Shop Vac or Vacuum Pump for vacuum forming machine?

Hello mates! I'm ready to start to build my own Vacuum forming machine and I have a question about the strength necessary to pull 2.5-3.0 mm HIPS thinness for chest plate and helmet Stormtrooper a like armor.

Which one offer the best pull? Or which one will last more and endure, considering medium usage. I don’t to expend money in something that doesn’t works good for my proposes.

I’ve considering a 2.5 HP shop vac and a 5 or 6 CFM Vacuum pump. Is enough? The size of pull is 80x60 cm.

Many Thanks!

David

Comments

  • Chris EllerbyChris Ellerby Los Angeles Admin
    Hi David,

    Many 2.5 HP shop vacs are in the 130 CFM range.  Basically, shop vacs move a lot more air a lot faster than vacuum pumps do.  Vacuum pumps are mainly designed for strength, rather than speed.  

    Vacuum pumps are ideal for things like degassing chambers where you need to pull and sustain a vacuum over time.

    Some vacuum form machines use a vacuum pump to pull a vacuum in a large dump tank, and then use the built up vacuum in the tank to pull plastic.  I've only seen a couple machines like that in person and they still used a shop vac to keep pulling the plastic down as it cools.  They used the vacuum pump and tank for only the first part of the pull as it only lasts for a brief moment.

    /Chris
  • I been Reading for a while on the web about this and I don't found any answer so quick and so certain about this till now. Thanks for that.  I got a few more question if I may. About the heaters, Fon Davis use an electric oven…What about the IR? Works better to melt the plastic sheets?

    Again thanks!


    David

  • I don't think IR heaters are very effective with transparent / translucent plastic because the infrared mostly passes straight through.
  • Chris EllerbyChris Ellerby Los Angeles Admin
    There are vacuum forming machines that use infrared heaters, but I'm not sure how they work on all plastics (such as clear plastics as Stuart mentioned) having never used one personally.  I use a small 4000w 220v machine for my projects: 

    Here is a short article that covers the types of infrared heaters used in vacuum forming:  https://www.infraredheaters.com/thermofo.html

    Infrared heaters designed specifically for vacuum forming are rather expensive, so I'm curious how cheaper heaters might perform.  There's no reason you can't test this with whatever IR heaters you find, just know that there's a chance it might not work and you'll be out a bit of money.  Such is the nature of DIY research!

    I tend to go with what's commonly used when doing my own projects, at least for the first time.  But there's nothing wrong with trying your own methods!  (just be safe)

    /Chris
  • When I built my machine, I used the electronics from a toaster oven. I found a 4 element one for under $25. It works great. Temp control, timer, and no guessing on wiring.   

    The rest of my design is a work in progress, but this part works great.


  • Hey Chris! Thanks for the info! Today bought my oven heaters! 1400 w each. Because I need a large machine (80X60cm) I got 8 in total.
    heaters

    Joel! I Like what are you doing whit the oven, wasn’t an option for me because the size of my vacuum machine. I will post some pics when I have updates. Thanks for keeping posting info!
  • Stuart McconnelStuart Mcconnel UK ✭✭
    edited February 2016
    8 x 1400W :o
    Hope you have a very good mains supply!
    General rule of thumb is around 3kW max on a single socket, or 5kW on a double socket.
    You'll need to be very, very careful about how you hook up an 11.2kW machine.
    You shouldn't normally exceed around 7kW on a single ring in a domestic application.
    I am of course assuming you're not on an industrial supply, which I maybe should not assume?

    Edit: Also, I was going on rule of thumb UK figures. If you're somewhere in the world that runs on 120V, that limit is greatly reduced. 120V 15A in the US? That's only 1800W peak per socket.
  • Thanks for the tip! I talk whit an electrician friend and he say me---Are you crazy? Haha…Too much energy…I got it, because I have a workshop, but for safety reason I will do the half.

    Do you know the Insulation that Fon Davis put on the top of the heater? I need to find it here. Thanks again!

  • Chris EllerbyChris Ellerby Los Angeles Admin
    I believe Fon used high temperature fiberglass insulation with a foil backing.



    /Chris
  • Hey guys! 

    I'm almost ready whit this project. Just need to check some electronics issues and I will be ready to vacuum forming for first time. 


  • Chris EllerbyChris Ellerby Los Angeles Admin
    It's looking great!

    /Chris
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