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Message ID: 256     Entry time: Fri Sep 24 13:40:22 2021
Author: Stephen 
Type: Progress 
Category: RTS for COC 
Subject: Modified 75mm RTS mount ring to host 80mm witness sample 

Simple machining operation setup and executed in Downs 228. Taking notes for future replication, and to drop the Photo Album somewhere useful.

Also thought this log would be helpful to communicate that we are able to quickly knock out simple mounts and mods like this in house.

 - Used Rotary Table for uniform circular cutting path; bolted down with 1/2" T-nuts and translated mill table to center ID of Rotary Table with edge finder. See Attachment 1 (more images in above photo album).

   --> 8" diameter Rotaty Table was a little too big for a standard end mill as the mill spindle is only offset from the turret by about 5 inches. There was not enough travel range in the direction toward the turret to reach the 40 mm radius from the Rotaty Table center. Could have cut in a different direction, but I didn't want to be caught later so I shifted to a larger radius cutter. While I was figuring this out, I managed to shear off one of the handles for locking down the Rotary Table during cutting - oops!

   --> Originally intended cutter was a .5" end mill, but I shifted to a 90 degree face mill for the extended radius given the above issue. I didn't feel too guilty about cutting the corners with the face mill, as the optic will have bevels and the acetal/delrin was soft.

 - I attempted to measure the 75mm diameter bore, and found the radius was larger by ~1mm. I then attempted to make a minimum 81mm diameter bore to host the 80mm optic, and overshot by a bit ( < 1mm ).

 - I elected to go for a greedy cut, creating a counterbore of the 75mm bore at an intermediate bore depth. This was an attempt to retain the 75mm bore function along with the new 80mm bore, and to fix either bore with the existing set screw. Liyuan verified that the new 80mm bore still behaves. So far, so good.

Attachment 1: IMG_9912.JPG  2.523 MB  Uploaded Thu Jan 27 11:59:14 2022  | Hide | Hide all
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