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Monarch Junior - finally joined the club


Oct 7, 2004
Grayslake, IL
About a year ago my wife bought me this Monarch Junior and a Boynton & Plummer Shaper for $500. The Monarch Junior is in surprising, good shape for being 100 years old, The only problem I am having is the drive key that runs in the slot in the leadscrew keeps falling out, and I somehow locked up the longitudinal feed knob. The main modification from the factory I can see is when someone change the electric motor and added pulleys on the counter-shaft. It is also missing the brake that use to be on the counter-shaft. It come with a set of collets, a 3 jaw and 4 jaw chucks, centers for the headstock and tailstock, and a bunch of tooling. I'm slowly figuring her out, and how to use her.

I worked at The Monarch from 1987 to 1997 working on their CNC turning centers, and finally have Monarch Lathe of my own, which is worlds apart from the lathes I designed.



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Keyway stock is usually standard in size and fairly inexpensive. Start with a new key.

If new key stock doesnt help to hold that key in the keyway in the slot you could take a center punch and put a couple punch marks on the bottom half side of the key to tighten it up in the slot The metal raises around the punch marks. Start light with the hammer until it feels good and tight in the slot.

Your key may be worn a little or the keyway slot in the shaft may have some wear.

Thats a nice lathe. Enjoy working with it and your shaper.
Your experience and knowledge from your work at Monarch is always appreciated here on the forum.
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See if there isn't a set screw in the belt groove of the pully that would hold the key and pully in place. If not drilling and tapping for a set screw would help
There should be one. I wasnt thinking about that at 5 am yesterday morning.