File Sharpening Saws
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Been sharpening my Spear & Jackson saw for rip cut. Did it once (and set the teeth) and was disappointed at how blunt the saw was. Worse than before I’d set the Bahco file to it. Sharpened it again, and it’s getting sharper.
I thought you only had to go at it once and it would be sharp enough. Evidently, this is not the case. Far as I can tell I’m doing it right so hopefully it gets sharper as I go along.
2 September 2018 at 10:14 pm #550830Did you joint the saw teeth before starting? Doing so before sharpening makes all the teeth the same height. After a couple of sharpenins without jointing, I found my rip backsaw cut very roughly. Jointing it made the problem go away.
3 September 2018 at 12:35 pm #550840Any flat single cut file works for that but do it carefully or you’ll just make work for yourself. Your saws are new and you’ve just sharpened them so it may be hard to see what you’re doing. If you take a black permanent marker and color the teeth, it will help you see what’s going on. Make one pass (and one pass only!) with the flat file and look at the teeth. You’re looking for a very small flat shiny spot on the top of each tooth and if you’re seeing random hits and misses, make another pass, but stop after each one and have a look. It works best if you lay the file down on top of the teeth and run the file from rear to front with just a small amount of pressure on the file. Again, be careful – it doesn’t take very many passes to completely remove the teeth on a 14 tpi back saw.
The next part of that process is more delicate. If the teeth were at different heights and you did the jointing properly, you’re going to have some teeth with wide flat spots on top and some where the flat file barely touched them. At this point, you have to go tooth by tooth keeping in mind that you’re filing two different teeth each time you drop the saw file into a gullet and you have to file away only as much metal as it takes to make the flat spots go away and that can be tricky. It’s usually not uniform. For some of the teeth you’ll need to remove metal from the backside of the tooth only without altering the front of the adjacent tooth and in other cases it will be the opposite. Some can be filed as you normally would if the adjacent flats are equal so just take your time and evaluate each tooth as you go. It often takes a number of passes on really messed up teeth to get them straightened out.
As new as your saws are, I doubt you have a big problem with this unless you really went wild when you sharpened the saw. You’re not the first guy that made his saw dull by sharpening it either! That’s actually pretty easy to do. Watch all the video’s that Paul has done and copy his method as best you can keeping the file dead square and level with saw plate as you push the file through and maintaining consistent pressure on the file. It’s not a race either. I’ve heard Paul say that he can sharpen a panel saw in 4 minutes but he’s sharpened a lot of saws. I’m pretty sure when I started, the process of sharpening a panel saw was more like a 20 minute or more task for me so take your time.
@mark68 how many teeth are on the saw you are sharpening? If you are just learning, and if it is more than around 10 tpi, maybe 12 tpi, I suggest you learn on something coarser for your fist attempts. This isn’t an absolute, “oh don’t do it!,” but if you could do your first attempts on something coarse, it may be easier to learn. A 6 tpi rip saw would be perfect.
3 September 2018 at 5:17 pm #550847I would imagine you’re OK as far as tooth height goes Mark, but checking it is always a good idea. What’s really important on a rip cut saw is that the file stay exactly perpendicular to the plate. If you’re off a little, you’re adding fleam to that tooth and if you’re consistently off at the same angle, when you set the teeth only half of them will cut correctly. The other half are at a negative fleam angle. It just takes a little practice. Have another go – it will get better.
[quote quote=550846] @mark68 how many teeth are on the saw you are sharpening? If you are just learning, and if it is more than around 10 tpi, maybe 12 tpi, I suggest you learn on something coarser for your fist attempts. This isn’t an absolute, “oh don’t do it!,” but if you could do your first attempts on something coarse, it may be easier to learn. A 6 tpi rip saw would be perfect.[/quote]
It’s 10 tpi. The teeth are quite uniform and the gulleys are nice and clean.
- This reply was modified 5 years, 7 months ago by Mark68.
[quote quote=550847]I would imagine you’re OK as far as tooth height goes Mark, but checking it is always a good idea. What’s really important on a rip cut saw is that the file stay exactly perpendicular to the plate. If you’re off a little, you’re adding fleam to that tooth and if you’re consistently off at the same angle, when you set the teeth only half of them will cut correctly. The other half are at a negative fleam angle. It just takes a little practice. Have another go – it will get better.[/quote]
No doubt my file work was off a little; I’ll pay extra attention next time.
Thanks for the advice.
I know the difference between cross cut and rip cut, but in the diagram I’ve attached (the red ink represents the direction of the saw cut), I’m not sure if I should be using cross or rip. Not sure if I’m going with or against the grain. If I had to pick, I’d go for a rip cut.
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You must be logged in to view attached files.Thanks Keith.
I guess it doesn’t help that I’ve sharpened the saw so it cuts on the pull stroke!
That’s me watching Paul and mixing up his right side with my left side 😀
Should I use the file to correct this (think it’ll be harsh on the saw file) or chalk it up as an error and use the other Spear & Jackson saw I’ve got (and not used yet)?
3 September 2018 at 10:45 pm #550857Can you make a picture of the saw plate or the front part of it? We’ll see if we can give you some suggestions. Don’t give up just yet! BTW, that sketch would show a rip cut but rips aren’t with or against the grain. A rip cut is any cut in line with the grain. Cross cuts are 90 degrees to (or across) the grain but it doesn’t have to be 90 degrees. Any angle where you’re cutting across the fibers and not with them is a cross cut.
- This reply was modified 5 years, 7 months ago by harry wheeler.
- This reply was modified 5 years, 7 months ago by harry wheeler.
Will this file suffice for using on the saw teeth
http://www.amazon.co.uk/Nicholson-Flat-Bastard-File-10in/dp/B0002JT3R0
Here’s a pic of the saw’s teeth (cutting on the pull stroke):
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