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Thread: Aluminum spring

  1. #1
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    Aluminum spring

    I am building my own shock absorber and have some aluminum to melt down. I want to know if anyone has had an aluminum spring on their coil shock. I can purify the molten aluminum and then add the magnesium oxide powder, pennies for zinc, copper rod, and maybe some little bits of chrome I can get to get 7075. I think a spring around 600 pounds would be good

  2. #2
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    Never heard of an aluminum coil spring. I've seen aluminum archery bows, so there's likely some spring there, but the deflection of a bow is different in comparison to a coil shock. Not sure how you would get from billet to coil with home grown equipment, though.

    -F
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  3. #3
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    I'd make an aluminum battle-axe for LARPing instead.

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    7075 has 1/3 the shear modulus of 1075. Even if fatigue was not an issue, I don't see how you could make the coil cross-sectional diameter small enough to allow even modest shock travel without coil-bind. But, YMMV, so try it and report back.

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    likely not possible to make something that will work better than currently available springs...not with Al


    creating the physical and chemical properties demanded from an Al alloy to do this job, as well as meeting appropriate combination of strength and elastic modulus (i.e., stored elastic energy or known as elastic resilience !), the consideration of other properties like fatigue strength/endurance, creep/relaxation and resistance to environment ....will surely exceed your budget to try to create this magical Al spring...

    try it though and report back please...don't let the fact no one has done it for physical and chemical properties reasons stop you

    Steel basically has infinite fatigue life if the flexing does not exceed about 50% of the elastic limit. Aluminum accumulates fatigue regardless of the degree of stress applied.

    7050 would be the way to go though if you are making a spring
    Last edited by 127.0.0.1; 1 Week Ago at 04:23 PM.
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    Quote Originally Posted by Hardtail Bryant View Post
    I am building my own shock absorber and have some aluminum to melt down. I want to know if anyone has had an aluminum spring on their coil shock. I can purify the molten aluminum and then add the magnesium oxide powder, pennies for zinc, copper rod, and maybe some little bits of chrome I can get to get 7075. I think a spring around 600 pounds would be good
    But why would you want to or what benefits do you think it would provide?

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    Quote Originally Posted by VegasSingleSpeed View Post
    7075 has 1/3 the shear modulus of 1075. Even if fatigue was not an issue, I don't see how you could make the coil cross-sectional diameter small enough to allow even modest shock travel without coil-bind. But, YMMV, so try it and report back.
    The coil shouldn't bind, it's moving 100% linear along with the rest of the shock. Getting a small diameter is probably a really big problem

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    The math is most of the budget by a long shot. Im hoping to buy a spring for the time being and build a diesel metal furnace. I have a lot of half cool stuff I bought from trade shows, most of which is good aluminum. Okay if steel has so much more elastic resilience, then why does RJ the bike guy only coldset steel frames? It's not like good aluminum can't safely flex like that. I bought 14 pounds of 3" x .75" 6061 billet studs the other day and aside from the other aluminum that cost 4x that, it looks and feels like the nicest stuff ever. And why 7000 series 50 instead 75? I've read and heard a ton about 75 being the king. I'm excited to share my shock build, it's legit salvaged

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    There is a company called SAR that makes an alloy bike spring that says their metal has better stats than titanium for everything and its cheaper

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    @Walt
    Bronze from shell casings. Bringing a gun-knife to a... Knife fight?

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    Quote Originally Posted by Hardtail Bryant View Post
    There is a company called SAR that makes an alloy bike spring that says their metal has better stats than titanium for everything and its cheaper
    So what is an (alloy)? That Titanium, Steel (chrome silicone or even AerMet) are also alloy's. That aluminum spring you described would also be an alloy.

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    Quote Originally Posted by Hardtail Bryant View Post
    The coil shouldn't bind, it's moving 100% linear along with the rest of the shock. Getting a small diameter is probably a really big problem
    "Coil bind" is when the spring compresses to the point that the coils touch each other. The point is, you'll never make an aluminum spring at 600 lbs/in with small enough wire diameter to allow the shock to go through it's full range of motion.


    Quote Originally Posted by Hardtail Bryant View Post
    There is a company called SAR that makes an alloy bike spring that says their metal has better stats than titanium for everything and its cheaper
    Any mixture of metals is an alloy. SAR's springs are made by Eibach and are not aluminum. They are likely using a different alloy of spring steel that achieves the desired spring rate using smaller wire diameter and fewer coils...thus, weight comparable to titanium.

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    Coldsetting a frame involves having material yield, something which is pretty bad for a spring as you want the spring to come back when the forces are removed.

    Best thing to do is to get a machinery handbook , look up the chapter with the formulae to calculate a spring, and plug in the numbers. I can't be bothered, but I guess the outcome will be something along the lines that you'll need 3 times the cross section of a steel spring, so you end up with the same weight but less travel before coilbinding is an issue.

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    For maximum post-of-the-year points, we need an MSpaint schematic of the proposed spring.

    -Walt

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    Quote Originally Posted by DHRracer View Post
    So what is an (alloy)? That Titanium, Steel (chrome silicone or even AerMet) are also alloy's. That aluminum spring you described would also be an alloy.
    Sorry, are you asking me what an alloy is?

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    @vegassinglespeeder okay but don't you know that coil shocks only move as much as the stroke does and the coil will never fully compress if you use your head? And aluminum is an extremely versatile metal just like anything else that can be bonded with other materials, I'm sure someone can figure it out. Also, I'm aware that SAR uses eibach. But I wouldn't bank on their alloy being comprised of mostly types of steel. And I wouldn't bank on them not using magnesium or aluminum for that matter. I wouldn't bank on their metal not being a larger package gram for gram either. Looks like their website is pretty credible

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    So basically if you set up any old coil where youre using the full travel of the stroke and trusting that your bump stop is solid like a real boy, you should never have this "coil bind". I only have heard of binding in a steering mechanism or other place where there are multiple geometric shapes aligning with tight tolerances in opposing directions. Basically i would have binding if i chose to create a swing arm that comprised of several parts that had zero mechanical flow. Maybe youre confusing it with stiction? Not sure, but that more has to do with two tubular surfaces wearing on each other now(no ****) btw i dont like when people show zero interest in my intentions but chime in with something nonsensicle in many kind of funny ways. Btw walt i will be posting more on this probably months from now. And also my entire project is just a bunch of very very nice aluminum so get used to it

  18. #18
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    Hey Walt, what do you think of this?
    Cast a big piece of nice aluminum in a
    long tube. Let it cool. Take it out. Have some old, cool machine shop guy lathe it down to let's say 7 or 8mm or maybe some other number of mm. Thank and pay him. Heat it safely. Think about how much space you need between each full rotation in the coil. Carefully spiral it around something round like a tube wide just enough for it to be a coil spring that functions with my home made shock that also doesn't suck. Then 90 flat shave down each end. Then use it to look at while the rest of the amazing project is being figured out. Also, all haters look at stinkyfab racing and then do your quickmafs and realize how good aluminum is for this. Then get even more sad when you find out that people have used rubber for bicycle suspension

  19. #19
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    your Al spring that can do the job will need to be extremely bulky, no way to make it fit a bike and perform as you want
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  20. #20
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    Aaand... we're done here. OP, feel free to start a new thread if you actually make a spring.

    -Walt

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