Full Chisel Blog

August 19, 2008

I Re-sharped a Saw

Filed under: Sharpening,Techniques,Uncategorized — Stephen Shepherd @ 9:57 pm

I recently posted about sharpening a 16 point rip saw that I had made a new handle for and used split saw nuts provided by Mike Wenzloff and have used it to cut some slots in 1/2″ diameter hickory muzzle-loading ramrods (a great source of hickory dowels by the way) and have cut some other stuff.

But I noticed the other day that the saw wasn’t cutting right and I looked at the teeth.  Now I have a feeling an apprentice may have cut into a nail or something, none of them will admit it, and the saw teeth in the center of the saw are unusually dull.  Now I do sharpen all of the teeth on my saws and I encourage my apprentices (I had 5, count them five in my shop today) to use all the teeth.  I know I do, so I am sure I did not cause the damage.

So I looked at the saw blade with 288 teeth total and wondered how to best go about re-sharpening.  I marked and carefully removed the new split saw bolts, removed the blade and contemplated filing all of the teeth again.  When I sharped the saw I could tell what teeth I was working on because they were rusted, so I could see the new metal and keep track of the little tiny teeth as I sharpened.

I jointed off the teeth to get them all to the same height, there was even more shiny stuff and it was difficult to see those little teeth, let alone isolating every other one.

But this saw, all of the teeth were still shiny and it looked like a nightmare.  Then I had a light come on in my head (not an incandescent light, they don’t exist in my world, but a grease light).  I light up a grease lamp, passed the blade in the flame and covered the teeth of the saw with soot.  I took care to get the soot on all the teeth (an alcohol lamp is soot-less so it doesn’t work, but a candle or oil lamp will).

I then put the saw into the chops, found the proper tooth to start on, then to my pleasant surprise, it was easy.  The teeth were black until I started filing, it was very easy to see the teeth that had been sharpened, so if I got distracted, which I do with 5 apprentices and one helper in the shop, I could go back and ‘see’ just where I left off.

This is an excellent technique which I will employ again on fine toothed saws, and when I was done the soot just wiped right off.  I also think the soot may have provided a bit of lubrication for the filing but I am not sure.  I will probably do it on the next saw I get that needs to be sharped, even with bigger teeth, but for fine teeth it worked great.

Stephen

6 Comments »

  1. For those of us who don’t have a grease lamp, I use engineer’s marking blue for the same job. I bought a pint and a half (actually a litre) of it a couple of years ago and thought “will I ever use this up”. Now that I have it, I use if almost every time I do anything with metal – it makes it so much easier to mark out or to keep track of what you are doing. I have even made a little bottle (a pill bottle with a small brush epoxied in the lid) so it is always to hand and I always have a brush for it. And cleanup is a breeze – general purpose paint thinners works a treat.

    Comment by Jeremy Kriewaldt — August 19, 2008 @ 11:41 pm

  2. This is a thorny problem because if you repeatedly sharpened all of the teeth when only the ones in the middle were dull, then eventually (and I mean *eventually*) the saw would have a noticeable concave profile. I thought standard procedure was to joint the saw and then sharpen each tooth as many strokes as necessary until the shiny flat had just disappeared, then when all of the flats are gone treat it as a ‘normally dull’ saw and sharpen the whole thing from scratch using one or two strokes per tooth, whatever you normally do.
    That having been said, I like the smoke trick. I guess a magic marker isn’t an option in your shop (that’s what a lot of people use). I use layout fluid for that kind of purpose, and I would expect that some kind of layout fluid would have been used even in the 19th century. It’s just a really thin lacquer. A dye, really. Easy to apply, and easy to remove. Not as convenient as the smoke if you happen to have a candle burning. I think you hit on a good, period solution for a common problem.

    M.Mike

    Comment by Metalworker Mike — August 20, 2008 @ 7:01 am

  3. Jeremy,

    I use smoke because, it is handy, cheap and correct to the period in which I work (mid nineteenth century Cabinet & Chair Shop). I will have to do some research to see how early that layout fluid was used. Paint thinner I know was not developed until later, but I would imagine turpentine would work, I don’t know if alcohol would? Thanks for your comment.

    M.Mike,

    I do much the same thing, the first pass brings everything down to proper height to remove the shiny flats, then a final touch up pass. I have got a few on the first go round but usually there will be a few teeth that need attention. I noticed that if the saw was machine sharped and the teeth are sharp(?) but on different levels, I have to go over it at least twice. But I did learn a trick and that is to file the high side first, if you don’t you will have to go back and do it again anyway, but it gets things closer. And like sawing when I am filing the teeth with a triangular file, I count my strokes.

    Stephen

    Comment by Stephen Shepherd — August 20, 2008 @ 8:39 am

  4. Neat little trick, Stephen. You can also use that when you’re making a handplane (from one piece of wood, not the laminated kind) and are trying to chisel the bed flat. If you “smoke” the iron and then wedge it in place, the soot left on the bed will show you the high spots.

    Comment by The Village Carpenter — August 20, 2008 @ 3:50 pm

  5. VC,

    Soot can also be used on socket chisels and gouges to help fit the handles. Works better than graphite and doesn’t interfere with glue or finish.

    Stephen

    Comment by Stephen Shepherd — August 21, 2008 @ 8:37 am

  6. We used soot to darken the sights of our rifles when I was in the Marine Corps. Now that has been replaced with Sight Black. A little spray on can. Darkens everything nicely but wipes off.

    Comment by James Ogle — January 15, 2010 @ 12:14 pm

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