How hard are jointer/planer knives?

Question

I have an Inca 410 jointer/planer and I would like an extra set of knives. They are no longer made, and are a strange size (8-5/8" by 1" by 3/32" thick). I haven't been able to find anything compatible, either.

McMaster sells D2 tool steel that is 3/32" thick by 1" wide by 18" long for about $28. They say it is "Wear-Resistant Air-Hardened D2 Tool Steel." Hardness is specified as "B89-B102" with a maximum attainable hardness of C62-C65. I have found a local sharpening shop that will cut it into two knives and sharpen them for less than $20.

My question is whether the initial B89-B102 hardness is enough, or if they would require additional hardening. If B89-B102 is enough, then $50 doesn't seem too bad for a custom set of knives. But if additional hardening is required, I imagine that would be expensive and extra complicated.

McMaster also have a 4140/4142 steel that they say is hardened to C28-C32. However, I have seen D2 mentioned for planer knives but never

4140/4142, so I don't know if this 4140 steel is appropriate?

Any opinons?

Thanks, Phil

Jim · Accepted Answer

D2 is a tool steel.  4140/4142 is a different beast entirely.I would use D2 and I would get it hardened to C61-C65.That would ensure maximum life for the knives.Jim

cgallery · Answer

Hi, thanks for the reply.Have any idea where I can get this stock hardened?  Is this something Ican find a local outfit to do, and would it be very expensive?Thanks,PhilJim wrote:

Prometheus · Answer

Have you asked the sharpening shop? They're usually pretty savvy about this sort of thing- you're just getting opinions that are sometimes great and sometimes crazy here. If you don't know, you can't pick the right ones!

CW · Answer

If you look hard enough, you might find a small machine shop that willharden for you. Good luck. The place that does ours has a minimum charge of$300.00. We do small stuff in house but send out larger quantities.

bc · Answer

Try Global Tooling @  web site says that they will cut to size. The prices are prettygood at least for standard sizes ( I got a set of 15" carbide tippedknives for $174.00) and I had no troubles with my order.BCPS The usual disclaimers, don't work for them, don't get any kickbackfrom them etc., etc.

Jody · Answer

I get all my knives from global. Very easy people to work with. They stock 3/23 knives but not in the size you need. They can cut a balanced set any length you need.

How hard are jointer/planer knives?

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