Jointer Knives and Straightness

[Mike Marcade]

I have noticed with 2 sets of brand new jointer knives (one from Global Tooling and one from Grizzly) that the ends of the knife are high and the middle of the knive seems to have a .005" - .009" dip in it. So when you put the cutting edge on a straightedge you see light in the middle of the knife and not on the edges.

Has anyone else noticed something similar?

[Mike Marcade]

Come on guys ... 21 views and no comments? Surely some of you have seen something like this.

[Jim Becker]

Maybe nobody ever looked to see if they were true... LOL! That said, I'd be unhappy with that situation for obvious reasons.

(I use Tersa knives so a test in the manner you describe wouldn't matter since they are totally captive when slid into the cutter head...and double sided)

[Mike Marcade]

Thanks for the response Jim. Not necessarily helpful in my situation but good information nontheless.

[Steven Wilson]

Nope, I would have them reground, unless your jibs can pull that out when you set your knives.

[Bruce Wrenn]

I have noticed with 2 sets of brand new jointer knives (one from Global Tooling and one from Grizzly) that the ends of the knife are high and the middle of the knive seems to have a .005" - .009" dip in it. So when you put the cutting edge on a straightedge you see light in the middle of the knife and not on the edges.

Has anyone else noticed something similar?

Mike, take two of the knives, and lay them on a flat surface, with sharpened edges touching. Do the edges still not touch? Put one knife in jointer and set it. Check with dial indicator at each end and middle. If the readings are the same, then head straightens knife. You might want to send Scott Whitting a PM and ask him personally. He is a sharp guy. Knows his stuff on sharpening of blades and knives for planers and jointers.

[Mike Marcade]

Mike, take two of the knives, and lay them on a flat surface, with sharpened edges touching. Do the edges still not touch? Put one knife in jointer and set it. Check with dial indicator at each end and middle. If the readings are the same, then head straightens knife. You might want to send Scott Whitting a PM and ask him personally. He is a sharp guy. Knows his stuff on sharpening of blades and knives for planers and jointers.

Thanks Bruce. When I put them in the jointer I set them with a dial indicator touching making sure that the far outside edges are .001" above the outfeed table. When I run the dial across the knive the center dips down around .008" on the worst one and only about .004" on the best one.

I will try to PM Scott too.

Thanks.

[Keith Outten]

Mike,

Several years ago I purchased a Makita slow speed sharpener so I could sharpen my own blades. One of the reasons was because most new blades aren't sharp nor are they straight enough to please me. I think this is the norm, most people who purchase knives, block planes, chisels and other types of cutting tools accept that they will have to be sharpened before they can be used.

The Makita is a fabulous machine, once you learn to use it properly your knives will be perfectly flat with a polished edge and so sharp you will respect them when you handle and install them in your planner and joiner. You will remove less of the edges when you sharpen them yourself so they will last many times longer than having them sharpend by a professional service. Your planner will run smoother with less strain on the motor when your knives are sharp and the quality of your lumber surface will improve.
.

[Mike Marcade]

Thanks Keith, that is an interesting perspective which I really agree with. My only issue is that my knives are carbide tipped. I think you need special equipment to sharpen carbide correct?

[Mike Marcade]

I think I will give Global Tooling a call tomorrow to see what they have to say about it too.

[Gary Keedwell]

Thanks Keith, that is an interesting perspective which I really agree with. My only issue is that my knives are carbide tipped. I think you need special equipment to sharpen carbide correct?

Mornin Mike...Yep, you need different grinding wheels for carbide. Hope you solve your problem. Keep us posted.
Gary

[Keith Outten]

Mike,

Whichever sharpening system you select you should be able to purchase stones for carbide.

[Mike Marcade]

Thanks Guys. I will keep you posted on my results.

[Dana Vogel]

Had the same problem not only with Global (Sunhill) but also the major name brand Amana Tools and BladesnBits. I have come to the conclusion that everyone is in on the cheap Chinese made crap where quality is of no concern but high profit margins are. I sent both sets back to their owners with a long complaint included and did what the other fellow suggested I bought the Makita system and have been happy since. I know these knives can be perfect because the set that came with my Grizzly 8" parallelagram jointer BTW which to my surprise were CT knives were dead flat,square, true and straight. "Don't Give Up The Fight for Quality " if we do they will have won.

[Dana Vogel]

Global Tooling will give you the same answer I got, We are not aware of any problems with our knives so send them back for exchange or refund. BTW I did both before problem was solved with the latter being the fix.