Author Topic: tip tips please  (Read 1021 times)

0 Members and 1 Guest are viewing this topic.

Offline stuckinthemud

  • Member
  • Posts: 1040
tip tips please
« on: September 05, 2017, 09:47:22 am »
Evening everyone.
When carving buffalo horn tips into (side) nocks, what are the approximate length:width dimensions I should be aiming for? The tips I have carved are over-sized, I think,at two inches long and the string grooves are a long way from piercing through the horn. They are 12mm across the socket, 14mm outside diameter.
Thanks

Offline Del the cat

  • Member
  • Posts: 6661
    • Derek Hutchison Native Wood Self Bows
Re: tip tips please
« Reply #1 on: September 05, 2017, 11:49:56 am »
Like most things... experience will get you there.
IMO it is by far the best way to mount the horn on the limb tip, then shape it. I used to try and shape 'em first.
The big first mistake is to start with a huge bit of horn... most blanks will provide both nocks rather than just one.
The effect you are looking for is as thin layer of horn that you can almost see through in places... so just 2 or 3 mm thick.
The groove must be a reasonable distace above the base of the nock (I often see nocks where it isn't) else it can split out.
Second common mistake is the hole is bored out as a conical hole at too steep and angle giving a short sharp taper. IMO a long slender slightly curve shape should be given to the tip and to the drill bit. There is video of me doing horn nock (not side nocks) on my Youtube channel ELB build along...  it even shows how to make mistakes :)
https://www.youtube.com/watch?v=k1VHUkDEGJA&index=9&list=PLBz2tD9476KQFyMBLEylQGh952tBT_mZB
People will doubtless have other opinions, but mine is that all surfaces should be smooth and rounded else they will chaffe the string.
I don't do them often, but there's one on this post from my blog.
https://bowyersdiary.blogspot.co.uk/2011/04/side-nocks.html
Del
Health warning, these posts may contain traces of nut.

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #2 on: September 06, 2017, 02:53:43 am »
Sidenocks are very different to Victorian nocks.  The horn needs to be very thin - virtually translucent.  If it's too thick you need to carve down through it too far, making everything lean when braced.

The MR sidenock was 70mm long, and the slot starts about 6mm from the base.  It needs to be cut at an angle slightly less than 45 degrees, and must go through the horn into the wood.  This is crucial for buffalo horn otherwise all the strain of the string is on the lip of the horn, which will split easily.  The wood needs to take the downward force, and the horn is there to support the wood from the crushing force of the string around the back of the bow.

Basically, the smaller you make the horn the better.  You don't want it to look like there's a chunk of horn at the end, but it should look more like the bow tip suddenly changes colour.

Offline Del the cat

  • Member
  • Posts: 6661
    • Derek Hutchison Native Wood Self Bows
Re: tip tips please
« Reply #3 on: September 06, 2017, 03:50:37 am »
I'm assuming Will's "6mm from the base" is a typo and maybe he meant 16mm?
Weapons of Warre has the scale drawing of the nock (see below) and it looks more like 16mm minimum to me, and nearer 20mm at the higher edge.
I'm willing to stand corrected if he has handled the nock and measured it.
Del
Health warning, these posts may contain traces of nut.

Offline colin1991

  • Member
  • Posts: 41
Re: tip tips please
« Reply #4 on: September 10, 2017, 02:56:59 am »
Keep them thin and no need for the bulb need the base like in a Victorian nock. Just blend them into the limb with a nice smooth transition. Like Del said, Mount them and then shape them on the bow.

As far as Buffalo horn splitting if it's not cut to the timber... Nope, I've got buff horn on 100+lb bows that's just into the horn and they hold up just fine. You will be able to tell straight away if the horn is no good when you're working it because it will crumble.

Will, sorry mate but you are really getting the engineering and mechanics of a horn nock mixed up. Horn is stronger in both crushing and shear that the timber bow limb. The horn provides a stronger surface and larger bearing surface for the string to contact, preventing the tip from failing. Cutting the nock groove into the timber is purely coincidence and simply because of the shape of the cone in the horn, the horn tip itself and the shape the groove needed to be to hold the string on the bow for that particular bow.  Better to have the groove too deep so the string can't possibly come off in battle than too shallow where it might.

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #5 on: September 10, 2017, 04:34:36 am »
137 out of 137 bows with the sidenocks cut into the wood is a lot of coincidence ;)

Offline stuckinthemud

  • Member
  • Posts: 1040
Re: tip tips please
« Reply #6 on: September 10, 2017, 06:09:36 am »
Well, my lack of experience showed up very quickly, I found a small void in the back of both nocks between the wood and the horn, but I found it the hard way when I cut into the void rounding up the horn tips. I think the taper I used was too long at 5cm, trying a shorter taper with a modified drill bit.

