Thursday, February 26, 2015

Restoring a Disston D-8 Panel Saw

A couple of years ago, I helped out in a neighborhood tool library.  We got a big influx of tools from one of our members' father's estate.  Among them was this little panel saw, quite rusty and far from usable.  The lower part of the handle was broken off, but I could read Disston on the medallion.  I thought it was highly unlikely that anyone would make use of it, so I asked the donor if I could have it, and he said ok.  It's hung on my tool rack for a long time.  I had some hope that it was a decent old tool, and I finally got around to restoring it this week.
Old Disston Panel Saw
I started by taking it apart, which was fortunately very easy.  The brass hardware is plated, which prevented corrosion inside the threads.  Then I wrapped a small piece of 220 grit sandpaper around a block of foam and applied a lot of elbow grease to the rusty saw plate, using plenty of WD-40 as a lubricant.  I used a scrap of plywood under the saw to prevent my bench from getting mucked up with the rusty oil slurry.  I wiped down the surface with paper towels, and another round with a new piece of sandpaper revealed the surface of the saw plate.

I was surprised to find that the etch was revealed, as well as the "10" stamped near the heel of the blade.  So I've got a 10 tpi Disston D-8 with a 20" blade, dating from somewhere in the 1947 to 1955 range, based on the "Disston USA" medallion.  The handle appears to be apple, not beech, which suggests 1947.  It was filed with a crosscut tooth configuration.

I'm going to make a new handle, maybe out of cherry, or maybe I'll go get a piece of apple or pear if I can find it easily.  The hardest part of making this handle will be forming the slot for the blade.  The D-8 slot was cut with a thin circular saw, which kept the top of the handle closed and helped hold the blade steady even if the hardware came loose.  This will be a challenge, since I don't have a circular saw that thin.  I might have to do something creative.

Another blogger cleaned up a nearly-identical saw last summer.  Take a look at Jonathan White's Bench Blog here.

Update:  Here's the saw, with a new cherry handle.
Cleaned up, but not yet sharpened
Here's how I got from here to there.  I took a blank of 5/4 cherry, and drew a rough outline of the handle shape using the old handle as a template.  Then I used the blade to precisely mark the location of the four bolt holes, and drilled them at the drill press with a 1/4" bradpoint bit.  Then I used a new 3/4 x 3tpi blade (to get a really nice cut) to resaw the blank in half at the band saw.  I smoothed the cut surfaces with hand planes, and then used the holes as a reference to draw the shape of the blade on the blank.  I also traced the handle again on this surface.  The area in between is the desired shape of the mortise.
Very shallow mortise will become the slot for the saw plate
I used a small router with a straight bit to cut a recess in the mortise area, the depth of the blade's thickness.  Then I glued the two halves of the blank back together, using a couple of 1/4" drill bits in the bolt holes to register the positioning.

After the glue set, but before it was totally dry and hard, I rough-cut the shape of the front of the handle at the band saw, revealing the thin slot mortise.  I ground an old hacksaw blade into a tool to clean out the squeeze-out at the bottom of the mortise, but after that bit of fiddling, the blade fit perfectly and snug.

I re-drew the handle shape of the blank, after using a jack plane to reduce the thickness by 1/8" or so.  After a visit to the bandsaw (1/4" x 4 tpi blade) and drill press (forstner bits), here's what the blank looked like.

The roughed out blank next to the original handle
Not very comfortable, but starting to look like a handle.  I took the blank to the drill press and made the shallow cups for the saw nuts and medallion with 1/2" and 7/8" forstner bits, respectively, and enlarged the holes on one side of the handle to 5/16" to accommodate the female half of the saw nuts.  The drilling was a painstaking effort, since the through holes meant I didn't have a center point to work from.  I just lined up the spinning bits as carefully as I could by eye, after tracing a circle on the surface.  I marked the side of the forstner bit with a thin blue felt pen to give me a consistent depth because the depth stop on my drill press is a piece of crap.  Next I used rasps to get right up to the layout lines, and then traced some contours with a pencil to help me form fair and consistent curves.

Offset layout lines help guide the rasps
  I recently bought this handle-maker's rasp from Tools for Working Wood, and it came in very handy for fine-tuning things and getting the inside of the handle shaped.  After about two hours of rasp work, I had the form to my satisfaction.  Another hour of hand sanding and card scraping got me to a comfortable and not too shabby looking end point.  There are a few flaws if I look closely but it feels good in my hand which I suppose is more important in the long run.  I put on a coat of natural Watco and will probably just add a little wax on top of that.

All done, with a coat of Watco
I used a Dremel with a fine wire wheel on low speed to gently clean up the saw nuts, and they came out pretty good with little effort.
The hardware cleaned up pretty quick with a small wire wheel in a Dremel