my jointer does not have jack screws, changing knives is a bit of a pain.

Lightly jointed and honed afterwards makes for those nice feathery shavings, but doing it every other week is getting to be a bit much! So for that 12" jointer, I may just go to a Byrd head and dedicate it to facing. I saw a nice cast iron base 8" jointer locally that would be a sweet edging setup, and with carbide knives, it could run for a VERY long time by moving the fence out as the 1" spot alng the fence dulls... So that was the original reason for the question.