What have we lost?

With the yard sale and flea market season now in full swing, old rusty tools shake off their dusty winter coats and wander out into the warm sunlight once more in hopes of finding a new home. Each Saturday morning in New England dawns with the promise of finding one of these long-lost treasures.

Last week, on one such morning, I stumbled across this apparently common table saw blade from a nest of saws in the bottom of an old tool chest…

I was first struck by it as the etch was very bold and it looked little used. As I picked it up to get a closer look at the etch, I then noticed what I first thought was a terrible sharpening job, but soon revealed itself to be a strange hybrid tooth geometry.

As soon as I got a chance to look more closely, I realized that this was no hack-sharpening job…this was a very deliberate filing…

It seems that the teeth are filed in groups of 2 + 5, meaning that there are two stout teeth followed by 5 finer teeth. The only difference I can see from the 2 teeth to the 5 is the degree of rake…the 2 teeth are more aggressively raked than the 5 teeth. This pattern repeats itself for the whole length of the saw…2 stout, 5 fine, 2 stout, 5 fine, etc, etc. You can see this very clearly in the picture above.

So what the heck is this all about?

The filing does appear to be factory original…meaning that this was the way the saw was filed by the Disston factory. The teeth are perfectly jointed and the fleam is very consistent on all of the teeth. Further, the saw has seen very little use…I know this because the blade is arrow straight (table, keyhole, compass and all narrow bladed saws are invariably found bent and kinked) and the etch is as bold as the day it was made.

If in fact the filing is not original and was filed by the owner, it was executed with such fine precision that it must have been done by a master filer, so that further suggests it was most deliberate. Either way, factory or custom, this tells us that someone very learned in the art of saw filing intended this tooth pattern….so there must be an advantage to it.

As I further inspected the saw, I tried to understand how this filing would benefit a table saw…

Table saws are intended to cut gentle curves in table tops and similar patterns, hence the narrow blade to follow a curved line. This means that in the wood, the teeth encounter grain parallel to the line and across it and thus make ripping and cross cuts. So does this strange tooth pattern help make both types of cut? Perhaps the aggressively raked teeth are intended to rip more effectively? But then why not file them straight across like true rip teeth?

I’ve never seen teeth like this before on a hand saw, and I’ve never read about them either. Disston and other saw makers patented many hybrid tooth patterns to improve the function of their saws…perhaps this is one more?

As I wonder about these odd teeth, it makes me think of what other knowledge of saw filing we’ve lost to history, perhaps never to find again.

In a way, we are starting over in this hand tool renaisance…we are reading Moxon and Roubo and Nicholson….all long dead. What secrets of working wood by hand died with them? Will we ever discover these secrets again?

What else have we lost to time and technology?

-Matt

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Published in: on June 11, 2011 at 9:08 pm  Comments (16)  

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16 CommentsLeave a comment

  1. The patent date is marked on the blade etch. No 151,363 May 26 1874
    That patent, for a compass saw, clearly shows the 5-2 rip/crosscut tooth pattern in the illustration.

  2. Can I please edit this quote and cast it in stone?

    “What else have we lost to…technology?”

  3. I wonder if you will find the filling to be of advantage in your work. I think there is equal chance that it was snake oil selling as there is that it was of value and am curious to hear how it works in practice.

  4. We are very much in the process of losing hand drawing and drafting skills. Sketchup leaves me cold.

  5. I would also caution you to curb your enthusiasm. The reason this filing pattern was more-or-less lost could be that it wasn’t that helpful. In much the same way that the Irwin Carpenter’s Saw : http://www.homedepot.com/Tools-Hardware-Hand-Tools-Cutting-Tools-Hand-Saws/h_d1/N-5yc1vZarg9/R-100564595/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

    is almost impossible to use, perhaps that filing pattern made the saw jumpy and difficult to control. The only way to know for sure is to use it or duplicate it for testing.

    An interesting find certainly, but if vintage versions of these are so rare, I am forced to wonder why.

  6. Matt,
    Regardless it is a fascinating find. I know I am looking forward to seeing you handle it,! I hope you post the process.

    Best regards,
    Albert

  7. Matt,

    Over at wkfinetools there’s an 1874 Disston publication that shows a combination saw with this “keystone” tooth pattern. This would argue for the “jack of all trades master of none” interpretation of the tooth pattern’s utility. It probably offers only reasonable speed in any direction, but it might beat a rip or crosscut in a narrow range of angles to the grain.

    I hope that you will experiment with it against saws with the same ppi as the small and large toothed sections. I suggest trials at 0, 45, and 90 degrees to the grain. If nothing else, it would be good mitering practice.

