How do you grind thin wide kitchen knives?

[Daniel Rohde]

I have been trying my hand at making some thin(1/16") kitchen knives and when I went to grind them(I was flat grinding) I found it to be really hard to keep the blade from flexing and with the knife that thin to

start with made it hard to get a grind that would reach all the way to the spine and the same on each side. It was just tricky and I was wondering if anyone had some kitchen knife grinding tips?

Thanks,

Daniel

 

[samuraistuart]

Would it be possible for you to hold a piece of scrap steel against the blade as you grind it.....to give it some rigidity? When I make my petty knives, after heat treat I cut the bevels, and I do that by hand, with a sheet of paper fastened to a flat surface, and then hold the scrap steel against the blade and grind into the paper. Worked quite well for me, although time consuming.

 

[Willie71]

A flat piece of steel with magnets to hold the blade to it is what I use.

 

[Mitchell Knives]

I actually make an aluminum template the exact size of the knife I'm grinding. I use the pin holes and a clamp to hold the blade in place. It not only keeps it from flexing, but also acts as a heat sink.

 

[butcher_block]

9 out of 10 times you will not want a full hight grind on 1/16 thickness stock. paring knives might be the exception to the rule. first thing you hae to learn when making kitchen knives is that most of the grinding is post HT and the other is that belt life is short. let me add that the life is not that short but since you cant break down the grit with pressure needed since it flexes the blade you have 2 options. one get a grinder dressing wheel or stone to break the freash grit out on the belt. 2 use the belts awhile and then when they slow down cutting set them aside for profile grinding and pre HT part bevel grinds (or heaver blade style knives that can take the force )

 

[Techtical]

Awesome idea on the aluminum template.

 

[Stacy E. Apelt - Bladesmith]

Wooden backing templates ( aluminum would work, but be much more expensive unless a particular shape will be repeated many times) are what most folks do. The same backer can be sued for final sanding and buffing. There are a variety of ways to hold the blade to the backer. Simple bolts and wing nuts work in some cases, and short stopper-studs and a strap around the tang work in other cases. All you need is a way to firmly hold the blade to the backer and have access to all areas to be ground.

I also use a large 10" grinding magnet with two parallel bars. It holds the stock flat and firmly.

For the reasons Lloyd stated, I usually don't do a FFG on very thin blades. I make the blade taper into a convex grind. That makes for a sharp edge but allows enough meat behind the edge for strength.

 

[elementfe]

If you watch some tutorial vids (Nick Wheeler has great ones on his youtube channel) you'll often see the knife edge up, flat on the platen, spine resting on a horizontal platform, being drawn across and at the same time pressed against the belt with a push stick of some kind. I'm pretty happy with the grind I get on 1/16 blades using that method.
Start with the push stick close to the edge (top of the blade) and work the bevel back down toward the spine by moving the push stick down a bit on each pass. Then do exactly the same on the other side.
It's touchy doing it this way post ht, you have to keep the blade cool since it's right up against the platen and tends to heat right up.

PS. you tend to get a bit more convex grind this way than using a backer....

 

[Daniel Rohde]

Thanks Guys! I really appreciate it!

so it's back to the grinder......

 

[ernestrome]

I find a disc grinder a great benefit for 'checking' or improving my belt flat grinds.

 

[Calvin Robinson]

I use a 9" disk grinder and a push stick.

 

[Don Nguyen]

I use a push stick and work rest. The push stick does everything; I lean my whole body weight with it. The other hand ONLY pulls the blade across the platen. It does not control the angle or pressure in any way. Now on 1/16" stock, you might not want to so much pressure, but the idea is there.

 

[Stacy E. Apelt - Bladesmith]

It might be a good point to make to newer makers reading this thread that the use of a push stick or backing board with handles is really important in hogging off bevels. With 36-80 grit ceramic type belts and lots of pressure ( necessary to make that belt type cut right), plus 2-3HP motors, a slip with a bare hand doing the pushing will take it down to the bone in a flash.

 

[james terrio]

I use a welding magnet... but note, I have a ceramic face on my platen. If you do not...

Magnet + thin steel on a plain steel platen can be... problematic (Naturally the whole "sandwich" is going to want to stick together and that's not good when there's a moving belt in the way.) The wooden backing board or push sticks others have described would be a much better choice in that case. I haven't tried it myself but I think thick (1/4" +) G10 would be stiff enough for those purposes, and you wouldn't have to worry about getting it wet when you dunk it in water between passes.

I don't put a whole lot of stock in relying on a magnet or metal backing as a heat-sink; in fact it might even cause more trouble. Especially if you're grinding hardened steel, it's easy to badly overheat the thin edge before you even notice the whole blade getting warm. So cool the blade often regardless of how you grind/hold it.