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Side rail location on breech casing


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#1 Larryx

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Posted 08 July 2020 - 12:31 AM

I am getting ready to mount the side rails on the breech casing and  decided to consult the print.  Lo and behold there seems to be  a difference between the mounting location on the right side ( bottom of  side rail  on the center line.)   and the left side which depicts the top of the side rail on the center line. Is the print correct?  It seems to me that would give a cocked  casing. If the print is not correct, which is the correct position.assuming each side rail is mounted the same in reference to the center line?

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#2 Swarfmonger

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Posted 08 July 2020 - 03:52 AM

You want the bottom surface of both rails on the centerline of the breech casing. Machining a radius on both of the rails mating surfaces to better fit the casing is a good idea as well. I would also recommend machining and fitting the box cam to the breech casing first so you can drill and tap the four flat head screws used to help support the side rails directly into the box cam.

#3 brk

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Posted 08 July 2020 - 06:12 AM

Swarfmonger is correct, the bottom of the breech casing sides are on centerline, or the top of the frame rails, right side drawing correct.

 

I didn't radius the brass side rails, but I did make a fixture to hold the side rails in position while brazing. I had used high temp silver alloy, actually silver brazing, my breech casing was made from thicker material, so I bored it and left it a little undersize, then silver brazed the sides on and the oscillator track on the bottom, the casing gets distorted with the high heat, then honed the ID of the breech casing to final size.   I think a person could get by with using silver bearing solder for this instead of silver brazing, I think 4%Ag / Sn solder has a liquid temp around 450°F.  This is what I used for soldering the oscillator assembly and my drum magazine.  I think I would have used it on the breech casing too.

 

I had silver brazed the magazine base assembly 48-23, but would have used silver bearing solder there too if I ever make another one.

 

I am not sure what others have used on the breech casing, whether they "silver brazed" or used "silver bearing solder".



#4 Larryx

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Posted 08 July 2020 - 02:55 PM

Thank you to both you guys for the quick response.

 

I could almost say it seemed obvious that the bottom of the rails was on the center line (taking into account that the main shaft has to align with the front bow) but  with the materials cost involved, I took the more prudent route and asked  someone(s) who knew. I

 

have machined the box cam to be a tight slip fit inside the casing so I will  do the screw thing prior to silver soldering. I am using 56% silver wire so I guess it is really brazing?. I plan to use the DRO smooth curve function to machine the radius in the side rails but my comprehension of the Chinglesh instruction manual is not all that great.



#5 Cutter

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Posted 08 July 2020 - 04:15 PM

Thank you to both you guys for the quick response.

 

I could almost say it seemed obvious that the bottom of the rails was on the center line (taking into account that the main shaft has to align with the front bow) but  with the materials cost involved, I took the more prudent route and asked  someone(s) who knew. I

 

have machined the box cam to be a tight slip fit inside the casing so I will  do the screw thing prior to silver soldering. I am using 56% silver wire so I guess it is really brazing?. I plan to use the DRO smooth curve function to machine the radius in the side rails but my comprehension of the Chinglesh instruction manual is not all that great.

 

 

This  might someone
 
.





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