Thread: K32 build....
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Old 01-12-2017, 02:34 PM
Protocall_Design Protocall_Design is offline
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Hi Shovelwrench -

The mounting holes on the rear sights are all the same for the newer round end style. The holes on the square end ones are all over the place, depending on what model they are for.

In the picture of the mill setup, here's what I would do.
Tram the head of the mill to the table (or the vise bed) so you know it is perfectly square (or as close as you can get).

Put the 2 clamp bars on parallels in the vise without the cylinder, the same way as they are in the picture. Rebore the hole for the cylinder. Mill .010 off the inside of each bar so they will clamp on the cyl. With the bars sitting on the parallels, put the cylinder back in the clamp. It will now be exactly perpendicular to the vise and the holes will be straight. This pair of clamp bars will fit all K frame cylinders.

When you dial in an outside circle with the CoAx indicator, you want the curved feeler to be on the other side of the part from the way it is shown, going around the outside circumference. For a hole, you will use a straight feeler. I have found the CoAx indicators are not as accurate as a dial test indicator or a good edge finder. I have a Blake (good one) and it's that way too.

With the cylinder in the clamp blocks and the front facing up, locate the center of the first hole with an edge finder. The .22 hole is small, so use the pointed end about .1 down in the hole. Run it at around 1000 to 1200 RPM and touch off one side of Y axis, zero the setting, touch off the other side and get a reading. Divide that number by 2 to find center. Do the same for X. This will get you exactly on center without the worry of whether the cylinder is indexed exactly along the X or Y axis. Do this for each hole. I don't know if you have a DRO or not. It's really a time saver. Otherwise make sure you compensate for slack in the leadscrew. Lock the X and Y so the table doesn't move during the cutting process.

Drill the hole through with a 19/64 drill, then ream with a .312 reamer.
Once all the holes are reamed through, you can turn the cylinder over and run the chamber reamer from the back side. The chamber reamer pilot will run in the .312 reamed holes.

This is probably more information than you actually needed, but I hope you find some of it helpful.

Best Regards.

Last edited by Protocall_Design; 01-12-2017 at 03:27 PM.
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