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Non Elegant solution

head space

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#1 Larryx

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Posted 21 May 2020 - 09:20 PM

I have been obsessing for over a fortnight  on how to insure my breach end of the barrels were all on the same plane. I did follow the suggestion of assembling the "barrel package" and turning the parts in the lathe. This did achieve some success but the  obviously interrupted cut resulted in an unacceptable finish and questionable accuracy. 

 

The guidance from the masters on this forum made it clear that accurate head space on all barrels is a highly desirable attribute of the build. After worrying myself out of a year  or two of existence, I came up with this very non professional but highly effective lash up, Measured distance from barrel end to rear barrel plate is now within 0.002 inches on all barrels...  

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#2 20Gun

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Posted 21 May 2020 - 11:25 PM

More than one way to skin a cat! Looks like an Atlas lathe?



#3 Larryx

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Posted 21 May 2020 - 11:37 PM

It is a Craftsman branded 12 x 36. Love the lathe, hate the dials. Very light etching on a minuscule dial makes for difficult setting by the dial. I have added dial indicators on each of the axis plus the tail stock so I can usually hit my dimension

 

I was lucky to have the extra length to be able to position the cross slide aft of the rear barrel plate.



#4 20Gun

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Posted 21 May 2020 - 11:53 PM

I have the exact same one. I don't like the dials either. I'd like to upgrade, but I have this one so well tooled, and it does the job. It will do for now.



#5 Swarfmonger

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Posted 22 May 2020 - 09:20 PM

One suggestion I would make is to make absolutely sure you thoroughly clean every square inch of that lathe after you’re done doing that. That grinder grit will be murder on the ways if you don’t.
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#6 Roller

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Posted 22 May 2020 - 11:09 PM

When using a toolpost grinder on a lathe I would lay a towel under the work area to protect the ways.

 

Frank


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#7 Larryx

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Posted 22 May 2020 - 11:26 PM

Thank you for reminding me and the community.

 

I actually knew that but I was so ecstatic having found a way to get the breech end of the barrels on the same plane after stressing about it for so long,  I neglected  to think and to protect the ways.. I recognize that  can be extremely dangerous at the least and fatal at the most around big, sharp,rotating machines! I have added a sign above the lathe which says ENGAGE BRAIN PRIOR TO TURNING ON THE POWER


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#8 bruski

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Posted 23 May 2020 - 02:59 AM

If you were getting some chattering while turning the barrel cluster, use a steady rest to hold it.

 

bruski



#9 Larryx

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Posted 23 May 2020 - 02:30 PM

I hope this this is only an academic discussion (with Murphy as a constant companion one never knows) but I would like to ponder how I would utilize a steady rest. The only surfaces I oud use for the steady rest to "ride" on would be either the front or rear barrel plates. The front barrel plate obviously has to be toward the chuck. In order to have any sort of concentricity I used the main shaft with ad- hoc spacers to take up the length of the non present carrier block ( or in my case the non existent cartridge carrier and bolt carrier.) This gives me a assembly to turn that has less than 0.002 in of runout. ( the chuck end has been dialed in and the other end is supported with a live center in the hole which was used to turn the main shaft.  Where would I place the steady rest?

 

There was little observable radial movement in the rear barrel plate but any that did exist was in quadrature to the cut.

 

I believe my main problem was the shape of cutting tool to tolerate the  interrupted cut. I originally selected a tool with a small but stiff finger shape. This was done because I first attempted to use a spacer for only the cartridge carrier. I really did not have sufficient room to work so I replaced it with a longer spacer to take up the space of both my carrier block pieces.

 

Any and all suggestions as to what to do "NEXT TIME" are solicited and appreciated.



#10 Roller

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Posted 23 May 2020 - 11:13 PM

Wow Larry, I had to look up the word quadrature to know what you meant!  A rigid setup is what you need, a dead center in the tailstock would help.  A tool with a high rake will also help,   Steady rest would be ideal if you could use it. 

 

Frank 


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#11 Larryx

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Posted 24 May 2020 - 12:08 AM

Thanks for the insight. I have to admit I deliberately used that word to reduce the number of people who would think "what a stupido - doesn't that guy know anything?" I was able to I believe successfully chamber all the barrels to what I hope is sufficient accuracy. I will be able to measure the  actual accuracy once I finish the bolts and measure the actual operating hardware. 

 

On the advice of this forum, I did not invest in a go/no go gauge but was using a live .22 round as a gauge. My bride of 57 years offered the advice that perhaps it would be better to use a different item as a gauge, so I rigged up one of the ,22 cal snap caps instead.



#12 bruski

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Posted 24 May 2020 - 02:03 AM

Your rear barrel plate is smooth on the OD isn't it? That is where I used mine I'll be it had to be opened up past it's maximum capacity to fit around the plate but it worked.

 

bruski



#13 Larryx

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Posted 24 May 2020 - 11:44 AM

10-4

#14 Cutter

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Posted 24 May 2020 - 02:57 PM

10-4

 

Mr X

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#15 Larryx

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Posted 24 May 2020 - 07:13 PM

Very clever, but I'm much better looking!


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#16 Roller

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Posted 24 May 2020 - 11:57 PM

I liked your previous avatar better!  You got all our attention with that one.

 

Frank


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