Re toothing a vintage tenon saw

[Bluekingfisher]

I bought an old vintage 14" brass back tenon saw made by "Clegg" from ebay a few months ago. I finally got the chance to have a look at it with a bit of refurb in mind.

The saw was in over all decent shape, I'm guessing a mid to late 19th century model? the tote just needed a clean and a light sand to remove some nicks. I removed some of the gunk with a 1/1 white spirit and meths mix, then a couple of coats of shellac followed by three coats of paste wax.

The plate was straight along its lenght, tight to the tote with minimal pitting. For a tool of its vintage it has faired reasonably well. Unfortunately the last owner has made a mess of the lfinal sharpening. The teeth were in a dreadful state with the edge cupped 3 - 4mm, Several of the teeth were also missing.

I never thought to take photos of the saw in its original state however, I decided I would have a go at re-toothing the plate. I had never until this point completely removed all the teeth from a saw, although I have sharpened my own saws for a while now, albeit leaving just enough trace of the tooth to act as a reference point for shaping/filing.

Anyways, I thought some may be interested in my attempts at rejuvinating this old tool.

The saw with the teeth filed off completely. The edge is now jointed straight, or at least as straight as I could make it



With the teeth removed, you are now on your own, as it were, no reference from the old teeth pattern to act as a guide. On the upside I now have the opportunity to decide how many teeth I want. I have several back saws with varying tooth confirgurations, although not one with 10ppi. which was what I decided on. I filed for a rip cut.

I had a look on the web to establish the best way to determine and layout the number of teeth. Paul Sellers has an interesting method on his webpage but I found a series of templates for various tooth configurations on the Norse Woodsmith page. Thanks Norse Woodsmith. You simply print off the chosen template and lay it over your saw plate.



I used double stick tape to hold the template onto the plate. In addition to holding secure, the tape acts as an aid when forming the teeth. Much like when drilling a glazed wall tile, the tape reduces the rick from the file skating or detracting off course as you file.

Here the template is fixed to the saw plate and held in the saw vice ready for the initial laying out of the teeth.



Then filing using the template as a guide. I used a xxslim 5" saw file on this saw, perhaps not ideal but it was what I had on hand. A new and sharp saw file is a must. I found out the hard way that using a used file when shaping the teeth is a receipe for disaster. You will end up forcing the cut which has an obvious and damaging effect on the teeth. The files are £3 - £4 ea. For retoothing a saw you will wear out one file. For subsequent sharpenings a file should sharpen 3 - 4 saws easily.

In case you are wondering how kong should you expect a saw to remain sharp before a touch up. Rob Cosman reckons using the saw regularly for dovetails etc should last around a year, frequent but not continual use would last 3 years. So unless you cut abrasive woods or hit nails, sharpening is in infrequent process.




After the first run.



Then with the template removed, the teeth layout is now established.



The teeth now taking shape, note the small flat spots on some of the teeth, these were removed on the next run.



Then just about ready for setting. I went for minimal set, figuring I can apply a little more if needs be.




Setting the teeth, then a final pass to sharpen the teeth. I apply Paul Sellers methology, a progressive rake over the first couple of inches of teeth, the first inch (10 ppi) shaped 15 degrees off plum, the next inch at 5 degrees. then the remainder filed plumb. It really does make starting the cut very smooth, preventing the need to draw the blade back to start the kerf line.



I used a Veritas saw file gauge this ensures an accurate and easily repeatable angle can be obtained.

The photo shows the gauge set at 15 degrees for the first 10 points.



After the final pass with the file the teeth are dressed with an abrasive diamond plate to remove the swarf from the filing.



Of course this is all very well, will it cut fast and true. The wood is Acacia, very hard and dense timber, no problems.



Of course once you have sharpened your teeth you need to have a means of protecting the newly sharpened teeth, A shrowd made by cutting a kerf in a stick is ideal.



All in all, around 2 hours from start to finish. A very straightforward and simple process. Just make sure you have plenty of light, good magnification and save at least one fresh face on your triangular file for the final pass, or you could of course have a couple of files on hand, which is what I will do in future. The files when new cut very quickly so take your time with a smooth, steady & repetative stroke.

