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Thread: Basic questions on saw sharpening - changing rake and fleam?

  1. #1
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    Basic questions on saw sharpening - changing rake and fleam?

    I've been sharpening some saws, a new trick for me. However, a couple I have were sharpened at some point in some deep past with what seem to be rather crazy angles. Not that I have a great sense for such things, but I've spent time reading up on this and they seem way off. I also may want to change a saw from cc to rip, or vise versa.

    How do I make rather drastic changes to rake and fleam? Rake seems more of an issue. This is all assuming I want to keep the pitch the same and not start all over from a bare filed saw plate.

    For example, the most course saw I have is 5 1/2 PPI. The teeth are quite a mess so I've held off trying to fix it up:

    5.5ppi.jpg

    Some of the teeth have circular areas in the base of the gullets, I assume from some mechanical filing something or other. Every other tooth has a severe rake on the upper area of the tooth, and some have very shallow gullets. This will take tooth-by-tooth focus. Another couple saws are much more even but not how I want them.

    It may actually be trivial, haven't tried it since I don't want to screw up something if I can avoid it by asking first (that's a rather rare concept for me!)

    Any pointers?

  2. #2
    Fitz, just give the saw a good heavy jointing before you start. Remove enough material so you have nice big flats. Then shape the new teeth. I assume you are going to shape them with a rip filing before you add any fleam, so once you're done with the initial shaping, inspect to see if remnants of the old profile remain. If it's not sufficient, joint a little more and redo.

  3. #3
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    +1 on what Steve said.

    Saws most likely get like yours in the picture when sharpened by someone who knows you're supposed to use a file but know nothing else about saw sharpening.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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    That would have been me if not for the creek.

    I sat down to try last night after jointing it to the point every tooth had a flat but realized I had two problems: needed good light (wait for daylight today) and it was hard to tell where each tooth should line up since there was done significant randomness. I'll print out a 5 1/2 PPI spacing template.

    There are circular areas removed from some gullets that undercut the teeth and deepen the gullets so it is hard to find a real baseline or target to track without a template. I'm excited to try, though.

    I got a few dozen NOS saw files in the 6 e.s. through 7 regular taper for very little some time ago, means it's time to learn more about saw filling. It seemed like there was a black art to it before but now the impact of the angles on cut make good sense, I just need the experience over time to see what is best. A sharp but imperfect saw is already much better than a dull imperfect saw!

  5. #5
    Pick a file for that saw and then keep with that file for it. The rounded gullets are probably because someone used a large file with a very large corner.

    bringing multi depth or mis-spaced teeth back to something close (and something close is all that matters, it doesn't have to be perfect - close and worked all the way to the point are where you're going to get cutting speed from) is just a matter of practice.

    It's your job to keep the file oriented the same way to get the rake in line - focus on that first when you're working the rounded gullet out of the teeth and then just decide forward or backward with the file (or straight down if everything is in good shape) to finish the work.

    Side comment in major tooth correction - if you focus on working the back of the tooth to reduce tooth height, you'll get more life out of the file. That means biasing pressure into the back of the tooth on the diagonal instead of straight down. Straight down is easier, I guess, but it leads to worn out file corners long before the sides poop out.

  6. #6
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    Hi Fitz,

    You've already got a lot of good advice here from folks who know what they're talking about.

    The link below is Vintage Saws.com, Pete Tartan's site (he founded Independence Tool company with Patrick Leach to begin producing dovetail saw's that were later acquired and are now sold by Lee Nielsen). This is a great primer about saw sharpening the pretty much covers everything you need to know. http://www.vintagesaws.com/cgi-bin/f...y/library.html

    Regarding shaping and re-profile teeth as you mentioned in the OP, a super helpful "jig" is a guide block like the one in the picture below from the vintage saws primer:









