Help wiring a single phase motor with reversing switch for my Lathe.

Reversing a single phase motor with a drum switch is simple when you understand what you are doing. A drum switch has a number of contacts set up so that some reverse and others just close. Simple inspection will let you determine which ones do what! One set usually does very little and just completes the circuit the same way no matter which way the switch is turned, simple ON/OFF If the terminals were marked ABC and abc the “C” will be connected to “c” in either direction. The other 2 will result in “A” connected to “a” and “B” connected to “b” in one direction of turn and “A” connected to “b” and “B” connected to “a” when turned in the other direction. In the center none are connected.Understand?

A simple description of a reversible single phase motor is there are 2 windings, one is the main winding and the other simply to start the motor spinning in the correct direction. Most use a centrifugal switch to disconnect the start winging when the motor has reached the correct speed. The main winding will run in any direction so it will be connected to the “C” type connection of the drum switch, simply ON/OFF. The start winding is connected to the reversing contacts A and B so that you simply reverse the connection to the start winding and therefore reverse rotation. One thing to remember because of the centrifugal switch a running single phase motor will not reverse like a 3 phase motor when the drum switch is reversed. It will continue running in the same direction! Simply because at run speed the start winding is disconnected by the centrifugal switch so to reverse direction you have to wait until the motor speed drops to below the centrifugal switch “turn on speed”

via Help wiring a single phase motor with reversing switch for my Lathe..

Jarno Tapers


Jarno tapers range from a Number 2 to a Number 20. The diameter of the big end in inches is always the taper size divided by 8, the small end is always the taper size divided by 10 and the length is the taper size divided by 2. For example a Jarno #7 measures 0.875″ (7/8) across the big end. The small end measures 0.700″ (7/10) and the length is 3.5″ (7/2).

The system was invented by Oscar J. Beale of Brown & Sharpe.

via Machine taper – Wikipedia, the free encyclopedia.

Pipe threads on a lathe – Practical Machinist – Largest Manufacturing Technology Forum on the Web

Bruce Nelson Aluminum  Join Date: Feb 2009Location: WisconsinPosts: 114

Set the taper attachment at 3/4 inch per foot taper. First machine a taper on the end of the pipe to the dimensions given in Machinerys Handbook. Then set the quick change gearbox to the number of threads per inch required. Then, cut the thread to fit whatever gage you have, or to specs given in the Handbook. Be prepared to withdraw the threading tool with the cross-feed handwheel at the end of the thread.If the thread is for common pipe joining use, machine the thread to a depth where the flat on top of the thread crest just disappears. If you dont have a sharp on the crest of the thread, the thread wont seal when internal pressure is applied.Threads for mechanical fasteners should have a flat on the crest of the thread equal to on-eighth the pitch. There should be no flat on the crest of a pipe thread, which are meant to be self-sealing. Note that when you cut 11 1/2 TPI, you will need to engage the threading dial on the same number.Metric threads would require transposing gears. I have never cut metric pipe threads before, but I would think that you would have to reverse the spindle at the end of the cut to return the tool to the beginning of the cut. or have a lathe that cuts metric threads Lord Byron

via Pipe threads on a lathe – Practical Machinist – Largest Manufacturing Technology Forum on the Web.

Proper way to unscrew lathe chuck?

Chuck up a piece of 1″ pipe that extends into headstock and has 8″ sticking out. Apply a 24″ pipe wrench near the chuck face pull with left hand and apply hammer smartly to the pipe wrench with the right hand. This gives something to hold onto and keeps from falling on the ways. A large nut welded to the end of a rod chucked similarly. 3/4 Impact applied to nut can work without getting the gear train involved.

via Proper way to unscrew lathe chuck? [Archive] – The Home Shop Machinist & Machinist’s Workshop Magazine’s BBS.

Jarno taper info

I measured my Monarch spindle adapter:

oal: 2.626″

length of ground tapered surface: 2.424″

large dia. 1.506″

small dia. 1.386″

The oal above is actually a nisnomer. It is the distance between the radiused edges, which is along the taper.

The actual axial length of the adapter is 2.6252 (calculated), so knowing that Monarch always dimensioned things to exact fractional values, it is probably 2 5/8″ long.

The calculated length of the ground portion of the adapter is 2.423

The calculated small dia. is 1.385″, based on a lg. end dia. of 1.506″ and a length of 2.423″, so it checks out pretty close. Besides, the small dia. end is hard to measure accurately.

via Jarno taper info – Practical Machinist – Largest Manufacturing Technology Forum on the Web.

My Monarch Lathe

Model A Lot 57 No 10
Swing 16″ Bed 7′
Conehead (driven by an overhead belt).
Quickchange gearbox to drive the carriage.
Cone clutches on the carriage and cross feed.
Posts I’ve read say the lathe was probably built around 1924-26.
I got the lathe out of Duke Nalon’s shop in Detroit, Michigan around 1980.