Author Topic: 240's sheep horn bow build with Tom Lucas  (Read 37935 times)

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Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #105 on: January 26, 2019, 08:00:32 pm »
JNY-have you built a few of these yourself, it sorta' sounds like it:)

Here is what i did today with a heat gun. Quite a bit better, no? This was my first time bending horn...OMG it bends exactly as much as you set it to...i noticed ZERO giving back.  In fact i over shot it on purpose the first two times and over corrected it!

I have heard of the horn "giving back" to the twist after corrections, a couple members had warned me of this.  I suppose we shall see., huh?
« Last Edit: January 26, 2019, 08:05:21 pm by NorthHeart (240m3srt) »

Offline JNystrom

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #106 on: January 27, 2019, 12:40:02 am »
Great! It's magical.  ;)

JNY-have you built a few of these yourself, it sorta' sounds like it:)

I might have, in previous life... In this life i have built couple of wood-horn-sinew composites. And more to come.

I have bow here that was really twisted and i gave it multiple heat straightenings, but now after half a year, it hasn't changed at all. I think it comes down to if you don't use enough heat, then the bend will undo.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #107 on: February 12, 2019, 12:58:26 pm »
Work on the horn bows continues slow but steady. I worked the limb dimensions down a bit after removing the sinew on the ends(became obvious it was way too thick). Braced the small bow and heard a little splitting sound as the string separated the sinew from the back of the bow about and inch(I got lucky). Glued it back down and promptly rewrapped the ends. I have decided to build up the nocks with sinew on the ends. More will be added since it shrinks after it dries. I am deciding now if I will reflex the handle ďset backĒ so that itís easier to brace. Looks sexy too. A bit intimidating to do this with the sinew already on the back but I know it has been done this way by a few others.

Offline loefflerchuck

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #108 on: February 18, 2019, 08:54:48 pm »
JN, keep in mind you have a wood core to keep the twist out. Horn and sinew alone tends to return

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #109 on: February 24, 2019, 03:50:25 pm »
Bent my short Sheephorn bow into the 5 curve profile. Got it initially tillered to brace at 3.5Ē and flexing it out to 12Ē. I have never held a bow in my arms like it was my baby until now :OK. But i must remember itís not a bow yet, Ill need to draw it further and make sure the string stays on, which is my main concern at this point due to narrow limb tips. Still Iím thankful that itís even made it to this point in its life.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #110 on: February 24, 2019, 04:04:46 pm »
For the method of bending the shape i used a form and a heatgun(carefully).  I must give credit here to Wizardgoat, i used his form shape as guidance for making mine.  Also i know Chuck uses forms of a somewhat similar design, so thanks to both these gents for paving the way.  If it weren't for deflexing on the form, im not sure that this particular bow would have a chance of holding at brace with out flipping around, as the string attempts to slide around the narrow limb area near the nocks.  This is still my biggest fear, and i may still use more sinew to try and build this area up even wider.  I had to make 3 strings just to get one with small enough loops to go over the horn.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #111 on: February 26, 2019, 09:31:58 pm »
I heated the larger of the two bows into a similar shape. It is now at brace too.  We will see what happens from here.

Offline loefflerchuck

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #112 on: March 04, 2019, 06:32:37 pm »
You've done a great job! Like I told you you can reheat the bow with the sharp hinge bends but this time use clamps on every inch of the limb to keep one spot from hinging. It either happened from that spot heating to bending temp first or maybe a slightly thinner spot. Check it with a caliper and even out that bend. I think the safest way is wrapping the limb with a heating pad and clamp to shape on the form

