Sharpen Dovetail Saw with Fleam?

[Stan Suther]

I've been steadily improving my saw sharpening skills by reading lots of sources and practicing on a bunch of old saws I've accumulated. Dovetail saws are of particular interest, and I do OK when just forming a straight chisel tooth. However, I've seen just a couple of references to putting a bit of fleam angle on a dovetail tooth so that it works better on crosscuts. Just wondering if anyone has tried that. Fine chisel teeth seem to crosscut fairly well, particularly if you first knife a line and channel to guide the saw, but it seems to me that a bit of fleam wouldn't hurt the chisel action when cutting with the grain and would improve the quality of cut on shoulder cuts. I gather from reading old catalogs that dovetail saws used to all have some version of a crosscut pattern, and the idea of filing them rip is a fairly new idea.

[Jim Koepke]

I've been steadily improving my saw sharpening skills by reading lots of sources and practicing on a bunch of old saws I've accumulated. Dovetail saws are of particular interest, and I do OK when just forming a straight chisel tooth. However, I've seen just a couple of references to putting a bit of fleam angle on a dovetail tooth so that it works better on crosscuts. Just wondering if anyone has tried that. Fine chisel teeth seem to crosscut fairly well, particularly if you first knife a line and channel to guide the saw, but it seems to me that a bit of fleam wouldn't hurt the chisel action when cutting with the grain and would improve the quality of cut on shoulder cuts. I gather from reading old catalogs that dovetail saws used to all have some version of a crosscut pattern, and the idea of filing them rip is a fairly new idea.

This is an area of personal preference. It is also a great reason to be able to sharpen one's own saws. Most of the cutting on dovetails is rip cutting, but there is the shoulders on the tail board to trim off. Currently my way is to have two different saws. If one also does mortises, then there is a lot more cross cutting involved.

It seems each time one of my saws is sharpened, something new is learned about saw teeth. So, it seems the only one who can really answer such a question is the person asking.

Here is a post of mine on using a rip saw for crosscutting and comparing it to a saw filed with fleam.

http://www.sawmillcreek.org/showthread.php?p=1232934

I think scribing a line all the way around and cutting just on the waste side will do more to leave a clean cut.

One thing not mentioned in that post was the crosscut saw was sharpened and tuned just before the cutting was done. The rip saw has been used for over a year since being sharpened.

I think the teeth per inch and the aggressiveness of the rake angle has more to do with how rough the cut will turn out than a little fleam.

jim

[Stan Suther]

One of the interesting things about researching this subject is the subjective variations on the instructions and advice I've seen. Tage Frid wrote that he always changed any crosscut saws he acquired into rip patterns because he thought they did everything he needed faster. But he also knifed lines that would be seen.

I have sharp crosscut saws that will do the job, but am just curious about the theoretical value of the added fleam (sorry, engineering background- can't help it).

[Derek Cohen]

Hi Stan

Fleam is not added so that a dovetail saw now "works better on crosscuts". Dovetail saws are for use on a rip cut and work best with the teeth filed rip. However, fleam is indeed a cross cut type filing. The idea is that angled crosscut teeth cut more smoothly (as they shear) than straight rip teeth (as they punch like a chisel), and adding fleam to rip teeth will soften the effort to saw.

Adding fleam is more important (a) when the rake angle of the teeth is vertical or close to vertical, and (b) when sawing in hard, brittle wood. Adding fleam will make the saw start more easily. For example, my LN dovetail saw has zero rake (vertical teeth) and cuts very aggressively but is hard to start in hardwood. On the opposite side if the spectrum, my Veritas (also 15 ppi/14tpi) has 14 degrees of rake, which makes for a very soft start.

The downside of going down the more-rake path is slower cutting (although this is not the case with the Veritas), which you do not want in a dovetail saw. Essentially a crosscut saw is going to cut more slowly, which is why it is not preferred for dovetails which, as has been stated, is a rip cut.

I have a Independence Tools dovetail saw. This is nearly identical to the LN - well it should be as it was the forerunner of the LN. I bought it in new condition a few years ago and sent it directly to Mike Wenzloff, who added fleam to the near-vertical teeth (about 4 degrees of rake). This transformed the saw. It starts considerably more easily than the LN. The amount of fleam added is far, far less than on a crosscut saw, being about 2-4 degrees. So in this regard fleam and crosscut filing does differ significantly.

Hope this helps.

I shall very shortly publish a review on the 20 tpi Veritas dovetail saw (which includes a comparison with the 14 tpi version) and all of the points are illustrated therein.

Regards from Perth

Derek

[Stan Suther]

Thanks Derek. What I had in mind in asking the question is to see what is the effect of adding just a few degrees of fleam to a zero rake rip pattern dovetail saw with 15 ppi. To me, I would expect no downside in adding this small amount of fleam, yet provide a bit smoother action in using the saw for the occasional crosscut. I would think the chisel action would be retained even with a few degrees of fleam. Looks like that is confirmed by Mike's approach. I've seen plenty of videos of people using their dovetail saw to make small crosscuts in the process of cutting joints, so this sharpening approach looks like it might be useful. I certainly would not plan to use this for any significant amount of crosscutting since I have several nice cutting crosscut filed backsaws.

I really enjoy taking an old saw and bringing it back to good performance through giving it a good sharpening. While I'm doing that, thoughts of these variations occur to me, so it's nice to have the folks here as a resource.

I look forward to your upcoming post on the Veritas dovetail saw.

