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Urgent help please !

  1. Mar 5, 2008 #1
    Guys,

    Need some help urgently! I have a thin shaft and a rectangular solar panel. The shaft is connected to a motor shaft and will rotate. How do I stick the panel onto the shaft so it can rotate ?
    The simpler the solution the better..

    Thank you everyone
     
  2. jcsd
  3. Mar 5, 2008 #2

    FredGarvin

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    Is there a framework that you can drill holes into on the solar panel?
     
  4. Mar 5, 2008 #3
    yes, there is a perspex frame and the shaft has a diameter of around 5mm.
     
    Last edited: Mar 5, 2008
  5. Mar 5, 2008 #4
    Stick the solar panel unto the motor.
     
  6. Mar 5, 2008 #5
    The motor shaft is connected to another shaft A with a coupling. Shaft A is where I want to place the panel so that it can rotate.

    How can I do that ?
     
  7. Mar 5, 2008 #6

    FredGarvin

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    I am going to assume that this is very low speed and low torque. Also I am assuming you can find the right clamp size. A small piece of unistrut and a tube/pipe clamp along the axis of the shaft could do it. You would attache the unistrut to the solar panel and the clamp attaches to the unistrut

    [​IMG]
     
  8. Mar 5, 2008 #7

    Danger

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    Since there's no appreciable load involved, other than the weight, you could also just apply a large glob of epoxy. Really, in this situation, there are a lot of options. I personally prefer the clamp approach such as Fred mentioned, but automotive body filler would probably do a decent job as well.
     
  9. Mar 6, 2008 #8
    So if I place epoxy along the shaft and stick it to the perspex, it will stick well ? Because the shaft is only 5mm in diameter and the surface area exposed to stick with is quite small.

    I hope you get what i mean.

    edit: or can i place a blob epoxy over the whole shaft and then the perspex, leaving the epoxy exposed when it hardens ?
     
    Last edited: Mar 6, 2008
  10. Mar 6, 2008 #9

    Q_Goest

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    It's hard to understand how large this thing is, but if only 5mm shaft, I suspect the unistrut idea will be too big. I kinda like Danger's idea of gluing with epoxy. Might want to rough up the perspex with medium or course grit sand paper first, but it should stick well. Also consider reinforcing the epoxy with fiberglass cloth such as by laying the cloth over a layer of epoxy and adding more on top. Or just take some fiberglass batting and mix it into the epoxy. The fibers add considerable strength and hardness to the epoxy.
     
  11. Mar 6, 2008 #10
    Hi Q, here are some pics, the first shows the frame behind the panel and the second shows the shaft.

    So how do I apply the epoxy ? Only in between the shaft and perspex (only on the surfaces touching each other) or should I put like blobs which cover the shaft, and then the bottom will be exposed epoxy ?

    The first way seems like the epoxy will be too little to hold them together ..
     

    Attached Files:

  12. Mar 6, 2008 #11

    Q_Goest

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    I'm unclear as to what the first picture is showing. In the second picture, is that the position you need the shaft in? If so, and without doing any calculations on it, it just seems like you'll need some reinforcment around the connection point. Maybe a few plastic (perspex?) brackets.

    Edit: One other thing. It looks like the perpsex you're trying to attach it to won't be balanced on the rod. If there are unbalanced forces on the connection, the connection also has to accomodate those forces. You might want to consider how you could balance the plastic thing on the rod so there aren't forces on the joint tending to break it.
     
    Last edited: Mar 6, 2008
  13. Mar 6, 2008 #12
    The first pic is the behind of the solar panel showing the perspex that I attached to it.
    The second pic was a bit confusing, here are some new pics to demonstrate what i want it to be like. (Of course, my hand is just there to hold it in place)

    Is this still unbalanced ?

    Anyone else have any comments, pls leave a post.
     

    Attached Files:

    Last edited: Mar 6, 2008
  14. Mar 6, 2008 #13

    Q_Goest

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    Thanks for the pic's rngd, that really helps. Attached are two possible suggestions. Just my opinion, but I think a counterweight would be helpful on this and would eliminate any undue stress on the rod/bracket joint. Don't know if you can put wood screws into the solar panel as shown in the attached, but you might simply consider making up some brackets out of that plastic you're using and gluing it on.

    As for type of glue, I'd think epoxy would work well especially since it has to attach perspex to metal, but there may be other types of glue that work better for this application. A better glue may be available for the perspex to perspex joint.

    I'm sure there are many other ways of doing this. Maybe Danger or Fred have some other ideas.
     

    Attached Files:

  15. Mar 6, 2008 #14

    Danger

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    Yeah, the pics make a tremendous difference in trying to envision this. I still like the mechanical support idea, but my thought was 90* out of synch with Q's. I was thinking of a flat strap with an axle hole, screwed or bonded to the edge of the panel. Q's angle bracket would definitely be stronger, but I was trying to avoid drilling into the back.
    My epoxy approach is somewhat primitive, but I've never been one to prefer form over function. The way that I was thinking of would be to lay the panel face-down on a table and position the axle where you want it on top. Then just slather on the goop, or press it into position if it's solid enough, so that it completely encloses the axle and forms a ramp up to it from both sides of the panel. (Think of a buttress weld, or sticking a drinking straw to a piece of cardboard with chewing gum.) I assume that you want to leave that electronics module accessible, so that would restrict your attachment to the left-most 3/4 or so of the axle. That should still be plenty. I totally agree with Q that adding glass fibre or some other structural material to the epoxy will drastically increase the strength.
    If looks are a concern, you can always do some grinding, sanding, and painting after the stuff has cured. I'm not convinced that a counterweight is necessary in this case, since it appears to be well balanced, but such can easily be imbedded in the epoxy on the 'back' side of the axle if needed.
     
  16. Mar 6, 2008 #15

    Q_Goest

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    Gluing it like Danger says would work too. If you do it that way, I'd also suggest roughening up the rod by running some course grit sand paper up and down it.
     
  17. Mar 6, 2008 #16

    Thank you guys ! That was exactly what I needed to know !
     
  18. Mar 6, 2008 #17

    Danger

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    You're quite welcome. Let us know how it works out.
     
  19. Mar 16, 2008 #18
    If it isn't too late...from the 3rd picture from your post on the 6th, it looks like you want it to attach to the rod in a parallel fashion. If you have access to a mill and some aluminum or a saw and some wood you can do the following: Get 2 L-brackets and place them facing away from each other fastened to the plate on opposite side of where the rod will be. Mill down the aluminum or saw the wood to a height where you can create a bridge between the 2 brackets without a gap between the bridge and the rod. Wood would probably be preferable so you could sand the shape of the rod into the bridge.
     
  20. Mar 18, 2008 #19
    hi weiszed, I already used epoxy to stick the shaft. I'll post some pics once i get everything up. Thanks anyway.
     
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