Attempt to design a barbell during lockdown Attempt to design a barbell during lockdown

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Thread: Attempt to design a barbell during lockdown

  1. #1
    Join Date
    Aug 2019
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    41

    Default Attempt to design a barbell during lockdown

    • wichita falls texas june seminar date
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    After placing orders for a power rack and bench on a local workshop, I am now planning to make a 'proper' barbell with spinning sleeves because I am not able to find one in any of the local shops. All good barbell manufacturers of my country are in states that are locked down and it looks like I won't be able to order one anytime soon.

    Here are my questions:

    1) Is the basic scheme shown in the attached figure alright? The scheme is based on what I saw in this Rogue Video:YouTube . (Shim is not shown but I will add it if there is any loose play after the assembly). I will take care of engineering tolerances, fits and finish while preparing the engineering drawings for the workshop. What I would like to know at this stage is that I am not missing anything serious.

    BB.jpg

    2) What is the recommended grade of the steel?

    I checked with a few steel suppliers in my city. Only available high strength steel options in this size are EN-18 (yield strength 35 ksi, tensile strength 80 ksi), EN-24 (yield strength 90 ksi, tensile strength 120 ksi) and super duplex steel (terribly expensive and out of question). In comparison, the tensile strength of Ohio bar is 190 ksi. Since I am unlikely to pull anything beyond 180 kgf (ever), is it okay to go for EN24? Any other material might have to come from another state.

    3) What is the engineering specification for the knurl on a typical bar? I prefer to have some medium to aggressive knurl - I just don't know how to specify that to a workshop.

  2. #2
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    Aug 2019
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    I see that the image isn't clear . I had to downsize it to bring it under the allowed limit of 19.5 kB.

  3. #3
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    Nov 2017
    Location
    WV
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    How are you going to heat treat the steel? You will have to find out the proper hardness for the type of steel that you use to get the desired balance of strength and flex. Making a bar is more complex then just doing the machining.

  4. #4
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    Aug 2019
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    Quote Originally Posted by Ken_L View Post
    How are you going to heat treat the steel? You will have to find out the proper hardness for the type of steel that you use to get the desired balance of strength and flex. Making a bar is more complex then just doing the machining.
    I ditched the idea when the machine shop gave a quote that wasn't very far from the price of a new medium quality barbell. And they couldn't even assure the quality of the materials they could source because of the restrictions in the interstate cargo movement.

    Also, the barbell manufacturer is now hopeful of shipping my order in the first week of June.

  5. #5
    Join Date
    Apr 2020
    Location
    Manhattan
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    13

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    Quote Originally Posted by PuliMorgan View Post
    I ditched the idea when the machine shop gave a quote that wasn't very far from the price of a new medium quality barbell. And they couldn't even assure the quality of the materials they could source because of the restrictions in the interstate cargo movement.

    Also, the barbell manufacturer is now hopeful of shipping my order in the first week of June.
    You made the right call man, I was going to say as an engineer your request to a machine shop was going to be extremely expensive and if you don't know about GD&T and steel grades you're going to get an inferior product at a high cost. Companies like Rouge pump out barbells by the dozen with a refined production process which is why an OPB is about $300 (which is actually really low for what you get quality-wise). If I got an OPB quoted to the exact specs of how Rouge makes them, I'd be willing to bet a local machine shop would run you about $3,000 if they made 1. If you had your bar made from EN-24 (never actually heard of this grade because it's only made in metric [metric round bar is super expensive in the US unless you source from Canada] but looked up the properties) your bar would've been so hard that you would have virtually 0 flex and I mean way less than your standard power bar. You'd probably crack that if you dropped it on a concrete floor or with a heavy deadlift whereas most bars would bend instead.

    Sounds like you made out alright though. I admire the drive to get a barbell. Sounds like you'll be back in business soon!

  6. #6
    Join Date
    Aug 2019
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    41

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    starting strength coach development program
    Thank you snake.

    Update:
    I would have loved to buy a barbell from Challenge because I have used them in the gym. But the company is not able to confirm when they can resume sales and shipping. So I ordered a Silver Rhino bar from Bullrock on Amazon the moment they returned after the lockdown. The manufacturer claims 210 ksi strength and 1800 lbs load rating for this bar. I paid INR 22000/- (US $ 290) and hope it is worth the investment.

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