Progressive tooth pattern for saw sharpening

[Daniel Rode]

I want to start sharpening my own saws. I ordered a set of Grobet saw files and I'm going to make a saw vice. I'll still need to acquire a saw set but otherwise I'll have everything I need.

The first saw I'm going to attempt is a rip backsaw. I'm considering a progressive pattern so it will start easily at the toe but be aggressive and fast in the center and heel. My thoughts are to make the first inch a passive rake, second inch moderate rake, remainder of the saw aggressive rake.

The second saw on the list is an 10 pt Diston rip saw (http://www.sawmillcreek.org/showthread.php?223135-Info-on-my-Diston-saw-find&p=2326773#post2326773). It's not a valuable saw but it seems well made and just needs a sharpening. I want to do a progressive rake on this saw as well but probably over the first 3" or so.

I want to make some guide blocks for the file end to help me keep the file at the correct angle. I saw them on a Ron Herman vid and also here at SMC (http://www.sawmillcreek.org/showthread.php?8198-Sharpening-Handsaws). I'll probably make fancy one like this (https://newbritainboy.wordpress.com/2012/01/21/saw-filing-guide/) (or 3). What I don't know is what angles to use. What's a good passive rake for each of these saws? What's moderate and what's an aggressive rake?

[Steve Voigt]

Dan,
If you've never sharpened a saw before, I strongly recommend starting with a fixed rake, and saving things like progressive rake and sloped gullets for later on.
Here's my reason. Saw sharpening is both easier and harder than you might think. It's easier in the sense that even if your first few sharpenings are ham-handed and inconsistent, your saw will still cut much better than it did. Getting to the point where your saws are working at 80-90% of their potential is shockingly easy, easier than sharpening plane irons and chisels.
However, squeezing that last 10-20% percent out of your saw, getting a saw that starts velvety smooth but cuts aggressively, is a lot harder. If you use a progressive rake from the get-go, it will be a lot more difficult to diagnose the flaws in your sharpening method and improve them. If you start from a simple, predictable baseline, it will be easier to figure out how to improve.
For rake angles: I think you are wise to start with your rip back saw; again, keeping it simple is good. A 5° rake and 0° - 5° fleam is a good place to start.
Just my $.02. Good luck; I'm always glad to see people going for it and sharpening their own saws. Gives me hope for the craft. :)

[Daniel Rode]

After reading your post, I realize I may be trying to run before I walk :) Assuming I use a fixed rake, is 5° a moderately aggressive rake? I have a couple of good sharp veritas back saws, so I have a decent idea how a sharp saw should behave. Moreover, the back saw I'm starting with is an "extra". If I screw up sharpening it, I can just start over until I get it right :)



Dan,
If you've never sharpened a saw before, I strongly recommend starting with a fixed rake, and saving things like progressive rake and sloped gullets for later on.
Here's my reason. Saw sharpening is both easier and harder than you might think. It's easier in the sense that even if your first few sharpenings are ham-handed and inconsistent, your saw will still cut much better than it did. Getting to the point where your saws are working at 80-90% of their potential is shockingly easy, easier than sharpening plane irons and chisels.
However, squeezing that last 10-20% percent out of your saw, getting a saw that starts velvety smooth but cuts aggressively, is a lot harder. If you use a progressive rake from the get-go, it will be a lot more difficult to diagnose the flaws in your sharpening method and improve them. If you start from a simple, predictable baseline, it will be easier to figure out how to improve.
For rake angles: I think you are wise to start with your rip back saw; again, keeping it simple is good. A 5° rake and 0° - 5° fleam is a good place to start.
Just my $.02. Good luck; I'm always glad to see people going for it and sharpening their own saws. Gives me hope for the craft. :)

[Mike Brady]

A progressive pitch would not be where to begin, although eventually I did sharpen a saw this way to make it easier to start in the cut. I had done probably ten saws before that one, and only the first few inches were progressive rake. Why not just get a few good conventional sharpenings under your belt before you try something pretty advanced? I have a couple of junk saws that I paid nothing for that are good laboratories for experimentation. You can re-file the saws later if you want to alter the geometry. You also need to learn to set teeth and correct the cut before advancing to more complex things.

I use about 5 degrees of rake on my rip backsaws. An aggressive rake is zero, but that would be for a full length soft wood rip saw. Make some Ron-Herman-esque guide blocks. I file rip from only one side of the saw, otherwise you need separate guide blocks for each side. See what other recommend for rake. Preferences will vary.

[Steve Voigt]

Assuming I use a fixed rake, is 5° a moderately aggressive rake?

I think so, yes. Here's a pretty good discussion of rake and fleam angles:
http://badaxetoolworks.com/Filing.php

[Jim Koepke]

I file rip from only one side of the saw, otherwise you need separate guide blocks for each side.

My first encounter with online saw sharpening information was from the Vintage Saw Library's "Saw Filing -- A Beginner's Guide."

The guide block he recomends is drilled through and each side is marked separately. (I will try to remember to take a picture later.)

