# Turning Bow Saw



## firemedic (Mar 28, 2012)

Started working on a new hand tool today... A Turning Saw.

This is a mock up for a nicer one but I'm sure it will be usable all the same. I went with an oak frame, 3/8" blade and aluminum pins to use as much as I could from what I already had on hand and keep the prototype cheap.

Pictures pretty much say it all... Once I get it done I'll try to do an over view of the build but if any questions, fire away!

~tom


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## Kenbo (Mar 28, 2012)

That's really cool Tom. If this is just the mock up, I'm really going to love the finished product.


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## Mike1950 (Mar 28, 2012)

Firemedic -looks good-but what really catches my eye in the clutter of your bench (better then mine when I am in the middle of project) is that very nice old open handled dovetail ? saw- I love those old tools also. did you not just get a Veritas? How do they compare? Mike


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## firemedic (Mar 28, 2012)

Thanks, Kenbo.

Mike, i had to go back and look at the picture but the only dovetail saw on the bench IS a Veritas. The other is a cross cut saw I built. That thread is over on wwt and will have some other saw builds as well.

As for how well it cuts, I gave it a very aggressive rake but shallow gullet so it cuts very fast but only practical for thin cuts. Its useless for rips (dovetails). I've got several other saws in various stages of rebuilds and resharpening that I could do a thread here on once done if you like. 

btw, that's one of my side benches, it seems to stay particularly cluttered! :)


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## Mike1950 (Mar 28, 2012)

Tom, I see the regular hand saw in the pic but what about the open handled saw about 2 or 3" to the left of the Veritas. I do read your threads. Cute little boy also!!!!!!!!


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## firemedic (Mar 28, 2012)

Yep... That's a cross cut saw! I use it for small cross cutting like mouldings or tennon shoulders.


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## Shop Dad (Mar 28, 2012)

Very nice work Tom! That shaped Tennon alone is beautiful! LOL is there a function or advantage to shaping it like that over a squared tennon?


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## firemedic (Mar 28, 2012)

Shop Dad said:


> Very nice work Tom! That shaped Tennon alone is beautiful! LOL is there a function or advantage to shaping it like that over a squared tennon?



Thanks, it allows for variations in blade size for one but mainly to allow it for flex when the blade is drawn tight by the tensioner.

EDIT: oh, and the mortice is under cut for the same reason.


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## Shop Dad (Mar 28, 2012)

Got it, makes perfect sense.


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## firemedic (Mar 28, 2012)

Mike, the before and after on that saw you asked about...


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## Mike1950 (Mar 28, 2012)

Tom, very nice modification.


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## firemedic (Mar 29, 2012)

bigcouger said:


> Nice there Tom looking for the finished product here an Im interested in one when you are done with it
> Roy



In a turning saw?


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## firemedic (Mar 31, 2012)

Well, still not finished but it works quite well! I'm surprised to see that it is easier to control cutting on the push stroke that may be a familiarity thing for me though.

I'm going to make a nice toggle that will pop into a shallow mortice on the stretcher. That will be Mahogany like the knobs.

One of my pin holes isn't straight, you can see that the knob looks slanted down. I didn't bore my pin holes prior to shaping because I see that as backwards on a mock-up. I'll be able to do that on the next though.

Also you'll notice I lightened up the stretcher a good bit.

I think it's a successful mock-up.


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## Brink (Apr 1, 2012)

firemedic said:


> Well, still not finished but it works quite well! I'm surprised to see that it is easier to control cutting on the push stroke that may be a familiarity thing for me though.
> 
> I'm going to make a nice toggle that will pop into a shallow mortice on the stretcher. That will be Mahogany like the knobs.
> 
> ...



I would think it would cut better on the pull stroke, with such a narrow blade, be less stress on the frame, too. 

Also, why lighten up the stretcher?


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## firemedic (Apr 1, 2012)

Brink said:


> I would think it would cut better on the pull stroke, with such a narrow blade, be less stress on the frame, too.
> 
> Also, why lighten up the stretcher?



I know, like I said it may just be an adjustment to a pull stroke. I lightened up the stretcher without a single qualms because it only has to endure compression stresses. There's virtually no lateral stress on it. I'm pretty amazed at how solid feeling the frame is under tension and I can only thank the wide well fitted tennons for that.


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## firemedic (Apr 1, 2012)

Went by my old mentor's shop today and took some pictures of this old saw. He's not sure of the origin of it as it was passed down to him. Anyone's guess as he's a 4 generation furniture builder... Each generation had one so the all the tools from the previous went to the next in line. Too bad the line stopped with him and he's 85 :( He's obliged to leave his tools to his three boys but what will happen to them after is anyone's guess. 

It's got rip teeth one it, which makes 0 sense to me being the blade can't turn. So rips would have to be in really short stock. The other possibility is it's a replacement blade or that the teeth were improperly sharpened. The later is my best guess being it's about 8 tpi which is kind of high for a rip saw of that size.


