Contact wheels - what sizes do you use

J S Machine

Well-Known Member
I built a grinder a few years ago, and bought a used wheel from someone. It is 7-8" in diameter. I can't recall the exact size but it is serrated and hard as heck. I'm not sure exactly how to gauge the hardness, although I know it is done by calling durometer. When I press the rubber on mine, it barely gives at all. I really have to press to get it to give. It has a noticeable bump or place the kicks up every time it comes around, and it is very difficult to use. This may be in the bearings and spindle system, or the wheel itself but I'm not sure where. If it is the bearings and spindle I can fix that easily.

I want to get a softer wheel, and maybe even a larger diameter. I was just curious what sizes you guys use, and whether or not you prefer serrated or solid. I think I may like the solid better.

I mostly make smaller blades on folding knives, but occasionally I'll do a larger knife.
 
Hello,
You should get a lot of responses here! I use a twelve inch smooth wheel, 70 durometer for most of my hunters. This allows me to get the grind up higher towards the backbone, less flats to deal with! 8" diameter would work fine for smaller narrow knives. I have various sizes to accommodate different knife styles and sizes. I use smooth wheels for everything, get better results when it comes time for finishing. With that being said, I am not a heavy handed grinder so serrated wheels and heat build up is not a big concern for me. All wheels require maintenance once in a while, whether they are poly or rubber they will need a trip to the machine shop to have them trued. Hope this helps!
Clint
 
I suspect the "bump" you are feeling is the belt joint. Although there is a possibility that you got your hands on one with a defect, or that is just not a "good" wheel.
I do very little hollow grinding on blades, but when I do, I use a 10", 70 durometer wheel. The difference between smooth and serrated wheels is: A smooth wheel removes material at a slower rate, but leave a better finish. A serrated wheel removes material faster then the same diameter smooth wheel, but the trade-off is a "rougher" finish.

70 durometer is the standard hardness used on just about all belt grinders.....its proven to be the best blend of usability and hardness. Generally is you choose to go to a softer wheel, say a 60 durometer, there will be a very noticeable difference in the hardness. Finishes will be smoother compared to a 70 durometer wheel, and the overall "feel" when grinding is "softer". The drawback is that a 60 durometer wheel or softer, is much more fragile....corners will round very easily, and if you "lean into it", a 60 durometer wheel is very easy to gouge, cut, or otherwise tear up. So essentially, if you go softer, be prepared for a more fragile contact wheel, that will require repair/replacement more often. Of course thats assuming you grind in the same manner you have with your current wheel.

My recommendation if you can't find a commercially available contact wheel to suit your needs is to go with SunRay Inc. They produce urethane wheels that I have come to prefer over rubber contact wheels. If you choose to go with SunRay, there are some things you need to know.....

1. They DO NOT keep wheels in stock, but rather make them to order. What that means is that the wait time is generally 4-6 weeks before your order ships.

2. SunRay's main business is as a military contractor (they produce rollers for tracked military vehicles), and being such they are used to working with military contracts. What that means is you MUST be very specific about EVERY aspect of the wheel(s) you want. I say that because I've had folks who ordered larger contact wheels from them, based on my recommendation, who have phoned and fussed at me...... one individual called up complaining to me that he had ordered a 12" wheel from SunRay, and that is wasn't balanced when he received it. When I asked him if he had specified that the wheel be balanced, his response was "No! They should have known to do that!" NO! If you don't specify it, then SunRay doesn't do it. So know what you want, and how you want it, and make sure you specify it when ordering.

I do a lot of profile grinding with a 70 durometer, 10" SunRay wheel, and like it very much. If I remember correctly, that wheel cost me $240, compared to $300+ for a commercially avaialble 10" rubber contact wheel. Mine is a steel core, with 1/2" ID bearings....... I prefer steel core contact wheels simply because I can replace bearings infinitely, versus aluminum cores which will only allow you to replace bearings once, or maybe twice before the bearing pockets get "stretched" and the bearings will no longer stay in the wheel.
 
Good responses. I have only ever had experience with one wheel, and that one being the one I mentioned. Before that I did my hollow grinds on a slow turning rock grinder designed for sharpening, and that really did take forever.

