[Alberg30] A30 mast support beam - Truisms

[Daniel Sternglass]

George Dinwiddie wrote:
> 
> Michael,
> 
> I don't think anyone is offended, but I think there is scepticism that
> a stainless steel channel is better...

Having fabricated a stainless channel after consulting with highly
skilled mechanical engineers, I gues I'll disagree. However, there is no
doubt that a lot of people's experience with the two Aluminum plates has
proven them adequately strong, and potentially simpler if you have to
make it yourself in a home shop. We had the good fortune of helpful
machinists in an automobile transmission prototype shop to help us...
> 
>...
>
> First, let's look at the choice of materials.  Is stainless better
> than aluminum?  I don't know the relative strengths of the alloys
> involved...

Stainless is far stronger per unit volume (total weight is not an
issue). However, it certainly requires specialized skills and equipment
to machine and weld. Also, no question that is definitely harder to work
if you have to do it in a home shop.

> It will, however, slightly reduce the clearance (I bump my head often enough) and
> will probably make the installation more difficult.

No and no in our experience. Our material was pretty thin (maybe 1/8" or
5/32"), and the headroom issue is negligible if it's a good fit.
Installation is actually simplified becuse you only need to jack from
the center and don't have to also support 2 separate side plates.
Drilling was no problem with an ordinary handheld drill, but I thing we
used carbide or similar bits. 
> 
> ...What advantages do you see for using a stainless channel?

We were led to beleive that the channel section was stronger becasue it
was less subject to torsion (twist) with a solid bottom, and we were
also told that this approach was less dependent on the integrity of the
original mast beam, which was quite delaminated in our case. It looked
like the original counterbore for the mast step bolts must have been to
half the depth of the laminated brace...

At any rate, there are many ways to skin a cat, as the saying goes. When
we made ours 15 years ago, we had spoken to some people who had done it,
and were told of the plate method, but since none were available
"ready-made," and we had access to the advice and machine shop
capabilitites, we went our own way. We have been extremely happy with
the results. Maybe it's overkill. Who knows...

--Dan S.
dans at stmktg.com
Watcher of the Skies, #201, 1966, Cyuga lake, Ithaca, NY
> 
>  - George
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