question re hot box

[Dick in Seattle]

I spent the day building my own oven (hot box).  It's basically Bingham's design... copied off of Boyd's but also modified a bit to meet my own needs.  Because of my muscle problem, I'm kind of shaky handling Boyd's... 1' x 2' x 88" of 1/2" ply if pretty heavy.  Also, my space problem is severe, I need to store my box on end, and I don't have 88" of height.   I ended up building my box of 3/8" ply, reinforcing the long seams with 3/4 x 3/4.   I also made mine 78", or 10" shorter.

Boyd's, as instructed by Bingham, uses four 200 watt bulbs.  I got the parts to do the same, but as I look at things, I'm wondering if maybe four bulbs is overdoing it in my smaller volume box.   I would either have two of the bulbs quite close to the ends, or have the four pretty close together, which I think might cause a hot spot in the center.

My question is what effect those of you with experience think might result from going to 3 bulbs?  My gut reaction is that it'll work... but what do I know?  :^)  If I did this, would I need to cook longer?  

Next question..  is there a ready source (appliance store... Radio Shack?) for a workable thermostat?   I don't have one yet... hoping to find one locally by calling around tomorrow, but if not, I'll phone Bingham's and wait...

Advice and input appreciated..

Dick in Seattle

[B M A]

Dick,
Alot of guys use a 3 bulb set up. Especially if you insulate it. Binghams plan only shows to line it with tinfoil so the extra bulb helps get the heat to a consitent temp.  As long as you are getting it to proper temp that is what matters. Also I know guys have used a hot water heater thermostat instead of ordering one.
Brock

[Pat B]

My box is lined with foil backed foam board and I have 4 light sockets but adjust the heat by unscrewing one or more bulbs. A Bingham thermostat limits the temp to about 186deg(F). I also use lights of less wattage(from 200w to 40w) for lower temps. When using the hot box I lay aluminum foil over the stave, bow or whatever beneath each lit bulb to to prevent hot spots.
   I have heard of some using a rheostat to control the temp and save energy.   Pat

[Holm-Made]

I use 4 150 watt bulbs and they work fine so 3 200 would also work.  I don't have a thermostat.  I have a dimmer switch to control temp.  The hottest I can get my box is 150 degrees on full power so I don't need a thermostat.  

180 degrees is too hot for my taste, with the shop attached to the house I worry about fire.  Make sure the box is deep enough so the bulbs are at least 12" away from the form. I had the form to close one time and almost had a fire.

I cure my bows at 130-140 degrees for about 4 hours, then let it cool for at least 4 hours.  I glue the overlays on with smooth on too and put the bow back in the oven at about 110 degrees for 2 hours then shut the oven off and let it sit until the next day.

Everyone does it a little differently and it all works.  I don't use any more heat then I have to because I don't like to dry the wood out.  I've never had a glue joint fail with smooth on epoxy and I've made a pile of them. Chad

[Dick in Seattle]

Thanks, guys...  It's apparent that it's not as critical a thing as I thought it might be.  Sounds like i should be fine.   I'm going to hit a local appliance repair parts store for a thermostat in the morning, but also pick up a dimmer switch.  I really like the sound of Holm-Made's setup.   I plan on having a thermometer on the box, so it would be no big deal to set it up with the dimmer, try it for awhile and establish the max and minimums and mark the temp spots on the switch.

So, tomorrow I'll go full speed ahead... install the lights, the insulation and appropriate switching.

[Apex Predator]

I use four 100W bulbs in the winter, and four 75W bulbs in the summer.  I get 150-160 degrees from this setup.

[Pat B]

I never take my box up to its max temp because all I use it for now is drying wood and maintaining low M/C in staves and reducing M/C in staves. Right around 100deg(one 60w to 100w light bulb) with the fan running does the trick for me.     Pat