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.

[Mike Marcade]

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.

Thanks for the info Dana. That is very helpful.

[Rod Sheridan]

I had the same problem with a set of planer knives that had been sharpened.

The sharpening service corrected their mistake for free, and gave me a credit for the value of my next sharpening.

Regards, Rod.

[Al Killian]

If your blades are off a few thousands, then they will probaly not be balanced. Which will cuase bigger problems down the road. I would send those back with a note asking for them to be either reground or replaced and have them checked before going out the door. For what they cost they should check them.

[Mike Marcade]

Tonight after work I am going to take the knives back out of the jointer and do some more analysis. I will keep you posted.

[Mike Marcade]

Update:

I emailed Global Tooling and they told me the knives are lineal ground in 31" long bars and then cut to length. The guy said it was nearly impossible to see the peaks and valleys of the magnitude I was seeing. He requested that I remove the knives from the jointer and measure straightness and flatness with a straightedge.

Sooooo .... thats what I did, and guess what? They come out even worse.

Knife 1: Cutting edge had a .0075" smile from one end to the other. Flatness was .010"
Knife 2: Cutting edge had a .010" smile from one end to the other. Flatness was .010"
Knife 3: Cutting edge had a .011" smile from one end to the other. Flatness was .020"
Knife 4: Cutting edge had a .020" smile from one end to the other. Flatness was .010"

I sent them this information. We will see how they respond back. :mad::mad::mad:

[Dana Vogel]

Mike, They are going to argue this point till the end fact is these Chinese factories are new to manufacturing CT knives almost to the point they may be produced in someone's backyard barn with no knowledge of the process. Know what really boils my blood is the fact the retailers are charging as if these were still made in the USA by Union labor shops there is no way a set of 4ea 8" knives can cost $200.00 (Amana Tools) that are made in China by $.50/hr labor.

[Bob Feeser]

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

21 views on this site, shucks that's just getting warm :)

[Mike Marcade]

Mike, They are going to argue this point till the end fact is these Chinese factories are new to manufacturing CT knives almost to the point they may be produced in someone's backyard barn with no knowledge of the process. Know what really boils my blood is the fact the retailers are charging as if these were still made in the USA by Union labor shops there is no way a set of 4ea 8" knives can cost $200.00 (Amana Tools) that are made in China by $.50/hr labor.

Thanks Dana, I am pretty familiar with Chinese labor ... just look who I work for. :D:D:D

[Mike Marcade]

21 views on this site, shucks that's just getting warm :)

Welcome to the party Bob! We have 506 views now! :D

[CPeter James]

Mike,

I like the others have tha Makita sharpener and haved used it for more than ten years with great success. I have the "green" wheel from Highland Hardware and it does a fantastic job. The knives are razor sharp and straight.

You said you bought the carbide knives because you did not want to have to change them. Ok, but they will never be as sharp as a HSS set. I can take the knives out of my Jet 15" planer, sharpen them and replace them in under 45 minutes. Same for my DJ20 jointer.

My advice: learn to change the knives in your jointer and planer. You may want to buy a set of Planer Pals, they do help. Find a system that works and get comfortable with it. Also get the Makita setup with the "green" wheel.

I use all air dried rough lumber and go through a couple of thousand feet a year. I sharpen my knives frequently and when things are right the surface will be plate glass flat and smooth. Sharp HSS is the way to go.

http://www.highlandwoodworking.com/index.asp?PageAction=VIEWPROD&ProdID=1460

CPeter

[Mike Marcade]

CPeter,

All good points taken. I am pretty good and very precise at setting the knives. I just need to work on my speed a little bit. The more I look at it and see the ease of sharpening HSS compared to carbide, the more I am leaning towards getting myself a sharpening system (most likely the makita, because I like the flat wheel design)

Thanks for all of the comments. Most likely the carbide tipped knives will probably be going back too. :mad:

[Mike Marcade]

Global Tooling carbide tipped blades going back with their UPS account number for a full refund. Brand new Makita 9820 Sharpener on its way to my house! Should be passing each other in the air. :D:D:D

[Bob Feeser]

Wow I was unaware of the Makita sharpening system when I bought the Tormek, and with all of the attachments it ran me more than twice the price of the Makita, and I love Makita stuff. Sharpening them on the Tormek with the planer jig is a very nice way to go though. You can also sharpen a wide range of blade sizes, but my jointer is 8" and my planer is 12" so with a 16" capacity on the Makita, that would cover more than I will probably ever need.
I was especially interested in your information about HSS steel creating a better edge. I agree that after sharpening you get glass smooth results.
Great post.


Mike,

I like the others have tha Makita sharpener and haved used it for more than ten years with great success. I have the "green" wheel from Highland Hardware and it does a fantastic job. The knives are razor sharp and straight.

You said you bought the carbide knives because you did not want to have to change them. Ok, but they will never be as sharp as a HSS set. I can take the knives out of my Jet 15" planer, sharpen them and replace them in under 45 minutes. Same for my DJ20 jointer.

My advice: learn to change the knives in your jointer and planer. You may want to buy a set of Planer Pals, they do help. Find a system that works and get comfortable with it. Also get the Makita setup with the "green" wheel.

I use all air dried rough lumber and go through a couple of thousand feet a year. I sharpen my knives frequently and when things are right the surface will be plate glass flat and smooth. Sharp HSS is the way to go.

http://www.highlandwoodworking.com/index.asp?PageAction=VIEWPROD&ProdID=1460

CPeter

[CPeter James]

BTW: I only use the 120 grit green wheel most of the time. You do not need a polished edge like a plane blade or chisel on planer and jointer knives. I have done it by finishing up on the 1000 grit wheel and find little if any difference, just takes longer. Experiment and do what you are comfortable with.

CPeter

[Mike Marcade]

The thing I liked most about the Makita was the flat wheel as opposed to using the round wheel on the jet and tormek. The price was right too. Thanks everyone for all of your suggestions. :)