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Thread: Tersa Carbide Knives

  1. #1
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    Tersa Carbide Knives

    Currently running 4 M42+ knives on my jointer cutterhead, which i think are the predecessor to the currently offered M+ knives. Honestly, i have no idea of how old these knives are. In any case, im thinking about switching out for carbide knives instead of repeatedly going through HSS knives every 6 months. From anyone that has carbide Tersas, about how long can i expect them to last? I process about 2,000 bdft of rough lumber a year. Nowhere near pro shop, but more than the typical weekend warrior. The knives arent cheap, but im thinking i can get two carbide knives and run two HSS knives to balance the head. This would cost me about $250. Not sure if i gain much performance by going to 4 carbide blades. The purchase makes sense if these knives will last as long as the byrd inserts in my planer. Im pretty sure i can go 2-3 years without rotating. I rotated them once after 1.5-2 years of use thinking i had grown used to dull cutters, and i didnt notice a surface or performance difference. Lastly, it looks like Rangate offers some form of diamond coating that they allege to last longer than carbide. Does anyone have experience with this coating?

  2. #2
    No knowledge of the coating. But I would try using just two knives. You can feed faster ,and that will help keep them sharp longer.

  3. #3
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    I always recommend TCT tooling. It is worth it in the long run or for me even in the short run. In your case there are some other things to consider.

    You will not gain anything by changing half your knives to TCT. The HSS knives will still lose their edge and require servicing at the same interval as you do now. Either that or you will carry on with half the knives dull and not doing any work.

    Six months between sharpening of your existing knives is excellent service. If I use anything other than TCT my interval is closer to 6 days - its the timber I use. Make sure the economics stack up and I am not seeing any evidence of this.

    I don't recommend leaving out 2 knives. It increases the load on the remaining pair - bigger shaving - which shortens life. increases vibration and reduces cut quality. Cheers
    Every construction obeys the laws of physics. Whether we like or understand the result is of no interest to the universe.

  4. #4
    I don't see anything about what kind of jointer. If it's a small machine Wayne might be right. But two knives will cut faster.
    Ive never like 4 knife jointers.

  5. #5
    I run a pair of HSS steel and a pair of carbide in my sac tersa head planer. It was actually reccomend by tersa.

  6. #6
    The carbide Tersas in my J/P lasted about 10x the HSS.
    --Mike Roberts

  7. #7
    i have carbide tersas in my 22" j/p. they are far superior to anything else i've used. i've also used the kanefusa diamond coated steel knives --- and i won't do that again. the main thing with the carbide knives is that they can be sharpened. the diamond coated knives are not significantly less expensive, and are disposable. to me, it's a no brainer, the carbides are worth every dime.

    i now use HSS/M42 when the carbides are out for sharpening. and, that's infrequent - many thousands of bdft before they start to show their age.

    -- dz

  8. #8
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    Would agree with David. We have been running Teresa carbide in our four sider for several years now. 2 knives with dummies in the other 2 slots. There is no advantage to putting hss knives in the other slots and running 2 knives vs 4 will not hurt anything either. The knife projection is slightly different between the 2 types. Martin claims most of the shops in Germany do two knives. The jointer since it is hand feed may be a little better with 4 knives. The power fed machines its hard to tell the difference between 4 and 2. We just slow the feed in difficult material.

    Just a guess but I think we have ran about 6 thousand feet of white oak, some of it knotty and 3 to 4 thousand feet of other mixed material in the last year and just turned the carbide knives last month. They have been sharpened twice. They may be done after this round.

    Also agree about Kanafusa, I have been using those in the jointer and planer but will go carbide when those are finished.

  9. #9
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    Carbide here as well. I change them out 1 at a time for the most part, picky stuff I will run two new, two old. Cut is better than HSS. not sure on BF., but there is about ten yards of hardwood shavings outside that all came off of one set. I stamped numbers on my head and keep track of what knives are shifted/changed on a piece of tape under the hood.

    Joe, I have a few sets I could send in to get sharpened. How much does that throw off the readout? Mine is mechanical so I can't easily zero it out if my knives were a different height.

  10. #10
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    Larry

    Throws the outfeed of the jointer and bottom head adjustment of the S4S just slightly for snipe. No noticeable changes on the read outs. Planer not affected at all.

  11. #11
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    Accidentally put this in the other thread:

    That is interesting, i wasnt aware of the opportunity to get another sharpening or two out of them. I assumed they were like the rest of Tersa's offerings in that it was two edges and then done. Do the carbide knives have more material? Looking at the steel blades i have now, i dont know how you can sharpen these things numerous times. Theres just not much material there. From what you all describe, that is what i wanted to hear and what i expected. This would be worth it if i got 1-2 years out of each edge. By the sounds of it, i might get 2-3 years out of each edge, which is kinda what i forecast for the byrd inserts.

    It is a 20" nonbadged italian jointer with a 5.5hp motor and a 4 knife tersa head from the late 80s. My intention with running 2 carbide knives versus 4 was only to save money. On a 4 knife head you can run 2 cutting blades and 2 dummy blades, but maintain the balance on the head. Cant do that on a 3 knife head. At $125-150 a piece, i dont want to go in for four knives if i can avoid it.

  12. #12
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    Where do you guys get your carbide Tersa knives sharpened?

    Why is it necessary to run dummy knives (for balance) in a 4-knife cutterhead?
    JR

  13. #13
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    Quote Originally Posted by Patrick Kane View Post
    Accidentally put this in the other thread:

    That is interesting, i wasnt aware of the opportunity to get another sharpening or two out of them. I assumed they were like the rest of Tersa's offerings in that it was two edges and then done. Do the carbide knives have more material? Looking at the steel blades i have now, i dont know how you can sharpen these things numerous times. Theres just not much material there. From what you all describe, that is what i wanted to hear and what i expected. This would be worth it if i got 1-2 years out of each edge. By the sounds of it, i might get 2-3 years out of each edge, which is kinda what i forecast for the byrd inserts.

    It is a 20" nonbadged italian jointer with a 5.5hp motor and a 4 knife tersa head from the late 80s. My intention with running 2 carbide knives versus 4 was only to save money. On a 4 knife head you can run 2 cutting blades and 2 dummy blades, but maintain the balance on the head. Cant do that on a 3 knife head. At $125-150 a piece, i dont want to go in for four knives if i can avoid it.

    Depending on cutterhead speed you will probably be fine with two.

    JR, it should not affect balance, I just leave two dull HSS in to keep the grooves clean.

  14. #14
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    For sharpening I send them to Unimerco in Michigan. 734 944 4433

    They have sharpened Leitz Teresa clones in both carbide and coated hss. I am going to send them a set of the coated Kanafusa blades just to see what happens.

  15. #15
    i live right near unimerco and i have had a tour of the place. the tersa knife grinder is really impressive. it's enormous, and clearly carefully installed on a custom pad to ensure it's flat. right now they have a 10 day turn on around on sharpening. joe, i think they won't sharpen the kanafusas, i've asked (in person), but hey, it's worth a shot - if they do yours, i'll bring mine over as well.

    --- dz

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