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Discussion Starter · #1 ·
i know a couple guys on here are building there own springers , i would like to modify my front legs to a wish bone style more like a freddy hernandez style...love that look, the big question is what matirial is safe? 1018? hot rolled cold rolled? i do need to thread the top and machine the bottom for the rockers so it has to be machinable, and i will be building a jig and heating it to bend... i just have no idea what is cool to use and work with, its a pretty important piece so i would rather not be impailed from it snapping...so what do i use? its solid 5/8 rod
 

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If it's solid rod now, and it's working, maybe 5/8" solid rod?. If so, use 1018 cold rolled, not A36 hot rolled. It's stronger from the cold working process and you don't have to deal with mill scale.

Bob
 

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I have never modified a springer, just built my own From scratch so I can't answer for what you need to do to the lower part of the legs. I use cold rolled 3/4" for mine and they are strong. Do you have a picture of your setup?
 

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Do NOT use solid rod. Use 1020 cold rolled mild steel, with .120" wall. I would go at least 3/4", preferably 1" for the OD.
 

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If it's solid rod now, and it's working, maybe 5/8" solid rod?. If so, use 1018 cold rolled, not A36 hot rolled. It's stronger from the cold working process and you don't have to deal with mill scale.

Bob
Does heating the rod cherry red to bend the legs affect the strength?
 

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Does heating the rod cherry red to bend the legs affect the strength?
One should never say never, but if you do it correctly any negative affect will be minuscule. Make sure you don't heat it any more than necessary, make the bend slowly, and let it air cool.

Bob
 

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Solid rod is not as strong as tube. Solid rod is more susceptible to bending than tube, since the walls of the tube make it structurally stronger than solid rod while maintaining enough flex to prevent cracking. Plus it's lighter, to boot.
 

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Discussion Starter · #11 ·
i agree with the tubing theor y, but trying to avoid it as i donthave acces to a good tubing bender plus ill have to make lugs for the bottom, i also dont care for the wieght of solid but for now i can work with it....the solid 5/8 lasted 30 hard years so far so id like to go that way. i was plaining on threading one end to retain the springs, making a new bottom spring plate out of 1/2" solid bar and welding the spring plate to my new rods after bending and machining. i was thinking of staying away from 4140 or allloys because i know theyre strong, but im worried about cracking/brittleness. but the truth is i really dont know what to use and i have a habit of overkilling things. thanks for the opinions guys.
its anold columbus i think..annd it rides awsome i want to keep it that way..
 

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Solid rod is not as strong as tube. Solid rod is more susceptible to bending than tube, since the walls of the tube make it structurally stronger than solid rod while maintaining enough flex to prevent cracking. Plus it's lighter, to boot.
That myth continues to be perpetuated. If one believes the assumption that a tube is stronger than a solid bar, then one has to believe that a tube gets stronger as the walls get thinner. Or conversely, the nearer to solid that a tube becomes, the weaker it gets? Illogical and incorrect. One of the elements that contribute strength to a round section structural member is it's cross sectional area. All else equal, the thicker the wall section, the stronger the member. Given that basis, a solid round bar can be thought of as a tube with a wall thickness equal to it's radius, thus providing the maximum cross sectional area for it's diameter. In addition to the beneficial mechanical properties gained through wall thickness, as tube increases in wall thickness, it gains resistance against collapse from lateral loads when under compression. A rod will bend. A tube will buckle.

I'm not arguing for the use of solid rod as a substitute for tube, as the choice will depend on application and material selection. Using tube often makes sense from a weight/strength viewpoint, but in no case does a tube have an advantage over solid solely in strength.

Bob
 

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i really dont know what to use and i have a habit of overkilling things.
You'll be fine with solid 1018 round, and it's the best choice given your lack of a bender. As for your habit of overkilling things, it's the thing to do if you're unsure about the stresses involved and uncertain as to the correct material. Beats under engineering every time!

Bob
 

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So if you aren't advocating one material use or the other, basically, you just wanted to make sure people knew you thought my response was wrong. My response was based on his particular application of making springer legs for a motorcycle, which in my opinion, tubing is the way to go. Since I am not a structural engineer, I am not going to argue with your statements about wall thickness, although I see assumptions in your argument that I think are wrong or incorrectly applied. What I do have, however, is a lot of experience on making, fixing and modifying front ends and frames, and from my actual, hands-on experience, I think tube is a better choice. That's all I am saying.

That myth continues to be perpetuated. If one believes the assumption that a tube is stronger than a solid bar, then one has to believe that a tube gets stronger as the walls get thinner. Or conversely, the nearer to solid that a tube becomes, the weaker it gets? Illogical and incorrect. One of the elements that contribute strength to a round section structural member is it's cross sectional area. All else equal, the thicker the wall section, the stronger the member. Given that basis, a solid round bar can be thought of as a tube with a wall thickness equal to it's radius, thus providing the maximum cross sectional area for it's diameter. In addition to the beneficial mechanical properties gained through wall thickness, as tube increases in wall thickness, it gains resistance against collapse from lateral loads when under compression. A rod will bend. A tube will buckle.

I'm not arguing for the use of solid rod as a substitute for tube, as the choice will depend on application and material selection. Using tube often makes sense from a weight/strength viewpoint, but in no case does a tube have an advantage over solid solely in strength.

Bob
 

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So if you aren't advocating one material use or the other, basically, you just wanted to make sure people knew you thought my response was wrong.
Not the case at all, and I'm sorry if you misconstrued my intent. My argument never was about whether tube or solid was "better". It was a response to your assertion that tube is stronger than solid. I took exception to the statement, and presented what I thought was a valid counterpoint. Like you, I'll say no more. Peace.

Bob
 
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