Tersa knife options - help needed

[Mike Leung]

I have an Inca 570 with a 3 knife cutter head. I know they offer 4 blade material options. I mostly joint QSWO but occasionally I would like to join glue lines on laminations and plywood and solid surface materials. HSS gives me beautiful finishes in oak but I can see fine lines from chips. I am planning on switching out to M42 for oak. What do you guys recommend for cutting everything else like glue lines? I couldn't stomach spending $240 on 3 carbide knives for such tasks. Should I use a combination of 1 carbide knife and 2 HSS for the occasional oddball rougher tasks? Any tersa users here?

[Mel Fulks]

Would not mix knife types . Balance etc. Most effective cheap thing to do when removing glue is take deep cut feeding fast.

[Erik Loza]

Mike, how's your dust extraction working? I've used HS/S on oak (and most other domestic hardwoods..) with great results. Your issue sounds almost like a feed speed or dust extraction one than a knife material issue. Just my thoughts.

Erik Loza
Minimax USA

[Jeff Duncan]

I believe those machines are fairly wide.....like maybe 10 or 12"? If so when you have to do that occasional odd material, slide your fence all the way back, (or forward), and have that 1" of knife just for such a task. You then avoid that inch for your regular hardwoods and don't have to go spending more money on upgrading knives;)

good luck,
JeffD

[Thomas S Stockton]

With a three knife head you really wouldn't want to mix knife styles like the other poster said.
I have a set of dummy knives for my 4 knife machine so you only have to buy 2 carbide ones, never used them. I buy the m42 and get real good results and they last well.
The best prices I have found for them are at www.globaltooling.com
Tom

[Mel Fulks]

Yep. The zone system.

[Lynn Floyd]

I have a Tersa head in a 16" SCM jointer. I started with hss and had dismal results, could just have been the brand knives, don't remember the name. We use hardwoods of all kinds. I switched to M42 and have had much better service, cheaper in the long run. I've found mdf and plywood glue hard on any hss. I hadn't thought of feed speed being a factor but I'll try upping it a bit as suggested, as this definitely affects finish in most cases. As a side comment, if you find a particular batch of material knocking out your planer and jointer knives, try cutting off a half inch of the ends (of the boards). Sometimes a load picks up sand and road grit in transit. This will be caught on the endgrain. Good luck with the Tersa head, they're great.

[Chris Fournier]

M42 is HSS. It is a great alloy even for working metal.

[Mike Leung]

Mike, how's your dust extraction working? I've used HS/S on oak (and most other domestic hardwoods..) with great results. Your issue sounds almost like a feed speed or dust extraction one than a knife material issue. Just my thoughts.

Erik Loza
Minimax USA

My dust extraction is good. I take super light cuts but I can try slowing down the feed rate.

[Mike Leung]

I believe those machines are fairly wide.....like maybe 10 or 12"? If so when you have to do that occasional odd material, slide your fence all the way back, (or forward), and have that 1" of knife just for such a task. You then avoid that inch for your regular hardwoods and don't have to go spending more money on upgrading knives;)

good luck,
JeffD

Great idea Jeff. It is 10.5" wide. I mostly use the rear portion for my jointing. I'll keep the front for the harder tasks.

[Mike Leung]

Would not mix knife types . Balance etc. Most effective cheap thing to do when removing glue is take deep cut feeding fast.


With a three knife head you really wouldn't want to mix knife styles like the other poster said.
I have a set of dummy knives for my 4 knife machine so you only have to buy 2 carbide ones, never used them. I buy the m42 and get real good results and they last well.
The best prices I have found for them are at www.globaltooling.com (http://www.globaltooling.com)
Tom

ok. I will not mix knives. Thanks for the source. I buy from simantech usually. I'll compare prices.





I have a Tersa head in a 16" SCM jointer. I started with hss and had dismal results, could just have been the brand knives, don't remember the name. We use hardwoods of all kinds. I switched to M42 and have had much better service, cheaper in the long run. I've found mdf and plywood glue hard on any hss. I hadn't thought of feed speed being a factor but I'll try upping it a bit as suggested, as this definitely affects finish in most cases. As a side comment, if you find a particular batch of material knocking out your planer and jointer knives, try cutting off a half inch of the ends (of the boards). Sometimes a load picks up sand and road grit in transit. This will be caught on the endgrain. Good luck with the Tersa head, they're great.
Sounds like M42 will work well for my needs.

Great tips everyone. The advice given is great. I do love the tersa head on my inca. Many friends have gone to spiral carbide cutter heads now but I like the finish I am getting with my tersa. I just hope that the knives will not become hard to buy in the future.

[Mel Fulks]

Light cuts are fine and can improve surface.But when dealing with grit ,glue,paint ,etc. less damage is done to your knives,by fast heavy cuts. Counterintuitive but true.

[Lynn Floyd]

When I say high speed steel I'm thinking of M2 or M3. I've been making molder and shaper knives with this steel for 35 years but I still don't know what the alloy is and wouldn't understand it if you told me, but I know the M42 holds an edge longer, especially in abrasive material. At any rate the Tersa knives we bought as hss did not perform well but the M42 did.

[Mel Fulks]

Just looked up the TERSA knives .They have a 'chrome steel', T1 which they just refer to as 18 percent tungsten,and the M42 . My guess is that anyone not happy with performance has the chrome.

[Lynn Floyd]

My apologies for a mistake in a post I made yesterday. I am at work now. The label on the
Tersa knives is KNICC410T Carbide, not M42. I guess this is why they hold up well. We buy them from Carolina Specialty Tools, Inc. They're pricey but good.

[Mike Leung]

Light cuts are fine and can improve surface.But when dealing with grit ,glue,paint ,etc. less damage is done to your knives,by fast heavy cuts. Counterintuitive but true.

I will remember this. I guess the idea is to take a bigger bite quickly to try and avoid the grit or glue on the surface.

[Mike Leung]

My apologies for a mistake in a post I made yesterday. I am at work now. The label on the
Tersa knives is KNICC410T Carbide, not M42. I guess this is why they hold up well. We buy them from Carolina Specialty Tools, Inc. They're pricey but good.
Thanks for checking Lynn. It costs $240 for a set of 3x260mm at simantech. I guess if the carbide does not chip easily and still gives a nice surface, it might be worth the investment.

[Zach Callum]

Tersaknives.com has great prices, and the knives they sell are genuine Tersa. You might want to try out the M42, the cut isn't quite as smooth as the hss, but they seem to last a bit longer. I have the same jointer, and have ordered many sets of knives from those guys.

[Mel Fulks]

The M42 is also a true high speed .Dont know why companies make no attempt to be clear about these things. The steel that sight lists as "high speed" is T1.Why don't they say so and mention they think it leaves a better surface than M42 ? I do give them credit for not incorrectly calling the chrome steel high speed. It is clear to me that they are pushing the T1,good choice,but they should add M42 will last longer on hard things like glue......that's what the OP needs to know to make his decision.

[Jim Becker]

I've been using just the M42 for some time now and they do the job.

[Larry Edgerton]

I use M42 from Global, best price I have found. As a side note I tried several "Clone" knives and none were up to the task. I buy Tersa Brand only now. Some of the places do nat actually tell you they are clones, and one even lied to me and said they were Genuine Tersa's, so watch who you deal with. The packaging on the clones is "Almost" just like the originals.