Author Topic: Elevation screw - left hand or right hand? (Read 1020 times)

Calamity Jane · « **on:** September 24, 2003, 03:38:27 AM »

On an original CW era cannon is the elevation screw left hand thread or right hand thread? On my drawings, it looks like it might be left hand....

Left means turn CCW (from above) to shoot higher; right means turning CW will raise the muzzle.

Thanks fellers!

Double D · « **Reply #1 on:** September 24, 2003, 09:54:25 AM »

All my references I have show right hand thread.

Calamity Jane · « **Reply #2 on:** September 24, 2003, 02:18:06 PM »

Thank you for confirming that!

It is especially comforting since I just finished cutting the square thread as a right hand thread :shock:

Double D · « **Reply #3 on:** September 24, 2003, 02:46:21 PM »

wouldn't have mattered to me, I would have cut it right hand anyway. No torque to counteract. You did cut it double lead acme right!

Calamity Jane · « **Reply #4 on:** September 25, 2003, 03:14:04 AM »

I cut it square, 4 threads per inch (as coarse as my lathe would go), single start., which gives 1/8" land and 1/8" groove - a nice strong thread. It's .5" major and 3/8 minor diameter with a 4" long threaded section.

That waz the scariest bit of machining I have done in a LONG TIME! I started with a 1/8" wide square nosed cutter but the cutting force (even at very fine feeds) was enough that the rod wanted to bend (which of course would have walked it up on top of the tool bit 'n' busted everythang to smithereens!) I ended up grinding up a square nosed cutter about 1/16 wide, cutting to depth (0.002" at a time), then displacing the cutter 1/16" to the side and doing it all over again!

Thank gawd my old Southbend is a belt drive! I waz usin the belt drive as a cluth and leaving the motor running. At 4 t.p.i. and even the minimum headstock speed, everything happens FAST! At least, using the "clutch" I could slip the belt and slow things down (to engage at the right index mark) and let the belt slip if something went wrong. A couple of times, the tool bit caught the work and would have @$#%#@ it if the belt hadn't slipped.

Next task: The base for the elevation screw.

Double D · « **Reply #5 on:** September 25, 2003, 12:38:08 PM »

My double lead acme thread comment was of course in jest, but I wonder what the original thread pitch was.

Those elevators were used for making range adjustments. I wonder if they had a set pitch for a specific barrel length.

I just dug out the copies original drawings of the 10 Seacoast mortar I got and every thread in the drawing appears to be left hand. I have a call in to The Publisher about our little discovery. Good eye Madam!