[pianotech] Aluminum Pneumatic Soundboard Press Reposting

jimialeggio jimialeggio at gmail.com
Fri Feb 19 09:28:33 MST 2010


David Love wrote:
> These are light but the aluminum is quite expensive--I was shocked when I placed the order.  The dimensions
> are 1 3/4" x 3" and the wall thickness is 1/8".  

I recently got some 2x3x1/8 from discount_steel online free shipping no 
tax $45/ 8' length.  
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320419674645 
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320419674645>

the only hard part of making these clamps was parting with the $'s for  
the  aluminum, but it was worth it.  Very light assemblies, and (big 
bonus for me) compact storage. I've got all my panel clamps, rib clamps, 
rib cauls, underneath my table saw out-feed table which used to be 
wasted storage space. (the quantity of stuff expands to fill the 
available space), with space to spare.

I went with a smaller 1-1/4 x 1-1/4 angle aluminum for the uprights. 

Because of the 8ft lengths I came up with these lengths which optimized 
the aluminum and I think will give decent flexibility on various 
glueups: 1/ 5',  1/ 4.5', 1/ 4', 1/3.5', 1/ 3', and with cutoffs and 
some wood 1/ 2' dedicated 4meter high treble clamp(weighs as much as all 
rest of them it does...green oak).

Extending the upper piece of aluminum for safety reasons would have been 
nice, but it blew away the optimal use of the lengths I had to work 
with. So instead,  I threaded a 1/4x20  bolt up through the extrusion to 
make sure the upper bar wouldn't slip out and boingle. (the pic on 
push-to-connect fittings shows one of these safety things)

All the radiused cauls are interchangeable, fit in all the clamps, can 
be slid out and in without removing the clamp from under the soundboard. 
The cauls have a groove which allows you to slide them anywhere along 
the length of the clamp to easily get the cauls' apex where it would be 
most useful (not sure this is important, but I figured an easy way to do 
it...so I did it)

> There is virtually no
> flexing.   I made (I think) two 3', three 4', and one 5' lengths (I'd have
> to go out to the shop and look again). 
> David Love
> www.davidlovepianos.com
>   
On my tests using a straight non-radiused piece of stock, pressing the 
straight stock into the caul deflected the 5,4.5,&4' clamps...not sure I 
care though...

It'll run its maiden voyage monday with radiused ribs. We'll see what 
deflections happen then, if at all.

Jim I

Jim Ialeggio
grandpianosolutions.com
978- 425-9026
Shirley, MA





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