Smooth On Do's and Dont's??????

[foamer01]

Does anyone have instructions and or do's and dont's for smooth on epoxy? We had a slight delamention near the string nock. We were trying to narrow down how this happened. We spread the glue probably to thick, which shouldnt cause a problem. We C-clamped it with good pressure hopefully not to much. We pust it in the hot box for about 6 hours. We ground the edges everything looked really nice. We then applied nock overlays (ebony) and handle overlay and cooked for about three hours. Then we applied some ebony overlays on the belly that we couldn't put on because of the c-clamps from the handle overlay, and cooked for another three hours. At this point the one tip opened up  about 2". Can Smooth on take this much exposer to heat? Or did I apply to much clamping pressure to the nock overlays because the ebony was a bit thicker and wasnt conforming to the tips and needed a bit more pressure to conform. Thanks for reading and would love to hear your thoughts.

[Mt. Clemens Bowyer]

foamer01
 When I built my first bow with the help of "Bingham Projects" and archery sites such as this one. Plus the reading of many books.  I have since learned that it is a good idea to use acetone to clean off all parts before the glue up process. You may have had contamination or oil that came to the surface. Especially on exotic woods, they say this can happen. Another 2 things that should be done is. Put the wooden parts in an oven for 1 hour before glue up. This will remove any surface moisture. also, be sure the handle and nock parts are roughed up with 40 grit sandpaper.
  My first bow that is a 68" recurve de-laminated on the front of the riser a few inches up from the fade out.  I removed the upper limb completely and will put on a new one when I receive the parts from "Bingham Projects". If when I finish it, its not a good shooter I will hang it on the wall.   Good luck John

[Dano]

When you cooked the overlays, did you cook them at a lower temp? Lower than the temp you used to cook the glue up.

[foamer01]

Thanks so much for the ideas so far. I failed to mention that all surfaces were wiped down with acetone, they were preheated before glue up, and surface roughed up with sand paper before applying overlays. We did unscrew 2 of the four bulbs in the oven, however, this brings me to yet another question. We have a small thermostat on the oven box that cuts the heat at if I remember right 185 degrees. Even if I unscrew 2 bulbs, the box will still go up to 185? It will just take longer to get there. So maybe we just over cooked the bow. The rest of the bow seems just fine though. And did I apply to much pressure to the overlays after the epoxy was already cured on the bow the first go round......... I would not like to repeat this. I have to much invested in a Solid Ebony handle, not to mention the time. Again thanks for your guidence and thoughts.

[Dano]

I'd I have always heard that if you cook your bow at one temp, you need to cook the overlays at a lower temp, so the glue up doesn't delam. I'd get a new thermostat.

[TNstickn]

The smooth-on web site states,"150 degrees for 6 hrs". you could be to hot. It uses the wording "mild heat". If your hot box is like the binghams design and set up, then near the top of your box by the bulbs is REALLY HOT. I use a thermostat regulated at the 150 degrees, and If I dont position my form correctly in the oven the bulbs have actually made burnt spots on my form within the first 45 min in the oven! Scared the crap out of me when I went back to check the air pressure to make sure I was good. Form height and box depth are exactly like the specs too!

[Mt. Clemens Bowyer]

TNstickn
 
 One thing you can do to prevent hot spots is to build a shield between the bulbs, and the bow form. Just make the shield, about the width of the form only.
 In my case the bulbs are installed sideways at the bottom of the hot box, with two computer fans installed. one on the right end, and one in the middle. I then built a shield as mentioned, installed over a frame made from 1/8" x 3/4" cold roll stock. For the shield I used aluminum foil, and aluminum tape. Seems to work great.  Good luck bowyers.      John

[foamer01]

Hi,
You guys are right. The best I can tell we overheated the bow. We cooked for the inital layup, we recooked for some handle and tip overlays, then cooked for some additional belly overlays. I had a nice talk with a gal from Bingham's and she said one time in the heat box and no more. For tip overlays, handle and such, she said smooth on with set in 24 hours with no heat. Keep in mind this is for overlays only. Smooth on's web site says "heating the epoxy to 150° F (65° C) for 4 to 8
hours will increase physical properties and performance." Thanks again for all your thoughts and help. This is why I enjoy this type of friendly helpful environment.

[Mohawkbows]

Try using a remote light bulb for your overlays and tips instead of using the oven twice. Smooth on will set up in a couple of hours in the 120-130 degree range.

[TNstickn]

Sounds good John. Thanks for the tip. Im gonna reconfigure my set up before my next glue up. Ill take some pics so you can check it out. -Greg

[Turpentine]

For tip overlays, I have used a 150 watt halogen light placed 8 to 10 inches from the tips with good results.
Turpentine