Question about original Ryobi/Freud blade

[cgallery]

I sent my original Ryobi/Freud blade off to Forrest about ten months ago for sharpening. It went along with my WWII blade.

While they were gone, I purchased a Diablo 40-tooth blade to use.

The Diablo blade served me well but it was clear that it was dulling (feeding stock was getting more difficult).

So I took out one of the DeWalt blades I got from Amazon during the Bargain Alerts posting (I think it was $14 or something). It cuts great, and doesn't require much effort to feed stock.

Then I decided to clean the Diablo blade and see if that would help. I cleaned it up and put it back on and it is clearly dull.

Finally, I decided to put the original Ryobi (back from sharpening, sitting on the shelf for ten months) back on. Cuts great.

In looking at the Ryobi blade, though, I noticed that the top of the teeth are ground at less of an angle than the Diablo blade or the DeWalt blade.

My questions: (1) I assume the greater the top-grind angle the better the cut? I also assume the greater the angle the more often sharpening will be required?

(2) When blades are sharpened, do they grind the tops of the teeth or just the faces? Or do the sides get some, too?

(3) Is the OEM Ryobi blade top grind _supposed_ to be less of an angle that my other general purpose blades? For all I know Forrest had to knock the angle down due to chipping of the carbide. The tops of the teeth are quite smooth (reflective--I can see myself). So I imagine Forrest worked on the tops, but I didn't study the blade that closely before sending it out.

(4) How do sharpening services know what angles to use? Is there a database of blades and angles or do they measure the blade or ?

Just trying to understand blade sharpening a little.

[Knottscott]

cgallery questions:

(1) I assume the greater the top-grind angle the better the cut? I also assume the greater the angle the more often sharpening will be required?

Correct on both accounts...assuming all other quality and design parameters are equal, those are expected results. However many designs use a balance of parameters to get their desired results, and any parameter change can influence the results.

(2) When blades are sharpened, do they grind the tops of the teeth or just the faces? Or do the sides get some, too?

AFAIK, most sharpeners top and face grind every sharpening. They don't hit the side every time but on some frequency.

(3) Is the OEM Ryobi blade top grind _supposed_ to be less of an angle that my other general purpose blades? For all I know Forrest had to knock the angle down due to chipping of the carbide. The tops of the teeth are quite smooth (reflective--I can see myself). So I imagine Forrest worked on the tops, but I didn't study the blade that closely before sending it out.

The original Freud/Ryobi blade was a 36T flat top grind (FTG), which is a grind typically seen in rip blades, but in this was configured with the tooth count and geometry of a general purpose blade.

(4) How do sharpening services know what angles to use? Is there a database of blades and angles or do they measure the blade or ?

That's an excellent question that I"m not certain about. There are factory set specs but I'm not sure how different sharpeners know. They may even be able to tell from looking. Scott Whiting is a well respected sharpener and wwer who frequents some of the forums...you might try asking him at WN or SMC.

[cgallery]

Thanks for the answers Dustmight!

I have read all your blade material and I find it invaluable.

Have you had a chance to compare sharpening services? It would be interesting to see how Scott (the sharpener), Forrest, and Ridge would compare to one another (for example).

It seems like a lot of the initial cut quality depends on initial factory sharpening. It seems like sending them to a sharpening service is a little like Russian Roulette. They probably aren't going to be any better than new, and stand a chance to be much worse because there seems like a lot they can get wrong.

My Ryobi's top grind isn't perfectly flat. I'd say it is off by about 1 to 2-degrees. I wonder if Forrest didn't have their machine adjusted properly, or if that is normal, or if there is a good reason to be a little angled. I guess I will never know.

[Knottscott]

Never compared sharpening services. I tried a local place once...the blade cut fine but they sure took alot of carbide off.

Maybe I'm wrong in thinking that the BT blades was an FTG...perhaps it's an ATB with a low bevel angle, or perhaps Forrest created one for you.

[Lonnie in Orlando]

Guys -

Thanks for the post and the answer.

A local shop sharpened my original equipment Ryobe (Freud) blade a couple of years ago. I noticed that it had a flat top grind when it returned. I had always thought that it originally had a ATB grind. Figured that the shop had screwed up, so I stored it in the rack and used my other blades instead.

Guess the shop was right.

- Lonnie