Lam Bow Perry Reflex Experiments

[Roy from Pa]

Little Ben...

How the heck have you been?

Been a long time.

EA40 is a great glue for bows and so is unibond800 for wood bows.

Unibond800 has a very low water content and gives me plenty of time the get the bow clamped up, plenty of time, and it has never failed me..

I can get unibond800 for a couple bucks more than titebond 3.

I don't understand why some guys sacrifice building a bow with titebond 3 when for a little more $$ you can get an industrial strength glue?

[Mad Max]

 I bought a pint kit of unibond and it was out of date,  it was like a hard piece of Jello in the can.

[Roy from Pa]

Send it back.

Don't ya check the dates on stuff ya buy?

[Mad Max]

Send it back.

Don't ya check the dates on stuff ya buy?

I could not see that far, online order

[Roy from Pa]

Send it back.

[Shredd]

I bought a pint kit of unibond and it was out of date,  it was like a hard piece of Jello in the can.

  Yah just need a stouter putty knife to spread it...   

[Longcruise]

I’ve built a number of wood bows “like glass bows” as you asked in your previous post, and I’ve dealt with some of the problems you’re taking about.
Titebond will swell the wood and the back and belly laminations will cup. To counteract this I’ve had success using a lot of clamps and only putting them on the edges of the limbs. Also, titebond adds a lot of water to the bow, so I would let it sit on the form for a week, then let it dry for another 3weeks or so. Trust me, it seems dry but it’s not. For these reasons I started using EA-40 epoxy. I did not bake it. Let it cure at room temp for 2days on the form. Had only one failure with EA-40 and it was in a bow I traded so I didn’t inspect after. I suspect the power lam was too thin. Sorry woodcarver, I still feel terrible about that.

Regarding the riser fades, I ran the core and belly lam through the riser so the fade was more gentle, others like woodcarver have had success running lams up the fades, but I think he thinks the lams at the fades to make the bend.

Also, much like woodcarver does, I pre-taper all three lams (I use hickory backing, various cores, and typically Ipe belly). They come off the form so close to final tiller that I round the corners and can typically go straight to low brace. Tillering is very quick, basically just a scraper and some sanding. As a result, the lams are well proportioned all the way to the tip. I taper each lam to .002”/inch. That seems to be about the sweet spot.

I don’t pre-deflex them. I just glue the lams up at once. One point I would note is that I think that perry reflexed Tri-lam bows take more set than a self bow, so you need to start with more reflex than you might otherwise. Maybe I’m just doing it wrong though and others may have different experiences.

Ben!!  Where you been??  Missed your building adventures in the tiny apartment. 

BTW, this is Monterey.

[LittleBen]

Been doing the parenting thing (1yo, 3yo, and 5yo), and the homeowner thing (80yo house), so time has been at a premium. Been making more furniture than bows, although I’m chipping away at a few. I lurk on here from time to time, but don’t usually comment at all. I just thought I would jump in on this thread because it was close to the process I’ve been using for my bows.
Glad to see a lot of the usual suspects still around. Hoping to stay a little more involved, just don’t expect any build alongs anytime soon.
To the OP, you can always PM or post if you have specific questions on specs and so on.

[mmattockx]

I don't understand why some guys sacrifice building a bow with titebond 3 when for a little more $$ you can get an industrial strength glue?

The problem is I can't get unibond for a bit more than TBIII, it is more like 3x the price up here if I mail order from the US. Shipping of a 1/2 gallon kit is $55 up to here from the place you sent me the link for. By the time I pay that and the exchange rate it will be ~$120 for that 1/2 gallon. I can buy a quart of TBIII for ~$25.

To the OP, you can always PM or post if you have specific questions on specs and so on.

I do have a question that I forgot to ask in my last reply. How thick are you making your lams, especially the ipe belly lam?


Mark

[wood carver 2]

I’ve never had a failure using tb3. I only use fresh glue.if it’s getting old, I save it for non stressed glue ups.
As far as set up time is concerned, the first couple of times were a bit hectic, but then I started to get really organized before I started gluing. All the clamps ready and close to hand. A wet rag for wiping up drips etc.
Dave.

[mmattockx]

I’ve never had a failure using tb3.

