[modeleng] Re: coarse threads

There is a fascinating (to me but then I love gears) treatise on early
QC gearbox patents called "Lathe Changegear Devices" or something
adjacent.... It's amazing to see the complicated and bizarre creations
people had. It was originally written when the original Norton box had
just been patented, so it was no more than another fairly good idea
amongst many. It wasn't until the improved Norton came along that gave
it the extra lever to select multipliers for the basic set that it
rendered pretty much every other box design obsolete...... at least for
imperial style teeth-per-fixed-length screws as opposed to metric-style
length-per-tooth screws... Is there such a thing as an inverted Norton
gearbox for doing metric-type series? How do the metric threadcutting
gearboxes work if they're not inverted Nortons?
chrisc

-----Original Message-----
From: modeleng-bounce@xxxxxxxxxxxxx
[mailto:modeleng-bounce@xxxxxxxxxxxxx] On Behalf Of Jesse Livingston
Sent: 27 January 2007 22:42
To: modeleng@xxxxxxxxxxxxx
Subject: [modeleng] Re: coarse threads

 No QC box, just old fashioned change gears--just like
 Great-grandpappy.


Al,

That is what I finally figured you had.  All the non-27 tpi lathes I
have 
used have been QC models.  I don't know nothin' 'bout your grandpappy,
but 
QC gear boxes were around in the late 1800s..

Jesse in Tennessee



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