Serrations in teeth

A forum about crosscut saw filing
Trilliumrock
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Serrations in teeth

Post by Trilliumrock » April 14th, 2020, 8:08 pm

Hi. I am intrigued by the the serrations in the teeth of this saw. I figured they were the result of the prior filing technique. However, the serrations are incredibly uniform in all the teeth. Can anyone tell me what this is? Thanks
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Jim_Thode
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Re: Serrations in teeth

Post by Jim_Thode » April 15th, 2020, 6:25 am

I believe that were filed with a double cut file. A double cut file may cut faster but the surface is not as smooth as a single cut file. I don't know of any experienced files that do that intentionally.

Single-cut files have a single row of diagonal teeth. These teeth run parallel to each other and extend the length of the file’s face. These files are good for both soft and hard materials.

Double-cut files have two sets of diagonally-cut teeth. The interlaced teeth create a diamond-like pattern which allow the file to cut twice as fast as a single-cut file. They are good for quickly cutting hard materials. The teeth will clog if used with soft materials.

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Starling_Saw
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Re: Serrations in teeth

Post by Starling_Saw » April 17th, 2020, 7:59 pm

Some of the filers in Western Canada did this to the cutters when using the saws for cutting White Pine. the serrations allowed the cutters to sever the fibers better. By using a course bastard file you can make the serrations fairly uniform. I've had a few people request this style tooth for cutting White pine at college competitions, and small logger shows in Western Canada.

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PATCsawyer
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Re: Serrations in teeth

Post by PATCsawyer » April 18th, 2020, 1:07 pm

As with many good ideas, nature got there first, including the Champion profile.

fullsizeoutput_190d.jpeg

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sumnergeo
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Re: Serrations in teeth

Post by sumnergeo » April 19th, 2020, 7:40 am

And here I always thought that a crosscut saw was nothing but big sharpened knife with some serrations! Perhaps little serrations on top of the big serrations help?

Imagine a 3 ft piece of carbon steel sharpened to a knife edge. Now, try to cut a 12 inch oak or pine log with that nice, sharp piece of steel. How far did you get?

Just for fun, I've been making some little wooden knives using mexican plum and pecan. They are great for cutting soft cheese or spreading peanut butter. Add some notches and all of a sudden the knives will cut hard cheese, summer sausage and even tomatoes!
non-serrated1.jpeg
serrated.jpeg
So, back to that big knife that didn't really cut that log. You can imagine a progression, mostly because we know what it should look like in the end: file to make a series of teeth; set the teeth. It is a big leap to go from there to adding teeth to clean out the cut but someone figured that out. So, little serrations on top of the big serrations could be the next big leap but I'll stick with my single cut file for now.

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Jim_Thode
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Re: Serrations in teeth

Post by Jim_Thode » April 19th, 2020, 10:37 am

I don't know about serrations on saw cutter teeth. Serrated edges are blades that have some kind of toothed or saw-like edge ground into the cutting surface. These are intended to be used much like a small saw with a back-and-forth motion.

With more blunt cutters and very springy wood maybe the serrations would cut more like a sawing motion but with more pointed cutters the normal cutting action is more like a chisel cut (non-sawing motion) where serrations would be of no benefit. Also with only the very tip end of the cutter ever contacting the wood there is little room to set up any kind of a sawing motion.

Even in white pine I'd have to have more evidence that serrations are a benefit before I'd believe it.

Maybe a serrated edge on my flat tipped toothed cutters would work where there is a sawing action on the cutting edge.
https://pbase.com/jimthode/image/169171221

Jim

Starling_Saw
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Re: Serrations in teeth

Post by Starling_Saw » April 21st, 2020, 11:49 am

Working on a one man saw today and thought I'd file a couple cutters with the serrations on the cutters, that have been a standard for White pine competition saws. It's not easy to file them consistently. And I'm out of practice with them anyways. It takes a little bit of file manipulation to get the serrations orientated correctly. It's not a common filing application either way, so most Filers don't bother. (The above photo with the serrations are definitely very pronounced, so they might have been ground in with a grinding wheel). Photo is of a cutter tooth with the serrations, and the files are of a Smooth and a Lathe file, which has very course teeth, which creates the washboard effect. The serrations work on the wood fibers like a serrated knife works with manila rope. Even though the tip of the tooth is focused on the cutting. the remaining part of the tooth also shaves off any remaining fibers that might not have been completely severed, thus lessening the friction that they would place on the body of the saw.
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cutter tooth with serrations
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comparison of files

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