Rip saw rake Angle - 90*

[Doug Mason]

Picked up a new tenon saw from ebay (on the smallish side)--will use it for hardwood tenons/dovetails/ripping. I have always sharpened my tenon/dovetail saws for a rip cut--and with a 8* rake angle from 90* (so 82 and 102 degree's). However, as I need to sharpen this saw, I am going to experiment and put the rake angle at 90* ( no rake angle at all). For thoses who have done this--wht are you're thoughts on having a straight 90 degree cutting tooth?

[harry strasil]

That's the way I sharpen all my rip teeth and I also put a 3 to 5° fleam angle on the front cutting side, with very little set, about .005 to .006 inch (the thickness of copy paper). I actually set the teeth more than that, but after setting, I use copy paper to cover the jaws of a smooth jawed vise and squeeze the teeth to get an even set, the very ends of the teeth cut thru the paper and its the most even set you can get and as you have a narrow kerf and are removing less material, its easier to follow a line and the saw cuts much faster.

[Joel Runyan]

Harry, is the small amount of fleam just to ease in the cutting? Do you notice any decrease in speed or trackability?

[harry strasil]

think skew angle chisel or plane on end grain, it gives you a slicing action instead of a tearing action.

and as you have a narrow kerf and are removing less material, its easier to follow a line and the saw cuts much faster.

Increase in speed as I stated earlier. Trackability is increased as the saw blade is not flopping around in a big wide kerf.

Try it my way, you will be amazed at the increase in speed because you are removing less material. Just remember to start straight on the line, with a narrow kerf its hard to get back on the line if you get off somehow. Iffen you don't like it, file it the way others do or some other way that suits you.

I have an old dovetail saw with fine teeth filed crosscut with about a 1 3/4 inch wide blade and a round file type handle, I can go the full depth of the blade to the spline in one stroke and then pick the piece I am cutting up with the blade in the kerf its so narrow, Its almost like cutting stick butter with a razor blade.

[Bill Kapinski]

So how many of you are thinking "I've never tried cutting butter with a razor blade. . . maybe I should try it" or is it just me.

Bill

[David Keller NC]

Picked up a new tenon saw from ebay (on the smallish side)--will use it for hardwood tenons/dovetails/ripping. I have always sharpened my tenon/dovetail saws for a rip cut--and with a 8* rake angle from 90* (so 82 and 102 degree's). However, as I need to sharpen this saw, I am going to experiment and put the rake angle at 90* ( no rake angle at all). For thoses who have done this--wht are you're thoughts on having a straight 90 degree cutting tooth?

Doug - Can't really comment based on personal experience, but in reading a bunch of stuff on this subject over the last year or so, my guess is that while your saw will be more aggressive (it will cut faster), it may be a bit more difficult to start, particularly in hardwoods.

The suggestion here is that you might try what Andrew Lunn does to his saws, and as reported by Chris Schwarz, is a compromise that gives an easy start and faster cutting. Andrew files his saws with a relaxed rake at the toe (not sure, but I think it's about 80 degrees), and gradually steepens it over the next couple of inches.

Of course, this implies that you use the toe to start the cut, and not all of us do. In particular, I'm usually using the portion near the heel on my dovetail and tenon saws to establish the initial kerf.

[Mike K Wenzloff]

Hi Doug,

Just a couple quick comments before popping off to work.

Depending on your experience, the PPI of the saw and the woods you use, you may well find a 90 degree rake is wonderful. If you use any of the Oaks, Ash, Hickory species (and some others), you may find it a bit too aggressive depending on the three things I listed above.

The beauty of filing your own saws is that if this saw does turn out to be too aggressive for your liking, it is simple to relax the rake and or add a touch of fleam to the face of the teeth like Harry mentions.

My personal preference is for about 4 degrees rake on low PPI saws with a bit of fleam on the beginning of the saw. My 20 ppi saw, the other end of the toothing spectrum for me, has as close to zero rake and fleam as is possible with hand filing.

Note that the bit of fleam on the low PPI hand saws (like the 3 1/2 ppi to 4 1/2 ppi rips) isn't for starting a cut but to ease reentry into the cut so the toe is less likely to kink.

My 10 ppi tenon saw has about 6 deg. of rake and zero fleam.

So experiement. It is so easy to change specs for yourself there is no reason not to do so.

Take care, Mike