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Thread: Take a bow

  1. #1
    Join Date
    Nov 2012
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    Default Take a bow

    Howdy folks

    I was getting ready to cut a saw handle in blackwood when i destroyed my old coping saw. Not a huge issue at the time - it was a relatively cheap unit.

    But in the breaking i saw an opportunity to make a bow saw.
    On to my old friend Google for some inspiration and to identify what was required.

    I noticed some kits and parts from Grammercy Gramercy Tools Turning Saw Parts
    But all up the parts and bits were a bit expensive - especially the brass bits - so i thought i would give making it all a crack. What could go wrong.

    So i thought about it a bit more - and bought some of the 12" blades - i wasn't going to make them

    Down to the commercial shed and couple of bolts later (5/16 for the curious)
    20131116_174016.jpg20131116_174043.jpg20131116_174116.jpg

    I hacked into them with a grinding wheel with some adequate results - not great but this is a proof of concept for me.

    Once done, i knocked up a template for the handles and went to town on some NSW rosewood that was pretending to be rubbish.



    20131130_174903.jpg20131130_180112.jpg20131130_180115.jpg20131130_181456.jpg


    A little bit of sanding and some jute later, I threw it together to see how everything looked and was holding together. The locking piece (in the twine) is a small bit of cedar.
    20131208_143936.jpg


    I was not overly happy with the jute - under highish tension you could hear to fibres starting to give way - so a bit later i will change that for some cotton rope or sash cord.
    Here is the finished(?) unit. Oiled up and ready to go. It works great - sliced into some pine really well - a bit of break out - but it is only a 10TPI blade.

    20131214_155047.jpg20131214_155112.jpg20131214_155131.jpg



    In the near future - probably next weekend - i will get some 5/16 threaded brass rod and make some pins from that. I intend to use a dome nut and washer on the outside - should look a heap better and the brass will cut a lot easier than the bolts did.

    Thanks for looking.

    Cheers

    Norm
    Can you imagine what I would do if I could do all I can? -- Sun Tzu

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  3. #2
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    Default

    Norm,
    Well done
    Another one for the to do list.
    Regards
    John

  4. #3
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    If you get some brass you could come around and turn them if you like. Rather than dome nuts and washers.
    …..Live a Quiet Life & Work with your Hands

  5. #4
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    Default

    Very Nicely Done!

  6. #5
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    Thumbs up

    Well done young fella!! Double the fun - making and then using!!!

  7. #6
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    Default

    nice piece of work

  8. #7
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    Default

    Thanks for the comments folks - they are much appreciated.

    It is very satisfying to use what you have made to make something else.

    Dale, thanks for the offer of assistance with the brass. I may take you up on it in the new year.

    In the meantime you did prompt me to think a bit more on it.

    There is nothing to stop me using the threaded rod and also fabricating a nut for it out of brass - maybe a 1/2" square rod?

    I may have to duck into George White and Co and grab a couple of small pieces.


    Cheers

    Norm
    Can you imagine what I would do if I could do all I can? -- Sun Tzu

  9. #8
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    Quote Originally Posted by enelef View Post
    Thanks for the comments folks - they are much appreciated.

    It is very satisfying to use what you have made to make something else.

    Dale, thanks for the offer of assistance with the brass. I may take you up on it in the new year.

    In the meantime you did prompt me to think a bit more on it.

    There is nothing to stop me using the threaded rod and also fabricating a nut for it out of brass - maybe a 1/2" square rod?

    I may have to duck into George White and Co and grab a couple of small pieces.


    Cheers

    Norm

    Even if your going to fabricate it why not use rod and just use a tap and die to just thread the end.

    George white will be expensive, you should be able to get what you want from most scrap metal places.

    You can just buy pins. A pair of pins ($17.95)US
    We designed these brass pins for a turning saw of our own design that uses 12" cross-pined blades (just like coping saw blades only longer). We also wanted to be able to handle a range of blade sizes, so these pins have a hook for cross-pinned blades, as well as a 1/16" hole for mounting drilled blades. The slot for the blades is .030". The pins have a wide shoulder to take the tension of the saw. Behind the shoulder the shaft has grooves and a flat for an interference fit so once a handle is glued in, it will not twist or pull off. Overall the pins are about 2 3/4" of which the front part of the shaft with the hook is 1 7/8" long.

