Hollow grinding as a beginner?

C

catcalls

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May 7, 2012
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I have seen people hollow grind, and like hollow ground knives that seem to slice better, however is it logical for me, a beginner to invest the money in a contact wheel, and all the other Hardware to make a contact wheel tooling arm so I can learn how to hollow grind knives. What would you recommend.

Thanks ahead of time...
Jack
 
Invest in two!

[video=youtube;0GVB0qkRF1c]http://www.youtube.com/watch?v=0GVB0qkRF1c[/video]
 
Wow, that is badass! Seems like it would be the quickest way to make perfectly symmetrical bevels. Am really surprised that he said he uses a single wheel more now??? Maybe b/c he can't use a big enough wheel or he doesn't like using smaller belts or something...

Looks custom made. I see he mounted the motor on the right on an X/Y axist drill press vise.
 
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I talked to a knife maker in Canada about a month ago, and he knew a guy who built a double wheel grinder. He said it was REALLY difficult to get the grind lines to line up with each other. That might be one the reasons why that the guy in the video went back to a single wheel, but that is me totally guessing. It's a pretty cool video.
 
If I recall, that was made by Charlie Lewis, who is a member here. He makes some great looking straigt razors. maybe he'll chime in about it.
 
That's awesome! I had a straight razor, Joseph Rodgers, it was 5/16" at the spine, 9/8" wide (razors measured in 8ths) and it was extra hollow ground, there was at least 1/2" of blade that was super thin. It was incredible, felt like a hollow ground but had the weight behind it to give it that wedge cutting power. I asked a buddy that makes straight razors how they ground something like that and he said they'd have to have two wheels to get that grind. Now I see how. Very very cool.

Red
 
invest in it, its a worth while investment and having the ability to do hollow grinds aswell as others is darn nice, hollow grinds are also my favourite looking too so do it
 
I just got back my first hollow grinds back from heat treat and I did a better job on them then my first flat grinds. With most grinders youll be getting a contact will wheel anyway, no?
 
I guess I fall to the other side on this. I made the investment to get a contact wheel, and attempted a couple of hollow grinds. Quite honestly, they didn't go well, and now I find the contact wheel gathering dust being thrown off by the standard platen.

To be clear, I did not invest in a tool arm or a jig to help me keep the hollow grind lines straight. Had I done so my results might well have been worth retaining.

But there is one other thing to consider... hand sanding. Inevitably, my blades are ground to a certain level on the grinder, and then I switch to hand sanding using a steel tool to get nice flat surfaces. Hollow ground surfaces are, by definition, not flat. So how will you hand sand them such that you retain the sharp defining line between the bevel and the flats? I found a way, but it is sub-optimal.

One last thing... some folks around here do hollow grinding without a big contact wheel. Look up "radiused platen" for more information.

- Greg
 
Dago Red said:
That's awesome! I had a straight razor, Joseph Rodgers, it was 5/16" at the spine, 9/8" wide (razors measured in 8ths) and it was extra hollow ground, there was at least 1/2" of blade that was super thin. It was incredible, felt like a hollow ground but had the weight behind it to give it that wedge cutting power. I asked a buddy that makes straight razors how they ground something like that and he said they'd have to have two wheels to get that grind. Now I see how. Very very cool.

Red
Click to expand...

I'm sure there are different ways to grind a razor but I think he could have meant that the razor had a shallow hollow grind on the thin part and a deep hollow approaching the spine. The two grinds are blended so you don't see a transition line. Just trying to help! :D



tryppyr said:
I guess I fall to the other side on this. I made the investment to get a contact wheel, and attempted a couple of hollow grinds. Quite honestly, they didn't go well, and now I find the contact wheel gathering dust being thrown off by the standard platen.

To be clear, I did not invest in a tool arm or a jig to help me keep the hollow grind lines straight. Had I done so my results might well have been worth retaining.

But there is one other thing to consider... hand sanding. Inevitably, my blades are ground to a certain level on the grinder, and then I switch to hand sanding using a steel tool to get nice flat surfaces. Hollow ground surfaces are, by definition, not flat. So how will you hand sand them such that you retain the sharp defining line between the bevel and the flats? I found a way, but it is sub-optimal.

- Greg
Click to expand...

Keep at it if you want to hollow grind, it just takes some work.

It's a lot like learning to use a computer or ride a bike, it is tough the first few times you try but eventually you get better with practice.

For hand sanding you can buy radiused sanding blocks. I forget who but one of the major knifemaking suppliers sells them.

I take a lot of my hollow grinds to 900 grit, at 900 they don't really need to be hand sanded depending on what you are going for.
 
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I use different size prescription bottles halved, and faced with desired grit paper, works very well for final finish rubs.
 
If I were to buy a contact wheel, where would you recommend buying it from? I know that usaknifemaker.com sells them for about $110, although I am insure if the quality. What would you do. I got a pheer, and it only came with a flat platen arm. I was thinking about the 8" wheel as I would mostly grind only smaller sized knives with it. What size do you guys use?
 
An 8" wheel is pretty versatile, and seems to be the standard size.
Hand sanding hollow grinds is easy to do with curved sanding blocks.
 
I built my own 2x72 however i use an 8" serrated bader mfg. wheel, they're spendy but spot on and of high quality.
 
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