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David Billington

wrote:
On Thu, 08 Sep 2011 18:51:41 -0500, "David R. Birch"
wrote:

On 9/8/2011 6:38 AM, Jim Wilkins wrote:

wrote in message
...

...
Vancouver only had a limited choice. They were prepared to get them
from Wagner if I was prepared to wait 6 weeks and pay - $12 a disc!

Ontario has a slightly better choice and I was able to order 3" diam
3/16" discs for - $0.78 a disc!
...
If anyone can explain the economics of this feel free to enlighten me.

Michael Koblic,
Campbell River, BC

Perhaps you found someone who already had the right tooling left over from a
previous job.

Welcome to the messy world of the build-or-buy decision that confounds small
outfits developing new products. One of the reasons I first learned machine
shop practice was to better understand production engineering. I inventoried
the punch collection for the shop's Strippit press and tried not to specify
hole sizes outside it. I wish electrical engineers would similarly bother
themselves to learn the standard resistor values and tolerances instead of
calling out 5K and expecting it exactly.

jsw

How about engineers who design for 1/16", 1/8" or 3/16" steel sheet
metal when the sheet metal industry uses 16ga(.059"), 11ga(.119") and
7ga(.180")?

David

No different than the construction businedd, designing for 2X4 or
2X6, or 1/2" plywood - when they are 1.5X3.5 or 1.5X5.5 and 12mm

I can remember talking to an old gent at a lumber yard on Long Island,
NY, and he said he could remember the days when a 2x 4 was a 2x4 and he
was referring to planed and prepared, then they started to shrink to
what we have today. He reckoned it was a ploy to get a few more pieces
out of a log and make a bit more money. Do they really need to take a
1/4" off each side to clean up rough sawn to a 2x4 planed and prepared.