Contact wheel corners: radius or leave square?

Mark Behnke

Well-Known Member
#1
Mine are square, and I have trouble in the plunge keeping it consistent through the grits.
Once it's radiused you can't go back.
Pros-Cons, advice.
 

Knifemaker.ca

Dealer - Purveyor
#2
Interesting question. I suspect even radiused, a 36 grit blaze plunge is going to be inconsistent with a flexible X16 Norax. I would guess your answer is more with breaking the edge on new stiff belts - than with radiusing the edge of the contact wheel. .... but watching for more answers.
 

Rudy Joly

Well-Known Member
#3
Don't do it.
There'll be times you'll wish you had that crisp edge on the wheel. You should track your belt over the edge till you find your happy place, some times it's almost nothing and other times I'll hang that belt over a good 1/4 inch. You can also break the edge of the belt with a bar of steel so it's consistant. Wobbly belts don't help either, save them for unimportant grinding. Another maker I know radiused his 8" wheel and over time wound up with a radical slope on the right hand side of the wheel, bad enough that the belt didn't even touch the wheel a good 3/8". That makes it hard to get even grinds. He may have been heavey handed on the right too but I don't think the radius helped any. Just my 2 pennies.

Rudy
 

Mark Behnke

Well-Known Member
#4
David Sharp who is making very good Loveless style knives, rounds the corners and gets very consistent plunges. I was wondering how many others do. The question has come up in the past and most every one as I remember advised against it.

More practice, more knives.
 

rhinoknives

Well-Known Member
#5
I hardly hollow grind at all but I do radius the corners on my flat platen with improved results.

Take some 220 paper and remove a slight amount, then test.
You can use a right angle square to check the amount you have removed.

Laurence

www.rhinoknives.com
 

Rudy Joly

Well-Known Member
#7
I find that the square edge helps on clean up in the higher grits after HT. I start my grind near the middle of the blade and backtrack into the plunge, this elliminates those annoying two inch marks on the blade and also helps kick the plunge back if I need to. I suppose the radius would work if you're grinding with a file guide and not freehand.

Click the link below to my album. The hollow grinds were done on 8", 10" and 12" wheels with square edges. You can control the plunge radius depending on the belt hang over.

Rudy
 

Mark Behnke

Well-Known Member
#8
I'm going to try your approach Rudy. Work into the plunge instead of out.

Enjoyed your gallery, especially the stacked leather ones.

Thanks
Mark
 

Rudy Joly

Well-Known Member
#9
Try different things Mark and sooner or later you'll find your own way. It works for me but remember it's only at higher grits and after HT. A light touch until you get the belt to do what you want. Good luck.

Rudy
 
#10
I've run this 10" wheel for many years and the edges still are pretty crisp. When grinding with a stiff belt I usually don't ru the belt over the edge and if I do, I only give it a little. Once I start using the softer ones,even at say 220, I move them over the edge 1/8" or so. They will round in the plunge very well and you can do it with lots of control. Frank
 
#12
Here is a suggestion that may help. If you have a speed control try going slower. I have one grinder with the 10" wheel and one with a flat platen. Both I run at slow speed for the maximum and then go slower at times. As well buy the best belts. They will give you the best return for your money. If your machine runs fast then by all accounts the Norton blaze belts will work best for you in the course sizes, otherwise try the 3M ceramics which are what I use. Frank
 

GHaile

Active Member
#13
Hi Mark. I run a Bader 8" serrated and have squared and radiused my wheel twice. I used a file, and square both times and it is dangerous. However i think it compliments my grinding style which is freehand, that being said touch has alot to do with all of this i cann easily create a very squared plunge with just a little movement of that blade and its plane with the wheel.
 
#14
Why have you had to square up your wheel , Sir? I'm wanting to make sure here that you understand I'm not trying to be rude or obnoxious. I have run this 10" wheel for over 15 years without either having the corners wear off or creating a condition where it had to be squared again. My knife making friends don't seem to create this problem either. I realize I have a very light touch because of my strength but still ? To see some of my work, please go to customknifegallery.com Frank
 

GHaile

Active Member
#15
Hi Frank! First.. I admire your work and will have a folder by you at some point, and actually youve complimented me on a piece i posted on another forum!!:eek: Now onto why i had to square me wheel, long story short it was used on a surface grinder and had a bit of uneven wear on it. I traded some archery equipment for it that was number 1, after i finished building my own 2x72, i proceeded to grind out in excess of over a 100 blades last year, and didnt have a flat platen so i was doing alot of profiling and i seemed to favor the right side and it wore different then the other side?? Now that I have a platen, small wheels, other grinders my little 7 3/4" serrated gets used apropriatly, im thinking about a 12" now!:biggrin: But i also know a few makers who choose to soften the edge too..
 
#16
I'm very pleased you added this info ! It tells people it isn't something that isn't common to happen. Yes I have thought of getting a 12" wheel. I say go for it rather than a 10" if you buy. Still, would you believe a 36" or even much larger? Well not a wheel but a curved platen oh so nicely made by Nathan the Machinist. I still have to make a mounting bracket for it and try it out. The compliment on my knives is very much appreciated !!!! Frank
 
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