On 5/22/23 18:36, BRIAN GLACKIN wrote:
Thanks Andy
The articles I knew of were of much more recent vintage.
This article confirms the design was originally for “shell” lathes where
they could manufacture a lathe in place and have it operational in 30ish
days. I was surprised it was WW1 as the cement technology at the time was
rapidly evolving.
By
On Mon, May 22, 2023 at 4:28 AM andy pugh <bodge...@gmail.com> wrote:
On Sun, 21 May 2023 at 23:57, BRIAN GLACKIN <glackin.br...@gmail.com>
wrote:
During ww2 they made lathes bodies out of concrete with imbedded steel
parts that were jigged in form or line bored for the spindle and tail
stock.
More info here:
https://flowxrgdotcom.files.wordpress.com/2011/07/new-method-of-building-lathes.pdf
(and it was actually WW1, the article is from1916)
Andy; We've a discussion on the new sheldon list about long term
stability of machined castings, brought on by my more or less annual
expounding on backgear meshing & how to check/fix it.
I have trouble believing that most of the Sheldon's were shipped with
the backgear engagement set at several tons which will generally flex
the teeth of the smallest gear, leading to microcracks which eventually
break the tooth off the gear at the root of the tooth form. Which is
exactly the type of breakage seen in these now aged machines.
This could be explained by a casting shrinkage of maybe 20 thou over the
last 80 years since the head castings were machined. Bringing the
spindle bearing hole, and the hole for the eccentric shaft that is the
backgear shifter shaft closer together. This would then result in the
over-engagement of the backgears, giving a heavy rumble noise and
vibration we've observed in these old machines when the backgear is
engaged. So much so that the top of the gear tooth, which should still
have its original machining marks, is worn smooth and even rounded like
mine are now. So badly worn that the hall effect encoder reading them
for spindle speed and direction has a hard time with the quadrature
timing variations that rounding causes. That corner wear is seen as a
variable width tooth.
Has such a long term after machining shrinkage study ever been done and
written up?
Thanks.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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