Trilam Q

[bownarra]

If you want to stick with the clamps definately make/buy a pressure strip it will stop those fat gluelines. Good luck Lam bows can be fun.

[simk]

I like your monitoring bownarra  would a 0.75mm steel sheet be appropriate as a pressure strip?

other trilam question: does the perry glueup relieve stress from the belly and instead put it midlimb towards the gluelines?

thanx!

 

[mmattockx]

other trilam question: does the perry glueup relieve stress from the belly and instead put it midlimb towards the gluelines?

Yes, a bit. The effect is not as dramatic as Dan Perry seems to think, but you can reduce the stresses on the belly surface by 2-5% with enough Perry reflex added in. Keep in mind this also increases the stresses on the back but that is not usually a problem for most woods.

EDIT - I went back and looked at Perry reflex in more detail. Dan Perry recommended that single wood bows (all lams are the same material) have the back be 1/3 of the stack and the belly 2/3. This results in the 2-5% reduction in belly stresses I stated above. For bows where the backing is much stiffer than the belly wood Dan suggests the back be 20-25% of the stack and the belly the rest. With this arrangement it is possible to achieve reductions in the belly stresses of 15-20%, which is very significant and explains why lam bows with bamboo or hickory backs often perform so well.


Mark

[simk]

hello again 
after screwing up and got underweight with no1 I did some more careful tillering today with no2
still needs a few finishing touches, currently drawing 46# @ 26", already shooting nicely
took a pic after every tillering step and put the frames together on my mobile phone
next time I'll taper the middle lam to mostly skip tillering 
 
https://www.youtube.com/watch?v=CYKJmW0AhOI&feature=youtu.be
 
cheers

[Pat B]

Looks pretty good to me.   

[DC]

Looks real nice. What kind of wood? Chrono? It looks fast.

[simk]

DC, it's ash-ash-yew. this pic is not the actual situation anmymore. Still fiddeling that top limb  not finished yet. Also remarked a little handshock shooting it today. this one is quite long and is supposed to be a target bow, probably not the fastest. also made a shorter version but it came underweight - rushed the tillering :-(
thanx for inspiration  how the heck do you keep so much reflex on yours? i really tried to do very careful tillering with this one but saved only 2,5 of 4,5". it might be the boo backing.... (?) Anyway planning some some little design changes again on the next one. will check the chrono sometime then...
cheers

[DC]

How thick/wide is the Yew? I'm pretty sure set is wood compressing/collapsing so what else could it be? I have tighter recurves on mine so I started out with more reflex. Some of mine had 6-8" of reflex off the caul and some of them gained reflex while tillering(Perry). You have more patience than me. First shot is through the chono

[simk]

DC, set is miracle, nobody has seen it under the microscope. but it happens and its a fact.
in this case its not classical set i think, its lost of artificial reflex, which i think is someting different. it's a matter of design. i will work on that 🙃 bow is 1 3/4" wide at the fades and close to pyramid. yew tapers from 5mm to around 2,5mm. i hardly observe any set with d/r's in the deflexed part where most work is done. cheers