Steel/Jig Strength

[Farrell]

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Thanks for the input. What other specifics might you have in mind?

I think recycling metal is an excellent ideal to pursue. But sometimes =
you just need what you need. I usually go to  =
http://www.metalsupermarkets.com/ .  Great place. They have anything you =
might want and will cut to your specs. Just order, load up your trunk, =
and assemble your jig (well, almost that easy).

Terry Farrell
  ----- Original Message -----=20
  From: Crashvalve@aol.com=20
  To: pianotech@ptg.org=20
  Sent: Monday, November 10, 2003 7:54 AM
  Subject: Re: Steel/Jig Strength



  In a message dated 11/10/03 7:17:11 AM, mfarrel2@tampabay.rr.com =
writes:






    I've made myself a little pneumatic contraption for laminating ribs. =
I seem to have just about everything worked out for proper function =
(actually, works quite a bit better than I had hoped!) except for some =
excessive jig flex. I have a 1.5-inch-thick Delignit pinblock =
incorporated into the jig for stiffness, but I still seem to be getting =
several millimeters of flex in the middle of the 5-foot long jig when I =
pressure up. So I think the solution is to put a couple of angle irons, =
or steel channels along the length of the jig. This thing is getting =
VERY heavy, so I prefer to not use any more steel than needed.




  I've no science background, but i've made numerous structural steel =
jigs.
  My first jigs used steel as a monoblock material, a "one piece big =
enough to resist" approach.
  That is off target. What you want is a little teeny bridge structure. =
In other words, multiple pieces of steel with lots of triangle shapes =
for rigidity. This way there is not too much mass, but great rigidity. =
If you don't want this large "fab" job, use a steel channel or even an =
"I" beam, but then it will be heavy; I store my big jigs outside and =
paint them. A necessity after my first 14 foot long soundboard jig. BTW =
don't order steel from your friendly supplier, check the scrapyards for =
material. You can't pick and choose as much, but it's way cheaper. You =
may consider this close to dumpster diving, but It is invaluable to the =
machine builder. At the scrapyard you don't worry so much about the =
calculations, just buy way over what you need, and start an outside =
storage rack area. If you start fab work like this, access a sawzall for =
cuts, or a torch. A resinod cutting disc in a tablesaw is a BAD idea. If =
you have specifics shoot them back, happy to answer from no-training and =
12 yrs. of practical experience.
  Glenn C. 
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