Gallery, Projects and General > Project Logs

A quickie alky lamp

<< < (2/3) > >>

Lew_Merrick_PE:

--- Quote from: Bernd on July 22, 2010, 07:47:24 PM ---Great recovery on that goof. I'm sure that was a bit disheartening at first though.
--- End quote ---

Herr Meister Muller, owner of the shop I apprenticed in gave me the definitions for apprentice, journeyman, and master that are appropo.  "An apprentice, he makes a mistake and knows not what to do.  A journeyman, he makes a mistake and fix it he can.  A master, he sees the mistake before he makes it and avoids it."  Four decades in the "trade" and I am still only a journeyman.

Bernd:
Well Lew, sounds like you need a bit more practice,right?  :D

Bernd

Lew_Merrick_PE:

--- Quote from: Bernd on July 29, 2010, 09:22:06 AM ---Well Lew, sounds like you need a bit more practice,right?
--- End quote ---

Hey, I've never screwed up a job so badly that I could not get new material and make it right!

Back in 1972 they changed the reference temperature from 70°F to 20°C (68°F).  I was working a NASA job making rollers that were ø1.750 +0/-.000050 tolerance.  I have no idea why such a tolerance was applied, but that was the job.  I lapped all 24 of them to size -- and then discovered that the inspection chamber was set to 70°F.  When I cooled it down to 68°F almost all the rollers were small!  Peder Muller (no relation to Herr Meister Muller), a Dane with whom I worked on numerous contracts, took them and froze them in liquid nitrogen -- and then struck them all using a brass bar dropped (using a guide) from 18 inches.  They all came "to size" within a couple of "hits."  (The liquid nitrogen freeze transmitted the force such that the rollers expanded consistently along their length -- a truly slick trick I have been able to use a couple of times since then.)

Tinkering_Guy:
Never heard of that trick before.  :bugeye:  I assume you mean the rollers were struck along the axis?  So they gained diameter but lost length?

Lew_Merrick_PE:

--- Quote from: Tinkering_Guy on July 29, 2010, 01:25:51 PM ---Never heard of that trick before.  :bugeye:  I assume you mean the rollers were struck along the axis?  So they gained diameter but lost length?

--- End quote ---

Yup.  The lengths were +0/-.010.  It was the diameters that were (stupidly) critical.  As I said, I have no idea why such tolerances were applied.  I have used functional tolerances in that range a couple of times when dealing with optics, but I designed adjustments in such that they could be "set" at the last minute using nulling techniques.

Navigation

[0] Message Index

[#] Next page

[*] Previous page