Saw file size?

[whiskywill]

Help please.

I was lucky to pick up a 14" 1920's Disston brass backed backsaw at a car boot sale. It is in superb condition and has a 12TPI rip blade but it could do with a bit of a sharpen. Several sources suggest that I need a XX Slim file but this chart I found on line suggests otherwise. Which is correct?



p.s. The saw cost me £4. :mrgreen:

 

[Mike.S]

By coincidence I was looking into file sizes yesterday and my equivalent 'chart' (gleaned from Mike Wenzloff and a.n. other sites) suggest a XX file - either 5" or 6" is what you need.

It does seem that file size is not consistent across manufacturers. I'm a newbie at this but the recommendation seems to be to try to obtain a file which has a face edge a smidgin over twice the saw tooth edge length, so as to minimise wear and tear of the file.

edit: IIRC the 5" was based on bahco files, the 6" on Grobet files.

 

[whiskywill]

Thanks, yet more choice. I wasn't aware of the Wenzloff site. Nice saws.

 

[Cheshirechappie]

I'm sure I've come across other saw-file size charts, probably with more slightly different recommendations! I think it's probably best to regard them all as 'guidance' rather than 'absolute'.

I think Mike S pretty well nailed it by saying that a sawfile is best sized as about twice the filing depth, so that when one corner (and a bit less than half of the adjacent sides) are worn, the file can be turned and the next corner used without there being an overlapping worn bit on the sides. That way, you get three 'lives' out of the file and don't waste two corners.

It's probably best to have only about three or four sizes of file to hand to cover all saws, and as long as you avoid really silly combinations like using a needle file on a big rip saw, or a 7" regular to try filing a 16tpi dovetail saw, you should be OK using 'near enough' files. Too small won't do the whole job, too big leaves excessive gullets and obscures your sight of what you're doing, but a size or so up or down won't matter too much.

Another factor is what you can buy. If the charts say 5" extra slim, but you can only buy 6" double-extra slim, don't sweat it. It'll do.

Don't forget that for topping (jointing) the toothline, you'll need a flat file. A smooth cut mill saw file is usually recommended for this, but almost any flat or hand smooth file will serve. About 8" is a convenient length, but a bit longer won't harm.

One last tip is to file slowly. Saw steel is hard, and won't respond well to filing at the same speed something like brass will. A 6" saw-file should take near enough a full second to travel it's full length through a saw blade - you should be able to see the filings coming off. Faster than that will mean the file 'skates' across the hard steel, taking off few filings but dulling the teeth of the file quickly.

 

[Billy Flitch]

Hi Will and Mike, I´m not an expert on saws or a sawyer or a saw doctor so if any one feels the need to correct any thing I say here then be my guest.
I was taught as an apprentice to fettle my saws and almost 50 years later I`m still doing them.Different manufacturers have different ideas of sizes,so you will get differences in what they say, because of this any thing I say can only be judged as rule of thumb.

So the longer a saw file the wider it will be a 7" would be about the widest so would be meant for a saw of say 3to 6 tpi rip and that will also give you two fresh faces each time you turn the file, a 4" file would be for say a 16 to 20 tpi. Your going for a 12 tpi so a 5" would be right. Now the next measurement slim, x slim or xx slim when they say these sizes they miss a word out and the word is Taper. The taper is the narrow part at the start of the file it is there to make it easy to start the file in the saw plate so it doesn't jag or catch as you introduce the file to the saw plate, so the sizes regular taper, slim taper, x slim taper and xx slim taper, as said mean different things to different manufactures once you have enough confidence
with the file I don't think it matters.

The biggest killer of a file is when the saw is to high out of the vice and starts to vibrate and screech it will knock hell out of the file,have fun, Billy. Sorry CC you posted as I was typing.

 

[Mike.S]

Billy

As I mentioned in my post, I'm a newbie at this, so welcome your and CC's practical knowledge/experience.

This video's been posted before but WW and others may find it useful (warning it's 2 hours long, but great imho).

Sharpening Western Saws

 

[whiskywill]

Monday evening television or a saw sharpening video? No contest. Thanks all.