Re: [ATM] OT how to cut threads

["Bob May" <bobmay@nethere.com>]

Depends strongly upon the lathe that you have.  Some lathes have stops for
the motion of the carriage while others don't.  Those that have stops will
make the job of settinu up the thread cutting a lot easier than those that
don't.
As to gears, some lathes have "quickchange" gearboxes where there will be
(usually) tow levers which go into different holes which will change the
feedrate.  Then there are the lathes which have a train of gears on the
backside of the head that need to be changed about to get a different speed.
The slow change gearing isn't hard to change about nor is it difficult to
setup so don't be afraid to make the changes in the gears as necessary for
the threading you are going to be doing.
I'll note here that it is wise to know how your lathe fully works and a
manual for that lathe is very helpful as it will contain the necessary chart
for how the gearing sets up and operates.
Finally, for the cutter, a 60deg. angle cutter is used with the crossfeed
set at 59 degrees and the cutter set perpendicular to the work so that it
cuts the proper 60deg. V in the work.  Depending upon the lathe, you can
either run the lathe at speed or cut by turning by hand.  The 59 degrees is
so that as you advance the cutter, one side of the groove is cut while the
other side is just dusted which keeps down the chatter of the cutter.
I suspect that there are probably several webpages that talk of cutting
threads on different lathes.  A Google search may be effective here.  I'll
also note that there are some good books on lathe operations that will
probably stand you in good stead.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


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