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Post by ET on Feb 16, 2009 9:40:38 GMT -5
Have a crazy idea that just manifested recently but require help with a project that requires 3-4 used Breech Plugs that anyone is going to toss away. I would gladly cover any mailing cost.
The idea is to try to resurface the mating face of the BP to the bore when pronounced gas cutting is seen. Now this might not work well with a standard 10ML-II but if your head spacing is set to fit a primer deeper than normal a possibility of salvaging or extending the life of a BP might exist if minimal metal removal is all that is required. Just an idea I would like to explore in my free time.
Also if anyone sees problems with this idea, please share your comments for considerations. Or if someone has already tried this I would enjoy hearing your results before getting my feet too deep in uncharted waters.
Ed
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Post by smokeless77 on Feb 16, 2009 10:23:15 GMT -5
Et By the looks of that b/p on the other thread you can almost get in there and tig weld it,and fill in the voids. Then run a chamfer bit over it. might be worth a shot.
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Post by edge on Feb 16, 2009 11:22:55 GMT -5
In the past I modified a Savage plug for use in a ML-1. Since the breechplug was too short for the ML-1, it needed to be lengthened so I just cut the end back and press fit an Ampco bronze bushing onto the end and re-machined it to the final size. With some good measurements you could improve the headspace for a custom fit. I don't have a picture, but here is a sketch: edge.
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Post by ET on Feb 16, 2009 11:37:02 GMT -5
Smokeless77
Appreciate the response with a suggestion. We could use your suggestions of TIG welding but a heat treat would be needed again to maintain the original hardness that a BP has. Also all impurities would need to be removed so only clean metal remains before TIG welding. Smokeeter suggested turning it into a modified (recessed) BP would be a good candidate IMO if the bore mated surface did not have so much gas cutting that has reduced the life of the BP. Now your suggestion of re-chamfering, enough to remove those voids, would be my first choice and the vent liner would only be slightly recessed if you wanted to closely maintain the original specs. But how many more inclusions might exist further into the metal?
That mentioned BP would be an interesting candidate to play with but I also agree with others who have mentioned contacting and sending it back to Savage first if he feels uncomfortable in continuing to use it. Joe Degrande can be reached by e-mail first to discuss this BP before doing anything else. Now if Savage has subcontracted the making of these BP’s then such evidence of insufficient QA monitoring would be an interesting topic for them to discuss.
Edge
As always your ingenuity for an approach for a resolution for a particular situation is impressive. I would never have thought of that one. The BP would easily lock/support that bushing into place. Boy wouldn’t that be nice just to replace a bushing instead of the whole BP when strong gas cutting appears. Just curious as to how well the bronze bushing stands up to any gas cutting pressure?
Ed
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Post by edge on Feb 16, 2009 12:01:09 GMT -5
The material was Ampco 45 which is a fairly tough material:
It is an Aluminium, Iron, Nickel, & Manganese Copper alloy.
I don't have the tensile spec on hand, but IIRC it is over 100 KSI which is considerably higher than non heat treated alloy steel.
edge.
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Post by ET on Feb 16, 2009 12:22:25 GMT -5
The material was Ampco 45 which is a fairly tough material: It is an Aluminium, Iron, Nickel, & Manganese Copper alloy. I don't have the tensile spec on hand, but IIRC it is over 100 KSI which is considerably higher than non heat treated alloy steel. edge. Thanks for the quick response and feel I might give this a try with a donner BP, when I find a few. Thanks also for the additional info on the ampco bronze bushing. This will give me a path forward when the time is right. Ed
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Post by ET on Feb 16, 2009 15:07:22 GMT -5
Well before jumping any deeper into this I thought I’d better try this approach with my current tooling and one BP that had some gas cutting on the mated surface. Made a .004” cut and here’s the result. So my search for some possible BP donors is definitely on. Ed
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Post by Richard on Feb 16, 2009 16:03:37 GMT -5
Ed I Just see you are looking for little projects with that new lathe ;D Richard
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Post by ET on Feb 16, 2009 16:33:45 GMT -5
Ed I Just see you are looking for little projects with that new lathe ;D Richard Okay you partially tagged me but would have been dead nuts if you said "Educational Project". ;D Now what has appeared is the concept of an outside replaceable bushing. If my equipment is good enough to produce this then I won't be buying anymore BP's. I also know a machine shop where I am on good terms that makes connections like these with putting one part in liquid nitrogen and slighly heating the other part. Quickly slip on the bushing and when parts reach equal temps they are really tight together. Just have to ask what tolerances are needed. Ed
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Post by Dave W on Feb 16, 2009 17:49:21 GMT -5
Looking forward to hearing more on this.
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Post by edge on Feb 16, 2009 18:20:06 GMT -5
The interference fit that you need is of minimal strength. If you have an arbor press that would be all that is needed since there are no forces trying separate the two pieces. IMO, 0.001 would be more than enough difference in diameters for a press.
Now if I had liquid nitrogen for free then I MIGHT use it...but I might not. The problem with shrink fits is the size of the part and you only have a cross section of about 1/2 inch. Without heating the part to be pressed you will only get about 250 degrees of usable temperature differential and the moment the two pieces touch the small part will reduce that quickly.
Large diameter parts that contract more than 0.010 make great use of this shrinkage, but you will have a hard time getting more than 1/10 of that!
In this application I would probably not even worry much about a press, and Loc-tite would actually be all that is needed.
edge.
PS a little press goes a long way, and too much is actually weaker since you can easily exceed the yield of the material.
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Post by ET on Feb 16, 2009 18:50:27 GMT -5
Edge
Good point I didn’t consider about quick heat loss in small components. My thought was the better the fit the less chance of gas cutting occurring between bushing and BP. But when I now rethink this the area between the bushing and BP will probably get a carbon coating so no gas cutting should occur here, just like a vent bushing in a recessed BP. But at least a reasonable press fit will probably be the way I go.
Thanks for the added points to consider. I think this will be an interesting project to learn from in my free time.
Ed
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