Blowing Arcylic Canopies Using Stuff From Around The Shop

Blown plastic from a plastics blow oven

Blowing an acrylic sheet after heating it is an easy way to make a smooth and transparent canopy or bubble for anything from clams to light fixtures. [Michael Barton-Sweeney] does it using plastic blow ovens he made cheaply, mainly from stuff which most of us already have in our workshops.

Plastics blow ovenAll you need is a way to heat the plastic, to then clamp it down around the edges, and finally to blow air into it as you would when blowing up a balloon. Of course, there are things to watch out for such as making sure the plastic is heated evenly and letting it cool slowly afterward but he covers all that on his page.

He’s also on his second plastics blow oven. The first one worked very well and is perhaps the easiest to make, building up an enclosure of CMUs (cinder blocks) and brick. He had success heating it with both propane and with electric current run through Kanthal wire. But the CMUs absorbed a lot of heat, slowing down the process. So for his second one he made a cast concrete enclosure with aluminum reflectors inside to focus the heat more to where needed.

We’re not sure of everything he’s blown acrylic bubbles for but we first learned of his ovens from the transparent clams in his underwater distributed sensor network. In fact, he was inspired to do plastics blowing from a childhood memory of the Air Force museum in Dayton, Ohio, where they visited the restoration hanger and watched the restorers blowing bubbles for a B-17 ball turret.

Though if you want to go smaller and simpler for something like a light fixture then you can get away with using a toaster oven, a PVC pipe, and a toilet flange.

13 thoughts on “Blowing Arcylic Canopies Using Stuff From Around The Shop

        1. Is it possible to post a new page, then change this page to some code that jumps to the new one? (not that the error requires ‘that’ much correcting.. just wondered, as an option)

        2. You should be able to change the Title fine, the original link should stay the same, seems to me I have edited the Title a few times with no problems.

          An automatic redirect should also be able to be done with the title if my memory is correct even using the site – did it a few years ago – bit tricky – an old spammer trick

    1. Maybe someone can design an arc furnace plasma system and you can claim you own the trademark for arcylic systems… wait maybe Hackaday will own that. :-)

      Neat to read about and see as a project also. I have a racing, cargo and tandem trike design that retrofits to one of my mountain bikes (or I guess maybe the neck on other bikes also) that I really want to design a enclosed fairing for the front end. Another one of those projects I started before I was ghetto drugged, mugged and thugged.

  1. This feels like doing things backward. Let me explain…

    Back in the mid 80’s, I was at a packaging line that did thermoform vacuum sealed packaging.

    So this consisted of a set of layers that became the packaged product. So from bottom to top it went in this order.

    Bottom fixed layer:
    Vacuum table.

    Second layer:
    Perforated cardboard backing.

    Third layer:
    Product to be sealed.

    Fourth layer:
    Plastic Sheeting.

    Top fixed layer:
    Heating frame.

    So the whole get along was you would lay the perf cardboard on the vacuum table. Then lay out all the parts on that cardboard. You would then pull a layer of plastic off the roll and under the heating frame. At this point things became hands off…

    The heating frame would kick in, heating the plastic to the melting point where it was drooped in a bubble, then the heating frame would drop at the same time the vacuum table would kick in. This mad a product that could make a saint curse to remove from the packaging.

    But I was thinking… plastic in the frame, heat from above, natural droop from the gravity, minimal air pressure needed to form.

    Literally, he is fighting a force that would make the sheet into a bubble by itself, and if you heat it slowly and evenly you don’t need an oven, though the reflectors may still be a good idea.


    1. > Literally, he is fighting a force that would make the sheet into a bubble by itself

      Hi Cecil, you may be misinterpreting the first image. That is showing the bubble facing upwards after it is blown. It is upside down when it is in the oven. The bubble can be formed just using gravity without any pressure, but it takes longer. People blow the bubbles with positive air pressure (or using gravity) instead of using a vacuum because a vacuum can cause distortion and produce a bubble that is not optically clear.

      1. There was some show on the Velocity channel a while back, where they needed to re-create a canopy for a restoration or resto-mod. They used a clamping frame and infrared heat sources (propane heaters?) underneath to sag the Plexiglas (or whatever) into the right shape. Once the initial sag began, they had to move the heaters around so the “sag” would be the right amounts. It may have taken more than one attempts.

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