Thread: Saw sharpening files 101

What I don't get is why they need to be tapered. As far as I can tell this just shortens the usable length of the file, and a non-tapered version would yield a longer file life (because of the longer stroke thing). So, can any of the wise heads shed some light on this please? Is it the case that you eschew the tapered part, until maybe that's the only sharp part left and you have to use it because you can't get a backup supply?? Or does it play a usable role?

Another thing I have wondered about is the various face widths in relation to corner radii. As Ian pointed out earlier, no manufacturer states the radii.

Consider if you will, the following:
100mm DEST, face width 4mm 29 teeth per cm
125mm DEST, face width 4.75mm 25 tpc
150mm DEST, face width 5.5mm 24 tpc

100mm EST, face width 4.75mm 26 tpc
125mm EST, face width 5.5mm 24 tpc
150mm EST, face width 7mm 22 tpc

100mm ST, face width 5.5mm 23 tpc
125mm ST, face width 7mm 22 tpc
150mm ST, face width 8.75mm 20 tpc

100mm RT, face width 8.75mm 20 tpc
125mm RT, face width 10.25mm 19 tpc
150mm RT, face width 12mm 17 tpc

and pulling out a couple of pairs of those for comparison:
125mm DEST, face width 4.75mm 25 tpc
100mm EST, face width 4.75mm 26 tpc

and
150mm EST, face width 7mm 22 tpc
125mm ST, face width 7mm 24 tpc

Noo then! Does this mean that within each pair shown, are they actually the same profile with the same corner radius, but just longer???

I suspect that the corner radii are indeed the same, and IF that's the case that simply means that the number of different files can be reduced and simplified quite significantly. The point being that if you select a longer file, with the greater subsequent stroke length, you'll get much more bang for your buck because there's bugger all difference in price.....

There would (probably) also be a smaller percentage of tapered area in the longer file, yielding even more bang for buck (if my premise at the start of this post is correct - the tapered are isn't particularly necessary).

For example, the 12 files listed above could be reduced to 7 files, and still retain all the different face widths, but with the longest possible file:
100mm DEST, face width 4mm 29 tpc
125mm DEST, face width 4.75mm 25 tpc
150mm DEST, face width 5.5mm 24 tpc

150mm EST, face width 7mm 22 tpc

150mm ST, face width 8.75mm 20 tpc

125mm RT, face width 10.25mm 19 tpc
150mm RT, face width 12mm 17 tpc

Again, can any of the wise heads shed some light? Am I completely barfing mad, or have I uncovered a hideous plot to sell more files (somewhat unecessarily ).

Originally Posted by FenceFurniture

....What I don't get is why they need to be tapered....

... Is it the case that you eschew the tapered part, until maybe that's the only sharp part left and you have to use it because you can't get a backup supply?? Or does it play a usable role?

Me too - there may be a very good reason, but I don't know what it is.

I use as much of the file as I can. It is unlikely that the narrowest (toothed) part of the file is less than the height of the tooth, except for needle files, which taper to a very sharp point. As long as you are removing metal from the whole of the leading & trailing edges of the teeth over the full stroke, all is good....

Indeed, there is great overlap with the corner radii - it varies a bit from manufacturer to manufacturer, but roughly speaking, as you move from one face size to the next within a given length, everyone moves over a notch. Then when you go to the next smallest length, everybody moves over one notch again. I think I've confused myself even, but what I'm trying to say is that a 4" EST file will be roughly the same corner radius as a 5" DEST. And you can indeed make use of that. Most of us can rationalise our file supply to just a few sizes. My problem is always with the finest - I want that tight radius for high tooth number saws.

You don't need to worry about saw files being too fine in the small sizes. While a sharp gullet is theoretically creating a stress point, it's not a big deal with small teeth used in wood. In practice it is unlikely that you could ever make a truly sharp (i.e. knife-sharp) corner because of the physical limitations of the file metal & method of manufacture.

Cheers,

Originally Posted by IanW

My problem is always with the finest - I want that tight radius for high tooth number saws.

Yes, very good point, I don't see any swiss pattern needle files on the list, but I'd definately put them in the "must have" category.

Regards
Ray

Originally Posted by IanW

Me too - there may be a very good reason, but I don't know what it is.

I use as much of the file as I can.

Sooo, do I take that you'd be happy with (indeed prefer) a non tapered file? The point being that the tapered are is where I've seen them get the "bends"........which may be a QC issue during manufacture, but it's nonetheless still there.....

