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Re: Beams for gantry

To: Conrad <conrad@conrad.uk.net>
Subject: Re: Beams for gantry
From: Rush <jdrush@enter.net>
Date: Wed, 04 Apr 2001 15:08:07 -0400
Conrad wrote:
> 
> Thanks again for you input Jon.
> 
> > deflection. This is just a quesstimate, but an I-beam of
> > sufficient stiffness might be 6 inches deep. That is why I
> 
> Hmmm. I cant really accommodate that - might just about squeeze 5
> inches, but I really don't want to rework the roof.
> 
> I only have a budget for steel, none for custom fabs or 'getting people
> in' so I'm after best guess and perhaps seat of the pants type help. I
> will have to take responsibility for something collapsing of course, and
> I generally work such that there is a backup if something breaks (the
> big crack in the king post on my JCB has taught me this). This is fast
> becoming a complicated looking task but it would seem silly to give up
> because of that. I'm pretty sure if I bung enough steel up there I
> should be able to make it pretty strong.
> 
> Options I appear to have for increasing strength but not height are:
> 
> 1. doubling up on the beam across the front
> 2. using a much bigger beam on its side (say a 7"x4")

That would be very smart.

> 3. welding/bolting 2 4"x2" lengths of channel back to back giving a
> 4"x4" beam

Also with in the do-it-yourselfer's bailiwick. Welding long like this can
cause distortion though. Use good welding technique, like preheat and
skip welding and don't be afraid to shim . . .

> 4. adding more roof support beams (spreading the load on the gantry).
>
> Cold get expensive on trolleys.
> 
> This all adds weight, but the side supports for the beam are very
> strong, double width concrete blocks. I like the sound of option 3,
> which would give a very low profile beam, with a thick vertical section.
> Would that appear to be on the right track?

Yes as far as the roof goes. See below.

> Could I then do the same
> with the roof supports, using 3"x2" channel? That would give me a 4"
> increase in headroom, just about perfect.

I'm not confident enough that I understand how you will affix the gantry
and route the trolley to say if it might work. Can you make a jpeg or use
asciiCAD?

Jon

>
> 
> Conrad


-- 
Yes, I know my message date is sometime in April 2001. Welcome to
my own personal version of the film Groundhog Day!

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