Wednesday, 18 March 2015

The Returning Bend!

The fast Bamboo backed Yew bow has been brought back... my heart sank when I was sent E-mails showing the lateral bend had returned.
On seeing the bow it was glaringly obvious, but the odd thing is it was worse than the original problem!
Something was shifting, the heartwood, the bamboo, the glue line?
I offered to completely refund what had been paid, or to replace it with a choice of bows.
A couple were tried and a similar 50# Bamboo backed Yew was chosen. The arrow plate is on the wrong side for a left hander, but I can do that at a later date when convenient. The bow was give an quick clean up, string grooves filed into the nocks and it was buffed up ready to get some use.

I can now play with the bent bow without any worry about ruining it or letting someone have a bow that isn't right. It's an opportunity to learn.

I took some pics and the bend seems to be at a point about 4" above the grip on the edge of where I'd done a belly patch to take out a worrisome knot.
It occurred to me that maybe it was that patch that was causing the bend, and if the patch can cause a lateral bend, then it can also cure it.
I'd also noticed when doing the patch last time I noticed that with the wood rasped away the bow had much less lateral strength, so that gave me my plan.

Rasp out the old patch and extend the area to be patched. Clamp the bow up with a good degree of over correction while the patch is glued in.
The patch itself will be hold in in the correction rather than expecting heat bend to hold it in.
The wrapping will come off tonight after a full 24 hours. I just hope I haven't over corrected!

You can see the rasped out scallop extends into the built up start of the grip. It needed a couple of tries to make the patch, and that was heat treated to match the belly of the bow before being glued in.

Ooooh Ha! A plan if the straightening doesn't work out I can remove the grip and make the bow into a 'take down' or 'carriage bow', it's something I haven't done and would be a nice addition to my collection. handy for travelling too.
Note:- The straightening didn't work and it gets made into a successful straight carriage bow. 3/32015

A bit of Flight Shooting:-
I took the flight bow down to the flood plain, it was still a bit muddy under foot, but clam and flat with no one about.
I had 4 arrows which I shot, packed away the bow and then walked out to measure.
My laser ranger finder target is a bit small once I got beyond the 160 yards which is where my "standard" field shooting arrow landed.
The next two arrows were only a couple of yards apart at 182 and 184 yards.
The furthest arrow was a slightly longer shaft and dropped at 215 yards, maybe it was the slight extra draw or maybe the slightly heavier weight. I'll weight the arrows and see if I can draw any useful conclusions.
The two main things were, I need a bigger target to sight onto (maybe a sheet of hardboard with aluminium foil glued to it. Secondly the venue is very good.

Those distances probably sound paltry, but it's only a 40# bow and I think archers are a bit like fishermen in so far as they will say they shot 250 yards, when it was really 250 small paces.
Another thing is, some of the ballistic equations you can find on-line where you plug in numbers and get results are nonsense as they ignore wind resistance, which for an arrow is very significant.

I'll plug in the arrow speed and see what range they say I should get.
E.g If I plug in 56.4m/s (which is about 185 fps) at an angle of 45 degrees they say I'd get 324 metres  (354 yards) range!
Lets try 165fps which is reasonable for a 50# longbow (165 fps is 50.3 m/s) that gives 258 metres (282 yards)

Working back the other way, the equations say that my launch velocity was 144 fps to achieve 215 yards. Well we know that's wrong, so it's all about the arrow and drag.


  1. If you cut a bent stave straight, the slightly skew grain can cause to twist it again, into the same direction, sometimes even stronger than before.

    Sadly, in my experience, most of the lateral bends I correct with heat will eventually sneak back as well. Very annoying. I tried leaving it clamped for a week, toasting the wood after bending (while clamped), over correcting more and whatnot. Very frustrating. The last time I corrected a mild lateral bend, I did so in the handle (as usually) because I imagine bending over and over will just bring the wood back to ist original shape. After heat bending it 3 times in vain, I just sawed it apart and glued it back together straight out of sheer frustration.

  2. Indeed! Even this last fix hasn't really done it.
    I've had some success straightening self Yew. I suspect the bamboo is the culprit here. You'd think 'boo was just straight, but when I planed this down to an even thickness it had a fair bit of twist. I made it V thin thinking that it would pull flat with no problem. Mind it could be a variety of factors combining to cause the problem. One would naively expect various errors to average out... but by sod's law they often all combine to make matters worse.
    I'm looking forward to making the take-down sleeves to do a carriage bow, it's something new to try :-)