I have never had issues with TBIII or plain old yellow carpenter's glue on a bow so far. If the joint is done properly it is stronger than the wood. My only issues were the set up time and the water content causing the lams to warp. If I can streamline the glue up so that it is all together quickly lots of clamps and pressure strips will hopefully solve the warping problem.

As far as set up time is concerned, the first couple of times were a bit hectic, but then I started to get really organized before I started gluing.

Hectic is a good word. I was pretty organized, but not nearly good enough for the time I had. My next try is going to be with the alternative riser design I posted above, which should be much faster to get assembled once the clock is ticking on the glue.


Mark

[LittleBen]

X2 what Dave said. Never had TB3 fail, and you get used to the glue up and it goes quickly.

I made my lams .150” thick and that would get me in the roughly 45# range (IIRC) at 28” on a 66” bow 1.5” wide with 12” riser. That’s with hickory back, hickory core, and ipe belly. But that’s also with black ipe, that’s extremely dense. Obviously the design you use, as well as the materials will change all that. Also small changes in stack thickness can cause large be increase in weight.

I have two of the same design both 12” riser 66” one .420 stack is 34-35#, .480 stack is nearly 50#
Another 18” riser 66” bow .420 stack is ~45#.
So you can see small changes can be huge.

I dealt with this by making numerous of the same design and only changing the stack slightly, or the length slightly and so on, then used the data to create a chart to give some idea where I needed to be with the stack. Also I would err on the lighter side because a too light bow can always find a home, but no one really wants the 68# mistake.

I don’t think I have the chart anymore, but also it only really works if you have the same belly, core and backing material. I cut lots of lams from the same boards so that everything was as consistent as possible. If I changed belly material, I would just make a guess about how that would effect weight.. In general, denser belly wood will increase draw weight, so you could guess that you might gain or lose a couple pounds going from one ipe board to another ipe board based on density. But going from ipe to yew, or Osage? Forget making any kind of accurate guess.

Is all this worth it? Maybe not. I did it because I had a lot of time, and it was cheap. And also I’m way better at engineering than I am at tillering, so it made sense for me. You could leave extra thickness on the belly lam, and tiller to target weight, but that’s just not how I personally chose to do it.

[mmattockx]

I made my lams .150” thick and that would get me in the roughly 45# range (IIRC) at 28” on a 66” bow 1.5” wide with 12” riser.

I'm impressed that you got lams that thick to make the bends, especially in ipe.

And also I’m way better at engineering than I am at tillering, so it made sense for me.

That makes two of us. I design my bows using software and it works out better than my shaky eye on a tillering tree starting from a raw stave. With wood there will always be a bit of refinement required, but it can be very minimal if the design and fabrication is done well.


Mark

[Roy from Pa]

The problem is I can't get unibond for a bit more than TBIII, it is more like 3x the price up here if I mail order from the US. Shipping of a 1/2 gallon kit is $55 up to here from the place you sent me the link for. By the time I pay that and the exchange rate it will be ~$120 for that 1/2 gallon. I can buy a quart of TBIII for ~$25.

Well that explains that...

[williwaw]

the titebond found at retail outlets is a smaller selection of a more extensive product line mfg by franklin.
lots of data on recommended practice etc. 
http://www.franklinadhesivesandpolymers.com/Wood-Adhesives-US/Wood-Adhesives.aspx

of interest to bowyers might be extended set time formulas in the titebond product line or wood mc recommendations for longer working times.

[Mad Max]

Those are really nice littleben

[LittleBen]

Thanks MadMax

[Mad Max]

Thanks MadMax

This could be my new calling
I've made 3/4 Boo back bows but I would have more control with the lams and Hickory back.
What other backings do you use? Maple?
Do you have a full draw picture?

[Pat B]

The tiller looks very good. I'm assuming this is all red oak, back, core and belly, is that right? Red oak is a marginal bow wood and especially as a belly wood. This could be why it took some set. Also, I think you may have over stressed the red oak at each stage of the glue up. Again, that being said, it is a well tillered bow. How does it shoot?

[Mad Max]

The tiller looks very good. I'm assuming this is all red oak, back, core and belly, is that right? Red oak is a marginal bow wood and especially as a belly wood. This could be why it took some set. Also, I think you may have over stressed the red oak at each stage of the glue up. Again, that being said, it is a well tillered bow. How does it shoot?

Pat I think you are on the wrong perry reflex topic, this is a older one