Originally Posted by RayG

Yes, very good point, I don't see any swiss pattern needle files on the list, but I'd definately put them in the "must have" category.

Regards
Ray

Which list Ray - one of mine?I've left them off because they are the same face width (4mm) as a DEST, and because Needles are double cut. It seems to me that people are only reaching for needle files in the absence of good quality 100mm DEST files. Furthermore, very happy to expand the list into what is required.

I note that Bahco Needles 140mm have a face width (and therefore smaller corner radius) od 3.3mm, and the 160mm have a face width of 3.8mm (from memory)

Originally Posted by FenceFurniture

Which list Ray - one of mine?I've left them off because they are the same face width (4mm) as a DEST, and because Needles are double cut. It seems to me that people are only reaching for needle files in the absence of good quality 100mm DEST files. Furthermore, very happy to expand the list into what is required.

I note that Bahco Needles 140mm have a face width (and therefore smaller corner radius) od 3.3mm, and the 160mm have a face width of 3.8mm (from memory)

I'm referring to the list of 7 files a few posts back, lack of good quality 4" DEST may in fact be the problem, I've yet to see a 4" DEST that can file 18 tpi properly. I'm not sure exactly where the boundary point is, but I'd guess 4" DEST is good for 12-15 tpi, and needle files for 15 tpi and finer.

Regards
Ray

Originally Posted by RayG

I'm referring to the list of 7 files a few posts back, lack of good quality 4" DEST may in fact be the problem, I've yet to see a 4" DEST that can file 18 tpi properly. I'm not sure exactly where the boundary point is, but I'd guess 4" DEST is good for 12-15 tpi, and needle files for 15 tpi and finer.

Regards
Ray

Ok. That was just an example list for the purposes of discussing corner radii/different lengths.

What are the face widths of the Swiss Pattern Makers Needles that you find useful?

Hi Brett,

I can't really give a good measurement of the face width because of the taper, but it goes from a sharp point to about 3.5mm, here is a picture of swiss needle file versus 4" EST and DEST nicholson's to give you the idea of what I'm on about..

SawFiles01.JPGSawFiles02.JPG

Sorry for the picture quality, the vallorbe swiss pattern is on the left, and the other two are the nicholsons.

Regards
Ray

EDIT: I'm sure IanW has covered this issue in some detail somewhere, with pictures of gullet sizes etc... but I can't find it at present...

Hmmmm, from what I understand is your "rather enviable" stash of NOS files.

Btw Ray, do you have an opinion on whether or not the tapering is required? That is, would you be just as happy with a non-tapered file (everything else being equal)?

I saw that comment earlier and it got me thinking as to what the advantage of the taper might be, I can see advantages for general work where you might be filing inside a tight corner, but specifically for filing saw teeth, I don't think taper is relevant. I've got a couple of saw filing machines and the files for those are tapered as well, but could just as easily be parallel and work just the same.

So, no, I don't know the answer, but I can't think of any reason why saw files absolutely need to be tapered.

Regards
Ray

This extract from the Pferd chart shows the difference between the different lengths with the same width face - it's the tpc count.

I have edited the previous post that raised the question to show the tpc for each of the files. As can be seen in this part:

125mm DEST, face width 4.75mm 25 tpc
100mm EST, face width 4.75mm 26 tpc

and
150mm EST, face width 7mm 22 tpc
125mm ST, face width 7mm 24 tpc

there is a very minor difference in the tpc for the relevant length/face parings. Hardly enough to worry about I should think (especially given that probably nobody ever concerned themselves about tpc ).

All of this AR nonsense is leading to putting together a simplified list of "necessary files", or as Ray says "must haves".

I'm going to contact a few saw other saw makers to see what they think about the taper. What I'm driving at there is that, depending on the consensus, I will investigate the possibility of getting some samples of non-tapered files made. In other words "Blunt End" or "Machete" files in smaller sizes (coz I have a feeling they'll be less hassle to manufacture). If this happens, it won't be quick....

To give you an idea, Liogier's Machete files are:
100 x 9 mm (Regular)
150 x 11 mm (between R and Slim)
175 x 15 mm (R)
200 x 16 mm (R)

Originally Posted by RayG

..... I'm sure IanW has covered this issue in some detail somewhere, with pictures of gullet sizes etc... but I can't find it at present...

I couldn't find it in a hurry either, Ray, but Brett did, on page two of this thread, and linked to the original thread....
Cheers,

correct me if i'm wrong but an educated guess as to why saw files are tapered would be so that you file from the back or bottom of the tooth up to the cutting edge. you start your file stroke below the point, um i think