tvodrd
*Flashaholic* ,
How to turn optics has been a frequent topic for mods. This is for those with lathes. For the first few I turned (Small 123) I faced a piece of stock and applied thin double-sided tape. I improvised a pin to center the optic against the tape and took light cuts with a carefully sharpened HSS cutter. The next time I needed to turn a few, I made a spring-loaded livecenter with a female conical teflon recess. I faced a piece of stock and glued some thin rubber sheet on it. With the livecenter pressing the optic against the rubber, I was able to take heavier cuts. I gave that one to Roth and made a much better one:
All the parts except for the thrust bearing and washers are avainable from McMaster. BofM:
1) 6061K11 1/4" dia X 6" hardened precision shaft ~$3.15
1) 57155K154 1/4 X 1/2 X3/16 double shielded flanged ball bearing ~$6.20
2) 57155k57 1/4 X 1/2 X 3/16 double shielded ball bearing ~$5.10ea
1pkg of 12) 9712K61 Belleville disc spring washers ~$3.60/pk
1ft) 8546K13 1/2" dia Teflon rod ~$4.25/ft
Unfortunately, McMaster doesn't list 1/4" thrust bearings, so you'll have to find a bearing supply.
1) Torrington NTA-411 thrust bearing ~$2
2) Torrington TRB-411 thrust race (washer) ~$1ea
I used a bench grinder to make a 2" length of the hardened shafting. I drilled a 1/4" hole abt 1/4" deep in a 1/2" long piece of 1/2"dia aluminum and Loctite'd it onto the shaft. Next I counterbored a 7/16" hole abt 1/4" deep into the aluminum end of the assembly. I then turned some teflon to press into the counterbore and pressed it in. Leave some excess sticking out the front! Finally, I cut a 60deg included cone into the teflon with a countersink. Slide on the disc springs, thrust bearing set, the flanged bearing, a ball bearing, a spacer, the other ball bearing, and an O-ring to keep things from sliding off.
Using the live center is easy. Put it into the tail stock and hand tighten it. Overtightening it will bust the ball bearings! Fold a small piece of sandpaper to go between the optic and a spud in the chuck and use the live center to press it against it. You can also use thin rubber sheet or glue the sandpaper to the spud. Put a drop of oil on the thrust bearing and go at it. I found I can take .050 deep cuts in a single pass!
The CR2II optic is a lucky break if you have 5C collet capability. I am able to chuck the face in a 45/64" collet. After turning the OD and step, I back out the livecenter/tailstock and have just enough optic left to allow parting with a 1/16" wide blade. Sure makes the shortening a lot easier!
The livecenter will cost you $25 or so but for me has been a very good investment!
Larry
All the parts except for the thrust bearing and washers are avainable from McMaster. BofM:
1) 6061K11 1/4" dia X 6" hardened precision shaft ~$3.15
1) 57155K154 1/4 X 1/2 X3/16 double shielded flanged ball bearing ~$6.20
2) 57155k57 1/4 X 1/2 X 3/16 double shielded ball bearing ~$5.10ea
1pkg of 12) 9712K61 Belleville disc spring washers ~$3.60/pk
1ft) 8546K13 1/2" dia Teflon rod ~$4.25/ft
Unfortunately, McMaster doesn't list 1/4" thrust bearings, so you'll have to find a bearing supply.
1) Torrington NTA-411 thrust bearing ~$2
2) Torrington TRB-411 thrust race (washer) ~$1ea
I used a bench grinder to make a 2" length of the hardened shafting. I drilled a 1/4" hole abt 1/4" deep in a 1/2" long piece of 1/2"dia aluminum and Loctite'd it onto the shaft. Next I counterbored a 7/16" hole abt 1/4" deep into the aluminum end of the assembly. I then turned some teflon to press into the counterbore and pressed it in. Leave some excess sticking out the front! Finally, I cut a 60deg included cone into the teflon with a countersink. Slide on the disc springs, thrust bearing set, the flanged bearing, a ball bearing, a spacer, the other ball bearing, and an O-ring to keep things from sliding off.
Using the live center is easy. Put it into the tail stock and hand tighten it. Overtightening it will bust the ball bearings! Fold a small piece of sandpaper to go between the optic and a spud in the chuck and use the live center to press it against it. You can also use thin rubber sheet or glue the sandpaper to the spud. Put a drop of oil on the thrust bearing and go at it. I found I can take .050 deep cuts in a single pass!
The CR2II optic is a lucky break if you have 5C collet capability. I am able to chuck the face in a 45/64" collet. After turning the OD and step, I back out the livecenter/tailstock and have just enough optic left to allow parting with a 1/16" wide blade. Sure makes the shortening a lot easier!
The livecenter will cost you $25 or so but for me has been a very good investment!
Larry
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