Education needed on effect of blade hook angle

[Gator95]

While I know what a hook angle is, I'm new to woodworking, and have a pretty basic question: what is the practical effect of hook angle on a saw blade, and what is the 'ideal' range for hook angle for a table saw vs. a mitre saw?

Does the number of teeth on the blade make a difference on the preferred hook angle? How does hook angle affect cleanness of cut on a crosscut vs. rip cut, and how does it affect ease of cutting/feeding on a tablesaw?

Is it practical to use a 60-80T TK blade for a mitre saw and also use it as the 'fine detail' blade for the table saw, swaping the blade between the two as needed?

[Knottscott]

While I know what a hook angle is, I'm new to woodworking, and have a pretty basic question: what is the practical effect of hook angle on a saw blade, and what is the 'ideal' range for hook angle for a table saw vs. a mitre saw?

Does the number of teeth on the blade make a difference on the preferred hook angle? How does hook angle affect cleanness of cut on a crosscut vs. rip cut, and how does it affect ease of cutting/feeding on a tablesaw?

Is it practical to use a 60-80T TK blade for a mitre saw and also use it as the 'fine detail' blade for the table saw, swaping the blade between the two as needed?

The hook is only one of many aspects that engineers consider when attempting to achieve a design objective. If all else is equal, a steeper hook will feed easier, but there is some tendency for more tear out caused by the steeper hook.

A steep hook is typically used on TS blades that will be doing some ripping...either a dedicated rip blade, general purpose type, combo blade, or in some cases a crosscut blade that will also be used for some ripping. 12° to 22° is the most common range for steep positive hook angles.

Sliders and radial arm saws benefit more from having a low to negative hook, but that's less critical on a straight CMS. Negative hook also poses less sever shock from impact, so is beneficial for carbide blades used in cutting metals and other hard materials. Hook angle and number of teeth are usually separate parameters, but you tend to see low to negative hook used more in situations where higher tooth count is also beneficial...like a plywood, veneer, fine crosscut blades, etc. I have seen a 30T ripper for a RAS with a negative hook, but is more common in higher tooth blades.

[steve-norrell]

Here are a couple of articles that I found to be helpful in deciphering the terms used for saw blades.

http://www.rockler.com/articles/disp...fm?story_id=72

http://www.rockler.com/articles/disp...#BladeGlossary

I have to re-read these about two or three times a year.

Regards, Steve

[LCHIEN]

Everything that Dustmight said is what I've heard and read elsewhere.
get a ripping blade with 24T and a 15-20° hook angle you'll be happy there.
Get a 60-80T blade with a 0-5° or maybe as wide as -5 to 10° and you'll have a good CMS blade. Generally I think you'll find its a pain to swap blades, swapping two blade will just be too much (where you have to remove the TS blae, then remove a blade from your CMS and remount on the TS) darn trouble. And then back again.

Also As DM said, there are a whole range of tooth top configuration options out there. Dustmight has posted long missives on blade selection and suggestions, you might look them up and read them.

[Gator95]

Excellent information and links- thanks.

[jgrobler]

Also want to convey thanks. Didn't know Rockler had that good article and blade summary.

[JimD]

A negative hook angle really helps a RAS. I used a slight positive hook blade for years and finally switched to a -5degree hook. With even a slight positive hook, a RAS wants to pull itself into the wood. With a slight negative, it does not.

The Freud Pro dado set is also a slight negative hook and helps saws like the BT3100 not pull themselves into the work faster than their motor can handle.

I like positive hook on the BT3100 except for dado blades but negative on the RAS. The blades I use on my CMS are positive hook but I'm sure a negative hook would be OK there too. You have to push a little harder to move a negative hook blade through the work but on crosscuts, forces are low anyway so it is hardly noticable. I have never tried a negative hook ripper but I would be concerned about the force required. Positive hook helps to pull the work through the blade which I think is good on the table saw.

Jim

[LinuxRandal]

A negative hook angle really helps a RAS. I used a slight positive hook blade for years and finally switched to a -5degree hook. With even a slight positive hook, a RAS wants to pull itself into the wood. With a slight negative, it does not.

The Freud Pro dado set is also a slight negative hook and helps saws like the BT3100 not pull themselves into the work faster than their motor can handle.

I like positive hook on the BT3100 except for dado blades but negative on the RAS. The blades I use on my CMS are positive hook but I'm sure a negative hook would be OK there too. You have to push a little harder to move a negative hook blade through the work but on crosscuts, forces are low anyway so it is hardly noticable. I have never tried a negative hook ripper but I would be concerned about the force required. Positive hook helps to pull the work through the blade which I think is good on the table saw.

Jim

Even the grind makes a difference.
Here is an example of a Mr. Sawdust blade (TCG 5 degree positive hook angle, 60 tooth)
http://www.youtube.com/watch?v=aUnZpUDvzgs
This is the blade recommended on the DeWalt radial arm saw forum. (capable of ripping or crosscutting)
Most people crosscut only and the blades normally sold for that are -5 degree hook angle, and ATB grind.

[JimD]

I've never ripped on my RAS and probably never will. For crosscutting I still think -5% is better.

Jim

[cabinetman]

The positive and negative hook angle will produce better results for the machines mentioned. For years, I used basically the same type blade on both the TS and the RAS. As for the climbing, or push that may be caused by a positive hook, you definitely feel the pressure. With a lot of use, you get conditioned to the feed rate. I found the negative hook for RAS's does not eliminate that tendency.

IMO, what does make a big difference is a sharp blade and the proper tooth count for the intended procedure and the stock being cut.
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