Contact Wheel Crowning

Jerry Hossom

Jerry Hossom

Joined
Aug 1, 1999
Messages
3,036
What is the best and most accurate way to crown a contact wheel? Any tips on this subject would be greatly appreciated. I'm tired of standing on my head to grind the second plunge.

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Jerry Hossom
www.hossom.com
 
wow..thats a cool trick...i agree with you, getting the two sides to be identical is next to impossible...what we need is one of those rocket scientist machinists here to tell us the real truth.....NEIL???

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http://www.mayoknives.com


 
First you need a really big checker board and a whole bunch of contact wheels and another knife maker who doesn't play too well!
 
Just tell your customers, "Yes, I could make the plunge cuts even, but this way people will be able to tell it's handmade." It worked with my brother-in-laws when I first started making knives, but we all know how smart brother-in-laws are. I got lucky I guess. I tracked the belt off one side, crowned it with a file and switched over to the other side. A little touchup on one side and they came out real close. I probably couldn't do it again that close if I had to.
Tom
 
I think E_Utopia probably has the right idea. Part of the problem might be profound right-handedness. I wrestle with that on every blade. Just when I get one hand trained to level, the other one wanders off. And since the plunge angle influences the shape, that may be what I'm not getting right. I can even them out as a secondary operation, but it sure would be nice to get it right from the beginning.

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Jerry Hossom
www.hossom.com
 
That drives me crazy Jerry!! I can get the side I grind with my right hand almost perfect everytime, but I always end up with a curve in the top of the grind I do with my left hand. Do you guys try to support the tip of the blade in the same way with both hands??? I notice I use my right fore finger for support, but on the left hand, I use the first knuckel. I'm trying to do it the same on both hands, but it is tough to get used to. What really gets me is when I get the right side just right and then end up having to redo it to make it match the left side. Which very seldom happens. I've just about decided to grind to my marks, and thats it. They'll probably end up as nice anyway. Take care! Michael

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Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!http://www.nebsnow.com/L6steel
 
If I know my wheel is square I just use a new bastard file and put a 1/8" radius on the corners of the wheel.Then I grind a knife and if one radius differs I alter the one I like least ,repeat steps one and two untill you grind both of your plunges the same or until you run out of rubber to take off your wheel whichever comes first.

If you need to true your wheel I use a sharp chisel against my contact wheel using my work rest as a tool holder (like a wood lathe ) then I check squareness with a tri-square. If all else fails give my knives to Tom Mayo to grind
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throw my contact wheel in the ocean,have a beer,dance barenaked in the shop and squeel like a girl scout till the cops show up.

Either way a day well spent in my opinion!

Aloha!!! Ken Onion
 
sounds like ken has already had a few beers.. btw...he doesnt bother to tell us how many HOURS it took him to get the wheel just the way he wanted it or the time he stuck the chisel INTO the wheel...or was that someone else....
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http://www.mayoknives.com


 
Why do you want to crown the wheel? Make it DEAD flat, and, if you ned to, round the edges SLIGHTLY.
Achieving a good plunge depends on letting the belt overhang and then softening it by using a piece of scrap stock to break it down a bit. That way, it won't gouge into the blank.
I have just one wheel, with the corners just touched off-I use it for every blade I grind, regardless of thickness or ho I want toe plunge to look.

Just keep practicing

RJ Martin
 
Don't drink the water when you visit Hawaii
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Scott Jones
Heck yea I invented it ...What is it???
Good things aint cheap and cheap things aint good
 
RJ, that is what I meant and try to do. I was just wondering if there is a slick way to true the wheel. The chisel idea of Ken's conjures up pictures of a chisel sticking in something I hold dear.

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Jerry Hossom
www.hossom.com
 
OK-Now that i know what you're asking, I can help!
To "true" a wheel, this is what I do"
Use 120 grit Silicon Carbide Paper attached to a sturdy piece of precision ground barstock. Use spray adhesive to put it on. Wear your respirator and good face protection.
With a belt on, apply the paper to the back (exposed) side of the wheel. Standing beside the machine helps. The wheel is rotating "up", so, the black dust is going to go in your face. Blow out the paper and wheel frequently-the paper will last a long time if you don't burn the grit off it from the friction.
Remember, don't let that block get away from you!!!! If you do, it'll get pulled around and break your belt and possible damage your wheel (you too)

Good luck

RJ Martin
 
RJ, the wheel I need to true is on my old Blademaster, which uses the contact wheel as the drive wheel. I assume you do this with the belt on because your machine, like my Wilton, uses another drive wheel. That true?

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Jerry Hossom
www.hossom.com
 
You got that right! So, you can do what I do, but, more safely and without eating all that black powder....

RJ
 
Jerry , The chisel way works wonderfully don't let Tom scare you my brother in law blew my wheel out sharpening his wood chisels.(rank amature)

Scoot your work rest real close to your contact wheel but not touching and use slight pressure the rubber will peel away like a dream and leave a beautiful finnish.

Sometimes I need to grind some crazy angles and steep[ recurves so I often need to change the surface of my wheels to accomodate those grinds and this method works well.

I also agree with RJ about the flatness needed to grind normal knives just roll the corners to an 1/8 " radius,the rest of the wheel should be flat.

Then go have a beer.

BTW I promise to keep practicing!
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Aloha!!! Ken Onion
 
Ok, I didn't realise contact wheels on these grinders were rubber, not steel. I'll definitely support the good, sharp chisel idea. And who better to have sharp tools?

--JB

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e_utopia@hotmail.com
 
Thanks RJ and Ken. I think I'll do both. I have an old wheel that I abandoned because it got so out of true that it was driving me nuts. I think I'll do some creative chiselling on that one and use RJ's method on my new wheel. My knives are pretty normal in general so nothing fancy is needed. the 1/8" radius is understood.

As for Tom's advice...
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As for the beer, if either of you are coming to the Blade Show, I'll buy.

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Jerry Hossom
www.hossom.com
 
I'll be at the Blade show and will take you up on the beer but I'll warn you I'm a cheap date (3beer drunk) I know it's embarassing .I think it's just lack of practice. I'll supply the cigars and look forward to meeting you in person.

Let me know how you like the chisel technique or if you run into problems
Aloha!!! Ken Onion
 
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