Question: How to start a flat grind on contact wheel

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frankdelalla

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Jan 16, 2015
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First post! I've lived on this forum for months and months learning about knife making. Really appreciate how generous this community is with it's knowledge. Thanks to all!

Finally have a question I couldn't find any posts about. Tried, but couldn't.

I've seen a couple of videos where makers started a flat grind by making a couple of cuts with a contact wheel and then bringing them together on a flat platen. Seems the advantages are 1) speed, and 2) increases belt life a bit. Can anyone give me some more DETAIL on how this is done, and maybe a bit of an apologetic for or against this method? Any help is appreciated.

Peace,

Frank DeLalla
 
That's how I am grinding all of my flat grind knives at this time.
After watching Tim Hancock demo this method, it all just made sense to me.
Belt life increased dramatically!!!!!!
Initial stock removal is very fast and even allows me to use older somewhat worn out belts for the beginning phase.
All of this is done on a work rest and efficiency and accuracy have both increased remarkably.
 
Very helpful. Thanks Karl.

I don't have any large contact wheels yet. Seems like a good investment if it helps with belt life that much.

Any chance you have a link to the Tim Hancock demo, or was that in person? Thanks again.
 
Hi Frank,

Welcome to BF! What you have described about the videos you've seen is pretty much it. The contact wheel will cut faster as well as give you better belt life (and probably better platen life). You start with your profiled blade blank and make a pass along the corner of the cutting edge to make a bevel down the whole length of the edge. I make 3-5 passes then flip it and do the other side the same way. I try to keep the number of passes even on both sides as I go. Also, I grind freehand without jigs. If you use a jig your technique may be different. Some people set their pre heat treatment edge thickness first then work the bevels up the side of the blade. I tend to set it close but not quite there yet then use the platen later to dial it in. Then I progress up the blade in rows, one right on top of the other, working both sides of the blade evenly. It is a good idea to have the top of your grind drawn or scribed onto the blade so you can judge where to stop your grind. I stop a bit short of the line so I can work up to it carefully on the flat platen. Once you have most of the material hogged out on the wheel you go to the flat platen (if you're doing a FFG). Now you're just taking down the high spots and fine tuning. You're walking your grind up to where you want the bevel to stop and setting your final edge thickness. Easy peasy. You got this.
 
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Thanks, i4Marc! Great info.

Do I want 8" or 10" wheel for this, or can I get away with something smaller like 4" or 6"? Trying to save money, but I'll spend what I have to. Thanks!
 
You can do it with a 4" or 6" wheel but it will cut more aggressively. Just proceed with caution and you'll be fine. Look around. You can find decent prices on contact wheels. The 8" and 10" wheels from Grizzly aren't very expensive and work pretty well.
 
I don't understand this. A wheel will give you curvature, so when you go to a flat grind you'd have to grind until the curve is gone. That seems like a lot of needless work to me. What am I missing here?
 
Hey David,

My understanding is that it saves some time and increases belt life, but I haven't tried it yet. That's why I asked.

Thanks!
 
frankdelalla said:
Hey David,

My understanding is that it saves some time and increases belt life, but I haven't tried it yet. That's why I asked.

Thanks!
Click to expand...

No problem, just sounds like a hollow grind to me, but I haven't seen the video's you mentioned either.
 
:thumbup:

I see what you're saying, David, but no, it's not a hollow grind. It's a series of cuts on the wheel stacked on top of each other in order to remove material quickly. The cuts are then then blended on a flat platen to make a flat grind. I was looking for a little more info on exactly how to do it well and whether it was worth getting a wheel to try it out.

I did some searching for one of the videos where I saw it done. It actually was Tim Hancock like Karl mentioned. Unfortunately, the video is no longer available.
 
I do it on all stock removal blades. I only do it with some of my forged blades, because most of them don't need a whole lot of steel hogged off.


A contact wheel cuts faster and cooler. So you can hog off steel FAST and increase belt life by cutting in a few hollow facets first. Then switch to the flat platen to smooth it out.


It's definitely not more work, it's a lot less work and much faster.


I showed it in this---

[video=youtube;RhijW7L9Cm4]https://www.youtube.com/watch?v=RhijW7L9Cm4[/video]
 
Thanks Nick. Great video!

Would a serrated wheel work well for this, or is there a reason to stick with regular wheels?
 
i4Marc;14571339 The 8" and 10" wheels from Grizzly aren't very expensive and work pretty well.[/QUOTE said:
I have looked on the Grizzly web site and the only 10" wheel I find is for their knife grinder and has no bearings as it is to be mounted on a motor shaft. Do you have the part number? Thanks, Steve B
Click to expand...
 
Several people take that wheel and either have bearing shoulders turned into it or mount it on a shaft that spins on a pair of pillow blocks mounted to a plate, mounted to the tool arm. It can be done for much cheaper than the other large wheel offerings,
 
I know this is a little old now, but I finally got to try this out. I got a serrated 8" wheel. This method is amazing. I'll never go back to the way I did it before. It's extremely fast and simple.

I ground 3 or 4 blades this way, and they all came out really well. Seems like a more reliable way to get the results I'm looking for. And SO much faster than the way I was doing it.

Thanks for all your help!
 
I do the same thing. First I grind in a steep edge at approx 45 deg on each side to establish my center-line. Then I either hollow grind or nip away at the main bevels in strips. I move to the flat platen to check my progress and eventually blend it all in. It is much faster and easier on belts. It is kinda like hollow grinding a tang before making it tapered.
 
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