I came home yesterday to find a box from Jack Huntington. He completed the gripframe much faster than expected.
I’ll spare you the obvious adjectives which describe his work. If you’ve ever considered his reshape, do it. He has done BFRs, XR3-REDs, and this Bisley for me. Nothing fits my hand better than his contouring and grips.
The 505 LFN mold also arrived from Mountain. It was on my doorstep less than 2 weeks from when I placed the order. You’re hard pressed to find better service.
Thanks again Lee for including us in this. I've got my eye on that mould! Did you have it designed to drop .513 505gr with Linotype? I seem to remember that you normally cast with Lino.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "One does not hunt in order to kill; on the contrary, one kills in order to have hunted...If one were to present the sportsman with the death of the animal as a gift he would refuse it. What he is after is having to win it, to conquer the surly brute through his own effort and skill with all the extras that this carries with it: the immersion in the countryside, the healthfulness of the exercise, the distraction from his job."
Post by Lee Martin on Feb 28, 2017 19:58:56 GMT -5
A Woodruff key cutter makes the bolt stops. Since I’m starting to do cylinders, I ordered a second. These come 1/8” wide and 1/2” in diameter. Clearly too thick for a 0.0960” notch. It has to be ground in a tool and cutter grinder.
Before milling the stops, I machined the ratchet boss 0.585” in diameter. Standard Ruger ratchet height is 0.150”. Mine will be shorter since I’m recessing the cylinder. 500 Linebaugh rims mic 0.060”, making the target height 0.090”.
I’ll now share some of the geometry involved in action timing. First, the cylinder is chucked in a horizontal indexing head and a mandrel is inserted. The key cutter is brought down to touch the top of the mandrel. The table is then raised 0.215”.
Math time. The stops on a Ruger are 0.704” in from the rear edge of the ratchet. My cutter measures 0.514” in diameter. That means the table is moved 0.961” from the back edge (0.704 + (0.514/2)). The cutter is cross fed until it touches the cylinder and our digital readout is zeroed on the Y-axis.
The cutter is slowly fed in to a depth of 0.060”. Dividing heads yield 9 degrees of rotation for one turn on the dial. The next notch, which is 72 degrees from the first, is positioned with 8 turns.
The next four stops are milled by repeating the above. Depth is monitored on our digital readout.
The bolt leads are done with a 3/8” endmill. Do not allow the endmill to reach the bottom edge of the notch. Otherwise, we’d lose our tight fit. Remember, the difference between my bolt and the stop is a miniscule 0.0008”. A depth stop is set to ensure we go no lower than the middle of the notch.
Post by Lee Martin on Feb 28, 2017 20:06:07 GMT -5
A large wheel cutter is how we ‘gear’ the ratchet. But we can’t do a straight cut; the geometry dictates these be offset 20 degrees to the rear plane. The indexing head is canted 20 degrees out from the x-axis. The mandrel is reinserted in the basepin hole and the cutter is brought up to touch the bottom edge. Drop the table 0.090".
Now here’s the trick to timing the ratchet relative to the notches. Dividing heads have a 40:1 ratio between handle rotation and spindle rotation. Turn the handle 40 times and the spindle moves 360 degrees. Hence, one turn equals 9 degrees.
The ratchet's teeth have to be offset within a narrow range of degrees from the position of the bolt stop. Our indexing head is rotated 1 and 24/57 turns (~12.8). The cutter is zeroed on the back edge of the ratchet. IMPORTANT – the zeroing occurs on the outer most edge of the circumference. Once that’s done, the wheel is fed into a depth of 0.060”.
To cut the next cog, the indexing head is turned 8 rotations. This is one of the most precarious steps in making a cylinder. If the ratchet depth and position relative to the notches are off, we’re screwed. An error here sends it to the scrap pile.
We're not quite done with the ratchet. Next time, I’ll mill relief cuts in between the cogs.