A great reference site on saw sharpening (existing teeth) does exist on the web and is available at www.vintagesaws.com. Most, if not all, of the sharpening procedures are covered on that site, some maybe in more detail than what I do. I will also cover some of the basics of saw sharpening well enough to do a good job, using my experience, from a "what users need to know" sort of perspective. But it certainly never hurts to check out other references for additional perspectives.
An important note - sharpening saws is pretty much impossible to accomplish without some sort of a saw vise, be it iron or wood. If you buy one, avoid the no-name steel versions and go for the classic cast iron ones from companies such as Disston or Wentworth.
Should you decide you would rather make your own - an excellent plan for a wooden saw vise is available on The Cornish Workshop's web site. I've used both cast iron and wooden saw vises, and each have their respective advantages and disadvantages. I've found that both types work well, and I personally don't prefer one over the other..
- Less than a week after I first wrote this, my Disston model 3D saw vise went the way of the dodo, developing a crack that essentially renders it useless. Not having another handy - I looked closer at the plans mentioned above. While it would work great for standard saws, it would not work at all on back saws without a great deal of modification. I decided just to buy another old Disston rather than try build a wooden one.
- Added 11/04/04 - Jasper Homminga has contributed a small article on making a simple wooden saw vise - available on this web site HERE.
Some advice for those who haven't done much sharpening, or have only sharpened larger saws - go slowly, and with a light touch until you get the hang of it. Even then, not all days are good saw sharpening days. There have been many instances for me while sharpening saws where I just about gave up in frustration because I just couldn't get the teeth to come out right - it took a little time away from it to get some perspective. Teeth as small as these are can be difficult to get right without some practice.
I've also found that a magnifying light is of great help when doing such fine teeth.
Joint the Cutting Edge Flat
Using a large flat bastard file, I straighten out the cutting edge of the blade. It's important that it be both perpendicular as well as straight, otherwise the teeth won't be on the same plane. To accomplish this, I use a square scrap of wood to guide the file along the saw blade, as is seen in this photo:
Commercial versions of file holders were made, but I've never owned one. I know my dad has one tucked away someplace - I've always gotten by with a simple scrap of wood. I wouldn't mind having one, though.
Marking the Teeth
I use a cad program to draw a set of lines that are spaced at the correct number of Points Per Inch (PPI) that I want so I can print it out to use as a reference. This can also be done with a square and a tape measure (using measurements on the tape, like 1/16" which equals 16 PPI), or if you have another saw that has the number of teeth you want you can use it as a guide.
In case you have no other options, I have made up some jpegs that have lines at the number indicated (pictures like the sheet you see me using in the photo below) that might do the trick. Right click on the following to download the one you want (warning, 130 to 190 Kb each) and print them off - the size of each jpeg is 7" wide by 10" tall at 150 dpi - using a graphics program such as Photoshop (I believe Microsoft Paint will work as well). If you print them directly from your web browser, you might not get the correct size - you should double check it in any case.
I mount the paper in the saw vise directly next to the saw blade. You could also use some spray adhesive to mount the paper directly to the saw blade, if that helps you. When done, a rag dampened with mineral spirits should dissolve the adhesive and clean it and the paper from the metal.
For me, at such a small scale, it's usually best to start out by simply marking out the locations of the teeth using an old file. Hold the file so one side is perpendicular to the blade so you can sight along side it to match the lines in the paper:
- The photos I'm using are for an 9 PPI blade, so that you can see what I'm doing better than if I used the actual photos from the 15 PPI (or so) blades sharpened for these back saws. The process is the same for either, however.
If you have difficulty in using a file, a hacksaw blade can also be used for this step. It's thinness allows you to see the lines more clearly. Really, all you need to end up with is something that can guide the start of your file in the next step.
Sizes of Files Used in Sharpening Saws
This is taken verbatim from vintagesaws site - I have no reason to quarrel with it:
|7" Regular Taper||
|7" Slim Taper||
|6" Slim Taper||
|6" XSlim Taper||
|6" 2XSlim Taper||
|5" 2XSlim Taper||
|4" 2XSlim Taper||
Absolute adherence to the above is not necessary, just recommended. You should try to be close, though. Too large of a file for too small of a tooth can lead to problems with with the file being too rounded at the corner to be effective, and the opposite can waste a file by using too much of its side up, dulling it when you try to use another corner of the file. I find I can use a file for shaping teeth for quite a while, but for final sharpening it really pays to use a nice sharp one. For teeth finer than 16 PPI, you can also look into using a needle file. I've not done this, but others have reported success to me using them.
Files less than 6" long can be difficult to find in your local hardware store. I've had good luck getting them from Lee Valley, Highland Hardware, toolsforworkingwood.com, and of course, they are also available from Vintage Saws.