Sharpening Carbide Tipped Saw Blades...... Grinder Set Up Ideas

[JoeLee]

Here is another question....

What would be the best method of indicating the tooth face so it's parallel to the table travel??
I don't want to dig into the bottom of the tooth when I feed it into the wheel.

JL....................

[Toolguy]

Hold a 6" flexible scale on the face of a tooth. Look down from above and line the scale up parallel to a T slot in the table by eye.
The scale greatly extends the surface of the tooth face. That method will be plenty accurate for this purpose.

[JoeLee]

I guess that would work, the eyeball method.

But what I just noticed is the tooth faces are hollow ground. I can even feel it with my finger. I'm not sure if they were ground that way or if the slight concave is due to wear. Unless you had some machine with some special cam action to hollow grind the center of the tooth I can't see how it could be done going in there with a wheel set up like mine. I can't duplicate it.

JL.................

[BCRider]

I suspect that the factory or a saw service used the outside of a tapered cup wheel to get that shape.

All my blades have flat front faces. The older ones with larger teeth show that they are hollow ground on the sides but the front faces are flat.

[john hobdeclipe]

I guess that would work, the eyeball method.

But what I just noticed is the tooth faces are hollow ground. I can even feel it with my finger. I'm not sure if they were ground that way or if the slight concave is due to wear. Unless you had some machine with some special cam action to hollow grind the center of the tooth I can't see how it could be done going in there with a wheel set up like mine. I can't duplicate it.

JL.................

The faces should be flat. What you're seeing is an artifact of poor / careless work. It could be from a worn, poorly dressed wheel that has a rounded face. Ideally you should have a flat face on the diamond wheel.

Having that problem, you can use the eyeball method anyway. Let the rule contact the top edge and the bottom edge. Line that up with your reference point (maybe use the diamond wheel itself,) and assume that is the hook angle. When you grind it, you won't really need to grind all the way down to the hollow part of the tooth face. Just clean up the top 20% or so, and touch the bottom of the tooth, too. Next time you grind it, you'll take a bit more of the hollow out. Eventually you'll be back to a flat face.

[JoeLee]

I suspect that the factory or a saw service used the outside of a tapered cup wheel to get that shape.

All my blades have flat front faces. The older ones with larger teeth show that they are hollow ground on the sides but the front faces are flat.

I know what your saying,but the tooth is not concave in the way you would end up if you used the outer or side of a cup wheel.
I believe your thinking cupped from side to side. These are concave from top to bottom. I don't think you can get that with any wheel style.

JL.................

[JoeLee]

The faces should be flat. What you're seeing is an artifact of poor / careless work. It could be from a worn, poorly dressed wheel that has a rounded face. Ideally you should have a flat face on the diamond wheel.

Having that problem, you can use the eyeball method anyway. Let the rule contact the top edge and the bottom edge. Line that up with your reference point (maybe use the diamond wheel itself,) and assume that is the hook angle. When you grind it, you won't really need to grind all the way down to the hollow part of the tooth face. Just clean up the top 20% or so, and touch the bottom of the tooth, too. Next time you grind it, you'll take a bit more of the hollow out. Eventually you'll be back to a flat face.

I always figured the faces should be flat too.
I'm sure is was a poor job as I mentioned the blade cut better prior to this guy sharpening it.

Looking at this picture, the tooth is concave from top to bottom, not side to side. (generic picture, not my blade)



I was wondering if I would have to grind the full face flat but you answered my question. Thank you. The top 20% should suffice. It'll depend on how deep it is. I'll give it a try tomorrow.

JL.................

[JoeLee]

I took a closer look at the concave faces of each tooth with 20x magnification. They are all polished smooth like a mirror. No signs of grinding wheel marks like I see on the sides. I'm just wondering if this is a result of the way the chip curls off the tooth wearing the centers down.

JL.................

[BCRider]

What kind of wood have you been cutting with it? It would need to be something quite abrasive to wear the carbide teeth.

As someone that has been considering setting up for my own sharpening this sure has been an interesting and educational thread so far.

