Author Topic: My horn bow build-a-long  (Read 125661 times)

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Offline DC

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Re: My horn bow build-a-long
« Reply #75 on: July 18, 2019, 10:39:06 am »
And with the alignment tooth and some sample grooves. Groovy ;D ;D

Offline gorazd

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Re: My horn bow build-a-long
« Reply #76 on: July 18, 2019, 02:55:11 pm »
Hello DC,

You can make pretty good scraper from saw blade... buy some blade like this in the picture and file only VERTICAL side of each tooth ! You make 45 degree from this 90 degree slope in just two moves !
Do not touch the other side !  :)  .... to not mess with symetry

Count the moves, one ore two moves more and symetry is gone  :-[


Here is my scraper made from butcher saw  8)








Thanks Bassman. I'm still in waiting mode so I thought I would try my hand at making a groove scraper. I used an old cabinet scraper for steel. I had a bit of a chore getting it soft enough to file and then it warped when I hardened it but the screws pull it down flat. It's 16 TPI. I'm having a tough time seeing the teeth to get them even. Maybe I'll go buy a pair of reading glasses. I was using a magnifying glass but trying to file one handed ain't my thing. I didn't notice how uneven the teeth were until I took the picture :-[ :-[. I still have to make the alignment tooth. I'll post a picture of it then. I'll have to play orthodontist with those teeth first though. I did a test scrape and even with the crooked teeth two pieces mesh quite well.
« Last Edit: July 18, 2019, 02:59:01 pm by gorazd »

Offline DC

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Re: My horn bow build-a-long
« Reply #77 on: July 18, 2019, 04:40:45 pm »
I may try that. I've got a bunch of old saws. I'll have to look and see how many TPI they are. The 16 TPI kinda looks small. Did you use the movable alignment tooth idea of Adam's?

Offline gorazd

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Re: My horn bow build-a-long
« Reply #78 on: July 18, 2019, 04:55:23 pm »
No,

I fixed the bow perpendicular on the desk ..the desk was the guideline for scoring blade.



I may try that. I've got a bunch of old saws. I'll have to look and see how many TPI they are. The 16 TPI kinda looks small. Did you use the movable alignment tooth idea of Adam's?

bownarra

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Re: My horn bow build-a-long
« Reply #79 on: July 19, 2019, 11:16:11 pm »
Remember the old bows weren't made with matching grooves. It is a nice thing to do but unnecessary. The more bows I've made the more I think it is a waste of time making matching grooves. My heaviest, most stressed flight bows have non matching grooves. One of them has survived two broken strings in the name of testing with no problems. With non matching grooves you don't have to bother making the teeth even in fact it is best if they aren't even.

Offline DC

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Re: My horn bow build-a-long
« Reply #80 on: July 20, 2019, 10:05:00 am »
I've read that and I may not do it on the next one(if there is a next one). I thought that it might be a little insurance on the first one and it's part of the whole experience I guess.

Offline DC

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Re: My horn bow build-a-long
« Reply #81 on: July 20, 2019, 07:10:13 pm »
I tried grooving a piece of wood similar size to the horn. I couldn't get the alignment tooth to keep in the groove. It kept following the grain. I finally gave up and made a trough. That seems to work better. The scraper I made from a cabinet scraper was too thin. At least that's what I think was causing a horrendous squeal that would feed back through my hearing aids and get worse. If I took the aids off I couldn't hear anything and I'm not sure which was worse. I'm just about done making one from a saw blade. It's a little coarser at 11 TPI.

bownarra

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Re: My horn bow build-a-long
« Reply #82 on: July 20, 2019, 11:06:57 pm »
Practise :)
It is easy enough once you get the hang of it. More tpi is better. Less tpi means you've got to groove deeper. If it was following the grain make the initial straight groove deeper. Use a scapel or very thin blade.

Offline JNystrom

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Re: My horn bow build-a-long
« Reply #83 on: July 21, 2019, 03:17:08 am »
Remember the old bows weren't made with matching grooves. It is a nice thing to do but unnecessary. The more bows I've made the more I think it is a waste of time making matching grooves. My heaviest, most stressed flight bows have non matching grooves. One of them has survived two broken strings in the name of testing with no problems. With non matching grooves you don't have to bother making the teeth even in fact it is best if they aren't even.

How heavy are your bows? Not many people make these with non matching grooves, so i'm really interested. Some people leave non matching groove bows lighter, cause they still fear the glueline. I feel there is some vital info still missing from the old way to gluing up core and horn.

My last couple of bows, i've used toothing plane blade. It's really a pleasure to groove with, it's high quality tempered steel and easy to sharpen with. I think you can find a picture of it from my hornbow thread here.