[Matt Edwards]

Good topic guys, I did some experimenting with one of the DT saws I made. It was originally filed 16 tpi rip with pretty much zero rake. It was a bear to start in all but fairly soft woods, and even then it was a little grabby. I had read somewhere about different tpi's, rakes and fleams on the same saw. So I gave it a try, what I ended up with was 4 degrees +or- in the first3 or so inches of the blade (toe). What a difference in this saw, it starts very easy with a slight draw backwards from about the 4 inch point to the first inch of the toe and then a relaxed forward stroke to full cutting. In soft pine and poplar, about 3 to 4 full strokes to base line. In harder stock it takes 2 to 3 more strokes given the same pressure. I caught myself using a different sawing techniques in different lumber with mixed results. When I forced myself to be more consistent regardless of stock, my accuracy was MUCH better.


Matt

[David Gendron]

Hope fully Mark doesn't mind.

This is from is webpage, Bad Axe Saws
"Rip: I start with a 15-degree rake at the heel for the first twenty teeth, then modulate to 10 degrees for the next twenty teeth. From there, I rake every tooth is at 5 degrees for an aggressive cut. I add five degrees of fleam on every tooth (regardless of rake), which reduces tearout on the opposite side of the cut. The rake relaxes again in the same manner at the toe end of the saw. After conducting the initial filing to set a consistent rake, I then rejoint the saw, establish 20-degree sloping gullets, and file off the points without shortening adjacent teeth so that every tooth does its duty."
"Crosscut: The rake modulation for the first forty teeth goes from 20 to 15 to 10 degrees at the heel end of the toothline, then I reverse that for the last forty teeth at the toe end. 20 degree bevels per tooth, and 10 degree sloping gullets. Though ten degree rake for the majority of the toothline is an aggressive cut, It achieves a surprisingly smooth finish on the wood."

I have two of jis tenon saw and they cut... Amazingly well!!

[Derek Cohen]

Hope fully Mark doesn't mind.

This is from is webpage, Bad Axe Saws
"Rip: I start with a 15-degree rake at the heel for the first twenty teeth, then modulate to 10 degrees for the next twenty teeth. From there, I rake every tooth is at 5 degrees for an aggressive cut. ...."
[I]"Crosscut: The rake modulation for the first forty teeth goes from 20 to 15 to 10 degrees at the heel end of the tooth...

I must say that this sounds backwards to me. I don't understand that one starts a cut with less rake (at the toe) and ends the cut with more (at the heel)!???? What am I missing?

Regards from Perth

Derek

[David Gendron]

I guess the idea with the tenon saw would be to establish the kerf with the heel of the saw? I know it work realy well with his saws...

[jim hedgpeth]

I started sharpening recently as well, and have learned a few thing that work well "for me". I dont know just how right it is but I like it. I use this basic method.......http://www.vintagesaws.com/cgi-bin/f...mer/sharp.html
Looks long but was a pretty easy way to figure out the basics.

You didn't mention just how much practice you have got in, so some of this may be old news for you. If so I apologize for being windy, just thought I would share what is working for me.

1. Start with a GOOD file. The first one I used was a Nicolsen, did ok. Then I got a Grobet, dont look much different, but it seems to make for a sharper saw. Gets the bottoms of the gullet better for some reason, even though they are both 5" 2xslim.

2. Carefully stone the sides after sharpening. This was my biggest trouble spot the first few times. Very easy to throw it out of balance.

3.I do like just a bit of flem, along with a near zero rake. I played with a few different setups, and so far this is the one I like best. Cuts fast, not too hard starting, and a little smoother finished cut than one without flem.

Keep trying things and keep track of what works for you. If it works well thats all that matters. If it dont....... back to the saw board...er...vise.

Have fun,
Jim

[Stan Suther]

Was doing some more sharpening this evening and re-read that section in Leonard Lee's sharpening book. He said that adding some fleam to a rip pattern eases cutting through difficult grain. Makes sense. In thinking about the common notion that dovetail cutting involves rip cuts, I realized that only the pins are purely with the grain, especially if it is in very strait grained wood. Otherwise, the tails are actually somewhat diagonal to the grain and depending on grain runuout, even pins are sometime not cut absolutely with the grain direction. So, all that seems to suggest a bit of fleam on a rip pattern can be advantageous, especially for dovetail saws. Obviously, straight chisel tooth filing on rip filed saws works fine for most cuts, but when you're in the hunt for "silky smooth" cuts, adding fleam may be worth the extra time and effort.

I'm going to try that at some point soon, but right now my old eyes are tired of looking closely at little saw teeth. Just finished a small fine toothed crosscut backsaw so I'm going to take a break.

[Don C Peterson]

I must say that this sounds backwards to me. I don't understand that one starts a cut with less rake (at the toe) and ends the cut with more (at the heel)!???? What am I missing?

Regards from Perth

Derek

That one confused me too at first, but if you read the whole thing it sounds like he uses more rake at both the toe and heel with the more aggressive rake in the "sweet spot" in the middle of the saw.

It makes sense because saws can be grabby at the heel too and since as the saw approaches the heel and the forward pressure on the handle (usually near the top of the blade) the tendency is sometimes for the saw to tilt forward rather than to move forward evenly. Reducing the aggressiveness of the cut might lessen that tendency, even if it does slow the cutting action...

[Jim Koepke]

Hope fully Mark doesn't mind.

This is from is webpage, Bad Axe Saws
"Rip:After conducting the initial filing to set a consistent rake, I then rejoint the saw, establish 20-degree sloping gullets, and file off the points without shortening adjacent teeth so that every tooth does its duty."

This is the part that confuses me. Does anyone have an explanation for this?

jim

[Chris Friesen]

This is the part that confuses me. Does anyone have an explanation for this? jim

He shapes the front of each tooth to the desired rake/fleam. He then joints the saw to make the teeth all line up, then shapes the back of each tooth to give the right gullet and bring each tooth to a point.