Years ago I had a freelance gig building a proof of concept model for a type of modular part. I whipped together a rapid prototyping machine out of a drawer, a bit of wood and aluminum scrap, my shop vac, some binder clips, and oven.
It was crude, cost almost nothing to make and worked pretty well. I ended up making a bunch of things with it, because it was fast and easy.
The lightweight armor for this puppet was pulled from solid resin prototypes in the course of an evening.
Eventually when the oven was replaced, I was asked not to put plastic in the new one anymore, since I had no immediate need for fast hollow plastic forms, I boxed it all up and put it in storage.
Returning to the former
Recently I found reasons to to develop a larger one, partly for some of the larger Drab Future models and partly for a friend, so I brought out the old machine and hacked apart an old space heater I’d had lying around along with some more scrap materials to try it out. Think of it as a ‘proof of concept’ basically to see what I ccould do in a night to get this up and running.
This looks like the heater;
http://www.infraredheaters.com/mcm.html
Wired the whole thing into some frame made from aluminum.
And this is the arrangment with the new frame and binder clips
Once the plastic starts to droop, lift it off and drop it onto the platen and flip on the vacuum.
Things to look out for; As you can see the heat is a bit uneven, so I need to build a better insulated box and better distribute the heat over the entire surface and I don’t think the shop vac I was using had a very good seal.
It’d be nice to get this mini machine working, but it is hardly a priotity. I’m going to need something better, bigger, and more modular, but I’ll keep it around and use some scraps to fix it up.
Design Goals
Started drawing up some designs, based on a few ideas I’ve seen online;
Construction
So I’ve begun by making the platen from parts I had on hand and looking at the size/shape of the work surface to see what will be useful and comfortable, mostly just holding up poarts to visualize and get the feel for it at this stage.
I opted for 2×2 because that seems to be a standard size of available plastic sheet, and should allow me enough working space for even large parts of armor.
This is about as far as I’ve gotten so far, and will need to consider picking up parts and materials to go any further.
Parts List
Looking at this list the estimate is about 300$ in parts, I’m hoping to make that less by being inventive…
Expendable Materials
24×24 sheets of ABS and/or HIPS at 1-1.5mm thickness
Currently it appears that they run about 8-10$ a sheet, not too bad, but considering the ammount of test pulls I need to do… yeah.
Heating element
50$ (might need two)
26.5 x 5.2 x 14.2 inches
$235 (220 volt)
http://www.build-stuff.com/FastHeatFlyer.htm
Vacuum/suction source
Looks like there are two options here, need to look at shopvac vs pump/tank. Shopvacs seem to be sorted by two factors, size and horsepower. I don’t need a very large one, but one that has a large force behind it. The advantage of a Ahopvac is that I won’t need to spend more time/money on plumbing and filters, and I’ll have an new additional tool for the shop. The downside is that it’ll never create as much force as a smaller pump/tank arrangment, and wouldn’t be able to pull double-duty de-gassing mold rubber.
I’m unsure what constitutes “enough” suction in terms of hp, it’d depend on the gauge of the plastic and other factors, but I doubt a shopvac could ever give “too much”.
3hp 44$
4.5 66$
5hp 80$
6hp 100$
I have a pump which should be rated pretty high, but needs testing as its been stored for awhile now. This solution will also require more set up for addign valves and fittings, but ultimately will be higher quality. Additionally plenty of pumps available online, ranging from $40-300+. The ratings for them refers to how many CFM, cubic feet per min, they can evacuate.
Reference Notes
His machines represent the “right” way of doing this, and most of the examples you see online are modeled after his designs.
He has built two and documented the builds for both of them, but I’m particularly impressed with the DIY nature of this first smaller build.
It appears he is using the same heater I have been looking at and a similar format and has been running into the same problems I would be, i.e. the wood oven box heating, so it’ll be good to study how he has solved them.
