Neck Turning Part Four, The Insides Turned!

[bikemutt]

I decided to jump in the deep end of the pool today, just get it over and done with, for better or for worse  .

Here's a picture of my super-premium, ultra-precision brass guide rod:



Ok, I exaggerated a bit; it's a 1/4" diameter piece of wood dowel from Home Depot. The picture shows where it's inserted into the brass holder.

Here's where it emerges:



The tool I showed in a earlier post is then used to seat and lock the brass into the holder. It's probably overkill but, I used my Wheeler torque wrench set to 10 inch-lbs to lock the brass in; that amount of torque is more than ample to prevent the brass from spinning in the holder without distorting the piece.



Alright, lets get to turnin', but first, let's review some important metrology. I apologize in advance for the lathe metrology console in the picture, it's as messy as my mind, but the key numbers are there.



X-Axis shows the depth of cut into the neck wall.

Z-Axis cutter axial position shows how far into the neck bore we are.

Spindle RPM is self-evident.

Cut quality (my terminology) is a ratio of spindle RPM to how fast we feed the cutter into the work.

These are what I keep an eye on so I'm not just wondering around like an idiot.

Here's a turn video, yes it takes time but, make it work, then make it fast. Check out the slow leftward turn on the 3 face screws, I'll bet that's the 612 or so spindle turn blended with the 60 frame per second video frame rate, fascinating  .

Inside Turn

Results are really what matters; every one of these 34 pieces indicates 12.5 thou neck wall thickness. I have not verified inside runout but I will, just for completeness. As for my pet peeve, surface finish, the Teslong borescope doesn't lie. What I show in this video is an inside turn, followed by a Teslong view of the outside turn. Everything looks different under magnification, while there's no incentive to look at outside neck turns under magnification, because we can see them; there's no other way to look at inside necks turns, because we can't see them.

Surface Finish In and Out

Finally, here's a quick video showing the unavoidable element of inside neck turning; the mouth may show scars. I guess that means no 100% cleanup for me  , lol.

Crapadoodeldoo

Next steps: Loading, and Shooting!