On Mon, 30 Jan 1995 ccamley@mmm.com wrote:
> Also, I know Ray Gibbons did *not* suggest building a box beam from 2x4s and
> 1/2" plywood to help suspend an engine. He did *not* suggest laying it over
> several trusses in the roof. Hence, if I did this and the whole garage fell
> down, my wife could blame me, but not Ray. But if he *had* made such a
> suggestion, what size would he have suggested making the beam in
>cross-section?
>
> |XX| ^
> | | how many inches?
> | | |
> |XX| v
>
> Thanks
> ------------
> Chris Amley ccamley@mmm.com
> TR-3A TS39449L
>
>
Oh, damn. I haven't the faintest idea. But if I *were* going to do it,
I would just guess at it and err on the side of making it much too
strong. You want something that can stand on edge and be reasonably
stable. So figure something more than 3 inches wide. You want it to be
light enough to move without a struggle, and it needs to span 4 trusses,
which typically are 2 ft on center, so it needs to be 9 or 10 ft. long.
For economy, you don't want to use huge amounts of material. I see two
choices, make it yourself or buy it. For the DIY route, I would suggest
a height about 1 foot, and a 3 layer sandwich as follows:
|X|X|
| | |
| | |
|X|X|
Where | denotes 3/8 inch plywood and X is the end on view of a 2x4. Use
2x4's the full length of the beam, and stagger the plywood joints. Use
copious amounts of construction adhesive, and screw the whole business
together with sheetrock screws. The 1 foot height is a guess, which
allows a 10 ft beam to be made out of a single 4x8 sheet of plywood. My
gut instinct is that should hold a TR3 engine. In fact, I think it would
hold several of them. But watch it as you begin to hoist the engine, go
up and sight along it and see if it sags, be cautions. And if it falls,
well, you know the disclaimer.
Or, go to your local building shop, and buy a couple of their readymade
I-beam type wood floor joists 10 feet long. Nail them together, and
stick them in the rafters.
How about it, all you engineers on the list. Can you be more scientific
than this? In college, I had a very understanding advisor, who allowed
me to substitute "Major Religions of the West" for "Strength of
Materials," and "Contemporary Philosophy" for "Statics." He did say, "I
worry what you are going to do if you ever have to choose a beam to
support something."
Now those chickens have come home to roost. There is an upside, however.
If the engine falls and crushes your spouse's poodle, Fluffy, I can offer
you religious and philosophical advice for dealing with the tragedy.
Ray
Ray Gibbons Dept. of Molecular Physiology & Biophysics
Univ. of Vermont College of Medicine, Burlington, VT
gibbons@northpole.med.uvm.edu (802) 656-8910
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