Heat Box question for 1st Bingham Bow build - also formica strip ?

[Longcruise]

 

[Crooked Stic]

I have always used about a .040 A boo prll. Not Formica. But as said my latest forms nothing at all.

[kenboonejr]

Thanks @Pat B for the suggestion about just duct taping the foam backed boards together.  Instead of $150 for plywood I bought two 4x8 sheets of 3/4 backed foam boards for $25.  Just used a scrap piece of thin plywood for the top with all the light sockets and switch mounted to it.  Just finished and tested it and hit 150 degrees before the thermostat clicked off.  That oughta be good enough right?

Here are some pics of what I did.  Thanks everyone for all the help!

[Longcruise]

That looks great 👍

[Crooked Stic]

I Spect that was way cheaper than plywood$$$ Looks nice to.

[Robertfishes]

That will work, nice job! I like to use a timer to shut light bulbs off.. I usually end up gluing up bows in the evening..so I prefer the timer to shut the heat off.

[Flem]

Awesome Looks great and easy to move around. At first glance I thought you used sheet metal corners, not tape. Makes me think foam board and plastic sheetrock corners might be a good structural and lite weight assembly.

[Pat B]

Glad it worked for you. Not my original idea just passing it on.   
 

[Mad Max]

your going to need some kind of Barn door handle (2) on top, of the top form, to let the form down into the hot box.
be careful

https://www.joom.com/en/products/5f8b1f2b5aa4af010666438c

[kenboonejr]

@Robertfishes - The timer is a great idea.  I plan to run this when I am home so I can keep a constant check on it.  I'm no electrician so I am kinda nervous to run this with me going to sleep

@Mad Max - Yea the handle on the form is a great idea! 

There is absolutely no insulation or foil under the top board.  It is only 3/16" or maybe 1/4" plywood that I had laying around so it is very flimsy and you can see light around the top edge when it was running.  I was just testing it and was planning to cut a sheet of foam board to adhere to the top board but when I ran the test it hit 150 degrees in about 20 mins so I don't guess I need to worry about it.

Thanks again for all the help!  Going to start gluing up a set of limbs next!

[Mad Max]

When you get the mass of the form in there it may take a hour to come up to 150

[kenboonejr]

When you get the mass of the form in there it may take a hour to come up to 150

So I figured I would get things heated up to temp before I glued the limbs together and then put the form in and start the timer for 4 hours.  So will that be good enough or do you think I really should add more insulation to the top?  It would not be hard to do.  Also, this is a small form because I'm just doing 1 limb of the recurve at a time - I just wanted to build the full size box, cause I'm already thinking of the next bow

[Mad Max]

4 to 6 hours, don't start the timer until you are up to tempter.
Then leave it turned off until the next morning more than likely.

[Longcruise]

I get up to 170 before putting the form in and cook for eight hours.  That's probably overdoing it but it will do no harm. 

Like Max says,  I leave it in the box overnight and pull it in the morning.

[Crooked Stic]

I think once your core temp is up in the form then more time does not do a lot of good. I know guys who use heat strips with thermometer hooked up once they get to temp they shut it off and let it cool to room temp.
And I have few that never seen an oven and doing fine.
.

[Flem]

One hour @ 200deg, done. With 2' baseboard heater and 4" axial fan, its up to temp in a few minutes and cooks like a convection oven. There is no good reason to cook for extended amount of hours, unless of course your light bulbs are taking their time heating up the mass they are tasked with. 

[Shredd]

    Great read, Flem...   Can you put that link in the Tips and tricks section so that it does not get lost??   Valuable info that all bowyers should familiarize themselves with...

   Although I don't agree with your 200* cure...   You are just thinking about the epoxy... You are not thinking about the wood...  There are things that can go wrong at such high temps...   I think a happy medium is best...  But that is just my 2 cents...

[Mad Max]

It may take you until noon to get one in the hot box.
So A hot box let's you work on the bow the next Morning 
And if you do over and underlays, striped riser and so on, you can cut day's off you curing.
That's the best thing about it.

[Crooked Stic]

Different strokes for different folks.

And I have done two limbs in the same day on the same form
.

[Flem]

Actually I have given the epoxy, the laminate and the wood, some thought. Here is some info from a paper called
"Bamboo in the Laboratory" 

I'm thinking since Bamboo has a much lower specific gravity than most woods and certainly less than any bow woods, that this info can apply to wood bow laminations with a generous margin of error built in.