Grinding Issues

G

gatorforge

Joined
Jul 2, 2010
Messages
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Hello all and thanks in advance for any help you can provide.

I'm just getting back into knife making after several years, and am having some grinding issues. I'm using a bevel jig like the one described in this video:

https://www.youtube.com/watch?v=fCbgRY5Gp8I

On the grind from the right (moving the knife along the grinder to the right, I guess actually the left side of the knife if you were holding it in your hand with the blade down) I am getting a good cut from plunge to tip, although slightly deeper at the apex of the belly.

On the grind from the left, I'm not getting much of a grind on the first quarter of the knife, but the rest of the blade is being ground nicely. Even trying to put more pressure where I want the plunge to be, it doesn't seem to dig in very well.

I've tried changing belts, and have adjusted the tracking, but to no avail. Any ideas would be appreciated.

Thanks
 
Sounds like something is not straight or level, either the jig, work rest, platen or maybe the blade itself is warped.
 
I saw that video. I had reservations about a jig with just one point of contact. I could see myself doing exactly what you describe.
 
You could be rocking the jig as you make the pass as it only has the one height adjustment screw. The one I made has two screws one on each end, so you're less likely to rock the jig out of level as you make a pass.
 
Are you Right or left handed? Even with a jig it can make a big difference! It sounds like you are right handed.

I am a righty, so I grind to the left first. Then match it with my domaniate right hand.
 
Thanks for all the great responses.

@NC Biker - Was considering that today, and likely will be making that modification when I get off work.

@Pittknife and @Maelstrom78 - I had considered that, and ran the plunge right up to the belt and applied a significant amount of pressure at that point, and it still seemed to take off very little material at the plunge.

@rhinoknives1 - I am right handed, and know that I do better work on my right than left. I have never tried starting on my left, but I will give that a go going forward.

If it is an issue with the surface as NC Biker suggested, would epoxying a piece of glass behind the belt give it a more uniform surface, in the event that it is a defect in the platen.

Thanks again.
 
You can use a piece of pyroceramic glass for your backer. Also, if the knife isn't flat on both sides then the bevel will not be straight. Try flattening both sides before you start on your bevels.
 
@Matt R - I believe it is, but I will double check. In the event that it is not, what is your preferred method for flattening, sans using a machine surface grinder?
 
Gator, you really should look into putting a piece of ceramic glass on your platen, it will really improve your grinds. For surfacing blades, I have a 100# magnet that I use to hold the blade flat against my glass backed platen in a vertical position and that get them pretty flat. The thickness is not always the same across the blade, but if you pay attention and measure as your grinding, you can get it pretty close.
 
Get a Bubble Jig and you'll eliminate all these issues. I sell them and I stand behind them. There is no better way to achieve grinding accuracy.

Regards, Fred
 
Fred.Rowe said:
Get a Bubble Jig and you'll eliminate all these issues. I sell them and I stand behind them. There is no better way to achieve grinding accuracy.

Regards, Fred
Click to expand...
I second Fred's bubble jig. I went from a sled type jig that you're using now, to a Bubble Jig to grinding freehand. I still use the Bubble jig when sharpening.
 
Same here regarding the bubble jig. Now i just use it for sharpening but I'm going to start using it for clips too.

I have to say that at this point I am glad I learned to grind without a sled type jig. Just IMO.

I also second checking the flatness of the blank.

Also know the blank can warp as you are grinding it too. Hence on videos you see maker's switch sides often.

I'm using AEB-L a lot and it does this like crazy! A lot more than the 1080 blade I ground out tonight.
 
I do all Bevel grinding post HT. I dip the blade wipe the front and watch the water droplets on the side I see for each pass. If there is steam I've gotten the blade as hot as I will go. I Dunk and repeat
 
Again, I can't thank you enough for the help and advice.

Fred, I will order one of your full kits off Jantz when I place my next order. I take it you need to grind without a tool rest when using the clamp?
 
Also forgot to mention, I did do some work on the sled last night. I added two more bolts running through it giving me three points of contact. It seemed to help a fair bit. I think the left side may have been dipping slightly. I went ahead and rechecked the tool rest and platen and they are at least square.

@NC Biker, where do you purchase ceramic glass?
 
I get mine from a local glass shop. it's called pyroceram and is used in fireplace doors. A piece 2"x9" costs me about 15 bucks. I've seen it on ebay also. Here is a link to where the guy is selling a platen and 2 pieces of glass. I've bought stuff from him before and he's a nice guy. If you contact him, maybe he'll sell you just one piece. I've also seen it on USA Knife Maker's site, but they always seem to be out of stock on about everything.
 
gatorforge said:
Again, I can't thank you enough for the help and advice.

Fred, I will order one of your full kits off Jantz when I place my next order. I take it you need to grind without a tool rest when using the clamp?
Click to expand...

Grind on the platen, its freehand grinding with a site reference. You don't need the rest. Using it to sharpen I work off the rest. Makes for some great edge bevels.

Fred
 
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