The travelling caul

[Kiwi craig]

The travelling caul pattern has travelled all the way to New Zealand thanks Lee.
Now I need a bit of design input from the TGers
I’m going to try building a glass lam r/d bow about 64 inches long and 45 to 55 pounds at a 28 inch draw length.
I’ve got flooring bamboo for the lams and 0.04 fibreglass for the front and back.
How long fadeout to fadeout do I make riser
How thick do the three bamboo lams need to be. They are going to be parallel because I haven’t worked out how to taper them yet.
How wide do I make limbs at the fadeouts and at the tips.
Any help would be much appreciated
Cheers Craig

[SEMO_HUNTER]

Somebody else will have to help you with the glass Craig, all my experience has been with wood so far and that's about as far as I'm going to take it I think?

All I can offer is that my total limb thickness with boo and osage combined is a little less than half an inch. I would keep the total stack 1/2" or a little less depending on how much you need to take off during tillering that should be plenty? But I don't know how much poundage the glass will add either.

Be sure and sign the back of the caul pattern with your name, date, and location before you send it out to the next guy. I've sent out at least a dozen patterns since this thing started. I guess guys just didn't want to wait for the travelling caul pattern?

Good luck with it.

[Bowjunkie]

I'm fairly new here at the Bowyer's Bench, and I have no idea what profile the traveling caul is, but if the limbs have no taper to them, you may end up with too much mass and stiffness in the tips, which may overwork the inner limb, slow the bow down and transfer handshock back to the handle. That's theory/conjecture on my part though, because I've never actually done it. I've tapered all of mine... to some degree.

The thing is, it will be impossible to taper them, or remove any material in thickness to affect the tiller once the blank is glued up with glass on the front and back. The only way you could change tiller on the bow at that point would be to alter the width taper and/or remove material by shaping the limbs trapezoidal or something similar... and those effects would be minimal.

Glass bows need the bulk of the work done(work that will ultimately affect the bow's tiller/action) done prior to glueup. So a few of the boo lams really should be tapered beforehand. You could send them to me and I'd taper them for you as I'm set up to quickly and precisely do so, but I have no idea what it would cost for you to ship them all the way here(Pennsylvania). It may not be worth it for you. Let me know though if it's something you'd like to consider.

With glass entombed laminated bows, the total amount of taper in the limbs largely determines the strung and drawn profiles, and how the limb works as its drawn. Most of my laminated glass/wood longbows have somewhere in the neighborhood of .003" - .0035" total taper per running inch of length. That's .096 - .112" total overall taper in the length of the limbs of a 64" bow. Small changes here can make quite noticable differences in how the bow looks, draws, and works.

For your reference, the last r/d longbow that I made here a couple weeks ago had these specs:

64" long

50# @ 28"

Overall Butt Thickness of .390" including the glass.

Total Overall Taper of .0035/1"

I used .050 clear Bo-Tuff glass on the back and belly.

16" riser from fadeout to fadeout

Moderate d/r profile

1 1/4" wide at the fades, with a straight taper to the tips

Trapezoid limb cross section

The wood lams were Wild Cherry

Hope this helps

[Roy from Pa]

Bowjunkie, that sounds like a Sissy Pants Bow Son...

[StoneAK]

I never signed the caul design so if you have it slap my name on it for me. Thanks
Lester Harper

[Kiwi craig]

Thanks for the feedback guys
It gives me a really good place to start from this time.
I might even get a bow out of this that bends unlike the last couple of tries.
Cheers Craig

[SEMO_HUNTER]

Bowjunkie you know what the profile of the caul is, your last bow you posted pics of what nearly identical. It's the hybrid R/D design and it's the best of both worlds in my opinion.....highly efficient.

Dangit Lester!! You were supposed to sign it, what were you thinking?      :D  

Here's the shape of the Traveling Caul.

 

2 unstrung profiles of 2 different BBO's that came off of it.

 

 

[Blkbird]

[Lee Slikkers]

Glad to hear it arrived Craig.  Good luck with...only fiberglass I ever messed with was boat building so you'll have to get advice from the FG guys.

[Bowjunkie]

Semo, yessir, that's a delicious profile.

Roy, yep, that's a Sissy Pants bow alright... being only 50 pounds of draw weight  

You know full dang well it wasn't for me.

[DVSHUNTER]

I would have never though that my drunken ramblings would make it to New Zealand! I love seeing all these bows from that design.

[KellyG]

they kinda of remind me of a long horn. :)I but I bet a HBI, BBI, or heck even an OBI would look really good the contrasting woods and all.

[DVSHUNTER]

I prefer the old school looks of osage selfbows on that caul  

[SEMO_HUNTER]

Originally posted by KellyG:
they kinda of remind me of a long horn. :)I but I bet a HBI, BBI, or heck even an OBI would look really good the contrasting woods and all.

Kelly I've got an OBI in the works for the near future after the bow swap bow is out the door. It's gonna be tricky but I've heard its a real screamer. I can't help myself so I gotta try one, but it will take a nice clean osage back to make it work. I hope I've picked the right one for the task and it's still drying but not quite ready yet.

David- You have no idea what you started, I went from part time bow making to now I just can't stop. Thanks buddy!