Fettling a Backsaw Handle

[Glen Evans]

Has anyone making their own saws had trouble with the mortise for the brass back?? I'm on my third saw and continue to struggle with keeping everything square and plumb.

I end up spending alot of time sliding the blade in and out and shaving as necessary to get a good fit. Often when the back is fully seated in the mortise I'll notice that the saw blade has deflected ever so slightly. The result is a slight wave in the saw blade at the heel.

The carcase saw I just finished up still has a slight wave. I'm tempted to leave the handle on, mount the saw handle in the vise and use a crescent wrench on the blade to try to remove the wave.

What do you saw makers suggest--fettle the handle or try to bend the back?

thanks
Glen

[Jim Koepke]

What do you saw makers suggest--fettle the handle or try to bend the back?

thanks
Glen

I am not a saw maker, yet. However, this is a situation that finds an answer through experience with so many other things in life.

If the back is fine without the handle, then it is the handle which is at fault. Trying to fix something that is not broken to correct an effect caused by something that is in error will only result in having two things that don't work.

As Will Rogers said, "don't fix it if it ain't broke."


jim

[Brian Kent]

I'm a total beginner at saw handles (4 total). But that means my mind is on this stuff.

Absolutely I would keep on working on the handle and not bend the blade.

What technique are you using for cutting the slot for the blade and the mortise for the back?

In the tutorials I've seen 4 ways to cut the slot:
1) Thin bandsaw blade with a fence.
2) Mark the center line with a marking gauge and saw freehand, beginning on all of the high spots and working in.
3) Clamp a saw blade at the right height - horizontal on the bench. Keeping the handle flat on the bench, rub it against the saw blade.
4) Grind a table saw blade to a super thin kerf. That one I totally do not understand. How do you grind a table saw blade?

I've also seen 3 ways to cut the mortise for the back:
After marking the size and location with a pencil or marking knife…
1) Drill a row of holes using a fence on the drill press and clean out with bench chisels.
2) Start to finish with chisels.
3) Fine saw to start and then chisel to depth.

Obviously out of 4 total I have not even been once through all the combinations.

What part of the handle is off? The blade slot or the back mortise?

Brian

[Jim Koepke]

Grind a table saw blade to a super thin kerf. That one I totally do not understand. How do you grind a table saw blade?

Use the sides to flatten your water stones?

jim

[Ray Gardiner]

Hi Glen,

Don't bend the back! fix the handle.

Make sure the blade slot is straight and centered on the handle, test fit with a blade BEFORE you start on the slot for the back.

Assuming the blade slot is ok and you have cut the back mortise a little bit off.

Then, in that case your best fix is to open up the back mortise a bit, it is probably tight on one side and pushing the blade across causing the deflection at the handle end.

Instead of a paring chisel, a small scraper is a better choice to sneak up on that final fit.

Regards
Ray

[Glen Evans]

I'm a total beginner at saw handles (4 total). But that means my mind is on this stuff.

Absolutely I would keep on working on the handle and not bend the blade.

What technique are you using for cutting the slot for the blade and the mortise for the back?

In the tutorials I've seen 4 ways to cut the slot:
1) Thin bandsaw blade with a fence.
2) Mark the center line with a marking gauge and saw freehand, beginning on all of the high spots and working in.
3) Clamp a saw blade at the right height - horizontal on the bench. Keeping the handle flat on the bench, rub it against the saw blade.
4) Grind a table saw blade to a super thin kerf. That one I totally do not understand. How do you grind a table saw blade?

I've also seen 3 ways to cut the mortise for the back:
After marking the size and location with a pencil or marking knife…
1) Drill a row of holes using a fence on the drill press and clean out with bench chisels.
2) Start to finish with chisels.
3) Fine saw to start and then chisel to depth.

Obviously out of 4 total I have not even been once through all the combinations.

What part of the handle is off? The blade slot or the back mortise?

Brian

Brian, I use the clamp method and with a non-backed Japanese pull saw (that has exactly the same kerf width of the 0.020" saw plate). I use sheets of paper beneath the handle to centre the handle on the blade. (I have noticed some drift with this setup despite a solid clamping--I actually used a tenon saw with a slightly wider kerf to make sure the cut was straight--maybe the problem is with the slot).

I use the same saw for starting the mortise and then chisel to depth. I use a float to get things cleaned up.

Consensus view is to rework the handle--I was leaning in this direction. I'll open the mortise and see if that straightens the blade--then if necessary I'll glue in shims to close the mortise back up.

Ray, I'm not sure what type of scraper you're suggesting---can you be more specific?

thanks
Glen

[Ray Gardiner]

Ray, I'm not sure what type of scraper you're suggesting---can you be more specific?

thanks
Glen

Hi Glen,
I end up with scraps of saw plate that I make into scrapers of various types, but any rectangular scraper will do for this job, because you aren't going to get much of an angle on it, working down inside that 1/4" mortise you can roll a bit more of a hook than you might normally use. Even if you don't sharpen it and roll a burr, you can just joint it square and push back and forward to remove very small amounts as you get to the last stages of inletting the back.

A friend who does a lot of gunstocks has a wide array of different shaped scrapers for inletting actions into stocks, this is a very similar process.

Scrape, test fit, scrape again.. and so on..

Regards
Ray

[george wilson]

I ground a circular saw to cut a .020" kerf back in the 60's. This was done on a plain 6" steel blade (no carbide teeth),for sawing plywood. I ran the saw with the throat plate taken out,and pressed the side of a grinding wheel mounted in a hand held grinder against it while it was running. This took a few hours,but it worked. I do not recommend this process to anyone: If you ground too deep,the saw blade might fly apart and nail you in the face. I was younger,and more foolish then!!

More recently,I mounted a similar blade on a faceplate in a metal lathe,and used the tool post grinder to thin out the last 1/2" of the rim of the saw to .020". The blade was running fairly slow,so this is a much safer way to do it. The edge of both these blades was only 1/2" high,and both were taper ground so as to not burn. They are only used to cut 1/8" deep for putting guitar frets in the fingerboard.

Back in the 70's,Woodcraft sold a blade exactly like my last one for very fine slitting. Wish they still did.

[Zahid Naqvi]

Glen, look at pages 13-15 of this guide (http://www.backsaw.net/SawHandles101.pdf) by a fellow creeker, Ray Gardiner. He recommends a simple approach to mark the inlet for the back/spine. I have used this method and you can get it working easily. For practice you can make a cut in a blank and try using this method to create the inlet for the saw back, this will allow you to refine your technique before you try it on the real thing. You can also glue thin slivers of wood to fill any imperfections.

Reading your description it seems you are not certain if the bend in the saw is being caused by the back slot or the slit/kerf for the blade. I'd identify what component is causing the twist before attempting a fix. As I mentioned earlier, you can try making the blade slit and the back slot in a square blank as practice and check if you keep making the same error every time, which might identify an issue with your setup (DAMHIKI).

Like everyone said don't touch the blade if it is straight, keep working the handle.

[Glen Evans]

Success!! Great advice everyone--the problem was actually with the slot. I noticed that the problem worsed as I tightened the saw bolts so I shimmed 0.005" and the problem disappeared.

Blade is pin straight and the cuts don't wander at all--now onto the dovetail saw to round out my set!

thanks
Glen

[Brian Kent]

Unless you show us pictures, I'll just assume it was an April Fools joke:D!