Offline wizardgoat

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #113 on: March 04, 2019, 09:13:45 pm »
Coming along great, I agree with Chuck, although Iíve never used his heat pad idea.
My last horn bow had many heat gun sessions, very short blasts then quickly clamp.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #114 on: March 05, 2019, 11:21:04 pm »
I heated the bigger horn bow on the lower limb in order to make the deflex a bit more smooth.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #115 on: March 05, 2019, 11:26:08 pm »
Big day today. Baby shoots her first arrows...the smaller sheephorn bow that is. I needed a tiller check from a veteran eye and my buddy James Rempp was happy to help. Often as he flexes a bow he tells me itís a bit stiff here or there. You can imagine my surprise when he says ďnice job, letís shoot it!Ē I told him to go ahead and be the first! Did you know that after all the research and work I had still never actually shot a horn bow! Well he really enjoyed shooting it and then later this evening I shot it too. So smooth and sweet! Thereís still some work to be done here and there, but I am happy to see an unbelievable amount of hours and learning lessons transfer into something that works. Just wow!

Offline Deerhunter21

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #116 on: April 22, 2019, 12:22:50 pm »
I know this ended a little bit ago but I never got to say congrats! You built a good bow! good job!
"Only when the last tree has died and the last river been poisoned and the last fish been caught will we realise we cannot eat money." Cree Native-American Proverb

A amature practices untill he gets it right. A master practices untill he never gets it wrong.

Russell - 15 years

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #117 on: April 22, 2019, 07:11:41 pm »
I know this ended a little bit ago but I never got to say congrats! You built a good bow! good job!

Thank you for saying so Deerhunter!  But i still have more to go, and the lessons continue. 

I haven't seen much info regarding the actual performance of sheep horn bows(fps and such).  I plan to do some testing to gain insight on both bows.  The short bow was drawing around 39# at around 16", 525gr arrow around 102fps.  Certainly wasn't gonna break any records, but i was thankful it was shooting and still in one piece.  Wanting to push further, i added another layer of sinew pulling it into more reflex and resulting in what would obviously be a higher pound bow.  But keep in mind how narrow the limbs were near the tips. It started tweaking the limb in this area due to the force necessary to brace the bow. Also the string loops were starting to slip down the nocks and actually debraced the bow when i attempted to string it.  So i put it back on the form to induce more deflex in the limbs with heat, only this time the sinew lifted from the horn in one area, all the way across:(  I don't know if its because i heated it too much, or if i simply exceeded the amount of times that hide glue will allow one to continue making heat corrections. In an attempt to repair this i injected hide glue into the crack with a syringe.  I doubt it will be as good of a bond as original but it was about all i could do at this point.  Also, this occured in an area where very little flexing occurs, so i still have hope. After all this i wrapped the entire limb with a light layer of sinew to hold things down.  The tiller still appears fairly close and this was the lower limb which will be stiffer anyhow.  Also i added more sinew to my nocks to keep the string on. 

At this point the draw weight is up, and i think i'm still ok on my horn/sinew ratio though its probably close.  Now i have some choices to make so that i can brace the bow without the limb tips tweaking from the force.  Either heat it again in the form to induce deflex into the limbs which should reduce the distance the tips have to travel to brace.  Or possibly build side plates to reinforce the tips and wrap it them with sinew.  One thing thats for sure is i keep learning about the horn bows, and thats as important to me as the bows themselves ;)

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #118 on: April 22, 2019, 07:13:26 pm »
Current profiles.

Offline NorthHeart

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Re: 240's sheep horn bow build with Tom Lucas
« Reply #119 on: May 02, 2019, 08:31:53 pm »
The small sheephorn bow is back with some zip! After separation of the sinew from the back in multiple areas I decided to wrap both limbs with sinew down the entire length. I used heat to re-tiller the bow and get some of the reflex out because the stress was causing the ends to start twisting at brace. I believe I finally found the balance between gaining more power and what the bow can handle without over stressing the limb tips. My old speed was a 525 gr arrow at 102fps. Itís now shooting an average of 137fps. The specs are 45# @ just shy of 18Ē. Now the question is one of how far it can be drawn safely? Iím sure even more speed and power lie there waiting, tempting me. I remind myself itís my first sheephorn bow ever, I deviated from original design concepts half way through the build, and made plenty of mistakes along the way. I am elated to see it come this far, and I now consider it a bow.