Tiller help please

[stuckinthemud]

I’m at 2/3 draw length, but I usually get most set when tillering the last few inches so I welcome your suggestions.
Andrew

[bentstick54]

What’s the length, and where do you usually get your set ?

[bjrogg]

My eye likes the bend of right limb. I think I would just keep removal even over entire limb.

Left looks a little stiff outer but my eyes might be tricked by tip length. My eyes want to tell me the left limb is longer but I don’t think it is. It seems to have a little character by the dark spot.

I’m just looking on my phone.

Looks pretty stout. Is it a for a crossbow?

Bjrogg

[stuckinthemud]

Length is 25” ntn, it’s a replica of the Dublin crossbow but in scotch broom rather than yew. There is character in that limb.  I usually get set in the outers.  I think the tips may be too stiff but there’s not much left there to remove, do you think the centre is bending ok?

[bjrogg]

I tend to end up like you with set usually in my others. I guess if I’m going to get set I think it’s better there than inner but that’s just my opinion.

I was guessing it was for a crossbow. And a pretty heavy one too.

I was thinking you could get center bending just a little. But I don’t know how that works with crossbow

Bjrogg

[bentstick54]

I’m seeing what Bjrogg is seeing. I think I would just take off evenly the entire limbs.

[stuckinthemud]

These old bows seem to often use a rounded belly so they do look stout, a bit like a mini ELB in some ways.  This one is a really mini little crossbow, 25mm wide at the centre and 19mm thick and only 63 cm ntn.  Funny thing it’s design is exactly the same as a larger one. The last normal sized one I built mostly recently is 95cm long, 30mm thick and 40mm wide at centre but only draws to 150lb - actually it draws to about 180lb but it uses a slightly shortened draw for longevity.

[stuckinthemud]

So, am back to close to full draw.  I’m at 10” from 24.5”ntn. (I remeasured)  I wouldn’t mind another 1/2” but 10” is ok.  I’ve got 2” of set, which is a bit annoying but I’m just too impatient, always drawing a bit further than I should I am not sure if the tips are a bit too strong, equally I may have weakened the centre a scrape or two too much. I’d be glad of your opinions.

[bjrogg]

It looks pretty darn good to me. Maybe just a little bit off left limb right in the area where it lines up with the bottom of that board. Probably wouldn’t take it from to small of an area there. I like the bend.
Where did you take set? Maybe you want to take a few scraps each side of the set to take a little stress off the set area?
I’d like to see the finished cross bow when you are done.

Bjrogg

[stuckinthemud]

Set happens 

[jameswoodmot]

Is there much history of Broom being used? From my very limited experience of it, mostly just clearing it where its growing as a weed, its pretty soft and foamy.

Also, are you dimentions consistant with the original? Im not familiar with the one you mention but most crossbows had very low brace height and stroke, 10" on a 25" bow seems like a lot compared to others ive seen.

[stuckinthemud]

There is absolutely no history of Broom being used historically for crossbows but it is an excellent bow wood once seasoned.  Strap it down while it seasons as it loses moisture very quickly and warps with a vengeance.  Flip side is it straightens with heat extremely easily.

I couldn’t find a piece of yew long enough in my stash, and I love working with Broom.  This piece has knots every 4 inches, including some pretty large ones but it still bends ok.  For length, width and tapers I have matched the original but I missed the thickness by 2mm as the pith was deeper than I expected. I also chose broom because I figured it would cope with a trapped/deeply rounded belly, as per the original.

Historic composite horn/sinew bows have the short stroke draw you refer to but historic wooden crossbows are much closer to archery bows in stroke to bow length ratio.  Not quite to the double plus 10% but much longer than the 8” of the hornbows,.

[superdav95]

So, am back to close to full draw.  I’m at 10” from 24.5”ntn. (I remeasured)  I wouldn’t mind another 1/2” but 10” is ok.  I’ve got 2” of set, which is a bit annoying but I’m just too impatient, always drawing a bit further than I should I am not sure if the tips are a bit too strong, equally I may have weakened the centre a scrape or two too much. I’d be glad of your opinions.

I like the bend on it like others have said.  are you going to be adding sinew

[stuckinthemud]

Probably not, not this time.  I did add a course of sinew to a similar bow and gained about 30% improvement in bolt speed, but no real increase in draw weight as I had to re tiller it.  I might re do it in yew though.

My main interest was in whether the original could have been built without set and I’m fairly convinced it couldn’t have been.  The original is described as being straight with only traces of sapwood at one end.  There are written sources in Italy describing crossbow makers’ guild rules controlling the ways in which sinewed wood bows could be made and sold in the late 13th century and the original is without context approximately of 12th or 13th century date..  A straight heartwood yew lath could indicate sinew, but it could also have been chewed on by borers or squashed under debris for 800 years. Also, why go to all the hassle of sinewing such a tiny bow? Why not just make a bigger one?  It’s all a bit of a puzzle.  Sinewed and 2mm thicker and in yew puts it at maybe 80 to 100lb, and that’s a punchy little bow, but 100lb in yew is easy to build…

[superdav95]

Please know that My thoughts or opinions on whether to sinew or not to sinew a little bow like this come from zero experience with making such a little bow.  But I’ve made several yew bows backed with sinew or other backings like bamboo or the like.  Sinew was not only the better enhancement to the bow but also resulted in more draw length compared to the original self bow.  Sinew has got to be the best natural enhancement available to a bow.  Pound for pound it offers more.   It would also be a match made in heaven for a heartwood belly that is know for excellent springiness and its ability to take compressive forces.  I bet if you were to find some high ring count heartwood yew and make another one of these with sinew you would see something special.  Just my humble opinion.