I spent more time over the last two days repairing machinery than making parts.... The switch on my lathe burnt out for the umpeenth time (I haven't been able to find anything that will stand up in this hick town).... My local supplier found a 12V 50A switch in stock and told me something interesting.... Apparently UL / CSA removed the AC rating on most switches a while back.... This switch used to be rated at 125V 20A, and they haven't changed the switch.... They use it on a 1 HP motor there, so I figured it can't be any worse than what I've been using.... The problem was that it was too deep to fit in the cavity on the top of the lathe, so I had to make a 3/4" deep plate with a 1/2" deep cavity so that the switch mounts 1/2" higher.... Looks kinda cool, I hope it lasts.... While I was at it I lubed, checked, and adjusted everything on the lathe as well....
The other job was to replace a broken handwheel on my horizontal bandsaw.... It's a Busy Bee Chinese special, and the handwheel that runs the clamping vice was plastic.... Needless to say, the hub split, and the only part that was reusable was the handle to spin it.... I made a new handwheel from a 1.5" cast iron pipe flange with a couple of adapters screwed into it to bush it down to smaller than the shaft.... I drilled it out, drilled and tapped it for a setscrew, and drilled and tapped a (metric) hole for the handle near the perimeter.... I works like a charm, and looks suitably "Coalmont" in nature.... I guess I've finally graduated from Hillbilly repair school....
Anyway, I finally got around to making the bolts for the two breeches, as below....
The front one with the handle screwed into it is for the .224 / .257 cal, while the rear one with the longer probe and larger diameter nose is for the .308 / 9mm.... On both bolts, the short smaller diameter nose section fits the smaller bore barrel (.22 cal on the .25 bolt, .30 cal on the .35 cal bolt), and the 60* taper is the transition to the O-ring size.... A matching taper inside the barrel guides the bullet into the chamber.... The shoulder on the bolt where the probe starts is flush with the back of the barrel port, so the chamber starts just behind the port, and the bullets have lots of length to align with the chamber before engaging the rifling.... The front driving band is just engaging the rifling as the rear of the bullet passes the front of the port, so the chamber is the length of the bullet from front driving band to base, plus the barrel port, plus about 0.030".... The O-ring that seals the bolt is captured between the end of the barrel and the breech, and the bullet slides through it on loading.... I really like this system for sealing the breech.... All the bullets are a loose fit through the O-ring except for the .257 cal, which is 0.007" bigger than the bolt at the driving bands on the bullet.... I think that will squeeze through the O-ring just fine, however....
I have ordered a set of 5C Collets and a square and hex mounting block set for them which will be really handy for making the valve and main tube.... Since they haven't arrived yet, I think my next step will be to make the chamber reamers for the .30 and .35 cal barrels and get the machining done on those.... Still a LOT to do on this project....
Bob