New Epoxy Putty Oven

I made a new putty oven for curing epoxy-based sculptures quickly. I’ve always found that when I try to sculpt in epoxies, I lose my focus while waiting hours for the epoxy to cure. Not to mention that the other demands of life don’t give me the luxury of waiting, even if I had the patience.

I typically have a little quiet time each morning after the dog gets his walk and is finally docile and asleep on the couch.  I probably have somewhere between 60-90 minutes where I could realistically get some hobby time in before the rest of the day's tasks come calling.  Hopefully, this oven will allow me to work on two figures at once; while I'm building up a putty layer on one, the other figure will be curing and by alternating between figures, maybe I can sculpt for a full hour.  

Originally I planned to use only three tins for this oven, but the figures I’m currently making are ~60mm high and the lid rested on their heads. The extra two tins provide plenty of space, and probably better serve to create a chimney effect.

My previous putty oven used a light bulb for a nice, steady heat source, but I’ll be damned if I can find an incandescent bulb here in my new home city. OK, to be fair, I have located expensive specialty infrared bulbs. Add to this the cost of the bulb socket, properly safe electrical leads, and the time sink of wiring everything up, and the project cost would be out of hand. The electric hot plate cost €19, puts out far more heat than I could need for curing, and is useful for other media (like melting wax).

I’ll need to figure out how to best set the heating element. My first experiment saw me spread out an epoxy/polymer clay mix on a glazed ceramic tile, which I placed in the oven with the burner set to 4 (of 5 maximum) for five minutes. I then turned the burner off and let the putty stay in the oven for five more minutes. Upon inspection I found the putty bubbled with browned edges, and required scraping to get off the tile. The tile of course required a tool to handle safely, and retained its heat for some time. The putty required only one to two minutes to cool and then was rock hard.

The stove certainly gets hot enough and cures the putty in minutes. I think the timing was actually OK and that the ceramic tile acting as a heat sink resulted in the “overcooked” appearance of the putty.

I’ll probably try mapping out the burner’s duty cycle after a three minute warm up on the “5” max setting. I think maybe 30% on, 70% off might be the right duty cycle, and no ceramic tile. 

Feeling the heat of the tile makes me think my original idea of heating sand would work. Looking for an ultra cheap option, I thought about heating sand in one of the aluminum tubs, and using that for a heat source.

DIY Airbrush Booth (Under $50 US)

 I finally cleaned up my hobby space.  That effort deserves a blog post all its own, maybe later, but now that the room is actually usable again I'm eager to return to a number of projects.  Since most of these projects require painting, it was a perfect opportunity to revisit my airbrush setup.

I never took a picture of my old airbrush arrangement but it wouldn't be hard to recreate.  Basically I wedged a 20 inch box fan into the open window, and sprayed directly into an HVAC air filter suspended by the airflow against the fan.  Based on the spray residue captured on the filter, the system worked but was as awkward as it sounds.  I decided therefore to make an actual booth, trying to keep it cheap while achieving good containment and integral lighting.

A few years ago, the Missus was throwing out two perfectly good lampshades, which I saved from the trash since their shape screamed "spray booth".  The initial idea was that the two shades would be nested inside each other, with the inner shade acting as a spray shield and light diffuser for the outer shade, which would act as the air tunnel and light mount.

Searching online I found an eight inch diameter, 420 cubic foot per minute flow duct fan, wired for 110V AC, at one of the big box home improvement stores.  Since it wasn't in stock I had to have it shipped to the store; the small nine inch cube-shaped box it came in turned out to be the perfect interface for the square frustum lampshades.

I purchased a string of cuttable LED lights online, the type with self-adhesive backing.  I assumed these were far more flexible than they turned out to be.  While I originally envisioned nearly covering the inside of the outer shade with LED strip lights, I could not bend the strip aggressively enough and therefore only used less than two of 16 feet of lights.

A simple cardboard sleeve acts as the air duct directing the fan exhaust out the window.  The window interface is a large piece of sandwiched corrugated cardboard; the cardboard sits wedged by the upper window and provides a shelf to support the air duct weight.

The original lampshade material proved too opaque for the LED strips, even at full brightness, so I tore it away and replaced it with cling-wrap, Dexter-style.  Obviously the intent here is disposability and easy replacement of the spray shield once it gets too contaminated with paint.  The LEDs feature an integral dimmer switch so I can reduce the intensity if necessary.

I accomplished a smoke test and the booth performed wonderfully.  Even with the filter (cut from a HEPA filter) the fan provides plenty of air movement and should direct any atomized paint overspray away from me.  As the pictures show, the booth offers plenty of light.  The booth's 14 inch edges give a pretty roomy spray area sufficient for nearly anything I want to spray, even terrain.

[Here is where I tried to upload the smoke test video but, you know, it's Blogger.  Worthless]

Lame screen cap because Blogger sucks

Breaks into four pieces that fit under desk

Although the booth hasn't seen any real airbrush use yet, I'm happy and confident with the build.  It needs some refinement, sealing the window interface connections, for example.  Still, the price is especially nice.

I paid $28 US for the fan, and $17 US for the light strip, recycling every other component from either trash or my bits boxes.  So, $45 US for the booth which is about 1/2 to 1/3 the cost of the small table-top ones online.

Honestly, I should've eschewed the LED strip and made the cost even less.  I had forgotten the hundreds of 3V individual LEDs I have in a random drawer.  Wiring up ten of these to a 32V power adaptor would've been trivial and probably offered similar intensity light with a better area distribution.  Oh well, lessons learned.     

"There it is"..not sure why I'm pointing.  Nice light though.