I suspect my wheel is harder than 70. I am aware of the belt joint and that is not what this is. The wheel feels out of true / balance. I did not know that it was common practice to be able to true the wheel. I will have to take it off and check everything out, and if it needs touching up I can easily put it in a lathe and do that. What I'm wondering is how I will hold the thing to keep what concentrically is there. I assume I'll probably have to build an arbor that the wheel will mount on that has the same OD as the bore of the wheel hub. I'll figure it out.

I think I could probably go with a smooth solid wheel. I don't get in a hurry while grinding. To put it in to perspective, It usually takes me a couple of hours to do a rough in, and then I heat treat. Afterwards I do the finish grinding and that usually takes another couple of hours, accompanied by extreme cussing and occasional throwing things. I'll admit the one part of knife making I am not 100% confident in is this. I have never done one yet that I was completely satisfied with. I do not use a rest or any type of jig, nor do I use a file guide. I free hand everything and the frustration is not something I look forward to. Watching the video of Bob loveless doing a complete grind in about 5 minutes amazes me.

I have got to improve because I'm fixing to start producing knives in greater numbers due to CNC capability, and then the blade grinding is going to be the bottle neck. I'm considering doing a few types of fixtures and other aids, because otherwise I'm gonna lose my mind.

The contact wheel has got to be right from the start though, so that's where I'm going to begin.
 
If you have a descent sized lathe, you can convert the 10" Grizzly wheels to bearings fairly easy. That's what I did, works great and only cost about $80.
 
The wheel feels out of true / balance.

If that's like the old 8" Grizzly contact wheel I have laying in the shop, with the cast aluminum core, its just a very poor example of a contact wheel. I've tried to "true" and balance the one I have...... without success. Running it at any speed, and it flopped around like a washing machine with an off balanced load! Its essentially a wall decoration in my shop. :)

I'll admit the one part of knife making I am not 100% confident in is this.
AMEN! If you ever do get 100% confident in all areas of grinding, I want your autograph! :) I've been at this pushing 30 years, and I still have to "correct" things every time I grind a blade. I'll admit something too..... every time I step up to the grinder, I just try to not goof up so much that I can't save it! :)
 
It's posts like Ed's above that keep me sane. Every tine I have something down it doesn't stay down. Errors cost more time which costs more money. Probably explains why I'm broke as a part time knife maker....
 
Every one has their own thing and contact wheels according to grinder. I have an eight inch on the old Wilton grinder. A 10 inch on a Jerry Braggs grinder. My main grinder is home built with an eighteen inch wheel.
My friend Rick Menefee is building a new grinder with a 20 inch wheel and he presently has been running a 14 inch wheel.
 
Here are some pictures of the wheel I have. I am not kidding when i say this thing is as hard as a woodpecker's ...

It is almost like it is dry rotted. No play in the bearings, but it does run out of round. It isn't much, but it is enough to notice. I'd say maybe 1/32" -1/16" out of true. I guess the good news is that it is so hard, a good sharp tool with negative rake should cut it just fine if i tried to true it. I guess I'd have to press the bearings out to do that.

I'm thinking about just buying a new, larger and softer solid wheel, say about 10". I have always wanted a larger wheel.





 
Yes, rubber wheels get harder with age. Not sure if this happens with urethane wheels or not? I am old school and like my rubber wheels from Bader, they have a steel hub that holds the bearings and are smooth and balanced. I tried to save money once by having my hubs re-tired at a "popular spot" to have this done and regretted it completely. Spend the money for quality contact wheels.
Clint
 
Yes, rubber wheels get harder with age

That is an excellent point....one that I didn't even think about. If that wheel has laid around for a long time, the rubber could be super hard....which is something it usually does right before you start to notice signs of dry rotting.

There was a time when my opinion mirrored Clint's....... I thought rubber contact wheels where the only way to go....then I purchase urethane because I simply couldn't get the size/configuration I wanted in rubber. Now I'm a big fan of urethane wheels. That was over a decade ago, and although I still have various rubber contact wheels in the shop, I prefer the urethane. OH.....almost forgot to mention.... urethane does not suffer from the same aging issues as rubber does.... no getting hard with age, or dry rotting.
 
You can try to get the high spot out by tracking your belt as far to the side as you can and try dressing it with a file or rasp,
sounds kind of dangerous but I did that once to sharpen the edges of my wheel and relieve a little at the edges.
it worked for me. I went real slow and careful, tracking the belt from one side to the other, like I said though, it's dangerous so if you attempt this and something bad happens I'll be back to delete this post and deny any further knowledge LOL !
 
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