Sunday, November 15, 2009

Making A New Turning Saw - Part V


There wasn't much left to do on the saw, but it still took me awhile. I snuck in one short work session during the week and one longer one today and the saw is done! Wahoo!

To mount the knobs and rods I had to bore holes through both arms near the bottom. First I had to rework the bottom section of the "handle" arm. I had left it wider than the other arm, and while I am sure I had a reason, I couldn't remember why I had done that, and it didn't allow for enough of the rod to clear the arm. While using the spokeshave, I went ahead and reworked the curve in the bottom of the stretcher to more closely match the curves of the arms. After that, I used a brace and bit to bore both holes.

Here's a shot of the saw, at that point:


That was all I accomplished during the week. Today I moved on to mounting the blade in the rods. After filing a flat to stop the bit from sliding off the bolt, I used my small hand drill to make the holes for the pins that would hold the blade. I experimented a little here, and heated the first bolt to red hot and let it cool. I wanted to see if it made a noticeable difference. It didn't. Hmm. That's the opposite of what I experienced with the bolt heads. Maybe I'm mental. I don't suppose bolts have that much carbon in the steel - so no dramatic change makes sense.

Here's a shot of the first bolt in the vise:


Then, using a hacksaw, I cut the slots for the blade. I returned the drill bit to the hole to help me align the slot at right angles to the hole. Here's the result:


Now it was blade time. I assembled the saw and measured the distance between the pins (3p finish nails) in the rods. Then I subtracted 1/16 of an inch and I had my distance for the pin holes in the blade. This would bring the bottoms of the arms together slightly, allowing for the blade to be stretched taught when the tension mechanism pulled the tops of the arms back together, and the bottoms apart. The 1/16th was just a guess. Turned out I should have made it more like 1/8th, but I'm getting ahead of myself.

I cut the blade with an extra 1/4 inch beyond each hole location. Here's my high tech band saw blade cutting apparatus:


It worked great and had no trouble cutting the 1/4 inch blade. The vise allows for more control and the use of body weight to assist with the cut.

To drill the pin holes in the blade, I just clamped the blade to a piece of scrap and had at it. It took some pressure to get started, but once it did, the bit had no problem. I did use my fist under my chin to help apply steady pressure on the handle of the hand drill.

I have heard of other's punching holes in the blade with a hammer, a punch and a block of hardwood (end grain up). I tried this before and didn't have good results. For whatever reason, I've had much better luck with just drilling. Maybe my blades are cheap or something...


Once the blade was mounted in the rods I could make the simple tensioning system. I cut about 12 feet or so of twine and soaked it liberally with mineral oil. It's my pet theory that the oil allows the fibers and strands to slide over one another and "self adjust" so that they all share the load equally. I have no proof that this works, but I dramatically reduced my breakage rate once I started using this approach.

To apply the twine, I wrapped it around one arm several times and then started looping it around both arms. When I ran out of twine, I wrapped the running end around the loops several times and then passed it through between them. I inserted the toggle stick between the loops and started winding. As the twine twisted tight, the extra oil got squeezed out. I just rubbed it into the saw.

To test the blade tension, I plucked it with a fingernail. Here's where I realized that I should have shorted the blade holes by 1/8 rather than 1/16 of an inch. The tenons were fully seated and the blade was not fully tensioned. The real fix would have been to make a new blade, and I probably will - at some point. The temporary fix was to put a washer between each knob an the frame. I kept on applying tension until it started to sound musical; changing from a "thunk" to a "twang!"

Time for some test cuts. Not very pretty, but that was my fault not the saw. I wasn't really watching what I was doing: I kept looking at the saw to see if it was flexing or moving. Nope - ship shape! It worked great.


Here's a final shot of the new turning saw posing in front of its predecessors:


Oh yeah - when I took that last picture, I had forgotten to snip off the nails that are functioning as the pins to final size. Quick work with nippers - should have done it before the picture. Doh!


11 comments:

  1. Very nice Dan!
    You'll appreciate the turned handles. I've found they are very comfortable when working with thinner, more delicate, cuts.