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #7 on: September 10, 2017, 07:12:30 am »
Your goal really with the inner cone is to shape it as close as possible to the natural cone left when cow horn sheds and the inner core falls away. 

It's very consistent in shape, and looks remarkably similar to the way most people grind their drill bits.  Obviously if you can use cow horn that has lost its inner core it saves you an awful lot of time!

If you can't use naturally hollow cow horn, a convex taper is the way to go, and 5cm is perfectly fine, provided the fit is good!  One good way of getting the horn to fit the wood perfectly is to chuck it in hot water for a bit, then tap it down onto the bow tip and let it cool to shape.

Offline stuckinthemud

  • Member
  • Posts: 1040
Re: tip tips please
« Reply #8 on: September 10, 2017, 08:35:13 am »
Thanks for the hot tip Wills! I made several mistakes on that pair of tips, I hand carved the hollows with flat tops to match the profile of the bow, spent hours finessing with chalk dust, lost track of how long each tip took, then messed up the final shaping on the bow! Its taken about 20 minutes a side with the drill bit! The cones currently measure 17mm across (the width of the limb at that point) by 22mm in length.

[img] https://stuckinthemudsite.files.wordpress.com/2017/09/img_20170910_164821.jpg [img]

apologies for the link, this usually works for inserting an image, dunno why its inserting a hot-link instead.
« Last Edit: September 10, 2017, 08:42:50 am by stuckinthemud »

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #9 on: September 10, 2017, 09:04:21 am »
Ideally you'd want a more slender, graceful transition from bow limb to tip.  It should all look like it's flowing from one element to the other, instead of limb - cone.  If that makes any sense?!

With a drill bit, the entire process of fitting the nocks should be about 5 minutes for both together.  My method is (if not using naturally hollowed cow horn):

1. Draw around the drill bit onto the bow tip, and shape it to match exactly.  I do this with a sharp knife and it usually takes about a minute per tip.  Use a scraper to smooth everything off and make it round.

2. Holding the horn tip in my left hand, I drill down into it holding the drill in my right.  This lets me feel if the drill is wandering off centre and I can easily adjust my angle to keep things straight.

3.  Push the horn onto the tip, and if it doesn't quite fit sand the tip slightly.  If it's a bit further out than sanding will allow, it goes into hot water and then gets tapped on with a light hammer.  This water method makes the process take longer but after you've done a few is very rarely needed.

4.  Fill the horn with hide glue (or whatever you're using) and shove it on and let set.

5.  Mark the position of the string groove and cut down to the wood using a good sharp knife.  Open the slot as wide as necessary, round everything off with the knife followed by a wipe of sandpaper and you're done!

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #10 on: September 10, 2017, 09:13:36 am »
Here's one I made earlier  ;D  It was for a 135lb bow and designed to be used with a linen string.



And this is what the wooden tip looks like, if you imagine the horn is removed




Offline stuckinthemud

  • Member
  • Posts: 1040
Re: tip tips please
« Reply #11 on: September 10, 2017, 02:18:03 pm »
Thanks Wills, that couldn't be any clearer. Looks like I need to re-profile my drill bit. Ironically, my first effort pretty much matched your example except I'd blunted the end by a tiny amount. Shouldn't have got so enthusiastic with the rasp, should have marked the taper on the horn. All good experience, I suppose...

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #12 on: September 10, 2017, 02:28:58 pm »
Funnily enough, loads of the MR bows have blunted ends.  Some are squared off, and quite a few are cut at upwards tapers, which shows that they either poked through the horn nock and were simply chopped off to be flush with the horn, or were carefully tweaked to fit the natural hollow in the cow horn when the bone core fell out.

One thing to note if you are interested, is that the nocks on both ends were cut at different angles.  Presumably the top one had a fixed loop, and the bottom a knot or running loop depending on the string material (hemp won't take a running loop but linen will) so if you're fussy about particulars and want to go for the loop - knot approach that's a nice extra touch.

Offline colin1991

  • Member
  • Posts: 41
Re: tip tips please
« Reply #13 on: September 11, 2017, 06:09:27 pm »
I'd say the fact that all the nocks would have been blended into the limbs similarly and been kept small in conjunction with thicker, natural fibre strings would account for the coincidence... Would you not agree Will?

Offline WillS

  • Member
  • Posts: 1812
Re: tip tips please
« Reply #14 on: September 11, 2017, 10:56:27 pm »
No  ;D

I believe the choice to go down into the wood was deliberate.  It also makes the nocks way safer if they're glued with something that isn't particularly robust.  If the string is locked to both the horn and the wooden tip and the glue fails or gets too damp, the nock can't rotate or slip.  If it's just cut into the horn there's nothing stopping it spinning on the tip. 

It does also help the infamous theory about removable nocks, but I am definitely not going there...  In fact imagine I never mentioned it. :-X 8)