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#1 Dave Janowski

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Posted 08 March 2004 - 06:20 PM

OK guys I need some help!

I am finishing a semi auto Richardson for a fellow member of this board, but I have a question: Did Colt Overstamps come from the factory with drum divots? If so what is the ball end mill diameter, and depth I should use to cut these correctly!

Another question does anyone have an actual print for a recoil spring for the 28/M1 TSMG?? I need to make a batch of springs for a customer, and Doug is in Beleize!

Thanks
Dave
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#2 Arthur Fliegenheimer

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Posted 08 March 2004 - 07:32 PM

Dave,
Answer to the first half of your first question, you betcha!

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#3 Mario Scarpino

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Posted 08 March 2004 - 08:53 PM

Dave,

From deep inside the Batcave, I have a drawing (number 45-1-2) entitled "Receiver Thompson Submachine Gun", signed by Payne and Eickhoff, dated May 7 (my birthday) 1919. This is not the "original" but a copy as you probably guessed. The last revision done on this drawing has a date of Sept. 1 1921.

For the forward drum slot, the following note points towards the dimple area you refer to: ".10 R. CUTTER .32 D." For the rear drum slot, the note reads as follows: ".10 R. CUTTER .42 D." I am not sure these notes mean anything to the average guy. They may refer to cutters that only Auto-Ordnance knew what they meant.

If the above info answers your question, if I send you my 1927A1 receiver (with barrel attached), would you machine the dimples in it for a small fee? Just thought I would ask.

I have a drawing (number 45-1-9) dated May 31, 1919 that contains several springs including the recoil spring. I am sure this is for the model 21, so probably no help to you.

Back to the Batcave!!

Mario Scarpino


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#4 Walter63a

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Posted 08 March 2004 - 10:03 PM

Dave, this is only a guess, on my part, but I think "cutter" could refer to a tool or the person doing the cutting, the ® abbreviation could refer to radius and the (D) to depth. The measurements .10, .32, and .42, were probably from the English, as opposed to the Metric, system of measurement. I would consult PK, if in doubt. blink.gif unsure.gif My 2 cents. Good luck! smile.gif cool.gif Regards, Walter
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#5 gijive

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Posted 08 March 2004 - 10:29 PM

Dave,

Think about your question for a minute. If the 1921/28 Overstamp was a variation made from the original 15,000 1921 Colt Thompsons and they were already manufactured and capable of accepting a drum, then why wouldn't the 1928 Overstamp model be identical to the machining on the 1921 Model?

Does anyone read the historical references on the Thompson gun or simply rely on the responses to an Internet chat site?
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#6 PK.

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Posted 09 March 2004 - 08:18 AM

The drum slot radius on the Colt (and Savage) is not concave, but convex. After studying some original guns and comparing with the measurements from the prints, I had cutters ground to produce the proper form. You can’t buy ‘um off the shelf unfortunately.

On the other hand, if the “dimples” are made with the ball mill, they are actually more functional.

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#7 Dave Janowski

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Posted 09 March 2004 - 01:01 PM

OK so if we use a 3/16 ball end mill on the "center of the slot that should cover it?

Thanks again guys

No one has a spring print? If anyone I should!!!

Dave
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#8 gijive

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Posted 09 March 2004 - 06:28 PM

Dave,

My apologies for the sarcastic post. I guess I misinterpreted your inquiry. I'm glad the gunsmiths on the list were able to provide the proper specifications for you.
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#9 PK.

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Posted 10 March 2004 - 10:40 AM

Dave, you asked; ”OK so if we use a 3/16 ball end mill on the "center of the slot that should cover it?”

Not if you want Colt type form. The ball mill will make a concave radius, which is the opposite of that used on the Colt & Savage.

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#10 Walter63a

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Posted 10 March 2004 - 01:01 PM

PK, I know the difference between concave and convex. However, could you post a photo or diagram of the difference (or explain it), specifically dealing with Dave's original question? I'm just curious and non-technical here! biggrin.gif blink.gif cool.gif Thanks, Walter
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#11 PK.

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Posted 10 March 2004 - 01:20 PM

I really wish I had a photo that clearly show what we are talking about but I don’t.

Try to visualize a funnel (you have to do this in 3d), normally the tapering wall is straight going form a small diameter opening to a larger diameter top. If the wall bulges out in a concave radius fashion, you have what a ball mill will produce. If the wall bulges inward in a convex radius fashion, you have the basic form of the chamfer.


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#12 Walter63a

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Posted 10 March 2004 - 01:28 PM

Thanks PK, but I think a drawing, comparing both, would help immenslely! ohmy.gif blink.gif biggrin.gif cool.gif Regards, Walter
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