Offline JNystrom

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Re: My horn bow build-a-long
« Reply #84 on: July 21, 2019, 03:25:32 am »
Sinew shrinking doesn't give the bow much reflex at all. Most of the gained reflex comes from tying the string between the tips and increasing the reflex after each layer.
The sal should be straight to begin with.
Adam explains the reasoning behind not having reflex in the sal it is to do with separational forces between the layers.

You can have reflexed sal sections, as many many bows back in the day had. Separational forces are real, bigger with thicker limbs, but doable with good glue up work.
Crab bows, korean bows, tatars and turkish flight bows area all believed to have almost tip crossing reflex before sinewing.

Sinew reflex is nice, but what really makes the form is the wood core and horn. If sal sections are straight before sinew, eventually the bow will also be straight in these sections after tillering. All these bow types i earlier listed, had quite generous reflex when off the string. Well, my bows either haven't been reflexed this much, but in the future they hopefully will be.

That said, for a beginner or for a really heavy 150+ pound bow its good idea to have the bow less reflexed. It raises the possibility for a successfull bow greatly.
Good luck!

Offline DC

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Re: My horn bow build-a-long
« Reply #85 on: July 21, 2019, 07:16:56 am »
 This bow will be 40-45# so I'm not expecting it to be a screamer. If it's any more than that it will be a wall hanger cause that's all I can pull. I'm doing this for the fun of it, just to see if I can.

 At 40+# I probably don't need grooves at all but what the hey.

 All my old saws had coarse teeth. 16TPI looked a little small to me but this 11TPI look too big. I'll look around.

bownarra

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Re: My horn bow build-a-long
« Reply #86 on: July 21, 2019, 11:22:39 pm »
The grooves stop the core from breaking. Look into how modern composite materials work - same principle.
Yes I know you can have reflexed sals, I've done it quite a few times. I have made a few different styles not just Turkish. With perfect gluing technique yes you can get away with it but take a closer look at those designs you mention - straight sals all feature :) A reflex out of the grip is not a reflexed sal :) As you say tip crossing reflex before tillering means little it is the shape of the core that matters. Only Turkish flight bows (out of those that you mention) had slightly reflexed sals before sinew.
I am just tillering two new heavy bows, one flight and one war. I haven't weighted them yet but I've had to make a press for these two, I can't bend them to brace by hand....they must be close to 150# as I've tillered a few 80/90/100# ers. The bow I mentioned before has shot over 600 yards (with less than perfect arrows) my goal is get close to the old record of 900 yards but these things take time!

Offline DC

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Re: My horn bow build-a-long
« Reply #87 on: July 25, 2019, 12:29:30 pm »
I couldn't get the alignment tooth to work so I went with the trough kind of idea. I scraped one limb of the test bow and made a pseudo "horn" piece out of a piece of Ocean Spray. It has the same density as horn(1.2) so I thought it was a reasonable substitute. After steaming the "horn" they fit together nicely. Here's pictures of the resulting grooves and the scrapers and jigs. I used the bending form as one of the jigs. I just made one scraper blade and move it from handle to handle as needed.

Offline JNystrom

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Re: My horn bow build-a-long
« Reply #88 on: July 25, 2019, 03:05:26 pm »
Yes I know you can have reflexed sals, I've done it quite a few times. I have made a few different styles not just Turkish. With perfect gluing technique yes you can get away with it but take a closer look at those designs you mention - straight sals all feature :) A reflex out of the grip is not a reflexed sal :) As you say tip crossing reflex before tillering means little it is the shape of the core that matters. Only Turkish flight bows (out of those that you mention) had slightly reflexed sals before sinew.
I am just tillering two new heavy bows, one flight and one war. I haven't weighted them yet but I've had to make a press for these two, I can't bend them to brace by hand....they must be close to 150# as I've tillered a few 80/90/100# ers. The bow I mentioned before has shot over 600 yards (with less than perfect arrows) my goal is get close to the old record of 900 yards but these things take time!
Well we need to disagree then about the sal reflex. All those bows had a huge amount of reflex, something that many modern era replicas lack.

Over 600 yards of distance would be a world record. How did you measure the distance?
It sure is true hornbows take all the time in the world to master. And then the shooting...

bownarra

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Re: My horn bow build-a-long
« Reply #89 on: July 26, 2019, 04:38:29 am »
Look again - no they don't have hugely reflexed sals. When the core was made and the horn glued, they are straight in the sals. As I said I've made a few bows of all the designs you mention.
I don't really care about modern 'records'. I measured it with a 100 yard tape. The heaviest bows I shoot with a machine. Upto 80# I shoot by hand and have managed just shy of 500 yards with that bow but as I say arrows haven't matched the bows perfectly.