Sharpening the 12 TPI Cross-Cut Saw

I've sharpened my Spear & Jackson cross-cut tenon saw a few times, but I've noticed that I'm not getting the teeth even.  Actually, not all that close to even.  I've got a case of "cows and calves".

Would you call that uneven?

The tops of the teeth are level with each other, but the gullets are small, big, small, big, ...  During previous sharpenings I tried to use the technique of jointing the tops of the teeth to get a small flat on each tooth, then filing away half of the flats when filing every other tooth going one direction and getting the remaining flats when filing the remaining gullets going the other direction.

Overview of the teeth

That hasn't worked out too well for me.  So even though the saw has been cutting reasonably OK, I wanted to fix the tooth geometry and re-sharpen it.  At first I tried drawing a line to guide my filing to get an even depth to all gullets.

Thought about filing to a line

But a much better idea is to use a template.  Fortunately Isaac Smith of Blackburn Tools has such templates on his website and I used the template for 12 TPI.

When you print a template, you have to make it print 100% size, not "print to fit"
And you should always check it with a ruler

First step was to joint the tooth line.

Using a shop-made file holder to joint the teeth

Template taped to the saw plate and clamped in saw vise
Template lines are aligned with gullets

You've got to see what you're doing when filing a saw.  Here's my setup.  Having a chair at a comfortable height is helpful.

Task lamp just above the work, headlamp providing more light
I use a 3X magnifying headlamp to see better

An end-on view

I needed to reshape the teeth, so I filed straight across the teeth like I would do for a rip saw.  Going from heel to toe, with the file in contact with the front of one tooth and the back of the next tooth, I filed each gullet putting pressure forward (on back of next tooth) or backward (on front of prior tooth) to end up with the gullet lined up with the template.

About 60% of the teeth in this pic have been filed.
You can still see the flats on the remaining 40% of teeth on the right.

This worked very well in getting the teeth more consistently shaped.

Teeth looking far better already

Next I used a Somax saw set to add some set to the teeth.  Jointing and filing up to this point had removed most of the set I had previously.

Setting with a saw set

I have a problem with this saw set.  Even though I have it set at the smallest amount of set, I still get far too much set.

Saw set at minimum amount of set

Contrary to popular belief, the numbers on the dial in the Somax saw set do not correspond to the number of teeth on the saw being set.  You just have to use it and gain some experience to know what number setting to use.  Even at the minimum setting (largest number) I get too much set.

Out of the saw set I had 0.0405" total set at this point.
It ranged from about 0.040" to 0.045" along the toothline.

I used a medium diamond stone to knock back the set and take off any burrs.

"Stoning" the teeth after setting

After that I re-jointed the teeth using a few strokes of the flat file.  Then I marked every other tooth to avoid any screw-ups.

Marked every other tooth

Using a little angle-setting jig to help guide my filing, I made two file strokes in every other gullet.

The filing jig from above: 20° angle on right gives me the fleam angle,
lines on the front of the jig help me align the file for 14° rake.

I did not try to remove half of the flats on each tooth - that's where I had problems with uneven filing before.  I just used two strokes on every other gullet, then turned the saw around and filed the other direction, two strokes in all the unfiled gullets.

Looking much better

I could still see small flats on many of the teeth after that, so I gave all the teeth one more file stroke.  The teeth may not be perfect now, but they are FAR better than they were.  And a test cut felt pretty good.

On most of my saws I write the pertinent filing information, as well as the sharpening date.

The Spear & Jackson filing statistics

All for now.  I'll write about the filing jig another time.  It's a great jig you can make in a jiffy.