As with many things people have different ways of accomplishing the same task. When cutting new teeth in plate filing from one side is fine. If a saw already had set, filing from one side did not give me good results. The saw tended to pull to one side and was difficult to correct.

As with so many things in life, 307813

At one time my thoughts would wander toward the idea of these "new fangeled" progressive rakes, fleam, ppi and other such ideas every time one of my saws was used. The closest any of my saws came to being set up this way was a rip filed backsaw having 5° of fleam included. With 5° of rake it is an aggressive saw that gets a lot of use. It isn't used a lot these days for cutting dovetails. It doesn't leave as nice a surface as my newest saw plate from Ron Bonz. The RB saw is filed straight rip. Not sure, but it may be filed 8° rake.

Before attempting a progressive filing on a saw my sawing ability got to a point where it seems unneeded.

Maybe what would be more helpful for folks just now learning to use hand saws wouldn't be discussions on saw sharpening, but a discussion on how to start a cut and keeping the action true to the line drawn for the cut.

jtk

[Roger Rettenmeier]

+ 1 on 5/ 5 (rake/ fleam). I have this on my tenon saw, and it works well in the woods that I use. I also use the guide blocks and protractor to keep my angles consistent.

[Steve Voigt]

Before attempting a progressive filing on a saw my sawing ability got to a point where it seems unneeded.

jtk

My thoughts exactly, Jim. I totally lost interest in stuff like that once I learned how to do a decent straight-up sharpening job.

[Daniel Rode]

The Bad Axe link is very helpful! It does a nice job of explaining the how and why. I'll start simple and try to get that right before I think about progressive.

[Daniel Rode]

I know how I start a cut. It depends on the cut, but I have a SOP. However, I have no idea if it's the best way and I'm sure I could improve my technique. I'd love to hear more.


Maybe what would be more helpful for folks just now learning to use hand saws wouldn't be discussions on saw sharpening, but a discussion on how to start a cut and keeping the action true to the line drawn for the cut.
jtk

[Stewie Simpson]

IMO. 10 degree's negative rake is a much better choice, and don't bother adding any fleam.

Stewie;

[Mike Brady]

Stewie, is that 10 degree rake just for a dovetail saw or would you use that on a tenon saw also?

[Jim Matthews]

I don't find my Rip cut saws working well at angles much steeper than 10 degrees negative.

It's the difference between scraping, and shaving in the kerf.
If the top flat of my file is tipped a little 'forward' my saws tend to cut well.

If the top flat of my file points more downward, my saws stutter and jump.
I've tried progressive rake, and that mainly effects tooth geometry
at the end of the saw I don't much use.

[Stewie Simpson]

Stewie, is that 10 degree rake just for a dovetail saw or would you use that on a tenon saw also?

Hi Mike. I have a personal preference for a 10 degree rake angle on both tenon and dovetail saws. By doing so, these same saws will perform very well on both rip and crosscut work. I also have a preference to not file any fleam on my backsaws. But that's a whole new subject, and I think best avoided on this forum as a topic open to discussion.

regards Stewie;

[Stewie Simpson]

I don't find my Rip cut saws working well at angles much steeper than 10 degrees negative.

It's the difference between scraping, and shaving in the kerf.
If the top flat of my file is tipped a little 'forward' my saws tend to cut well.

If the top flat of my file points more downward, my saws stutter and jump.
I've tried progressive rake, and that mainly effects tooth geometry
at the end of the saw I don't much use.

Hi Jim. 10 degrees negative rake is the max I would apply on any saw. Regardless of its rip or crosscut definition.

regards Stewie;

[Tom M King]

I've never bothered to do any "progressive" filing. In fact, I had never even heard about it until fairly recently. I don't think I've ever put any more than 5 degrees rake on a rip saw either.

[Daniel Rode]

Now I'm getting a head ache :)

I want to make sure I understand the terms correctly. Negative rake would mean the front edge of the tooth would lean backwards toward the heel? So 10° negative rake would be less aggressive than a tooth at 0° (perpendicular). A 5° rake as Steve suggested would be a negative rake as well, right?

You'e suggesting a somewhat more passive setting than Steve and no fleam for a rip back saw?


IMO. 10 degree's negative rake is a much better choice, and don't bother adding any fleam.

Stewie;

If I followed correctly, what do you prefer 10°? Also, Do you feel the fleam is unnecessary for a rip saw? I'll make crosscuts with it but any cut I care about would be knifed all around.

[Stewie Simpson]

Hi Dan. Standard Rip saw teeth are not fleamed. Crosscut saws are. A rake angle between 5 and 10 degrees is a suitable range to look at for a rip tooth. If your slightly undecided, select 8 degrees as a happy medium.

A front tooth angle of 90 degrees is generally regarded as being at 0 degrees rake angle.

http://www.disstonianinstitute.com/glossary/ripteeth.gif

[Jim Koepke]

I want to make sure I understand the terms correctly. Negative rake would mean the front edge of the tooth would lean backwards toward the heel? So 10° negative rake would be less aggressive than a tooth at 0° (perpendicular). A 5° rake as Steve suggested would be a negative rake as well, right?

You'e suggesting a somewhat more passive setting than Steve and no fleam for a rip back saw?

