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Author Topic: .38/.357 prototype  (Read 72429 times)

Offline 4171

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.38/.357 prototype
« Reply #340 on: September 19, 2018, 10:48:19 PM »
Bruski

No problem, can’t wait to see how it turns out.

Mike
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Offline Cutter

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« Reply #341 on: September 20, 2018, 03:38:12 PM »
A temporary set up to find the correct clearance

 


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Offline bruski

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« Reply #342 on: September 20, 2018, 05:34:11 PM »

Cutter,


 That is looking way to cool. It is functioning like a well oiled machine, smooth.


 


bruski


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Offline Cutter

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« Reply #343 on: September 21, 2018, 12:03:54 PM »
Thanks bruski 

 

 

These are the dimensions I came up with to keep

the cartridges rolling and feeding.

Notice in the video the cartridge will push up a little to

help the flow.

 


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Offline Sparky_NY

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.38/.357 prototype
« Reply #344 on: September 22, 2018, 07:45:46 AM »


 


A temporary set up to find the correct clearance

 


 




Do you have the ejector pins installed on the pan of that gun?   IF you do, it appears they are doing the majority of the ejecting function.     A drawing is one thing,  seeing one function is another !


(I am going to use the pins, I cut the slot in the bolts when I made them.)


 


Works great, like all your guns.

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Offline Cutter

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« Reply #345 on: September 22, 2018, 10:39:40 AM »


Do you have the ejector pins installed on the pan of that gun?   IF you do, it appears they are doing the majority of the ejecting function.     A drawing is one thing,  seeing one function is another !


(I am going to use the pins, I cut the slot in the bolts when I made them.)


 


Works great, like all your guns.




 


 


Yes, ejector pins are in, 3/32 dia. sticking out .040

I milled a .045 flat on the bolt. I have very little down force

on the cartridge, the stiff springs hold the extractor in place, until

the pins do the ejecting, just opposite of my 22 with no pins.

 

The Stick magazine with the cartridge movement over

the pan is similar to the 22

« Last Edit: September 22, 2018, 10:41:43 AM by Cutter »
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Offline bruski

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« Reply #346 on: September 22, 2018, 08:22:14 PM »

Well I have a bit of useful information about extruded brass bar. After machining the cartridge grooves in the brass stick magazine I noticed a slight bow in the length at about .010. I didn\'t give it much thought and started to machine the backing plate for the stick which needs about .125 removed from it. I took about .040 for the first pass then the second also at .040 then noticed that the ends were not cutting at .040 deep. They were more like about .010 with the middle much thinner than the two ends. Basically a banana shape from end to end. 


  The only thing that I could come up with is the extruded bar needs to be stress relieved by heating it up red hot and then let it cool down. I thought that mostly it is the cold rolled materials that need stress relieving. Oh well, right now I am looking at a bowed backing plate and a straight stick magazine that should have been together. NOTTTTTTT!


 


bruski


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Offline Cutter

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« Reply #347 on: September 22, 2018, 09:32:29 PM »


Well I have a bit of useful information about extruded brass bar. After machining the cartridge grooves in the brass stick magazine I noticed a slight bow in the length at about .010. I didn\'t give it much thought and started to machine the backing plate for the stick which needs about .125 removed from it. I took about .040 for the first pass then the second also at .040 then noticed that the ends were not cutting at .040 deep. They were more like about .010 with the middle much thinner than the two ends. Basically a banana shape from end to end. 


  The only thing that I could come up with is the extruded bar needs to be stress relieved by heating it up red hot and then let it cool down. I thought that mostly it is the cold rolled materials that need stress relieving. Oh well, right now I am looking at a bowed backing plate and a straight stick magazine that should have been together. NOTTTTTTT!


 


bruski




 


 


That’s kinda normal, but it can be straightened.

Then use a flycutter to finish both sides ( light cuts )

A single point tool reduces tool pressure and

puts an end to the Big Banana

« Last Edit: September 22, 2018, 09:33:06 PM by Cutter »
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Offline Sparky_NY

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« Reply #348 on: September 22, 2018, 09:41:41 PM »

Want a stainless banana to go with the brass one?


 


I found a 1/2 x 4 wide 304 stainless flat bar at a friends fab shop.   I was thinking for the frame rails.   Well, we rip cut it to 2\" wide with his plasma cutter and it came out nice.    AFTER it cooled it warped.  It did it on the 1/2 side not the larger flat side.   It warped about 3/4 over 40 inches.   I was surprised because a plasma does not put a lot of heat into the work piece, its so concentrated., unlike acetylene.


 


I am undecided how to proceed.   I know with steel if you cut both sides equal it minimizes the warp..   Don\'t know if stainless works the same.    For now, I just put the pieces aside.   They would make nice frame rails.   Being 2\" x 1/2\", I don\'t need the whole 2\" width anyways.  


