Need advice on type of motor for raising weight within a case

Discussion in 'The Projects Forum' started by torontob, Mar 11, 2012.

  1. torontob

    Thread Starter New Member

    Mar 11, 2012
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    Hi everyone,

    Hopefully I am not on the wrong forum as I see it's all about circuit boards. If so, please guide to right one.

    I have a Pelican 1650 case (http://pelican.com/cases_detail.php?Case=1650) that I want to use as a custom demo box for some electronic goods.

    The case is very nice and it comes with three foams so they can be cut to place equipment inside to be safe for transportation.

    This case is deep so my equipment is at the bottom of the case on top of the foam. I want to give it a nice high-tech look and feel by installing a motor that will raise the foam and equipment by 4-5 inches when I open case's lid. Equipment + foam is 3.5kg. If I add an acrylic sheet under the foam which I think I need, it should still not be more than 3.7kg.

    I have a power backup UPS mounted inside this case so power is abundant.

    I would like to know what kind of a motor and poly system I need to do pull this job so that it looks professional and yet allows me to make the best use of space underneath as well.

    Any feedback is much appreciated.
     
  2. John P

    AAC Fanatic!

    Oct 14, 2008
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    My suggestion is a d.c. gearmotor driving a scissors jack.
     
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  3. KJ6EAD

    Senior Member

    Apr 30, 2011
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    You could try adapting an automotive electric window operator.
     
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  4. B F Clanton

    New Member

    Mar 12, 2012
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    The scissor jack is a simple way to achieve this but may monopolize the available space. The car window motor is defiantly the way to go as it is very powerful and easily reversible. I would use 4 pieces of course threaded all-thread rods. One in each corner with a chain connected to sprockets connecting all 4 rods. The motor connect directly to the bottom of one of the rods. The chain and sprockets can be from bicycle parts. The rod only need be ¼” to 3/8” diameter. You could have the chain run around the top for show (chroming all the parts would be a nice touch) or you could conceal the chain by running it around the bottom.
     
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  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Could you give us a side view sketch to show spacing?
     
  6. torontob

    Thread Starter New Member

    Mar 11, 2012
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    First of all, thanks everyone for the great input.

    John P: Scissor jack might not be best as it will take a lot of space. I would like to know more about the type of d.c. motor you mentioned. Given the weight of what I want to pull-up what sort of a very small motor should do? I checked there are lots of different d.c. motors. P.S. I am in Toronto, Canada and would appreciate a source for it as well. Also, my power source is a UPS so the motor should be able to plug into wall socket type of power = 120v.

    KJ6EAD: Any specific model you would suggest?

    B F Clanton: I like the idea of sprockets, but not sure how this would look like. I have attached a diagram of what I think you meant. Please correct if I am wrong. Sprockets have to come with a holding shelve so it can be pinned to glued to the box. Can you recommend some? Doubt bicycle ones work. Too big.

    Bernard: Attached are few pics of the case with equipment placed the way it should be on final product.

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    Thanks again,
     
  7. torontob

    Thread Starter New Member

    Mar 11, 2012
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    ***Please use CTRL+- (CTRL plus Minus) to make the screen smaller so you can see the picture clearly on Chrome, Internet Explorer, or Firefox.
    Posting more pics here due to limit of 6 per post:

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  8. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Are you stuck with AC from the UPS or can you tap the 12-24VDC from it?
     
  9. torontob

    Thread Starter New Member

    Mar 11, 2012
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    Only power source is the AC UPS so far. I can add a 12v battery but that would take extra space, etc...I would like to avoid.
     
  10. torontob

    Thread Starter New Member

    Mar 11, 2012
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    Okay, so upon re-reading this again, I gather that rod like this (http://tinyurl.com/all-thread-rod) should be wielded to sprocket like this (http://preview.tinyurl.com/sprockit-colour) and then the motor wielded to the the bottom of one of the rods. Few questions with this:

    1- Where can I put the motor if I want to show the chains? I mean the motor would be head-down onto the rod the lid might not close?! How small of a motor are we talking about? Should I check the local car parts grave-yard? or do you have a suggestion for any specific model?

    2- Where would the bottom of the rods connect?

    3- Did you have bolts in mind? I mean how would the board raise up? bolts glued on four corners on top so the rods can go into them?

    4- Can I do the chroming of these parts at home?

    Thanks again
     
  11. John P

    AAC Fanatic!

    Oct 14, 2008
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    Maybe I was being misleading just saying "scissor jack". Most items you can find on the Internet by searching on that term are big things for lifting cars(!!) and I meant something much smaller, like this:
    http://www.labdepotinc.com/c-334-lab-jack.php

    The advantage that I see with this kind of device is that it's self-contained, and the top deck (if that's what they call it) moves vertically relative to the bottom with no need for any additional guidance--slides or guides or bushings etc. The KISS principle! But if you have a machine shop ready to do your bidding, and a pile of hardware all ready to bolt together, go for it.

