Saw file size?

[KMC]

I am planning to learn how to sharpen my own saws.  In my reading I have found differing recommendations on the appropriate saw file size to use.  

Lee Valley and others recommend using a file with a width that is twice the size of the tooth.  But Wenzloff & Sons recommends the opposite in that you should use the smallest file that will still completely cover the tooth.   

Using a file twice the width allows the file to last twice as long as it can be rotated to a fresh surface.  Does using a smaller file provide different advantages?  What is everyone's preference for file size?  

Thanks.

[Pedder]

I'm with Mike Wenzloff. You need to see what to do. Better view with a shallow file. And file wear at the edge. When the edge is long gone you could use the flat as long as you want. So the twice as long point is just not true.

Cheers
Pedder

[Mike Brady]

Now try to find those XX Slim files....they are the ones usually sold out.  Sure, the luxury of using up a file on one sharpening is not a big deal cost-wise, but not knowing if you will be able to get another one is unsettling.  There are plenty of good filers (Daryl Weir) who use a file that is larger than the gullet.  Doesn't seem to ruin his work.

[RonB1957]

If you do a search on this subject, you will no doubt find lots of opinions, etc. There is generally some sound logic to them. So rather than speak of pros and cons and opinions, I can just tell you some of the file sizes I use as I try to avoid using too many sizes. I am always keeping my eye open for NOS files or good deals on them to avoid running out. 
 Disclaimer: Results may vary. :

Some sizes:
15 ppi to 21 ppi --7" needle files. Either Grobet ( made in Italy ) or Bacho
12 ppi to 15 ppi--5xx ( Bacho )
8 ppi to 11 ppi--6xx ( NOS  Nicholson or K&F ) Then Bacho
7 ppi to 8 ppi--7x/ or 7xx ( NOS K&F )
5 ppi to 7 ppi--7x
Notice, everything is a range and/ or over laps.
No doubt, some one out there will find fault with my choices for I am just a moron swimming in a sea of geniuses. :
Lunch time is over.
Best of luck to you.

[Admiral]

You've gotten advice from some accomplished saw filers already, all much better than me.  That being said, and at the risk of further muddying the waters, your choice may depend on whether you're filing just to sharpen fully formed and jointed teeth, or rehabbing an old saw.  If the former, I can see value in using up two sides of a file that fits your tooth height, especially on the real small point saws as it absolutely is easier to see what you're doing.  But say if you're hand sharpening 5, 8 or 10 pt handsaws, and say it has missing teeth or was badly sharpened such that it requires two or three or more jointings and filing passes to just form the teeth properly, unless you have a Foley retoother I would say it would get pretty expensive to keep yourself in files, as in such situations I've used up three edges of a file before I've even gotten to the sharpening.

So, I've gone with the two times height of tooth theory, tempered by Pete Taran's commentary in his Primer, but he is clearly in the three usable edge per file camp.  You'll find that FTWW say one thing about sizing files, LV another, so there's a lot of opinion out there; Lief put together a compilation chart of suggestions from several sources in the link below, and Issac from Blackburn has a slightly different take, see link.  Pick a theory and go with it!  Then draw your own conclusions.

 
http://norsewoodsmith.com/content/unders...file-sizes   



http://www.blackburntools.com/new-tools/...index.html

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[url=http://norsewoodsmith.com/content/understanding-saw-file-sizes]http://www.blackburntools.com/new-tools/...index.html

[AHill]

For higher tpi saws, a smaller file allows a larger gullet, because the radius of the point of the file is smaller.  Larger gullets mean faster cutting. The rationale for 2x the tooth height is that you can use all 3 sides of the file vs. only one.  (In other words, in theory, a file that's 2x the height of the gullet lasts 3x longer than a smaller one that's full height.)  Being able to see what you're doing is a strong point as well.  As mentioned before, if you're reshaping, I'd use one 2x the height., then joint the teeth, and use a small file that's full depth to get that extra gullet depth.