The rake was also very confusing for me. I used to work with bicycles and there the fork rake was forward and saw rake is backward.

The rake leans toward the heel or handle of the saw. If the rake went 10º forward it would likely dive into the wood and get stuck. Maybe the easy way to remember is the more rake, the easier the saw starts.

Fleam or no fleam is one of those things like a secondary bevel or a back bevel. Everyone has their own opinion. On my thick plate rip back saw the teeth are a little more aggressive than most of my back saws at 5º rake. To counter that a little when the saw is used to crosscut it was given 5º of fleam. My dovetail saw has no fleam. The plate on that saw is fairly thin and at 14ppi w/8º rake, it isn't all that aggressive.

jtk

[Jim Matthews]

In practice, I run through the first time and if it cuts well - I'm done.
If it doesn't, I go back and 'relax' the tooth angle to get a better 'glide'.

I have found on larger saws that polishing the back of the teeth
with an EZE-lap hone keeps them sharp, longer.

[lowell holmes]

I suggest that you download the Ron Herman video on sharpening saws from Popular Woodworking website. It is the best I've seen and will save you a lot frustration.

Never mind, I see you have already done that. You should be ready to go.

[Isaac Smith]

Perhaps I missed it, but I did not see the size of the backsaw you are filing. We can spitball rake angles at you that may or may not work for you, but there are several factors you need to consider. Even then, the only way to really know what works best for you is through trial and error.

The most important factor is the hang angle of the handle. While 10 degrees of rake makes for a very relaxed tooth on this 18" tenon saw (first picture below), it is quite aggressive on this 9" dovetail saw (second picture below).

http://www.blackburntools.com/new-tools/new-saws-and-related/custom-saws/gallery-kenyon-seaton-tenon/images/kenyon-seaton-19-apple-01.jpg


http://www.blackburntools.com/new-tools/new-saws-and-related/9-dovetail/gallery-qs-elm/images/9-dt-qs-elm-05.jpg


These two saws are extreme cases, but they make it easy to see how dramatically hang angles can differ. The high hang angle of the dovetail saw directs more of the push stroke down into the wood. To limit how much of a bite each tooth takes, you need to relax the rake or use very light strokes. Relaxing the rake is the better method, in my opinion.

The first of the 9" dovetail saws I made was initially filed with about 5 degrees of rake. It was nearly unusable in any but the softest of woods. I refiled it several times, relaxing the rake each time. I finally got it cutting to my satisfaction with somewhere between 12 and 15 degrees of rake.

The second factor is the type of woods you work with. If you cut nothing but pine and poplar, you can get away with an aggressive tooth. If you start working with denser woods, that same saw may become very jumpy or hard to control. Ring porous woods like oak and ash are also tough for me to cut with really aggressive teeth.

Tooth size also plays a role. Finer teeth can be more aggressive since their size already limits the bite they will take.

All of this applies mainly to rip teeth, and assumes that the teeth are really sharp. Dull teeth are, well, not very good at cutting.

[Daniel Rode]

Thanks for the information. BTW beautiful saws and nicely photographed to boot!

I had not given much thought to the hang angle. The backsaw I plan to sharpen first is a 12" long, 12-13 tpi, IIRC. The hang angle is not as flat as the large saw, but not too far from it. My Veritas Crosscut is 11", 14 TPI with 15º rake and 15º fleam and it can skip a little when starting. It's not overly aggressive in the cut though. No complaints, it's actually my favorite saw.

As for the wood, it all depends. Pine, Oak, Cherry and Walnut. I prefer the latter 2 but I do a lot in cheap pine and white oak. I cut pine more than any other wood, but the cut's I really care about are in hard woods.

[Stewie Simpson]

Hi Isaac. I must admit I struggle with the notion that a dt saw requires a much higher hang angle. There is already enough weight within the hardback to provide downward pressure on the saw teeth. From a user perspective its also much easier to control the dt saw when the handle hang is set more favourably towards the direction of the forward travel. Just my thoughts.

regards Stewie;

[Steve Voigt]

Beautiful saws as always, Isaac. That's also the best explanation of the relationship between rake and hang angles that I've seen.

[Pat Barry]

Hi Isaac. I must admit I struggle with the notion that a dt saw requires a much higher hang angle. There is already enough weight within the hardback to provide downward pressure on the saw teeth. From a user perspective its also much easier to control the dt saw when the handle hang is set more favourably towards the direction of the forward travel. Just my thoughts.

regards Stewie;
This would be an interesting thread discussion in itself. I'll throw in 2c that the hang angle must be related to the typical position that the work is done at. For example, Issacs dovetail saw seems like it would work best for someone who prefers working with the cut in a relatively high position - I'm thinking it would be uncomfortable to use it with the work down low. This would however cause you to work from the near corner when doing dovetails for example, but that might just be the best solution to cutting to the line. That saw hang angle would seem to me to want the saw to be tipped backward and down becasue your wrist will want to be in a comfortable position for the work. I could see a guy like me who's eyesight is not what it used to be, liking to do this type of detail work up higher really liking this saw design.