    This kind of motor ought to do the job:
    http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_162191_-1
    (I hope the link works).

    The amount of power required for this task is tiny. If you have to run from an a.c. power source, a wall wart should give you all the current you need. A car window motor is way too much (IMHO) and heavy and bulky.
     
  12. torontob

    Thread Starter New Member

    Mar 11, 2012
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    Thanks John P. I see how the scissor jack can a solid and much easier option now.

    The motor you referenced is pretty small. That should be able to raise 3.8kgs weight?

    Also, how would I connect this to the scissor jack? Mostly likely glued or wielded? And can I install a two switch so it goes up and down?

    If in case I chose the option of sprockets, is there a place I can find sprockets and thread-rods combos or do I have to put them together?

    Thanks again,
     
  13. John P

    AAC Fanatic!

    Oct 14, 2008
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    Any motor can move any weight! You just have to apply gearing to increase the torque, which of course will decrease the speed at the same rate. But I'd guess that in this case you don't want it to move very fast--what you have to do is figure out how much torque you need and how much speed. Chances are speed is easier to work with, then you can make a rough guess at how much weight you'd be able to lift.

    Mechanical construction is always the most difficult part of a project. That particular motor mounts with screws driven into its face, and there's a boss surrounding the output shaft that would locate it accurately. You'd have to figure out how to connect the motor shaft to whatever it is that you're driving.

    I think whatever system you end up with, you'll have to do the assembly yourself, unless you can find something that someone else put together and didn't use (for sale on eBay?) In general catalog sonly list simple machine parts because after all, how many of any complex device would they ever sell?
     
  14. torontob

    Thread Starter New Member

    Mar 11, 2012
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    John P - Even with the scissor jack you prosed, I probably still have to suspend the four corners of the acrylic that goes under the foam because of stability.

    1- I want to give it a 3 seconds time to raise up or down. Will be looking for the formula soon.

    2- Is there any way I can use some sort of glue to lock the items to the case? I don't think I can screw this and it would be a waste of the case. It's supposed to guard against rain too now.

    Thanks again
     
  15. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    The pictures were nice but did not convey desired information. What is the distance from inside bottom of case to the bottom of the platform when in low position? Distance from bottom to rim? Distance from bottom of platform to rim in raised position?
     
  16. torontob

    Thread Starter New Member

    Mar 11, 2012
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    Bernard - thank for input. Full info from case URL: http://pelican.com/cases_detail_specs.php?Case=1650

    It's a Pelican 1650 with following dimensions:
    L x W x D
    28.57" x 17.52" x 10.65"
    (72.5 x 44.5 x 27 cm)

    Lid Depth
    1.81"
    (4.6 cm)

    Bottom Depth
    8.84"
    (22.4 cm)

    Total Depth
    10.65"
    (27 cm)

    Weight with foam
    28.06 lbs.
    (12.73 kg)


    ***Weight I want to raise is 3.8 kg. Max 4 Kg.

    So, it's 8.84 interior with lid and in rest position the board will be lowered by 5" from the rim and I want it raised by 5" (or maybe a bit less as corners have to be suspended?!) sot leaves about 3.84" at the bottom when resting and ~8.84 when raised.

    Best
     
  17. John P

    AAC Fanatic!

    Oct 14, 2008
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    I think you asked about attaching the machinery to the inside of the case. You could do that by gluing a sheet of plywood to the plastic with construction adhesive, then screw everything else to the plywood. But note that once the plywood is installed, you will no longer have access to the underside.

    What you said about the 4 corners sounds right, unfortunately. It might depend on how well centered the load is. I thought of another way you might build your own scissor jack, which would support the load near the corners, and also have the feature that the place you'd have to apply force wouldn't rise along with the load. What you'd have to do here is push one end inward, which you could do with a motor either pulling a cord or driving a screw. The diagram just shows the mechanism from one side, but you'd want to build it as a frame which would be almost the size of the case.

    [​IMG]
     
  18. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Another possibility, loosley based on the sissor jack. One advantage is , when raised, is supported on all four corners. There is a track on each side of platform, roughly square C section, similar to drawr slides; should be as long as possible to add strength to platform. The two pulleys,P1&2, are cross connected with 1/16 in SS cable so that connecting arms close towards each other. AS John P suggested, all mechanisims are mounted to a bottom mounting plate- forgot to show. Compression springs could be added on each end to help counter ballance weight. A gear head , high torque motor is coupled to cross shaft with chain or cog belt. A possible motor is G17949, Electronic Goldmine, 3V to18V, .46A no load. 4.5 RPM @ 12V. I bought one cause it looked interesting, & if interested, I will measure torque. Must go- past my bed time.
     
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