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  1. #1

    Cart Fabrication Questions

    (Also posted on yotatech.com http://www.yotatech.com/showthread.php?t=76849 )

    I'm working on building a cart to haul a load of 250lbs max. I'm going to use two of these cart wheels form Northern Tool (#145124) rated for 125# each.



    I need to construct an axle with 1/2" shafts for the wheels. My thought is to use 1" square aluminum tubing with a wall thickness of 1/4" This way I can fit 1/2" solid round bar stock inside the tubing and have it welded on the ends.

    My dimensions right now are 21" of square tubing with two 7" round bar stock (1/2" OD) inserted 3" into the tubing, i.e. 4" sticking out both ends, which the wheels will sit on. The wheels have 3" hubs, so the extra inch is for the welds on the end and a cotter pin or castle nut/pin connection to keep the wheels on.

    On to the questions! "BRILLIANT!!"

    1. Any thoughts on overall strength? Does this sound strong enough?

    2. Any estimates or educated guesses on how much a fabricator would charge to build this for me?

    I stopped in at the local metal distributor/fabricator and they quoted roughly $60 bucks. They figured 1/2 hr of shop time ($75 per hr.) plus materials. They pretty much pulled that number out of their :booty: and I didn't get it in writing so I'm half expecting a new number when I head back with drawings.

    Anyone out there want to build it for less than $59.99?

    Thanks for the help.

    Erich

  2. #2
    Administrator Cebby's Avatar
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    Re: Cart Fabrication Questions

    Erich - sorry, I moved it...

    What is this for? Sounds like a two wheel cart for O/A tanks or something else that is upright? Almost like a large wheeled appliance dolly?

    If you are using aluminum, this cart will get expensive (both materials and fabrication). Does it need to be lightweight? Corrosion resistant?

    If you have a post a sketch, that would help. We can help you with the design - which would have a large bearing on the weight capacity. Materials alone won't dictate capacity. If you can't scan/generate dwg electronically, let me know - you can fax it to me (my faxes get converted to PDFs since I use Webfax) and I'll post it up.

  3. #3

    Re: Cart Fabrication Questions

    Quote Originally Posted by Cebby
    Erich - sorry, I moved it...

    What is this for? Sounds like a two wheel cart for O/A tanks or something else that is upright? Almost like a large wheeled appliance dolly?

    If you are using aluminum, this cart will get expensive (both materials and fabrication). Does it need to be lightweight? Corrosion resistant?

    If you have a post a sketch, that would help. We can help you with the design - which would have a large bearing on the weight capacity. Materials alone won't dictate capacity. If you can't scan/generate dwg electronically, let me know - you can fax it to me (my faxes get converted to PDFs since I use Webfax) and I'll post it up.
    No problem on moving it. I thought it might go in this section, but since it's not a finished project I didn't know for sure if this was the right spot.

    Close but no cigar on the O/A tanks cart. The cart does need to be both light weight and resistant to corrosion. It's not for shop use, but for outdoor purposes. Is that vague enough? Basically this is the first phase in a yard cart with an attitude that won't stay in the yard

    Here's a sketch






    I guess I should get off my butt and dust off the strengths of materials text book and see if I can put some edumication to use

    Erich

  4. #4
    Contributing Member MXtras's Avatar
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    Re: Cart Fabrication Questions

    I have not run any numbers but at first glance, it seems a bit on the hairy edge to hold more than maybe 150 pounds. I would suggest stainless or going just a tab larger with the axle diameter - 1/2" alum rod is not going to hold more than about 75 at 3"-4". It seems a bit small to me.

    Again - these are shooting from the hip.

    Scott
    If it wasn't for the last minute I wouldn't get anything done

  5. #5
    Administrator Cebby's Avatar
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    Re: Cart Fabrication Questions

    What if you did 1/2" stainless rod inside your alum tube. Instead of welding it, run the rod the whole way through (rod=29" or so). You can drill a hole in the middle of the rod (and tap it) and a slightly larger one in the aluminum tube so you can run a bolt into the rod to keep it from skating around.

    When I asked for a drawing, I meant of the whole cart. Is there going to something overtop of the full length of the alum tube (like a box of some sort)? The reason I ask, is that if you concentrate all the weight in the center of the unsupported tube, it may also fail (not as much if sleeved like I've suggested tho)
    Last edited by Cebby; 01-22-2006 at 09:56 AM.

  6. #6

    Re: Cart Fabrication Questions

    Quote Originally Posted by Cebby
    What if you did 1/2" stainless rod inside your alum tube. Instead of welding it, run the rod the whole way through (rod=29" or so). You can drill a hole in the middle of the rod (and tap it) and a slightly larger one in the aluminum tube so you can run a bolt into the rod to keep it from skating around.

    When I asked for a drawing, I meant of the whole cart. Is there going to something overtop of the full length of the alum tube (like a box of some sort)? The reason I ask, is that if you concentrate all the weight in the center of the unsupported tube, it may also fail (not as much if sleeved like I've suggested tho)
    I don't have the rest of the cart drawn up. I have an idea, but I'm still chewing on it. The loads onto the axle, from the cart, can be considered two point loads 2" in from both ends of the square tubing (125lbs each).

    I think I'm going to make my life easier and sign up for a membership at Efunda.com to use thier calculators.

    I'll look into the stainless steel. A solid rod all the way thru would increase strength, no doubt, I just don't know if the added strength is required yet

    Erich

  7. #7
    Contributing Member MXtras's Avatar
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    Re: Cart Fabrication Questions

    Two things I have learned -

    1) you almost never regret going big.
    2) you almost always need something bigger.

    Scott
    If it wasn't for the last minute I wouldn't get anything done

  8. #8
    Administrator Cebby's Avatar
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    Re: Cart Fabrication Questions

    Any updates Erich?

  9. #9

    Re: Cart Fabrication Questions

    Quote Originally Posted by Cebby
    Any updates Erich?
    Opps, been away for a while. I had the first prototype built for $53 IIRC out of plain carbine steel to keep the cost down, etc, and who ever fab'ed it got a little excited with the grinder. He left it totally FUBAR'ed

    I'll post a pic to explain, but the 1/2" rod is not round any more. I gave them a very straight forward drawing that said nothing of finished grinding so, I'm not sure why this unknown welder went to such lengths to mess it up

    Then the wheels I purchased last minute off eBay were described as made for a 1/2" axle but are really 5/8". So I have nothing that works at this point.

    It's okay though. I'm going to try it again with a much better set of tires from Northern Tools that need a 3/4" axle. I also plan to keep the overzealous grinder away from my second axle.

    Erich

  10. #10

    Re: Cart Fabrication Questions

    Well here's another update.

    I said I was going to share some pics of the first axle that never worked out.

    Here it is.


    You can see the neck I was talking about


    And it's not round anymore. If I put a washer on it it's obvious it isn't 1/2" diameter either.


    Here is a pic of my new set up. I was talking with my parents neighbor who does fab work as a part time job and he welded a 3/4" alum rod in 1" channel for me as a wedding gift . It works great and even has a little camber thanks to some extra heat


    I'm finally making some progress since duck season is here and this cart will play a pivotal roll in my hunting plans.

    More pics to come!

    Erich

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