    A tip for cutting saw blades. I offer it because I too often pinch my finger tips when using shears. (Wanna see how I know?) Instead, grab a file and mark the blade enough to get well into it. Then, use your metal vise (or even vise grips) and snap at the filed line.

    Beautiful saw!

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  2. Bob - Thanks! I like the look of the turned knobs a lot. To be honest, I have never used them as handles - it just doesn't feel right to me. I always hold the frame arm just above the knob - but what do I know? Maybe it will be different with the turned handles - I'll give it a shot.

    Thanks for the tip on snapping the blade.

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  3. What type of twine do you use? I've simply used jute twine because it's what I had laying around and found it broke well before I got the saw up to the proper tension. Maybe I need to make a trip to the hardware store for some different type of twine.

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  4. Nifty. How does it feel in your hands? You'd mentioned that your prototype was better than the successor; I'm wondering how this one seems. Or haven't you had enough time to fool around with it yet?

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  5. Kent - The twine on this saw probably came from the Borg. It's standard stuff - cotton I think. It looks exactly like this picture over on Wikipedia.

    I think I've used jute before, and it did last longer with the oil treatment, but it's not as good as this - I think the strands frayed and separated.

    Brian - Well I haven't used it much, but it is vastly superior to the second one. It feels solid and acts like it knows what it is doing - if you know what I mean. I think it might be a little top heavy - the center of gravity is just above my hand hold. I'm not sure what effect, if any, this might have on use. I really like the thicker arms, it feels more like a plane tote in my hand

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  7. Dan,

    Great work, now that I know how you've done this Project, I'll be attempting the same thing, but not til Spring lol, Don't have a Woodstove to keep my Shop warm and don't have any other heating means.

    Love the work on the Saws... Oh wanted to tell you, I just Won a Stanley #191 SW Rabbeting Plane off ebay for 19 Bucks with 7 Shipping, you know much about The Rabbeting Plane?

    Mainly buying some to help with my Handtool collection, but wanted some that will help me with small projects where my power tools can't help me.

    I know this Plane will be more for my Medium to large projects, but just wanted to ask.

    Thanks for the How-To on this Saw, was great watching you put it together.

    Handi

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  8. Handi - glad you enjoyed the posts, and I hope you have fun making one too.

    I think the #191 is pretty similar to the #78, but without the fence. This is not a problem, you just use a batten to guide the plane. Or, you could use your finger tips under the plane as a fence. Once you get the rabbet started, the plane should guide itself. Sounds like a good tool for your collection.

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  9. Dan,

    I hope so, This one kinda looks like the Bullnose Rabbet Plane with the Guide/Fence, Cept this one don't have one it appears and it also don't have the Upper Blade the other one has.

    There is a Rabbeting Plane I seen that has 2 Blades, 1 at the Tip bout an 1" Down or so and the other is about 2" From that one, maybe 3".

    I will Post the Pictures on my Blog if you want to take a Gander at them and see what you think, since you know more about Hand Tools then I do at this time.

    Handi

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  10. Handi - Yeah, the #78 has two blade positions (but only one blade). I've never used mine in the front bullnose position though.
    I'll check out the pictures.

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  11. Greg's Comment: I was wondering what you might recommend with regards to blades to someone without access to an old bandsaw blade. Also, how long are your saws and is that the optimal length. Last but not least, how is your handle design working?

    Greg - Well, first I should say that I didn't use an old band saw blade - I happily cut up a new one! "No electrons for YOU my friend!" They're pretty cheap and easy to find locally (or on Amazon etc. if needed). You could also buy blades specifically made for bowsaws, but where's the fun in that?

    The blade is about 14 1/2 inches long. I can't remember why, but it seems to work well. I don't think it is exactly "optimal" - you could easily make it longer if you wanted to. For cutting stock of less than 1 1/2 inches thick, it works fine. If you were going to cut thicker stock, you would want a longer blade with lower PPI. Of course, you could make a second stretcher and just swap out to use the longer blades...

    I'm very happy with the handle design. I need to tweak the tenons to allow the cheeks to pivot more and deliver a smidge more tension to the blade, but the handle design itself is working great.

    Thanks for commenting.

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