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  • Help designing lift mechanism

    Discussion in 'The main mechanical design forum' started by cylon58, Jun 9, 2014.

    1. cylon58

      cylon58 New Member

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      Hi guys,

      First let me confess I am not a mechanical engineer or anything related. I am at best a hobbyist woodworker in need of advice from people with more knowledge and experience in mechanical design to complete an upcoming project.

      OK, now that I said my peace, here's what I'm trying to accomplish:

      I am wanting to build a sewing cabinet for my mother similar to this: http://www.rockler.com/deluxe-sewing-center-plan

      My problem is that my mother has this machine: http://www.brother-usa.com/homesewing/ModelDetail.aspx?ProductID=NV6700D#.U5YGRyhmr1U

      It weighs 69.5 lbs, but the best lift I've found designed specifically for a sewing machine cabinet is rated at 50 lbs max.

      My thoughts so far have been focused around linear actuators. The weight problem would easily be addressed by any of the cheap actuators I've found on ebay. I'm uncertain about the best way to make this work. The embroidery machine is 13.1" tall, so the stroke on the actuator would need to be at least that long if I want a direct connection to some sort of bracket mounted to the bottom of the table. With that long of a stroke the top of the table would need to be at least double that height from the ground. BUT, my mom is short and would like a table that the height can be adjusted on, so I'm afraid the necessary table height would be uncomfortably tall for her.

      Are there any ways to use an actuator with a shorter stroke to accomplish this? Or are there better options other that a linear actuator.

      Also, any ideas on brackets and a system to ensure the table raises and lowers while staying in a perfectly flat position (for safety and long term reliability).

      I'm completely open to any suggestions on how to accomplish this task. My only limitation would be cost and the ability to use pre-made components.

      I hope my intrusion into your community doesn't offend anyone. I read through a bunch of posts here and felt like this would be a helpful and welcoming forum.

      Thanks,

      Geoff
       
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    3. Lochnagar

      Lochnagar Well-Known Member

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      Hi Geoff,

      I am not very knowledgeable on the practical issues of operating sewing machines - so I am a little unclear of why you feel you need such a large vertical adjustment to the height of the sewing machine - no doubt there is a reason - just I can't see what it is. I would have notionally have thought +/-75mm would probably have been adequate to make it comfortable to operate the sewing machine.

      However, I would have thought something like a leadscrew and guide with a "travel block" as shown in the animation below would be all you are looking for. Igus are very helpful - so if you give them the dimensions to the the offset load - then they should have something that will suit your needs.

      Hope this helps.

      http://www.igus.co.uk/wpck/2359/drylin_sht
       
    4. cylon58

      cylon58 New Member

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      Lochnager,

      Thank you for the reply. I know nothing about sewing machines either, but I am pretty good at woodworking :)

      I want to be able to put this sewing machine in 3 positions relative to the table surface. Position 1 is all the way up, just like it was sitting on top of a solid table. Position 2 is all the way down, so that the sewing machine is completely under the table surface and an extension wing can be folded on top of the table. Position 3 is slightly lower than position 1, so that the part of the sewing machine that the fabric lays on is flush with the table top (I will then make an insert to close any gaps between the machine and the table). Maybe the photos on this page will help clear this up: http://www.thewoodwhisperer.com/viewer-projects/daves-sewing-cabinet/

      I need either a motorized or gas powered mechanism to do the lifting (springs are not out of the question) because my mother shouldn't be trying to lift a 70 lb sewing machine.

      Here is a video demonstrating the 3 different positions using an air lift mechanism: https://www.youtube.com/watch?v=tvKrB9oHwBw

      My problem is that no commercially available sewing cabinet lifts are rated for the weight of my mother's machine.
       
    5. Lochnagar

      Lochnagar Well-Known Member

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      Hi Geoff,

      Thanks for enlightening me on the detail of the raising and lowering requirements for the sewing machine in the video link you posted. I guess there are a couple of options:-

      1) You could add a DC motor and gearbox (like Maxon Motor/gearbox) to drive the Igus leadscrew (I posted previously) possibly via a small chain drive to get a further gear reduction.

      2) Alternatively you could buy the one below - which lifts 145lbs - which is more than the weight of the sewing machine.

      Hope this helps.

      http://www.rockler.com/whisper-1000-flat-panel-tv-lift
       
    6. VJmech

      VJmech New Member

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      Hi Geoff

      I try to create a simple sketch for your requirement see the attached picture . You can easily make this one by using off self parts.
      please let me know if u need more details.

      [​IMG][/IMG]
       

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