Author Topic: Cutting the MSH slot?  (Read 2063 times)

Offline javaduke

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Cutting the MSH slot?
« on: December 11, 2013, 09:27:36 AM »
Folks, I'm new to this forum, apologize if this is FAQ.
I'm starting my first build from the 80% frame. No progress so far, just getting all the parts and tools. One thing I can't figure out is how do I measure and cut slots for the MSH. Can anyone please explain the process to me in details? Also, any particular tool recommendation? (if I understand correctly, keyseat cutter is the right tool for this, but can anyone give me more details as to which size should I buy?) And also how about that tiny slot for the sear spring, how do I cut it?

Thanks a lot!


Offline g85349

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Re: Cutting the MSH slot?
« Reply #1 on: December 17, 2013, 09:26:57 PM »
The slots for the main spring housing are measured from the main spring housing hole. Hopefully you have a good set of drawings.  This job is best accomplished on a mill with DRO.  This is not a job for a drill press and will be difficult if you are making your cuts using hand wheel calibrations only. You must accurately orient your frame to account for the angle of the main spring housing so you will need either a sine bar or other angle setting system.  The main spring slots and the sear spring slot can be cut with keyseat cutters.  The width of the keyseat cutter must only be less than the finished width of the slot you want to cut.  You may make the cut in several passes to get the proper width.  The diameter of the cutter must be small enough to avoid damage to any surrounding surfaces so several sizes may work for you.  If you use a keyseat cutter for the sear spring slot you will probably have to grind the shaft of the cutter to reduce its diameter to allow it to reach into frame to cut the slot. The sear spring slot can also be milled with a small diameter end mill.

Good luck.