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Thread: Feedback on my power rack design

  1. #1
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    Sep 2020
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    Default Feedback on my power rack design

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    I just finished designing a power rack for my home gym, and I would like some feedback (good, bad, and ugly) on it. You can find the 3D model here: link. It is based off the power rack shown here (link), but I made a few changes to (in my opinion) improve the design. The most significant change that I made was I made it possible to place the spotter bars at nearly any height. Additionally, I put the spotter bars inside PVC pipe, which is a pretty simple change that could obviously be done on many other racks, but I haven't seen anyone else do it. Maybe that's because it's a bad idea (if so, I'd be very interested in understanding why), but it would seem to me that it would greatly reduce the wear and tear on the bar from a large weight being concentrated on the extremely small area of contact between the bar and the spotter bars.


    A couple notes:

    1. According to my calculations, each knob should be able to easily generate enough load to support 1000 lbs of weight.
    2. I put a spacer block halfway up the posts two try to keep the posts straight. This obviously limits the options for placing the spotter bars, but my expectation is that the limitation would be quite minimal. However, I would be very interested in hearing feedback about a better placement location. Alternatively, I could make the spacers at the top and bottom several times longer than they are and remove the center block, but this wouldn't be as effective at limiting the warping as what I currently have.
    3. I've seen other homemade power racks use black iron pipe for spotter bars. This seems like a very bad idea to me since it seems extremely likely that the pipe would not be able to support the weight when squats get up very high. The steel rod I'm putting in the PVC pipe in my design can be found here: link.



  2. #2
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    Am I reading this right? You're going to use hand-tightened threading as a way to bear load that will potentially keep you from dying?

    Quote Originally Posted by tlewis3348 View Post
    [*]According to my calculations, each knob should be able to easily generate enough load to support 1000 lbs of weight.
    Show me your calculations please with your assumptions.

  3. #3
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    Quote Originally Posted by AndrewLewis View Post
    Am I reading this right? You're going to use hand-tightened threading as a way to bear load that will potentially keep you from dying?


    Show me your calculations please with your assumptions.
    Well, there's egg on my face. A previous version of this (see here) had grooves in the posts because I assumed that the hand-tightening would not be sufficient. Then, I did the calculation and multiplied by 4 instead of dividing by 4 and got 960 lbs as the maximum load that can be supported instead of 60 lbs (based on what I've been able to find, 2 ft-lbs of torque should be able to be produced on a 2.5 inch knob, which produces 240 lbs of clamping force). I removed the grooves because it would obviously be much easier to manufacture.

    In light of that, thanks for pointing out an obvious flaw and my boneheaded mistake, and please let me know if you can find any other flaws in my design.

  4. #4
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    I'm curious how the wood would hold up to normal wear and tear, alongside more abnormal abuse (e.g., getting smacked by a 45 during loading/unloading, whacked by a bar, etc. - the things that shouldn't happen but are going to anyhow). For a 'normal' example, if it were used by two people with different height settings for everything, I could see the constant moving of the hooks and spotter bars eventually wearing out and expanding the grooves. Would that be an issue in the long run? What happens if somebody is rather rough re-racking after their final heavy squat set? Would that impact hurt the wood?

    Asking because I legitimately don't know the answer. I'd definitely want a longevity assessment before using one.

    So far as the PVC sleeves on the bar - I don't know if it's a good idea or not, but I'd personally assume it to be a wear component that gets replaced occasionally. That might be why people don't do it; it's just one extra step of maintenance.

  5. #5
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    May 2020
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    I would not rely on friction to securely hold the bar.

  6. #6
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    Quote Originally Posted by Hooper View Post
    I'm curious how the wood would hold up to normal wear and tear, alongside more abnormal abuse (e.g., getting smacked by a 45 during loading/unloading, whacked by a bar, etc. - the things that shouldn't happen but are going to anyhow). For a 'normal' example, if it were used by two people with different height settings for everything, I could see the constant moving of the hooks and spotter bars eventually wearing out and expanding the grooves. Would that be an issue in the long run? What happens if somebody is rather rough re-racking after their final heavy squat set? Would that impact hurt the wood?

    Asking because I legitimately don't know the answer. I'd definitely want a longevity assessment before using one.

    So far as the PVC sleeves on the bar - I don't know if it's a good idea or not, but I'd personally assume it to be a wear component that gets replaced occasionally. That might be why people don't do it; it's just one extra step of maintenance.
    Regarding wear and tear on the wood, that could potentially be an issue, I guess. I was assuming that since there are many designs around the internet for power racks made out of wood that it wouldn't be that big of a concern. Ultimately, I seriously doubt that a dent here or there would do much harm to the overall strength. I suppose over time the edges of the grooves (which I would be shaped as shown below) will become rounded off, but I would think it'd take quite a bit to have them so rounded off that the no longer function. As an added protection, I could put a "backstop" in front of the posts where the bar will be getting racked in order to prevent parts that are more structurally critical from getting dented. Finally, since I built it myself, I will probably be more careful to keep from banging things around on it than some random dude would be. Eventually, my son (who's currently 20 months old) may end up using it, but at that point it will be old enough that it will be about time to replace it anyhow. In any case, as I further refine the design, I will try to keep in mind potential wear points and think about how to minimize their effect as much as possible.

    Regarding the PVC sleeves, if the wear is extreme (e.g. I have to replace them more than once a year), then that'd be one thing. I guess if I wear through them sooner than I was expecting, I can always just not replace them since the bar inside will just be a piece of cold-rolled steel.

  7. #7
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    This is one of those things that's pretty much always easier and safer if you just pony up the money and buy a quality power rack. I've just never understood wanting to build a rack out of wood.

  8. #8
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    Yeah, my questions were out of sheer ignorance, not of any actual critique. I hadn't heard of wood racks before, so I'm not the one to judge. Good luck with the project!

  9. #9
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    Quote Originally Posted by Cody Annino View Post
    This is one of those things that's pretty much always easier and safer if you just pony up the money and buy a quality power rack. I've just never understood wanting to build a rack out of wood.
    I agree. Especially since rectangular tubing and c-channel is so available. You could literally google "weld shop" or "machine shop" near me, go there with Starting Strength and tell them "I want this" pointing to the CAD, and they could do it.

    It's not like barbells.

  10. #10
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    May 2020
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    starting strength coach development program
    I built my SS rack for around $650 without the floor. Pickled the steel and drilled all the holes myself and had it welded at a local shop. Currently working on the second one to put in Jiu Jitsu gym we attend. They are very good racks.

    We originally had a wood rack but it quickly became frustrating to use. If you’re going to build, build steel.

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