« Last Edit: September 22, 2018, 09:44:41 PM by Sparky_NY »
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Offline bruski

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« Reply #349 on: September 23, 2018, 01:33:04 AM »

I managed to salvage the backing plate although it is now .250 thick instead of the .375 that was planned for. I put the banana in the press with a block on each end, then pressed it down a little past straight. Got the map gas torch out and heated it up to about 300 degrees F. and let it cool down. It was now pretty much straight but the ends were much thicker than the middle so a few lite cuts on both sides fixed it.


 Back in business again headed forward now figuring out the block that it attaches too.


 


bruski


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Offline Sparky_NY

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« Reply #350 on: September 23, 2018, 10:57:57 AM »

OK OK,  so I took a few naps....   but I am making progress !     


 


Bolt carrier assembly complete and slip sliding nicely.    I made the rear half from aluminum, had the brass but was chicken shit to cut it,  LOL   Next is the barrel plate I suppose.


 


(extractors are all done,  I removed them for now, have to shorten the dowel pins a bit)  (one firing pin assy made and installed, left long)


 


Also, thinking cams are not that far away, price of DOM is surprisingly high for that size.   I need 3-1/2 ID, 4 OD,  time to get something ordered.


« Last Edit: September 23, 2018, 11:00:05 AM by Sparky_NY »
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Offline bruski

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« Reply #351 on: September 23, 2018, 06:08:17 PM »

Sparky,


 I used black iron pipe for my cam material on this build. Seems to work ok without any heat treatment but Kasenite is on stand bye.


 


bruski


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Offline bruski

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« Reply #352 on: September 23, 2018, 06:14:26 PM »

In all actuality, Delrin would also work or any other type of plastic. It doesn\'t add to the weight any either. I can just barely carry my prototype to the firing area about 50 yards from my shop any more. When I do make it there, I need to catch my breath a little before doing anything else.


 


bruski


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Offline Sparky_NY

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.38/.357 prototype
« Reply #353 on: September 23, 2018, 09:41:51 PM »


In all actuality, Delrin would also work or any other type of plastic. It doesn\'t add to the weight any either. I can just barely carry my prototype to the firing area about 50 yards from my shop any more. When I do make it there, I need to catch my breath a little before doing anything else.


 


bruski




Yea, and your prototype does not have a housing, rear cover, recoil plate and a lot of other pieces that a complete gun will have.    I see the weight as getting pretty high, guessing 100-150 lbs but that is only a guess.     I believe the original gatling weighed about 300 lbs as I recall.

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Offline Sparky_NY

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.38/.357 prototype
« Reply #354 on: September 23, 2018, 09:44:09 PM »


In all actuality, Delrin would also work or any other type of plastic. It doesn\'t add to the weight any either. I can just barely carry my prototype to the firing area about 50 yards from my shop any more. When I do make it there, I need to catch my breath a little before doing anything else.


 


bruski




Interesting idea....  I will have to research around and see what is close to 3.5 ID and 4: OD out there.

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Offline Sparky_NY

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.38/.357 prototype
« Reply #355 on: September 23, 2018, 09:46:18 PM »


In all actuality, Delrin would also work or any other type of plastic. It doesn\'t add to the weight any either. I can just barely carry my prototype to the firing area about 50 yards from my shop any more. When I do make it there, I need to catch my breath a little before doing anything else.


 


bruski




Put one of those minature V8\'s you are building on it and drive the sucker out to the range.


 


Sorry,  couldn\'t resist that one !   LOL

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Offline Cutter

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« Reply #356 on: September 24, 2018, 10:53:41 AM »
For what it’s worth,

This would be my first choice in plastics.

Oil-Lite Cast Nylon

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Offline Sparky_NY

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« Reply #357 on: September 24, 2018, 07:08:03 PM »


 


For what it’s worth,

This would be my first choice in plastics.

Oil-Lite Cast Nylon

 




After your post I looked into it,  best I could find was $85 a foot for the size I need.      Tonight, I just picked up a 3\" electrical PVC coupling,  its ID and OD are perfect as is the length,  cost $2.85  

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Offline Cutter

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« Reply #358 on: September 24, 2018, 07:29:50 PM »


After your post I looked into it,  best I could find was $85 a foot for the size I need.      Tonight, I just picked up a 3\" electrical PVC coupling,  its ID and OD are perfect as is the length,  cost $2.85  




 


 


Skarky,

Check with Mike aka 4171 he has some DOM, your size
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Offline bruski

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« Reply #359 on: September 24, 2018, 11:25:58 PM »

Sparky,


 If you decide to use the DOM tubing in the end, the PVC coupling would be perfect for practice.


 


bruski


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