Is it safe to produce laminated wood core fiberglass limbs with smooth-on cured at room temperature instead of a hot box? The literature says room temp cure is a stronger bond but strong doesn't necessarily mean flexible.
Thanks,
Charles
Madison, AL
I always heat my glass/wood laminated bows, but I have cured many all wooden backed bows and tri-lams and such with no heat... simply because the way I clamp them up, they don't fit in the box... never had a problem.
I'm pretty sure it will be fine. Your bow will be less resistant to high temps, like sitting in the car while you're shopping. A hotbox makes the bow more resilient to heat. Better wait for the other's input before you glue up though
2:1 a:b is supposed to give more strength/higher heat resistance. I think the heat just helps it set/cure faster IMO. With smooth on cured is cured...
I'm no expert...knew a guy that had made maybe 15 fiberglass bows, all cured at room temps. He swore he had never had one delaminate.
If you want to avoid the need of using or building a hot box, you can put it in your car in the sun. Temp in the car will depend on ambient temp, color of your car. etc., but it got up to 140 in my car the other day and that was by 10 am in the morning.
Here is the site that gives the info.
I think you will be fine but as mentioned it might not be durable to a lot of heat. I know that I have several risers out there that are room temp cured with no problems.
web page (http://www.smooth-on.com/tb/files/EA40.pdf)
Yep.
I have done a lot of smooth on at room temperature.
Most of the time it is fine but I have had delaminations when the outside temperature is 90 or above at shooting events. The bows had been left on a rack in direct sun as well. I try to avoid those conditions.
I have also had the bamboo backing blow and some Ipe bellys blow. No sign of stress or pin knots, I think the problem was just weak material.
I also learned that I have to rough the surfaces pretty well to get a good epoxy bond in the lams.
I have used a rotary file in a drill motor and scraped the lams with a piece of course hacksaw blade. Kind of time consuming, but smooth sanded lams are prone to separating since the glue cannot penetrate as well.
I built a hot box out of round air duct using an electric heater connected to a rectangle air duct box. I use it mostly for drying staves and arrow shoots such as Black Locust and Rosewood.
I have been thinking about trying to glue some smooth-on lams in it with the heat control to about 150 to 180 F. This would be to try a better hold on some reflex/deflex designs that seem to fail more than straight limb lams.
I do pretty good overall - but seem to have quite a pile of failed bows (about 1 out of 10 lam bows)
I think I will try to make Atlatl throwers out of those this winter. Hate to waste wood!
I've glued up 1 bow without curing and it's fine....But I also don't shoot in high heat and it's never been left in a car.