A Stealth Iron

Last time I posted about the iron project, I was lamenting the fact that everyone had a straight-forward pathway of how to turn their foam models into plaster models, while I had no idea how to turn my multifaceted, mixed medium model into something that looked real.

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I started modelling the thing in CAD, so I could decide which parts I needed to 3D print and which I could laser-cut into a framework for plaster modelling.

After meeting with my lecturer to discuss solidworks techniques and my plan for building, he assured me that it would be fine if I wanted to 3D print every single part. This was great news for my time/quality sections of the triangle, but it wasn’t looking great for cost. I measured my solidworks model and worked out it to be around 800grams in ABS plastic. At $0.15 per gram using the uni’s material, it wasn’t looking feasible.

The catch with the uni printers is that you only have to pay for material, not time. So when I asked the digital workshop tech whether he thought I should buy a whole reel online and wait for it to ship to me and he just offered me a new reel on the spot, I had to admit that $42 was an exceptionally good deal.

The other great news is that solidworks estimates the weight of solid material. These machines print solid faces, with honeycomb centres, which weigh a whole lot less. I was able to print my whole iron, including rafts, support material, mistakes and reprints using less than my 700 gram reel.

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I started printing parts straight away. Since most of them would be overnight jobs anyway, I tried giving them the highest resolution that would fit between 5pm and 9am timeslots.

The quality on this Zortrax M200 machine turned out brilliantly and my plug-in joining system meant I could see what the assembled parts would look like without having to glue them together.

I decided to print some smaller, less complicated parts on the UP Mini that we have constant access to. A couple were fine, but when a 5 hour print came out rubbish, I made a vow to do all my printing on the Zortrax and not waste any more time or material.

While running prints, I was able to sand and paint other prints and also refine my design on parts I hadn’t quite settled on yet. I tried lots of versions of the heat controller. None of these made the cut.

In this time I also tested the plastic welding cement I’d been recommended. I was astounded by the strong bond a thin coat of water-thin liquid was able to create.

I also tested the trigger I’d created. I used a spring-bar from my collection of watch parts to insert the trigger as a hinge. I tested it with a rubber-band ball and was ecstatic when I got a metal spring to fit into my pre-determined holes. So ecstatic that I forgot to take a picture of it before glueing the whole thing together. (I’m sure you can imagine the glory).

It was unfortunate that a public holiday was arising. I wouldn’t get the opportunity to run multiple prints. Then I realised… I can load a single print full of as many parts at the highest quality possible. I’d have 40 hours to kill, and by gosh I’d make the most of it. I fit on all of the segments of my main component as well as a bunch of smaller pieces.

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It did not end well.

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I’d mentally prepared myself for something to wrong with the print, but it still made my heart sink when it did. What was meant to be five neat, interlocking pieces turned into a jumbled mess. The printer had shifted off axis twice during the print and then gone completely haywire before finishing.

Fortunately, most of the small pieces survived unharmed, but the main component of my iron would need to be fixed.

I could either try reprinting it, or salvage the parts that I had and reprint the sections that didn’t make it. I tried to salvage it first, with the knowledge that I could alway reprint if I had to.

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I’d bought Apoxie sculpting putty because my digital workshop tech, who makes plastic toys professionally, advised it. I like taking his advice. It’s generally right. This time was no differen’t. Despite its significant price and me not knowing how to apply it properly at first, this was the most incredible modelling material I’ve used. It made fixing my model approachable, even with its 24hr curing time. I recommend it highly.

Meanwhile, my outer components were looking fantastic.

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Everything was starting to come together and the sheer number of pieces I had was getting more and more daunting.

I needed multiples of my water tank to demonstrate that the iron came with a set of five that the user would change over like a magazine of ammo. I used cheap plumbing silicone to cast my mould because there was no way I could afford the professional model-making silicone. It came out pretty dodgily, but good enough to show that there were multiples and still having the original 3D print to show what they would actually look like – priorities!

I cast these out of casting plaster so they were really fragile to work with. I’d like to attempt a different material for this process in the future, though I’m not sure what yet. I tried repairing them with Apoxie and Plastibond, but they were both so strong that I’d sand away all the plaster before they would budge. Spack filler was too soft to even join to the plaster. In the end I came up with a mixture of spack filler and concrete bonding glue that took a while to set, but went on easy and dried the right consistency.

The thin arms I printed were really brittle. I tried reprinting them, but it didn’t work well. They’re a difficult shape. I strengthened them with apoxie and broke all of them, glueing them back together as I went. I really didn’t want to have to make these out of metal at short notice. After a full cure of the apoxie, I tested their strength by pulling on either end. They held up. They would do.

I’d printed the ball and socket joint first so that I could make sure that it worked. It was perfect. After painting, it was highly vulnerable to scratching, so I taped it it itself to prevent it from moving around too much.

I laser cut my sole plate. This was the last thing I designed. Because the iron hovers and the heating element only covers the bottom two thirds of the sole plate, I had to come up with ways to make the heat/steam travel. I tried a bunch of versions. Many of the more complex ones ended up looking way too alien-like and one of them was the exact logo for star trek. Straight lines were the best option.

For the handle, I sprayed some rubberised under-coating on the bottom half, so that when I sprayed matte-black paint on the whole thing, the fingers would have a very subtle sense of extra grip at the bottom.

As the due-date grew closer, I was spending a lot of time priming, sanding, painting and waiting. When you don’t wait, it takes longer. And that sucks.

With the intention of placing a torch inside the main component which would emit an orange glow, I glued some coloured gels to the inner lens and stuck a reflective aluminium sheet to the inside to amplify the glow.

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I procured some lead shot so that I could add some realistic weight to my hollow plastic model.

I was very happy with the final result, overall. There were a few scratches on the paint and I broke one of the arms trying to wrestle it into place, but these were all things I could live with. In hindsight I should have put a little more effort into the sole plate, by chamfering the edge and maybe filleting the inner cuts.

When I finished it, I setup a photo studio and lit it with the sun from the window and a series of white and black objects reflecting and cutting light.

I was impressed with everyones final models.

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Other military irons:

Sci fi irons:

Athletic Irons:

Luxury Irons:

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