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Cocking ring dimensions on print?


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#1 Larryx

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Posted 09 September 2020 - 11:27 AM

Can someone direct me to where the  final contour of the cocking ring assembly is shown.   48-10 and 48-11 which are on the same sheet show  construction dimensions ( 1.498-1.500 ) but I don't see where the  ramp structure etc are described or defined..



#2 maccrazy2

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Posted 09 September 2020 - 06:33 PM

I believe there is a print you cut out and glue to the material in the plans.

#3 Swarfmonger

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Posted 09 September 2020 - 06:56 PM

The height is important but the contour in question is not at all critical. In fact, when I asked Paul about it he said you could just mill it vertical and it would make no difference. Just scale the angle off the print, lay it out on the ring and take it to size with a bandsaw and file. That’s all I did and it works great!

#4 Larryx

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Posted 10 September 2020 - 02:14 PM

Thank you for the responses.

 

Keeping in mind that I even have a problem falling off a log, the  foolproof template method apparently did not work for me. I did the template thing, carefully cut and filed to the line etc. At the time I completed the  cam, I was not ready to install/adjust/etc, so it rested safely in a secure drawer for over a year. I finally  got to the point where I installed the cam carefully in the casing and proceeded to what I assumed would be a routine dialing in of the  cam system. I did reach the point Paul had predicted with interference occurring at the corner of the cocking ring. I will skip the next few steps but what I discovered was an approx 0.250 interference. That is outside even my tolerance ability.  I searched the print to see if I could determine how I went so wrong, but there is no easy way to  compute/extrapolate/ find  dimensions for the cocking ring profile. Easiest solution: REPLACE THE CAM. 



#5 bruski

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Posted 10 September 2020 - 05:25 PM

Are you guys talking about the box cam or the cocking rings?

 

bruski



#6 maccrazy2

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Posted 10 September 2020 - 06:12 PM

Crap. I was thinking box cam. My bad

#7 Swarfmonger

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Posted 10 September 2020 - 11:30 PM

Are you sure both the cam and the ring are located/indexed properly?

#8 Larryx

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Posted 11 September 2020 - 02:08 PM

I believe the cocking ring is oriented so that the sear falls off the highest part of the cocking ring ramp at bottom dead center.  The print is actual size so when I place my recoil plate assembly  complete with cocking rings on the print, everything lines up exactly as it should. MY problem is that the  cam surface is not high enough  to keep the bolt cap from hitting the corner of the cocking ring.

 

I have subsequently remeasured my  cam ( lay it along side the full size template on the print and determine if that is to print,)  and determined that the rear portion is too short by the amount expected from my results. I now why I had the problem but during my troubleshooting  I was not able to find a similar method to do that on the cocking ring profile. Thus my questions.  

 

It was probably not the wisest decision to take up a project of this complexity while the only formal training in machine shop was in the 6th grade well over a half century ago. This demonstrates the immense power of a forum like this one to assist those who need assistance.  Thank you again to all who are willing to so generously of their time and expertise. I am still very much a newbie and when completed this will be a lifetime achievement project


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#9 Sparky_NY

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Posted 11 September 2020 - 11:10 PM

It was probably not the wisest decision to take up a project of this complexity while the only formal training in machine shop was in the 6th grade well over a half century ago. This demonstrates the immense power of a forum like this one to assist those who need assistance.  Thank you again to all who are willing to so generously of their time and expertise. I am still very much a newbie and when completed this will be a lifetime achievement project

When I built my first gatling gun,  I built it largely to get more experience machining.   I had just gotten a manual bridgeport.   I knew it would be extremely challenging.   I figured the worst is that I would have to remake some parts BUT I would learn a LOT about machining when done.    It also got me into CNC machining,  the front cross piece of the frame is what got me into CNC.    The guns are a fringe benefit as far as I am concerned.


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#10 Larryx

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Posted 11 September 2020 - 11:50 PM

I agree with your thinking 100%



#11 rayhawk

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Posted 12 September 2020 - 10:01 AM

You can find the cam dimensions on the Box Cam drawing, just a bit indirectly. Note the .825 dimension in Sec B-B, that refers to the 0 degree, or TDC position. The linear delta between TDC and BDC is shown on the cam path view, at 1.175. If you add 1.175 to .825, you come up with the nominal BDC length of 2.000". This could also be shown in Sec B-B at the bottom of the part (BDC). Let us know what your length at BDC of the box cam is.

 

Also, I found the easiest way to see what was going on is to take the Recoil Plate Assembly with the rear half of the box cam out of the breech casing, and take a bolt by hand, guiding it around the path. It won't be perfect, but it will help you see if you have any major issues.

 

 

Attached Files



#12 Larryx

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Posted 12 September 2020 - 02:00 PM

Thank you for your response.  

 

To "review the bidding" so to speak, I got into the situation when I thought I was really making progress when I was able to assemble much of the gun and was able to see how things (mostly moving things) fit together.  I ran into the situation described by Paul in the assembly instructions where the bolt hit the corner of the cocking rings. I did eventually  get to the procedure you describe with the recoil plate and it became obvious that something was the incorrect size.  There are 2 main components involved - the cocking rings assembly and the rear part of the cam. Measuring the rear part of the cam is doable with a little thought, but I questioned whether measurement of the cocking ring assembly was possible. Thanks to the suggestions posted here I learned that my cam - the rear part was the wrong dimension.  I am starting to amass a cache of cast off parts from several such instances.


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#13 Cutter

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Posted 12 September 2020 - 02:27 PM

On my first build I used a short piece of casing
material for a visual.
This makes it easy to dial in with confidence.

Attached Files


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#14 Larryx

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Posted 12 September 2020 - 03:09 PM

I have such a piece. Great suggestion. Saves wear and tear on the X Ray eyes.


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