    Another design issue: how to attach the handle to the brass? Some modern saws use an obvious solution - cross-pinning the handles to the brass. It's not that hard to do, but we wanted to offer a kit that could allow everyone to make a saw. That meant adding cross-pins to the kit, and the need to locate and drill through metal and wood rounds together. This is a real problem if you don't have the right tools. Gluing the hardware into the handle is simple enough, but brass doesn't readily stick to glue. So, our ultimate solution was to cut some grooves in the shaft and then file a single flat. When the glue hardens in the handle, it catches in the grooves to prevent pulling out. Glue on the flat prevents the brass from turning in the wood. With the tension on the blade taken firmly by the brass shoulder, the glue doesn't even have to be very strong.


    Here is a complete set of drawings
    http://www.toolsforworkingwood.com/e..._full_8x14.pdf



    Here is a different approach.
    …..Live a Quiet Life & Work with your Hands

  10. #9
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    Hi Norm,

    Nice job Norm.

    Did you taper the pins? I discovered (too late) that the traditional way was to taper the pin and the hole slightly, so that as you crank up the tension it locks the blade orientation and doesn't spin around while you are cutting.

    I used 3/8" threaded brass rod, details here.. Making Bow Saw Handles - Step 1. Tapping the Handle for 3/8" - Saws Seen - Saw Scene - Saws I've Seen

    Regards
    Ray

  11. #10
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    Default Just Pictures...








  12. #11
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    Quote Originally Posted by RayG View Post



    Did you change your mind about cutting the slot with the hatchet and decide to use the hacksaw instead???
    …..Live a Quiet Life & Work with your Hands

  13. #12
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    Thanks for the info RayG. Very interesting about the taper - but i could see how it would be useful.

    Unfortunately, i don't have the requisite machinery or knowledge to do most of that -but I should be able to re-purpose an old file handle and maybe () finish with something similar.

    I can also experiment a bit with other hardware. I have the measurements now so.....


    Dale- i will take your advice and will go up the road to the local purveyors of scrap metal to see if they have any useable brass on the weekend.


    Cheers
    Can you imagine what I would do if I could do all I can? -- Sun Tzu

  14. #13
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    You can put the round brass in a electric drill and spin it against some sand paper. Low tech way to do same.
    …..Live a Quiet Life & Work with your Hands

  15. #14
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    Enelef - good effort. It is indeed very satisfying to use own-made tools, and I see you are well on the slippery slope, thinking about improvements already.

    I like to put a handle & knob at each end. Apart from appearance, they are very handy if you use your bowsaw for cutting a lot of curves, making it easier to twist the blade this way & that to allow the blade to reach the cutting points. As Dale has shown, there are a number of ways to attach them, the main consideration is making sure they are firmly locked onto the shaft, so they don't come undone when you are adjusting the blade. My design for the metal bits is over-elaborate, but not hard to make if you have access to a lathe. I'd take DSEL up on his kind offer turning brass is easy & great fun. This is what I currently favour, turned from 1/2" diameter rod:

    Metal bits.jpg

    The screw for the handle is silver-soldered into the turned shaft, and usually, just screwing it tightly into the handle is enough to lock it, but if it wants to undo, a bit of epoxy or Loctite will discourage that. (The difficult part is finding the screws, the chain hardware stores don't carry large 12 or 14G brass screws any more).
    The shaft for the knob is also tapered and threaded for a split nut, which is much more elaborate than necessary, I do it that way because I can. It could be done other ways, but however you attach it, you do want the knob to lock firmly so you can turn the blade without having it come loose. I only taper the shaft where on the handle end, and that seems to be enough to hold everything firmly once the cord is tensioned up. It takes very little taper to lock the shaft when the saw is tensioned up (1.5 degrees is fine). Another way to make it lock under tension is to use an O-ring between handle & arm - I used this method quite successfully before I had my metal lathe.

    You may not see the value in being able to lock it now, when the saw is new and the shaft fairly firm in the arm hole, but if you use it a lot, the holes wear, and then it can be very annoying, trying to keep the blade from twisting while you are cutting tight curves...

    Cheers,
    IW

  16. #15
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    Thanks for that Ian.

    I do wish to take Dale up on his offer in the new year. In the meantime I will try out a few other options within the limits of my workshop to see how they go.

    I do like the idea of turning either a 1/2" or 3/4" round bar down to dimension, then having a large decorative brass washer/plate spreading the load.

    I can also definitely see the added value in the handles, for changing blade alignment


    All the best

    Norm
    Can you imagine what I would do if I could do all I can? -- Sun Tzu

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