Chicopee Center Fire shop built project

[dgoddard]

I am considering taking on the project of building Frank De Haas' Chicopee Center Fire rifle.
I would like to know if anyone has built one of these using his suggested alternate technique of arc welding the reciever ring to the receiver side plates. Just looking at the cross section of how he suggests doing this I would expect that the distortion of the threaded hole would be excessive, also his fit of the side plates to the receiver ring appears to leave some serious thin spots.

I am uncertain as to what caliber to make it. but I am considering possibly a pistol caliber (e.g. 9x19 or 357 mag) or possibly one of the cartridges originally developed for black powder. I am aware that a low pressure cartridge of large bore diameter might still provide more force against the breech than it can stand. So I am wondering just what calibers have been successfully chambered for this caliber. For instance would it like be adequate for a 45 caliber. 45-70-500 would be nice but I think it would require a larger receiver ring.

I am thinking of making the side plates from 1/2 inch cold rolled 1018 plate and machining them down to produce the support shoulders at the rear of the side plates rather than silverbraze them on. I am however concerned that the cold rolled plate will have have internal stresses that may cause unacceptable distortion.

I would appreciate comments and advice from others who have made one of these rifles.

My primary machines are a 12x36 lathe and a 10x50 Lagun FTV-2 vertical knee mill.

[Harold_V]

I am thinking of making the side plates from 1/2 inch cold rolled 1018 plate and machining them down to produce the support shoulders at the rear of the side plates rather than silverbraze them on. I am however concerned that the cold rolled plate will have have internal stresses that may cause unacceptable distortion.

That's a matter of using proper procedure to rough, then finish. Distortion is, more or less, guaranteed. How you deal with it will determine your degree of success.

Harold

[dgoddard]

That's a matter of using proper procedure to rough, then finish. Distortion is, more or less, guaranteed. How you deal with it will determine your degree of success.

Well the problem is that I have lots of 1/2 x 4 bar stock, but to make the part would result in removing material from only one side of the bar. Since the residual stresses may be balanced between the two rolled surfaces, I would be disturbing the balance of of the surface stresses.
So:
-- Do you think my expectation is correct?
-- Can you suggest an approach to deal with it?
-- I figure that I can tolerate something like 0.010" over a 4 inch length, where I will mill 0.25 off of the half inch plate. so do you think I can do it the way I was thinking?
-- What approach would you suggest?

I will probably need to build a fixture to be able to weld it and get good alignment as well as reduce weld distortion.

[alphawolf45]

Decided not to comment.

[hammermill]

although de hass doest recommend this i have seen this action upscaled into the 223 and 3030 range even to the point of a distructive until it failed test cycle.

[Harold_V]

-- Do you think my expectation is correct?

Dead on. It's guaranteed the part will respond poorly, and it has nothing to do with you, or the way you'd do the machining. It's the nature of the material. I guarantee it will move. How much is the question.

-- Can you suggest an approach to deal with it?

You'd go a long ways towards minimizing the distortion by either annealing or normalizing the material prior to machining. Best scenario would be where you could rough the part, anneal, then take finish cuts on all surfaces afterwards. That way you could eliminate the problem instead of minimize the problem.

-- I figure that I can tolerate something like 0.010" over a 4 inch length, where I will mill 0.25 off of the half inch plate. so do you think I can do it the way I was thinking?

It's possible---but for sure it would work after annealing or normalizing. I still favor having the ability to rough and finish all surfaces. It's good shop practice and eliminates the need to compromise.

-- What approach would you suggest?

If it was my project, I'd follow my own advice (which is why I make the recommendations I do---they reflect my work habits). YMMV. There are other approaches, including rough machining, straightening, then finish machining, ignoring annealing or normalizing operations.

I will probably need to build a fixture to be able to weld it and get good alignment as well as reduce weld distortion.

Can't address that issue---I never worked as a weldor.

Harold

[GeorgeGaskill]

I would follow Harold's suggestion and anneal the cold rolled before machining it. That would get all the residual stresses out of the material and prevent movement when you weld on it (which will anneal parts of it anyway.) And you might consider annealing after welding, too.

[dgoddard]

I would follow Harold's suggestion and anneal the cold rolled before machining it. That would get all the residual stresses out of the material and prevent movement when you weld on it (which will anneal parts of it anyway.) And you might consider annealing after welding, too.

Well, the problem with that is why not just use hot rolled to begin with. The annealing would simply result in coarse grain soft steel. I am not really sure that with all the silver brazing that de Haas did that he did not end up there anyway, but I would like to retain whatever strength benefit I can. There will be local annealing at the weld, but that is a rather long weld and I am planning on using .250 side plates with a full penetration integral backing strip weld. That should result in a fairly good quality and fatigue factors and there will be 4 lineal inches of weld with a 1/4 inch throat loaded in shear for a total of 1 square inch of weld metal. Given that the weld wire is likely better alloy than the cold rolled steel, I expect that the weld will not be the Achilles heel of the action (providing I can make a good weld. But if I anneal the whole thing I am not so sure that the locking surfaces in the action will be all that adequate. A normalizing or just stress relieving heat treat would seem more advisable than an anneal.

So far I have received at least one report saying that out of numerous welded Chicopee actions there has not be a serious problem with distortion.

However, In the multitude of counselors there is safety (Prov 11:24) so keep the comments and view points coming.

[Metalshaper]

D,

go to the Home gunsmith site and look up the Chicopee on Steroids build. Or the latest chicopee test build on the garage gunsmith site.

the One on the home gunsmith site was made in 30-30, with some mods to the design. the second ( Garage site ) the guy built one in .223 with the idea to test it destruction! He had to go to EXTREME measures to get his to fail.

With careful attention to the build process, the Chicopee is a very workable design with a lot of built in safety margins.. Or so it seems!

Respect Always
Metalshaper/Jonathan

[GeorgeGaskill]

Presumably you could case harden after machining/welding and get back the wear resistance.

[dgoddard]

D,

go to the Home gunsmith site and look up the Chicopee on Steroids build. Or the latest chicopee test build on the garage gunsmith site.

the One on the home gunsmith site was made in 30-30, with some mods to the design. the second ( Garage site ) the guy built one in .223 with the idea to test it destruction! He had to go to EXTREME measures to get his to fail.
Metalshaper/Jonathan

Had no luck finding those pages, do you have a URL for the ones you refer to?

[hammermill]

this will get you to sites and a wealth of info on this rifle construction


http://garagegunsmithing.com/index.php? ... com_search


http://www.homegunsmith.com/cgi-bin/ib3 ... d10cb45379