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## firemedic (Apr 1, 2012)

bigcouger said:


> Neary like mine my granddad gave me, it was pasted down to him from his dad an his dad before him, Mine has a Munich Crown on it its hard to see now, I tried to get a picture of it but dosent show at all unless you fell it. It dosent have a bolt in it tho an has a different blade to, the blade is from my granddad an still is sharp I keep it maintained but it stays on the wall to
> Roy



Wow! That looks incredibly similar to yours! I can barely make it out but are those cross cut Tuttle teeth on your saw?


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## firemedic (Apr 3, 2012)

bigcouger said:


> I think so, an there sharp to  here is a close up picture of the teeth tho
> Roy



Yeah, appear to be Tuttle CC Teeth. Cool man!


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## firemedic (Apr 3, 2012)

Did a lil more R&D yesterday. Tried a 24" 1/2" 4 tpi skip blade (the previous was 21" 12 tpi 3/8") and discovered something I should have figured before hand. Flex back blades in that larger size are all but useless for a bow saw! 

The blade had so much flop to it that it was very difficult to control. I had a go at a 4" wide piece of poplar and got frustrated after spending 10 min ripping only 2.5" down with nothing even close to straight. Picked up a D-8 and ripped 5" along side of it no time just to make sure I wasn't crazy.

So that brings me to TRYING to have a tech rep from Simonds Int to call me back about hard back wood ripping blade stock... 

Stay tuned!


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## firemedic (Apr 3, 2012)

My best explanation of what's going on is the front of the blade is hardened and the back is untempored. My understanding is that most bandsaw stock is made soft back so that it holds up to the abuse of the small turning radius of smaller band saws. 

What's happening is the hard front of the blade holds tension while the back of the blade is not under enough tension - relatively speaking. The the back of the blade flops around... With a hard back blade the front and back will both be tempored the same so that this doesn't happen... Hopefully! 

Talked with Olaa in the manufacturing dept at Simonds Int today. Nice guy. 

Anyway, they are sending me a sample box of hard back blade stock to try out all 1 1/2" to 2" wide and 4-8 pitch some variables pitch as well... Once again, stay tuned!


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## jxmcguire1 (Apr 5, 2012)

firemedic said:


> My best explanation of what's going on is the front of the blade is hardened and the back is untempored. My understanding is that most bandsaw stock is made soft back so that it holds up to the abuse of the small turning radius of smaller band saws.
> 
> What's happening is the hard front of the blade holds tension while the back of the blade is not under enough tension - relatively speaking. The the back of the blade flops around... With a hard back blade the front and back will both be tempored the same so that this doesn't happen... Hopefully!
> 
> ...



Trying to use the full strength capabilities of steel in a real setting usually leads me to think "steel is kinda funny stuff", but one way that makes it easier is for the blade cross section to be wide and a little thicker, Bimetallic power hacksaw blades that are so desirable due to their shatter resistance in service are usually fairly thick, often 1/8" or even more. The all hard blades are usually kinda thick too. In an engineering sense, the blade can be looked at as both a thin beam and a thin column. These metal working counterparts usually have the advantage of being mounted to a saw frame with an especially heavy or large cross section that can apply the stress level (tension) to the blade that makes it remain fairly straight in use. I'm not familiar with the amount of tension that a bow saw frame can produce in a woodworking blade, but I suspect it is quite a lot lower than in the metal work machines. That said, you might try an extra thin blade that has a full width to see if the saw frame can fully tension that thinner blade. It was quoted in the bandsaw / resaw video recently that bandsaw blades need about 10000 psi or 10 ksi on the blade crosssection to work well and not buckle or bend / deflect from the sawing forces.

If the blade width in the gullets is 1 inch, and the blade is 0.035" thick that gives 0.035 square inches. To develop 10 ksi in the blade requires 0.035 x 10000 = 350 pounds of force directed along the blade direction. For a blade that is 0.025" thick, it drops to 250 pounds of force. If you wanted to do a little experiment to see what amount of force your saw frame can produce in the blade, you might be able to rig up a plain ole bathroom scale in a jig or fixture and acually measure it directly (without the blade in place of course, so the force is applied to the scale springs rather than the blade).

Just a few thoughts . . .

/rant


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## NeilYeag (May 7, 2012)

firemedic said:


> Shop Dad said:
> 
> 
> > Very nice work Tom! That shaped Tennon alone is beautiful! LOL is there a function or advantage to shaping it like that over a squared tennon?
> ...



I also liked the Tenon, I am just finishing up a 12" turning saw, and really struggled to get the fit correct. No where near as precise as yours.

Neil


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## firemedic (May 15, 2012)

Thanks, Neil. This project has been on a but of a stand still for the last few weeks due to a heavy work load and my blade stock samples never arrived :(

I'll be around the mill tomorrow and I'm thinking I'll grab a piece of 1" bs stock, grind new rip teeth, harden and sharpen it. I'm in the process of setting up a small metal kiln for that and for some custom moulding plane irons.

I hand sawed the tenons an cleaned them up with a 72 router plane. I think that works well because it allows you to keep coplanar sides to the tenon without perfect sawing.

Cheers


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## firemedic (Dec 1, 2012)

Finally got back to this one, I got both mock-ups done. Now on to Joe's hand planes!


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