Replies

1. 
   Lataxe | Dec 01, 2009 01:47am | #1

   J,

   There is a set (also expensive) of knives for the planer/thicknesser I have.  As I use a lot of difficult hardwood such as a teak and iroko, I did make enquiries all over the place to see if anyone had experience with them.  Not many did.

   But the two people I found who had tried them had returned to HSS knives because (they said) the carbide knives were too vulnerable to catastrophic damage; and they didn't actually stay that sharp for very long, according to the fellows I talked with.  Both were professional chaps who used their PTs all day long in making (respectively) first/second fitting stuff for houses/shops and posh hardwood kitchens.

   *****

   The knives in my machine are 10 inches long.  Although I've no personal experience, I can understand that it wouldn't take much of a too-deep cut or other accidental misuse to cause such a long piece of carbide to fracture, snap or shatter.

   So - I ain't taken the risk; but this is just a second-hand opinion I'm relating.  Like you, I'm hoping someone will come along who has extensive experience of such knives........

   Lataxe

2. 
   bill5335 | Dec 01, 2009 05:53am | #2

   A week or two ago someone posted that they were very happy with a honing jig for jointer blades from Lee Valley. The jig is used with silicone carbide sandpaper (with PSA ) placed on plate glass .

   I think the jig is about $60.  Since I'm so cheap, I am going to try to machine my own version.

   Bill

3. 
   observer | Dec 01, 2009 07:43am | #3

   Used carbide knives once in a planer I rented.

   While running western red cedar 1 x 6 through it, one of the knives disintegrated. Fortunately, it was only one so no arguments with the supplier about misusing the machine.

   I now have a couple pairs of HSS knives and a universal grinder.

4. 
   philip | Dec 01, 2009 08:21am | #4

   Joint,
   I only use carbide knives (two) on my thicknesser which is a heavy duty machine.
   What length are those knives from Infinity that you mention? Whatever, the price is suspiciously low and I would suspect that they are not quality carbide, and therefore to be avoided.Cheap carbide knives are a liability.
   The real thing is expensive and you can see examples if you look up Leitz tooling. These knives are top quality heavy industrial, with the carbide backed by suitable steel. Very durable , not prone to chipping at all, ground to mirror polish and expensive.
   Unless you are using much abrasive timber and have a suitable heavy machine you are better off using high quality HSS in place of the usual stuff that is supplied with DIY machines, and you can extend the time span between grinds by hand honing them regularly.

   Philip Marcou
1. 
   jointerman | Dec 01, 2009 09:39am | #5

   Philip,They're Italian made knives. At $147 for a 8-inch 3 knife set, I wouldn't really call them cheap. While you're right that there are different grades of carbide, it's only three long strips of carbide bonded to steel, as opposed to a labor intensive 40 to 80 carbide teeth welded onto a saw blade.While the Leitz stuff does look incredibly nice, I'm only looking for cutters themselves. It doesn't seem as if Leitz makes those for my jointer. Any way, this is the website.http://www.infinitytools.com/Carbide-Tipped-Planer-Jointer-Knives/products/1109/

1. 
   philip | Dec 01, 2009 01:33pm | #6

   If you need to find alternative knives to Infinity the salient details are length, width and thickness-the manufacturers are not concerned with the name of the machine-unless they purpose make them for a specific machine.So for example you would measure your knives and look for matching sizes made by a company like Leitz, Gudo, Omas or whoever.Philip Marcou

5. 
   blewcrowe | Dec 01, 2009 03:34pm | #7

   I put carbides in my planer (Delta 15") and my joiner (DJ20). They were expensive but if you don't put any metal through them, they last a LONGGGG time.

    

   Denny

6. 
   RickL | Dec 01, 2009 04:39pm | #8

   My sharpener charges $8.80 to sharpen a 24" planer knife. I'd look for a new sharpener.  If you get carbide knives don't get solid carbide. Get the type whare the carbide is brazed to a steel backer plate.  We used solid carbide on epoxy glue-up, abrasive woods with high mineral content and such. Carbide shatters when it hits a srew and is expensive.  You might consider going to an isert head. 4 rotatable edges of carbide.  A local school I work on their machines has one and the inserts are in their first rotation for 6 years so they should get 24 years from one set of cutters if they use them as they have.

7. 
   Don01 | Dec 01, 2009 10:34pm | #9

   I have carbide in my 8" jointer. I think they cost me around $200.00 CAD from the manufacturer. So far they have performed well. The HSS did not take kindly to some teak I was working with. But I had a few BF on them.
   They are getting sharpened this week.

   Don

1. 
   jointerman | Dec 02, 2009 03:57am | #10

   Thanks for the info! I think I'll go ahead and get a set soon... Hopefully before I need to replace my current set of knives.