    The tip of the file goes in the hole. The line represents the rake angle, which is usually expressed as the angle of the leading/cutting-edge of the tooth relative to vertical line perpendicular to the long axis of the saw. In other words, 0 degree rake angle (pretty aggressive and only applicable for rip saw) the cutting edge of the tooth would be 90 degrees (perpendicular) to the long axis of the saw plate. Common rake angles for full-size rip saws are 5° (Disston's standard prior to 1928) and 8° (Disston's standard after 1928). This means the leading-edge of the tooth is angled back towards the handle by the amount of the rake angle. LV Also makes a saw filing guide that does the same thing and you don't have to create a whole bunch of these guide blocks for different rake angles and size teeth. I've never used it, but I hear good things from those that have. I use 12° of rake for coarser pitch crosscut saws (>8 PPI), and 15° for finer pitch finish cross cut/joinery saws.


    As David another suggest, the best way to reestablish the correct spacing, profile/height and rake angle for rip teeth is to joint the saw with a 10 – 12 inch mill file. I use a red marker highlight the little flat spot on the top of the teeth. F

    Then use the guide block with triangular tapered saw file (or a 5 PPI pitch saw, anything between 7-8" slim, X slim, XX slim or even 6"slim will work fine). Starting at the handle end of the saw and working from one side of the saw only; file straight across until the red flat spot is gone. As David said, the way to adjust the spacing of the teeth is the bias the pressure on the file either towards the toe, or the heel so that when the flat spot is gone the apex of the cutting edge of the teeth has "regrown" consistently space relative to the tooth behind it.

    If the tooth line is in really bad shape I would recommend leaving a little bit of flat spot remaining the first time around and do this twice. This sounds way more complicated to describe than it is to do. With a little practice you'll get the hang of this quickly.

    Once you have the tooth profile/height, rake angle and spacing established, for a crosscut saw you can then add in the fleam angle. To get a consistent fleam angle, I just draw lines on top of my wooden, shall shop built saw vice, which are easier for me to see that a guide block (particularly when using a magnifying visor). Again starting from the heel and filing every other tooth that is set away from you. Then flip the saw around and do the other teeth from the other side.

    Set, joint one more time and then just lightly touch up the cutting edges. For the final steps, I like to use the smallest saw file that still covers the entire cutting edge of the teeth – this results in a deeper gullet in between the teeth that carries a bit more sawdust and keep the saw cutting quickly, particularly in thick stock.

    For me at least, the other thing that's really helpful is use a sharp file! I mark the apex of the triangular saw file that I start with so I can keep track of when I need to rotate it to a fresh edge. The quickest way for me to screw this up is to keep using a file long after it's dull. This is really most relevant to full-size saws. With finer pitch back/joinery saws, your removing relatively a lot less steel and one quality file will go a long way. The picture of your tooth line really doesn't look that bad (I've seen waaaaaay worse), but depending on the hardness of the steel, you could easily go through two quality files to get to a finished, Sharp saw.

    I would highly encourage you to give this shot. Anything you do will make the saw cut better than it does now. As your execution improves, you'll be better able to squeeze out that last 10 – 15% performance when everything comes together, but that's really just icing on the cake. In a lot of ways, precision tuning your saw to a high standard is analogous to sharpening plane irons and chisels; just getting them reasonably sharp makes a big difference. The last 10 – 15% of "sharp" is equivalent to the super fine grit stone or stroping plane irons, that just makes them more fun to use and the edge lasts longer. Just my opinion, FWIW.

    All the best, Mike

  7. #7
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    Starting at the handle end of the saw and working from one side of the saw only
    This is another one of those opinions like tails first or pins first.

    My tendency is to file every other tooth and then come back from the other side.

    I have done it both ways and taking the extra time to work from both sides works for me.

    Especially if you are doing a crosscut saw or adding a little fleam it is best to work from both sides of the saw.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  8. #8
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    For a fleam angle reference, I use a trick I came up with for helping keep on track sharpening chainsaw chains. I lay a strip of plywood (could be paper or anything else really) behind the saw that has a bunch of lines drawn on it at the desired angle. It's in the field of view behind the saw you are sharpening, and it might surprise you how it helps without having to slide anything else along the saw. A single degree is probably more than most people realize, and you can easily see if you are not in line with the drawn lines with the file. I keep several commonly used such marked strips of thin plywood in my "Saw Sharp" toolbox.

