December 20, 2018
Positive heresy: unconventional saw filing tips
By Trevor Shpeley
That being said, just because something has been done a certain way for 50 years doesn’t mean it’s been done the best way. The field of saw filing is still wide open for experimentation and improvement. Nothing is sacrosanct. So here are a few tips that are slightly off the beaten track and may work for you.
Use an extra short-bite die to bring up a tooth on un-swaged steel. The extra short-bite will pull from higher in the throat of the tooth and will forge it wider than the standard short-bite. You need to use caution so that you don’t pull too much and cause the steel to crumble, but in my experience that upper limit is a lot higher than you might expect. Using the XSB will usually allow you to get a couple of good runs out of a fresh tooth before it needs to be re-swaged with a regular short-bite to give it it’s proper shape.
Don’t be afraid to experiment with different sized dies than are normally considered proper. We use No. 5 swages on saws that would normally call for a No. 4. Likewise, we use a No. 6 where theory says we should use a No. 5. If you go down this rabbit hole, be aware that you may need to adjust your throat depth when you run a frost notch and that pulling too hard can bend your teeth over. Once you figure it out, you will make beautiful full-bodied teeth of a type that are hard to achieve with a standard setup.
When you have a hard back, the normal (and probably best) way to deal with it is by flipping the saw over on the grinder and running it around under light pressure until the hardness is gone. This is time proven and it works, but is it overkill? Try taking off the hardened edge on the bench by using an angle grinder with a sanding disc. You can brace your hand in the gap between the anvil and the stretcher rolls while the saw is running and get a surprisingly even grind that takes a lot less time and manpower than flipping the saw on the grinder.
Do you have an IMW guide cutter that uses the inserted cutter in a large steel flywheel? Consider adding a second cutter 180 degrees to the first by milling out a new receiver slot. Set the first cutter to cut 0.005 larger than you want the final size to be. Then set the second cutter to the proper size. Make sure the second cutter is inboard of the first cutter. The first cutter will hog out the bulk of the babbit while the second will leave you with a very smooth surface and stay sharper longer.
Have you ever noticed how hard it is to roll out a bump that runs directly below the gullets? The stretcher rolls that have built in dishing rolls have a tough time with that area due to the bottom wheel extending out towards the ends of the teeth causing them to bend. A great way to deal with that problem is to build yourself a moveable dishing-block that utilises the track that your saw-gate travels back and forth in. The one I made uses a bandsaw guide block cut to half-length. On the top surface that the saw contacts, the corners are slightly rounded off. Underneath, you need to drill and tap for six bolts. One on the centerline, one inch from each end with bolt heads that just fit in the slot for the saw-gate, and one smaller bolt in each corner to act as legs that the unit will slide on. Adjust the height for 1/4 inch or so above the stretcher wheels and you are set to just slide it in and out of place whenever you need to roll in tight to the edge of the saw (or any other place if your stretcher rolls don’t include a dishing wheel). Contact me at the Saw Filers Discussion group on Facebook if you would like pictures.
Use shims underneath your guide pads to re-use lightly damaged pads so that you are not spending all your time pouring new ones. Cut yourself a bunch of different thicknesses from plastic shim-stock and use a punch to take out the holes for the screws and water jets. Make sure you don’t put in so many spacers that you lose your pocket, or worse, run the cutter into the guide screws.
I can think of dozens of tips and tricks we weren’t taught in school and every other filer could probably come up with dozens more. The trade of saw filing evolves in dribs and drabs, not mighty leaps, so do your part and try something crazy!
FULL DISCLAIMER: Some of these I found myself, most I shamelessly stole from other people; thanks folks for your unknowing participation in this column.
Trevor Shpeley is a former executive of the BC Saw Filers Association and works as a filer at Kalesnikoff Lumber in British Columbia.