[JoeLee]

I've cut everything from pine, walnut, oak, mahogany to pressure treated lumber, etc. various plywoods etc. This was just my general purpose blade. But it used to cut really clean prior to me having it sharpened years ago. I haven't used this blade in probably 10 years. I've kept it hanging around because I knew someday I would have the capability to properly sharpen it. Now I'm there. I can't remember how much I used it after the last guy sharpened it. I didn't use it for any good cabinet or furniture work because it just didn't cut like it did when it was new. I quit using it because I could tell something wasn't right as it took a fair amount of force to push wood through, even soft wood, and it was noisy. All the signs of a dull blade. I was going to bring it back to the guy but I think he closed up shop and croaked shortly after he sharpened it.

JL..............

[JoeLee]

Here is a video of one of the Foley machines but I'm not sure this was the type this guy had. I don't remember the reciprocation arm. It was a big machine relative in size to a BP mill less the table. The wheel came down form the top and hit each tooth and an arm indexed the blade similar to the indexing arm on the machine in the video. If I could find some pictures of some of the older Foley machines I may recognize it.

Notice the clamp supporting the blade's outer dia. This is something I'm going to have to address because as my set up stands I have a feeling that blade is going to ring as soon as the wheel contacts it. Ringing equals vibration and that can destroy a wheel in seconds and well as leave a crappy finish. I'm going to have to come up with some dampening setup. I don't know if I can accomplish it by simply holding the top of the blade down with my finger while feeding it into the wheel or not.

JL.....................

https://www.youtube.com/watch?v=TvU0CjdYzu4

[JoeLee]

Well I gave it a try this morning. I touched off on the first tooth. The first thing I noticed was the wheel was not hitting the full face, just the top part of the tooth's side. That's telling me right off that the tooth faces are not square to the body of the blade. My fixture is indicated in dead flat in all directions. I had to move in about .003 just to hit both sides of the tooth and that did take the dip out of it. I indexed over to the next tooth and the wheel didn't even touch it. I had to move in .004 to touch that tooth.
And then the other problem is the space between the groups of teeth, that throws your finger setting off.
So that is telling me that all these teeth have been previously ground inconsistently. I'm not sure if the error there is the tooth I was indicating off of or the tooth that was to be ground. Either way.............this has become a big PIA and for what I can buy one of these blades for new, about $40 or so it's not worth the time to pursue this any further. Just thought I would give it a try. Some things just aren't worth the time to do and I don't have to prove anything to myself or anyone else.

JL...................

[EddyCurr]

I've enjoyed the thread. While I had nothing to offer, the contributions by you and others are interesting.

Nothing ventured, nothing gained.

[JoeLee]

On a final note.....the other issue I ran into on my test run is the blade pushes away from the wheel as I traverse the table to take a cut.
I figured this would happen with the finger resting on the face side of the tooth. I didn't think tightening the cone down on the arbor hole would provide sufficient holding force. This is why in my original set up I had the finger positioned behind the tooth. This would prevent the blade from being pushed out, the force between the wheel and tooth would force the blade into the finger. I may make one more attempt at this as I hate to be a quitter.
If you watch the video the Foley machine has two fingers. I believe one indexes the blade while the other prevents the blade from being pushed out from the wheel. Time for a shot of Jack Daniels.

JL................

[JoeLee]

I finished the blade the other day. I had to reset the tooth rest to grind the teeth that wouldn't line up during the first operation. They are marked with a red line.
To grind each tooth I had to back the saddle out bring the blade in and then move the saddle in until the tooth just touched the blade. Then I had to move the saddle in anywhere from .005 to .010 to clean up the entire face. Each tooth took a different amount of infeed to clean up. This could have been due to the inconsistency of each tooth thickness from the previous sharpening which I did not do. Or it could be the way the tooth rest was hitting the blade, I don't know. Anyway............. I tried it out today and it's cuts like new, sharpening made a huge difference.
Maybe I'll try my 7" dado blade set next !!

JL.............