Replies

1. 
   Guest_ | Feb 02, 1999 12:53am | #1

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   I think a manual one would be much safer and simpler to home build.

   If you still want to drive it with a garage door operator, how about counterweighting and overbalancing by 50% of load, making mechanism tight enough (or even look into over speed brake) so it won't free fall, and then driving the counterweight.

1. 
   Guest_ | Feb 02, 1999 01:13am | #2

   *Richard: I like your approach. Anything off the shelf is going to be far cheaper than cobbling it together yourself. A garage door opener has adjustable limit-of-travel points and will stop and reverse if it whacks into something firm. And you can get cheap wired and wireless controls for the top and bottom of the shaft. Seems like it would handle a one-story dumbwaiter, but might need some screw extensions (or one of the cable models) to handle a two-story height.I can't think of a reason not to mount the opener vertically. Only the electric motor is sensitive to position. If it was designed to operate with its shaft in a horizontal position, it probably doesn't have tapered bearings to take a load along the axis and you should only use it with the shaft in a horizontal position. But if you mount it vertically above the the shaft, there might be enough room. Will you extend your "elevator shaft" into the attic to accommodate the length of the opener's screw drive? A cable-dive unit would be more compact or you could mount the screw-drive unit vertically alongside the dumbwaiter and use two pulleys to center a cable over the dumbwaiter.Note that one advantage of the screw-drive units is that they can push as well as pull. Cable-drive units would need to pull against a positive weight so you could counterbalance as much as would reduce you maximum load.Think about some kind of wheels on the dumbwaiter and runners on the wall. I'd use something simple like 2x4 runners and solid rubber wheels off a roll-away tool chest (non-pivoting). Pocket door tracks and such would be tempting but a real pain to install and fix if it ever gets off track (like pocket door always do). Bill's got two good ideas there. Counterbalance it by the unit's weight plus 50% of the load. Garage door openers don't dead-lift all that much because garage doors are "counterbalanced" by the springs on the hinges. A Urban-Ore/ construction slavage yard would have LOTS of old cast iron counter weights and pulleys from double hung windows. Or talk to a window installer and offer a few bucks each for the biggest counter weights they can salvage off their next retrofit job. Have fun with it. -David

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   Guest_ | Feb 02, 1999 03:23am | #3

   *David makes some good points. Just remember if it takes the head of the next owner (or even just a finger), they'll probably be looking for you.For guiding - do it like an elevator - opposing "t" rails and adjustable guides. A continous piece of hardwood and some wood "shoes" is probably simplest. (Browse in a book store for "stagegcraft" type books - almost every one has an illustration of a lift for raising someone through a trapdoor.)Counterweight should be guided too - but taught wire ropes and thimbles on the weight will do. You can use steel or iron weights but consider making a flat "pail"; fill with sand to get approximate weight - then pour with sackcrete for final. (If your really good at calculating weight, pour it flat with eye bolts and guides all imbedded - but a real treat to remove a little weight.)Build in a lot of adjustment - even if it's assembly with screws but no glue so it can be changed.Of course then there's the hydraulic approach - valves to alternately fill or empty the counterweight tank........................

2. 
   Keltic | Feb 02, 1999 05:49am | #4

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   Richard, check into using a jack shaft commercial door opener. They are used for high lift or full vertical lift overhead doors. They would be built much heavier than a screw drive opener and could take more abuse, but would be a much higher cost.Nearly all the parts you would need for your project are overhead door parts including track, rollers, and lift drums and cables. Good Luck

3. 
   Richard_Stallard | Feb 02, 1999 05:49am | #5

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   I am trying to design a budget dumbwaiter, and thought I could power it with a screw drive garage door opener... Seems like a good idea with all the safety features inherent in screw drive openers. What I don't know is how much an opener will lift, and if I can run it vertically? Any thoughts on this? Thanks!

4. 
   Ronmex | Dec 03, 2015 01:04pm | #6

   dumb waiter

   Danny Liptor describes building this device. He omits to tell you how to extend the travel, usually controlled by the electronics. Can anyone help?