December 2020: Lessons from the
By Jim Thompson
Over ten years ago, I conceived the idea of installing a dumbwaiter in our home. The master closet is above the laundry room/garage entrance, so these are two places in close proximity. I was remodeling and expanding the closet anyway, so it seemed to be a good time to tackle the project. I built an elevator shaft in the corner of the garage where if fit just exactly where I wanted to place the doors in the closet and in the laundry room.
There were two objective to accomplish with this new piece of "machinery." (1) make it easier to move dirty/clean clothes between the first and second floor and (2) since my wife and I travel a lot in our work, move full suitcases between the two floors.
Unlike a garage door with moves from a relatively heavy position (vertical) to a relatively light position (horizontal above on the overhead tracks) and which can then be designed so that springs aid the opener motor, the cab of the dumbwaiter is a straight lift. After lots of experimentation, I decided that a counterweight was the only choice to balance the load up and down. There is a cable that goes from the top of the cab to the top of the shaft, then through a couple of pulleys and down to the counterweight box. The counterweight box, with a movable pulley, only travels half as far as the dumbwaiter, 5 feet and 10 feet, respectively. Hence the counterweight box has a 2:1 weight disadvantage as compared to the dumbwaiter itself.
I run the whole thing with a garage door opener standing on end and connected to the counterweight box*. The opener is hung by a clevis near the top of the shaft and the motor end hangs freely at the bottom. This is also the reason for the counterweight box moving only half the distance; otherwise I would need a garage door opener with a ten foot travel.
There was about three months worth of experimentation at the time of the first build to get the whole thing to work reasonably well.
A long story to setup my point for this column.
This past summer, I got to thinking, this machine is ten years old and it probably would not be a bad idea to inspect it and rebuild it if necessary. I engaged my neighbor, whose avocation is cabinet maker, and had him build a new, improved cab for the dumbwaiter and additionally help me with the rebuild.
We started on Saturday, 21 November 2020. We worked on it nearly every day last week, taking off US Thanksgiving Day. We replaced the cabling, cab, garage door opener, and guide wheels. We rebuilt the counterweight box. We finished Sunday evening, 29 November 2020.
Here is the kicker. With two of us working on the reassembly, we could do a very careful job of aligning everything. In this case, alignment, is everything. Much smoother, less counterweight for the same load, less noise while in operation.
Takeaways: (1) better alignment reduces weight. (2) a reduction in noise indicates a reduction in effort necessary to do the job the equipment is designed to do.
We can remember this example for nearly any mechanical project on our paper machines. Yes, I now have a dumbwaiter compliant with our Light Green Machine Objectives.
*If you would decide to do something like this, buy a garage door opener that uses a stepper motor to determine the shuttle position, not proximity or limit switches. A stepper motor version works much better. I use the "Chamberlain" brand.