    The table or compass saws might actually be the most sensible application for this tooth pattern, especially for carpentry of the Victorian houses of the day which featured segmental and roman arches in Italianate, gothic arches in Carpenter Gothic, and turrets in Queen Ann. That’s alot of curved sheathing, siding, subflooring, and flooring to cut.

    As to the tooth filing, I would speculate that the larger teeth still rip better than the small teeth of a regular crosscut, but the crosscut filing left a better quality sawn edge. The small teeth improve the crosscut and make the saw startable.

  8. Matt, it seems Disston certainly did produce saws with that tooth pattern in the factory. Today I was thumbing through a Disston catalogue from 1945. In the description of the D-17, it says:”This is a double duty type saw. can be used for either ripping, cross-cutting, or cutting diagonally. Alternate sections of five cross-cutting and two ripping teeth with fine teeth at point for starting cut.”

    While your saw is not a D-17, the tooth pattern sounds the same. In fact, the shape of the blade looks like it comes from their “No.3 Nest Saw” in the 1945 catalogue. This nest came with 3 blades in the set: a 10 inch Keyhole saw (10 points), a 14 inch Compass saw (8 points) and a 16 inch Pruning/General purpose saw (8 points). It is the latter one which has the same profile as yours.
    Hope this helps.
    Cheers,
    Greg.

  9. Hi Greg,

    I’ve filed a few Disston D-17 DDD saws. One of the worst cutting saws I’ve ever used for both crosscutting and ripping. In essence, both crosscutting and ripping is compromised. Each one compromises the other. I think this is true with any “hybrid” filed saw. The tooth profile is a little different than the blade in the nest of saws in that all the teeth are the same size but have the extra deep gullets separating the crosscut teeth from the rip teeth. This saw is a bit rare in the wild. After trying to saw with them, it’s apparent why.

    Matt…. Looking in a 1918 Disston catalog I see two nest of saws, each with a Table/Pruning saw included, with teeth just like your saw blade. The only difference is, these don’t have a nice full etch like yours. One nest is a No.3 and the other is a No.5. Each nest has three blades. The Table/Pruning blade is the same in each nest, but the other two blades are different. I’m probably looking at the same two nest of saws that Greg sees in his later catalog dated 1945.

    Take care,
    Marv

    • The jury’s still out on this tooth geometry being effective, as I’ve yet to sharpen it up and give it a whirl. I have always found that the effectiveness of any “hybrid” tooth geometries being tied closely to saw plate thickness and tooth size. If you think about it, that’s why dovetail saws can cross cut decently well….they have small teeth and a thin saw plate. I think that’s also why saws like Mark’s Bad Axes work with hybrid filings….Mark uses thin plates for his saws and it helps the teeth cross cut.

      -Matt

  10. By comparison, what should the proper filing be for a keyhole saw that sports 8 ppi?

    Ok, ok. I recently picked up a vintage keyhole saw (dull as heck) and while I sharpened it at a 15 degree rake and a 20 degree fleam don’t have a clue if this is good for the type of work I’ll call upon it to to. It’s not too good on ripping the test board I tried (no surprise there).

    Any suggestions, experience trial and errors to share?

    In any event, the filing on Matt’s recent acquisition is fascinating. I agree with the notion that if it was all that handy that the design would have proliferated and we’d see it more frequently on our tool hunts. But alas…

    Regards,
    Brad

    • HI Brad
      Traditional filing for a keyhole saw would be ro fleam….filed straight across like a rip saw. But for me, I like a little fleam to help with the smoothness of cut and going across the grain….about 5 to 10 degrees is nice.
      Matt

  11. Thank you Matt. That’s a BIG help in getting this saw to perform.

    What rake angle, if any, do you go with on a keyhole saw? I’m looking forward to trying these sharpening specs. I was disappointed in the saw’s performance after my initial jointing and filing.

    Regards,
    Brad

    • Brad
      Rake is tough with these saws because its based purely on the skill of the sawyer. For a relative novice, you def don’t want too much rake as they are easy to jam in the kerf and kink. That said, try 10 degrees or so negative rake with a touch of fleam…this should cut plenty fast and give a decent finish.
      Matt

  12. Matt,
    Wow. What a difference a sharpening makes. 10 degree negative rake combined with 5 degrees of fleam did the trick. I actually have a saw that I’ll reach for to complete inside stock cuts and won’t have to worry about jamming.

    Thank you for helping me put this vintage tool back into use. I could not have done it without your expertise.

    Regards,
    Brad

    • Brad
      I’m so very glad that geometry worked for you….thanks for the support and keep up the great work!
      Matt


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