    To help develop a feel for what a file will do, rig up something that holds a white sheet of paper right behind your practice saw. Notice how the shavings vary that are thrown on the paper with different types of file strokes. I like light long strokes.

    I use the little blocks like in Mike's post, but I drill the hole at the fleam angle by cutting a wedge on the slider, and put it under the block on the drill press. I like to use the whole file. On one of my LV orders, I'm going to be tempted enough one day to buy their file holder, when all the little premade blocks are worn out. Most of the time, if I'm in the middle of a job, and need to whet one, I'll just use the file. I like starting in the smooth, no tooth zone at the end of the file to get a running start when I'm sharpening a chainsaw chain, but it doesn't work out so good with the triangular files held with both hands. A chainsaw chain requires you to push straight back into the tooth, and you almost never do that on a handsaw, but knowing how to do one makes the other easier, sort of like riding a bike, I guess.

    I always sharpen from both sides, crosscut or rip. I guess because I learned to sharpen a chainsaw chain first. I used to send my saws out to sharpen, but the guy who did them died in 1982, and when I sent them to someone else, they were ruined to the point that I taught myself out of desperation.
    Last edited by Tom M King; 08-18-2014 at 8:47 PM.

  9. #9
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    For a fleam angle reference, I use a trick I came up with for helping keep on track sharpening chainsaw chains. I lay a strip of plywood (could be paper or anything else really) behind the saw that has a bunch of lines drawn on it at the desired angle.
    Just one set of parallel lines on a sheet would work. Just set them to the angle being used at the time.

    Here is something I rigged up to keep my fleam angle consistent:

    http://www.sawmillcreek.org/showthre...am-Bevel-Gauge

    I have plans to improve the design but this works okay for now.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  10. #10
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    Quote Originally Posted by Jim Koepke View Post
    Just one set of parallel lines on a sheet would work. Just set them to the angle being used at the time.

    Here is something I rigged up to keep my fleam angle consistent:

    http://www.sawmillcreek.org/showthre...am-Bevel-Gauge

    I have plans to improve the design but this works okay for now.

    jtk
    Thanks for the link Jim. That's a very slick way of keeping the angle consistent.

  11. #11
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    Sorry, computer got put away during the massive temporary migration of EVERYTHING in rugged rooms to have them cleaned to get rid of the slight dog smell. Then had to wait for them to really dry thanks to the strong wet dog smell that emerged the next day. Gah.

    I finally am writing on my phone since I still don't have our set up. I won't reply to each because of that but I am so happy with all the advise. I am trying a combination of things sugfested and it is going great! I learned a lot from the above replies and readings linked and an on the second pass. It is also getting easier.
    Thank you!

  12. #12
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    Sounds great. I think reluctance is the biggest thing holding people back from learning. I was at a talk that Bob Ballard gave once. He told a story of getting Prince Charles to go on a dive with them in the North Sea. Prince Charles was on the edge getting geared up, and they were hanging 110 pounds on him to overcome the thick wetsuit inside the dry suit. Prince Charles said, "But I calculated this last night, and it only came up that I needed 55lbs." Bob Ballard said, "Yeah, that first fifty five pounds is to overcome buoyancy. The other fifty five pounds is to overcome reluctance."

  13. #13
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    That sure fits. I'm finding this quite doable. It's taken done reading, and questions here have helped a ton, but there isn't any huge mystery involved, at least at this beginner level. Reading the debates and opinions across blogs left me with the strong impression there were impenetrable mystical formulas involved. I'm sure there may be once you get past the early stages but it seems I can get nice results without.
    One comment really stuck... You'll learn more from sharpening one saw than reading a hundred pages.

    Now I've got another question about what to angles, cc vs rip etc to make each saw. I'm going to start a new thread. Thank you all!

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