Episode 3

Dave shows how to use dry ice to expand a pop bottle to rupture and also how to make a spring

LisaFarrows
Instructables
The instructable to go with the springs is after the jump (AKA Click this link…)

Dave shows how to use dry ice to expand a pop bottle to rupture and also how to make a spring

LisaFarrows
Instructables


Make your own springs in secondsMore DIY How To Projects

Finally here is a link to the raw video file

4 Responses to “Episode 3”

  1. Darren Landrum June 12, 2011 at 10:35 am #

    Hey, guys! I had a question about making springs. My question has to do with hardening the steel to get the nice high k (spring constant – I once studied physics in college :) ). Once you have the shape, don’t you want to use a torch to heat the spring to glowing, then quench it quickly in water? Or does it really work well enough to form the TIG wire in the proper shape?

    Thank you! MM has quickly become my very favorite “backyard engineering” podcast. :)

  2. Dave spencer June 12, 2011 at 3:17 pm #

    I used stainless steel for these springs, if you tried to heat treat them, not much will happen due to the carbon content. Spring steel has the correct carbon content to heat treat. If you used spring steel and heat treated it, you might get a stronger spring than mine but my stainless ones have been strong enough for repeated work on my gate for years now and they dont corrode. Stainless springs are used a lot in food production. Thanks for the compliment too!

  3. Darren Landrum June 12, 2011 at 9:46 pm #

    Ah, I think I get it now. Basically, between the gloves and the drill you can apply a great deal of force to shape the stainless steel rod. I might have to give that a go sometime.

  4. Darren Landrum June 17, 2011 at 8:50 pm #

    And now that I’ve finally caught up with the comments in the Instructable, I can see you’ve already been grilled on this question. I personally love the one where the guy said that you can’t possibly have made a true spring because it wasn’t tempered afterwards, as if there’s some platonic ideal for a spring. If it does what you need a spring to do, it’s close enough. :)

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