Good luck should you try to bring that old saw back to life. I must admit I found the whole process very therapuetic.

David

 

[custard]

Cracking post! And the Norse Woodworker link was really useful. Thank you!

 

[Trafalgar]

That's an impressive bit of saw doctoring. Very nice saw!

 

[bugbear]

Nice work (and photographs).

I prefer progressive pitch to progressive rake; pitch is pretty much self sustaining, once
created, whereas rake needs setting on you guide every time.

The effect is broadly similar in terms of starting the stroke.

I use a computer printed template to get the progressive pitch setup.

(of course, progressive rake can be added to the existing teeth of a saw, swings and roundabouts)

BugBear

 

[rafezetter]

A very good post, I've been meaning to do some saws for a while, that tooth guide is an excellent cheat.

 

[JonnyW]

What an excellent post David and extremely interesting.

I bought an old tenon saw off ebay with the intention of 'trying' to sharpen it myself, but when it came, it clearly needed re-toothing. So it went in my 'too scared to try' drawer.

I'm going to print your post off and give it a go - let's face it, I'll not go to jail if I don't do it correctly! There is so many books you can read on the subject - sometimes you just have to man up and give it a go.

I had the chance when I started serving my time to watch an old master at work; he was retired and used to come in and service the machinery and sharpen and re-tooth the workshop saws amongst other things. I remember he offered to spend time with me and learn me the ways. I was 16 and knew everything there was to know about woodworking, and had just bought a bag full of assorted disposable saws, which in my opinion were the future of woodworking and were the dog's nuts. So I brushed off the old guy off as being the workshop dinasour and a dying breed.

God damn it!!!!

Excellent post again David.

Jonny

 

[swagman]

Excellent work David. Congrats.

Stewie;

 

[Bluekingfisher]

Thanks gents for the kind words and comments, very much appreciated and pleased you liked it.

Custard - I should have added the link for the Norse Woodsmith saw filing guides, so here it is.

http://norsewoodsmith.com/files/file/sa ... plates.pdf

Paul (Bugbear) I could have gone that wat too, I suppose it comes down to what one feels is practical or logical at the time and then becomes habit. My only cocern with progressive pitch is there may need to be a change of file during the process ( depending on the size of the teeth of course) I have the commercially available Veritas guide which makes the change of rake angle a 2 second job. Horses for course as you say. However for those interested in the progressive pitch rather than rake this link, also from the NWS page may be of assistance.

http://norsewoodsmith.com/files/file/Progressive.pdf

Raf & Jonny - I have added the links to the guides above for ease of reference. I hope you can use them.

Stewie - kind words indeed coming from you.

Thanks all.

David

 

[JonnyW]

Thanks for that David, much appreciated.

Jonny

 

[D_W]

Once in a while, you'll see a chinese triangular file in a package at a home store with tiny edges on it (something not very good overall), and maybe double cut. If you can locate one of those, they are fantastic for starting teeth - basically digging where they start because the edge is so sharp - they'll stretch the life of your better files a bit, too, by not subjecting the corners to so much more work than the sides like they are subjected to when cutting new teeth.

Job looks well done! I've never had a problem with any saw as long as the teeth are similar in tooth height and set. The rest of the details are pretty forgiving.

 

[Derek Cohen (Perth Oz)]

Excellent job David - both the pictorial and the filing. There should be a category here for tutorials. This would fit in nicely.

Regards from Perth

Derek

 

[John15]

Brilliant David. Your photos and notes have made this a very interesting post.

John

 

[rafezetter]

Hi David - TY for those pdf links, but after you comment to Paul, which do you think would be easier to do from a 100% never done it before novice perspective?

 

[AndyT]

I'll add my appreciation of an excellent clear post to encourage everyone to try this.

Have you tried the rip teeth for cross-grain cuts? Having watched the same Paul Sellers video, I did a rather more battered saw following his directions and was surprised at how well it works both ways of the grain.

