Let’s make a saw…part 2

So now that we have a decent donor plate–thanks to highly sophisticated scientific methods–for our already nice Disston #12 handle, we can begin the transformation of the donor into our new saw plate.

The first step is to decide on a pattern, and for us, that’s easy enough. I’m staying traditional and making a straight back saw with nib, just like this #12 had originally. We could also do a skew back, as per a #112, but I want to stay true to this saw’s spirit. And since we’ve decided to go with a 22 inch saw, we mark out the new rough length on the donor plate. Now because this donor has been used and is not at full depth, to maximize the depth of our new saw, we want to take all the length we can off of the toe…that will maximize the depth of our plate. But since this donor originally had a let in handle, and our #12 handle is a traditional pattern, we will have to remove the relieved area on the donor to create the proper hang angle and shape of our new plate. I’ll use the old used up plate to mark the heel angle…

We lose a little length and depth here, but the rest comes from the nose, which we also mark for the proper angle.

Here she is marked out to rough length for cutting…

To cut saw steel I use an abrasive disk mounted in my drill…simple and effective. And you don’t need to cut all the way through the steel…just about half way to score it and then break cleanly with vise grips, or even your hands if your feelin’ lucky. Clamp the plate to your bench and cut slowly with the wheel….you’re in no hurry.

 Here’s the cut on the nose…

And breaking it along the score line…

I do the same with the heel and here she is roughed out ready to have the final pattern scribed and cut…

Now I use the old plate to scribe the nib pattern onto the donor. I use a scratch awl, and interestingly enough, the layer of rust makes a great medium for scratching on….scratch deep and the fresh steel is exposed showing crisp lines to file to. I also use the old plate to scribe in the final heel angle and heel return. Here’s the nib…

 

Here’s the nib pattern scratched in…

Its over to the grinder now to grind to the line of all except the nib itself (that is done with a triangle file…the same we use for sharpening). I use a grey aluminum oxide wheel, 60 grit, and this works great. You don’t need to worry a great deal about drawing the temper of the steel here…it grinds easily and a dip in water cools it, and even if you do blue it, its not a big deal in this area of the plate. Here I’m grinding the final shape of the heel…

Now I’m almost done with the final shape…its on to the fun part…filing the nib! I love doing this as its so easy to do and just looks so gosh darn cool. All you need is a triangle file….I’ve used as small as 4 inch double extra slim taper and as big as 7 inch slim taper. Here its a 6 inch extra slim taper, which seems to be just right. I mount the plate in my Disston saw vise and first start with the area behind the nib and rough in the depression…just file straight down into the steel like you’re shaping a new tooth, then do the same with the front of the nib. Its really a simple task….just remove the material until the nib is left. This is a great task to learn for repairing old saws (like #7’s) that commonly are found with the nib broken off. Here ‘s a look in progress…

Like I said its quick work….here’s the finished nib…

Now I bring the plate to its final dimensions with a mill bastard file. I mount it back in the vise and file all of the edges–the back, toe and heel–smooth until all the grinding marks are gone and the they are true (use a straight edge to guide you).

And here’s our donor saw plate shaped to finality and ready to be cleaned…

 Tune in tomorrow and we’ll clean her up and mount the handle. It won’t be long now!!!

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Published in: on October 29, 2010 at 9:38 pm  Leave a Comment  

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