Retoothing a no. 7 Disston panel saw.

[lowell holmes]

I have an old Disston handsaw (complete with the nib). The saw plate is sound except for grunge and a broken tooth. I intend to retooth the saw following Tom Law's video.

I would appreciate any tips concerning grinding the old teeth. I intend to start on a low speed bench grinder (free hand) and then floating the plate with a mill file.

The old teeth are 8tpi crosscut and I think I will keep that tooth pattern.
The saw appears to be No. 7 Disston with 22" saw plate, 3 bolt handle and lambs tongue. It is not taper ground and seems stiffer than taper ground saw plates..

[David Weaver]

Where is the broken tooth?

I wouldn't grind the plate with a power grinder, a good fresh mill file will run the teeth off completely in a couple of minutes - they will come off a lot faster than you think (much faster than a low speed grinder - low speed grinders and freehand aren't a great combination, anyway).

You can do it however you like if you're using a file, but if you don't do it every day, definitely cut the teeth straight across (add the fleam at the end once you have a good set of teeth) and put together an angle guide for the end of the file to make sure the rake is consistent. Mind the teeth as you're going and make sure you don't have any deep ones or shallow ones. You can "move" them a little bit when you're filing if you see an outlier developing.

Use the mill file to cut the teeth down until there are notches from the bottom of the gullets and then file from there. don't grind the teeth completely off all the way through the bottom of the gullet because starting new teeth evenly is a pain. If the broken tooth is all the way to the bottom of the gullet, still leave the grooves and if that tooth is still low once you've cut the others, joint later on until you get a fresh area for a point where the old tooth broke off.

If you take a caliper, you should find that the saw plate has taper. It may feel heavy and thick, especially if it's very old, but it should have some taper. My old 7 doesn't have a lot either, but there's some there.

[Chris Vandiver]

Photo?
If the plate is not taper ground it is doubtful that the saw is a Disston #7.

[David Weaver]

Make sure you have several files on hand to do this. My old spear and jackson had a couple of file killing spots in it. It took 3 grobet files to cut the teeth fully (it had a frown, so I had to cut more than full depth at the ends). If there was someone local with a foley toother, I wouldn't have cut the teeth by hand.

[lowell holmes]

Thanks David and Chris. This is exactly the feedback I was looking for. I will joint it with a file, leaving enough of the teeth to mark the spacing. I will shape the teeth and then sharpen the fleam.

Photos are attached. The medallion is a Philadelphia medallion. I will have to find my micrometer (old age memory), but a caliper shows .03" at top, and bottom of the heel and toe. The broken tooth is 3" from the heel and is 50% gone.


195153195152195151http://www.sawmillcreek.org/images/misc/pencil.png

[David Weaver]

The reason I asked the question about the teeth is because for purposes of having a good working saw, a tooth 3 inches from the heel is not the worst thing in the world.

I would be tempted to leave it alone, but filing teeth into a saw is good practice and a good learning experience.

[Chris Vandiver]

I just measured the taper of an old Disston #7(circa 1888-1895) and compared it to a Disston #12(circa 1896-1917). Measured at the toe(top and bottom).The #12 tapers from .029-.017 for a total taper of .012. The #7 tapers from .033-.0185 for a total taper of .0145. Both saws are 8ppi. Plenty of taper in the #7s.

[lowell holmes]

The tooth spacing is not uniform at this time. I will attempt to even things out. There is an 8 on the saw plate, but the tooth spacing may be the result of a lot of years being sharpened by may people. I have good working saws. This is a fun project for me to learn on.

[Jonathan McCullough]

I'm fixing up a Disston No. 7 right now. If that were my saw, I'd clean it off thoroughly and carefully with mineral spirits. Rust and old tar accumulation can affect micrometer readings--you may find different measurements after cleaning it. I wouldn't retooth or joint the whole thing unless it had a pronounced "frown" rather than a belly. If one of the teeth are broken, I wouldn't worry about it--that won't really affect performance all that much; at 22 inches and 8 tpi, it's got about 175 other teeth to spare, and after a couple of sharpenings, it'll "grow" new dentition.

[Mike Siemsen]

Don't worry about the saw plate thickness, it doesn't matter for what you are doing, focus on the job at hand. I would tell you to not completely re-tooth the saw, just joint it straight and file it sharp. It doesn't sound like you have filed a lot of saws so this will be a good one to practice on. As you joint and file a saw the broken teeth will "grow back" so just joint and file the saw, use it a bit, then joint and file it again. After 2 or 3 sessions of shaping teeth and sharpening the saw the tooth will be back, you will have more saw plate left and everything will be grand. I have a Foley re-toother, which is a good machine, but it takes off one entire tooth height, you only need 1/2 a tooth height. Foley's do not do progressive pitch either, which many old saws have.
If you haven't seen it yet use Pete Taran's saw filing primer at http://www.vintagesaws.com/cgi-bin/frameset.cgi?left=main&right=/library/library.html
It is a great tutorial. Just focus on jointing and shaping for now!
Mike

[lowell holmes]

I appreciate the feed back from all you fellows. I intend to do pretty much what Mike, David and Chris have recommended.

Since my post this morning, I have disassembled the saw and cleaned the saw plate by wet sanding with mineral spirits starting with 220 grit all the way to 400 grit. The saw does have a taper grind. I have measured .007' TO .008" of taper in it. I have touch up sharpened my LN saws and some old Disston back saws. This is the most ambitious sharpening effort to date. I will have to reshape some teeth and will attempt to sharpen the fleam uniformly.

The saw is a $12 saw, so like you say, a good one to learn on. It is a Disston and the medallion is a Philadelphia medallion. I can see a suggestion of the etching, but really can't bring it out to read. I think it is a no.7 panel saw with a three saw nut handle.

I can't decide how to go about refinishing the handle. I'm leaning toward scraping, steel wooling and some sanding. I don't normally use blo, but in this case, the old dry wood sure looks thirsty. I have just used Johnson's wax on two other saws, but I understand wax will be something of a problem.

[David Weaver]

It looks like a 7. $12 or not, it should turn out to be a very nice saw, as good as anything you could buy new manufacture.

[george wilson]

Unless it bothers you to death(like it would me),the single tooth isn't going to affect the performance of the saw. It most likely will not even get engaged in the wood where it is. Even if it did,you wouldn't feel it.

[lowell holmes]

The real issue for me is the teeth are mis-shapen. I want the teeth to be well shaped, sharp. and for the set to be correct for sawing a straight line.

Since LN introduced their panel saws with the nib, I've wanted one. I don't know why, I just do.:)

[george wilson]

You can take a regular saw,and file the front end into a nibbed saw.

[lowell holmes]

Yea, I know, but this keeps me occupied and something to do. I bet you understand that.:)

[Jim Koepke]

I have a spare nib laying around on a piece of saw blade.

I'll happily send it to you.

jtk

[Steve Branam]

That's a right pretty saw there! Is it really worth filing all the teeth down just to restore one missing one? You could do a partial filing halfway down to get the spacing more orderly and start on the missing tooth and leave it at that, then over the next four or five sharpenings bring it to final shape.

[lowell holmes]

When I get into a project like this, I seldom do anything that is not reversible early. I try to feel my way into the project.

At this point, largely because of the responses to this string, the saw plate and saw nuts have been cleaned. The handle is next. I plan nothing extreme. just some steel wool and scraping and maybe some oil to replenish the dry wood that is borderline dry rot. . A replacement handle can be made without destroying the old one.

A simple sharpening will be next. I have no plans for re-toothing at time.