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View Full Version : Any special things about turning, drilling 8620 alloy steel?



Buckshot
06-20-2004, 06:53 AM
........I'm going to be making a couple 577 Snider actions and have the 1.25" 8620 steel bar. Mainly the machine work will consist of drilling and then boring bar use. Either end will have some single point threading. There will also be a bit of milling to be done, but the drill and boring bar work will be the most substantial metal removal.

Any oddities to 8620 that precludes the use of HSS tools? My boring bars are of the carbide insert type, btw.

Oops. One more quesiton :-). Welding 8620. There will need to be 2 small welds made to attach the breech block pivit blocks. Neither will be substantial and neither is subject to any firing strain. They merely provide attaching points for the pivit rod.

Thanks,
Rick

Forrest Addy
06-20-2004, 08:45 AM
8620 is very weldable if you use a little prehead. Use the appropiate rod if strength and post weld carburization and heat treatment is important. I've used 8018 to stick weld and S100 to TIG but there might be better choices. I would not reccomend welds in the bolt lug area. That should be all parent material.

8620 is very machinable with HSS. I've made tons of parts from it. I've even used it for molds and appearance parts.

While tougher than mild steel 8620 gives better finishes and chip formation. Use water based coolant from a squirt bottle when drilling deep holes. Peck drill after the chips quit self extracting from the flutes. Use a black cutting oil or bacon grease for threading.

Rustybolt
06-20-2004, 11:16 AM
It's as tough as 4140. HSS is fine just use lots of coolant, it wants to wear out tooling faster than 4140. I think for an aplication such as a receiver it's a better choice than 4140. It heat treats well. We made cam rollers out of it and hardened them to 62 Rc and never had one crack or shatter.

Forrest Addy
06-20-2004, 11:22 AM
BUT there's not enough carbon in 8620 to develop significant hardness. It has to be carburized before it's heat treated.

Buckshot
06-21-2004, 05:15 AM
..........Thanks for the replies. That answer's all my questions. I can do it :-).

Forrest, there are no locking lugs on the Snider. All it is in reality is a tube closed at one end and a milled opening on top. The barrel screws in the open end. The breechblock is nothing more then a solid steel rod which swings into the action through the milled out top, and sits between the cartridge base and the closed end of the action (tube).

The welding consists of adding an ear to the front and the rear of the action to provide mounting places for a rod. The cylindrical breechblock pivits in and out of the action on the rod. If it weren't for the breechblock falling out, you could probably get by with merely attaching it to the rifle with a beaded chain :-)!

Best,
Rick