I'm building a lift, probably 1,000 $ max, but mostly 500 or less. Is there
a chart that gives different structural configurations and their relative
efficiencies?

i.e. .............. a bar joist design
a pyramid with lifting point at the apex
two poles with a right angle peak point of attachment
and one horizontal purlin
a plain truss shaped span, pitched to the roofing,
with diagonal bracing ............

16' wide span, verticals 8', then up with the framework. I actually need
two so I can lift my boat entirely with straps. Weight of boat, about
1500#.

I have been googling, but no luck yet.

Material would be 3 x 3 x .120" tubing MIG welded together, and gusseted
mostly wherever possible, and lateral bracing to help side loading.

TIA

Steve

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"Steve B" wrote in message
...
I'm building a lift, probably 1,000 $ max, but mostly 500 or less. Is
there a chart that gives different structural configurations and their
relative efficiencies?

i.e. .............. a bar joist design
a pyramid with lifting point at the apex
two poles with a right angle peak point of attachment
and one horizontal purlin
a plain truss shaped span, pitched to the roofing,
with diagonal bracing ............

16' wide span, verticals 8', then up with the framework. I actually need
two so I can lift my boat entirely with straps. Weight of boat, about
1500#.

I have been googling, but no luck yet.

Material would be 3 x 3 x .120" tubing MIG welded together, and gusseted
mostly wherever possible, and lateral bracing to help side loading.

TIA

Steve

Flickr of ideas ....................

http://www.flickr.com/photos/deserttraveler/

Steve B wrote:

I'm building a lift, probably 1,000 $ max, but mostly 500 or less. Is
there a chart that gives different structural configurations and their
relative efficiencies?

Machinery's Handbook?

Good Luck!
Rich

On Jan 31, 4:35*pm, "Steve B" wrote:
I'm building a lift, probably 1,000 $ max, but mostly 500 or less. *Is there
a chart that gives different structural configurations and their relative
efficiencies?

i.e. .............. *a bar joist design
* * * * * * * * * * * a pyramid with lifting point at the apex
* * * * * * * * * * * two poles with a right angle peak point of attachment
and one horizontal purlin
* * * * * * * * * * * a plain truss shaped span, pitched to the roofing,
with diagonal bracing ............

16' wide span, verticals 8', then up with the framework. *I actually need
two so I can lift my boat entirely with straps. *Weight of boat, about
1500#.

I have been googling, but no luck yet.

Material would be 3 x 3 x .120" tubing MIG welded together, and gusseted
mostly wherever possible, and lateral bracing to help side loading.

TIA

Steve

Most of that sort of thing is found in second and third year ME texts
as student problems. Get the solution guide. Also engineering
mechanics under statics.

Stan

Most of that sort of thing is found in second and third year ME texts
as student problems. *Get the solution guide. *Also engineering
mechanics under statics.

Stan- Hide quoted text -

- Show quoted text -

In my day, these excercises used to work on paper but rarely in the
real world. The values for Youngs Modulus and maximum stress are all
given in the question and may not be realistic.
Also don't forget to consider the stress in the welds, esp[ecially end
effects. If possible, design so the welds are not stressed by the load
or are in compression.
Finally, proof load the finished structure.

John

"John" wrote in message
...
Most of that sort of thing is found in second and third year ME texts
as student problems. Get the solution guide. Also engineering
mechanics under statics.

Stan- Hide quoted text -

- Show quoted text -

In my day, these excercises used to work on paper but rarely in the
real world. The values for Youngs Modulus and maximum stress are all
given in the question and may not be realistic.
Also don't forget to consider the stress in the welds, esp[ecially end
effects. If possible, design so the welds are not stressed by the load
or are in compression.
Finally, proof load the finished structure.

John

I am going to fishplate most of the connections, too. That should improve
it greatly. Without totally using destructive testing, I think it will
handle the load I want.

Steve

On Feb 1, 3:32*pm, "Steve B" wrote:
"John" wrote in message
...
Finally, proof load the finished structure.

John

I am going to fishplate most of the connections, too. *That should improve
it greatly. *Without totally using destructive testing, I think it will
handle the load I want.

Steve

I test beams for deflection by clamping two together with spacer
blocks at the ends and pulling them together in the middle.
The best truss design:
http://en.wikipedia.org/wiki/Truss_bridge

jsw