Saturday, 18 June 2011

Re-toothing a Thomas Flinn saw.

A while back one of the board members of the Carpenters Fellowship asked me to re-tooth a Thomas Flinn & Co saw, changing it from cross cut to large graduated rip.

Well the saw has finally got to the top of the pile so I spent a couple of hours on the saw today.

The Carpenters Fellowship had a batch of saws made by Thomas Flinn & Co, in Sheffield. The saws were made with a custom etch showing the CF logo and tag line.

I'm not that keen on these saws, I don't like skewed backs and the handle is huge, angular and for me has no redeeming features.

For me the handle is only marginally better than the plastic handle throw away saws. On the plus side they can be re-shaped, rounded and made more comfortable, but you still have a handle that a gorilla with and extra finger could hold.

The picture to the left shows the handle in comparison with one of my favorite 19th C handles.

One thing I should say, is that these saws are very cheap for a re-sharpenable saw, so I suppose you get what you pay for.

Right, that's the end of my critisism of another saw maker, lets get to work...

The first thing I did was remove the handle, as this is a modern saw, the saw nuts come off really easy, with no risk of damage.

I number the saw-nuts and note their location in the handle, ready for replacing later.

This isn't really needed on a new saw like this, but it's best to keep in the habit. When your restoring an old saw the saw-nuts like to go back into the original holes, and don't normally sit right if you've moved them around.

Then I removed all the cross cut teeth, and joint the blade with a mill file to get a nice clean straight line.

I then re-cut a new set of teeth with a fly press. This is a really nice way of punching out the teeth without adding any heat into the saw blade, The spring steel is hardened and tempered to the correct hardness, addition of lots of heat would change the hardness of the steel and make the saw either over hard and impossible to sharpen or to soft and the saw would become blunt easily.

Punching the teeth tends to put a curve into the blade, so before I can sharpen the saw and reattach the handle the blade needs a bit of saw smithing to get it back to being straight.

The finished saw, with it's handle back on and all the teeth sharpe.
I haven't put any set on the teeth on this saw, Tim Potts, knows his saws and I'll let him choose his own set for the timber he is cutting.

You can see from the picture that the tooth line is graduated. The ppi at the tooth line is: (toe to heel)
4" of 5 ppi 
5" of 4.5 ppi
6" of 4 ppi
3.5 ppi for the rest of the saw.

The large rip teeth on this saw will probably be used to cut large section green oak, used in making timber framed houses in the UK.