 

[Bluekingfisher]

Gents - Again, thank you all for the kind words, great to see it so well received.

I must point out I am relatively new to all of this, certainly the re-toothing from scratch. I have much to learn although the snippets of advice and information provided here on the UKWS by others far more experienced than myself have been the inspiration to "give it a go". Like most Hobbiest, once you have an interest in one particular topic you tend to soak up information like a sponge. What I am trying to say is, if I can do it anyone can armed with a little basic knowledge and understanding of what is required. So thanks all.

D_W The file I used to cut with the template was an old file anyway, worn out other than the aris where it was still lively enough to etch the saw plate. What I had intended to do was use a small hack saw You can see it in the back ground of some photos lying on the bench) with the first inch or so of the teeth ground progressively off to prevent the blade from snatching. This was one of the tips gleaned from the Paul Sellers YouTube video.

Derek - Again coming from someone with your experience is praise indeed.

Raf - I can't say I have the experience to comment to any degree of credibility. I suspect the wya to go is what you think you can work with. My concermn with Pauls methos is should you file cut a plate with 16ppi for example the progressive pitch would require points of around 20 - 22 or so, which are very small teeth and could be easily obliterated should the utmost care not be applied.

Andy T - I haven't managed to learn the art of crosscut filing yet, something I intend to tackle although to be honest all of my cross cutting is done with the rip configuration. Perhaps the rip profile is not best suited to plywood etc where the fibres would undoutedly blow out. For timber, I haven't had cause for concern.

John15 - Pleased you liked the post, many thanks.

Thanks again all

David

 

[D_W]

I never had much luck with a hacksaw. I can't be precise enough with it. A worn out file as you've used is a good idea, too. I don't know how many teeth I've filed from scratch, but it's not that many compared to a true saw maker - I've always had the best luck just doing all of the work with files.

As far as crosscut goes, I can only provide one tip so as to keep the teeth in good order - focus on the front of the teeth for most of the cutting when you install your fleam, it will keep you from filing down the tooth in front of the one you're working on accidentally (which creates the cows and calves thing). It's pretty easy if you do that, same condition of teeth needing to be equal height applies. Less fleam first and add more if you need it. A tooth that rasps from too much fleam is pretty slow and pointless.

 

[Cheshirechappie]

Splendid job! There's enough depth of blade on the saw to give another lifetime or two of service, as well.

I did like your advice to make slow, steady strokes with the file. Most people push files far too fast in harder steels, which just shortens the life of the file. The harder the workpiece, the slower the file stroke, in general. If you can see the filings coming off, things are about right. Use the full length of the file too - you've paid for all the teeth, so you might as well use them. Generally, a six-inch file in hard steel should take almost a full second for a complete pass.

 

[Corneel]

Generally you don't need progressive teeth for a 16 ppi saw. The teeth are allready so fine that it doesn't bring much. It is in fact more something for very coarse saws and even then, more trouble then it's worth.

 

[swagman]

The saw plate depth and gauge will determine the range of tpi.

 

[Derek Cohen (Perth Oz)]

The saw plate depth and gauge will determine the range of tpi.

That doesn't sound right, Stewie.

Tpi are determined by the task that the saw will be put to. More teeth for a finer cut, less teeth for a coarser cut. Less rake for an aggressive cut, more rake for a softer start. Square teeth for ripping and increased fleam for crosscut (fine teeth work here as well). I have deep saw plates that are 20 tpi, and shallow plates that are 15 tpi. And longer and shorter with different tpi. One cannot tell by looking at the plate, per se. Only gauge is more predictable: the coarser the cut, the more the saw is likely to have a thicker gauge.

Generally you don't need progressive teeth for a 16 ppi saw. The teeth are allready so fine that it doesn't bring much. It is in fact more something for very coarse saws and even then, more trouble then it's worth.

Kees, I agree. I have tried a few progressive filed dovetail saws, and really did not like them. The nature of the teeth force one to start the cut at the toe of the saw. Anywhere else and the teeth are coarser than may be desired.

Regards from Perth

Derek