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Thompson Manufacturing Drawings


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#1 Doug Richardson

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Posted 16 September 2003 - 01:02 AM


THOMPSON MANUFACTURING DRAWINGS

As the supply of original Thompson parts diminishes and the prices go higher and higher for those that remain, the temptation to manufacture new ones increases. I have no problem with that as long as the newly made parts are as good or better than the originals. It seems, though, that everyone who makes parts claims their parts are “made to the original specifications/drawings”. When I have made inquiries to the makers as to where they got the “original specifications/drawings” (I’m always searching for original Thompson engineering data.), I am invariably told that the “original specifications/drawings” were derived from studying an original part. You can’t have it both ways. Either you have the “original specifications/drawings” or you don’t. Copying an existing part is not manufacturing to the “original specifications/drawings”. There is no way of knowing what the original design dimensions were or what limits were placed on manufacturing deviations (tolerances) by the engineers to assure that the parts are interchangeable within every gun. Manufacturing is an imprecise activity at best. Parts are never exactly in accordance with the original design dimensions. Therefore, copying an existing part, which already deviates from the original design dimensions, adds more manufacturing deviations, producing a part that may not fit in every gun.

Part of the solution to the problem of bad parts is to at least start with the original specifications/drawings. As many of you know, I have every original specification/drawing for the WW2 U.S. Army Thompson guns. (I don’t have all the earlier drawings.) However, there are hundreds of them in various size formats and in varying conditions. And they are packed away in storage. Even though I have tried to help wanabe manufacturers in the past at no charge, the time involved is excessive, particularly when no great benefit to the Thompson world comes of it.

I have, therefore, decided to restore and digitize all the drawings and make them available to everyone. The only exceptions will be those full size drawings that I already offer and drawings of parts that I either manufacture or intend to manufacture. The price will be $20 per drawing including E-Mailing, Faxing or snail mailing. Drawings sent by Fax or snail mail will be 8 ½” x 11” computer printouts. Bear in mind that every part has its own drawing and if it is a part of a permanent assembly, there will be an assembly drawing. For example, there is no one drawing showing the manufacturing dimensions of the pivot plate. There is an assembly drawing which shows all the parts in position and instructions as to how the parts are assembled. Then there is a drawing for the plate, another for the trigger axis and another for the sear axis. You need to identify the exact drawing you want by number and name. If you do not know the number or are unsure as to the true part name, provide a COMPLETE description of the part and the model of the gun it goes on. I offer full size gun assembly drawings that number and name every part in the gun, which should help. If you have any questions regarding interpreting the drawing after you receive it, I will try to help you. Because of the nature of this product there will be no refunds unless I make a mistake.

Make checks or M.Os payable to M.K.Witter as usual and mail orders to: Doug Richardson, 2100 McReynolds Road, Malibu CA 90265. Tel: 310-457-6400, Fax: 310-457-3010, E/M: ThompsonSMG@Mail.com
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#2 PK.

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Posted 16 September 2003 - 08:52 AM

Cheers to you Doug,

The problems illuminated in your early paragraphs have plagued us all for years. Unfortunately they may still, but at least there will be no excuse other than the inability of some to utilize the information you now make available.

When you say you will digitize this information; what exactly do you mean? Scans of the originals, AutoCAD or ????

Thanks again for the effort, it should prove a blessing to us all.

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#3 Doug Richardson

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Posted 16 September 2003 - 11:02 AM

PK
Drawings are being scanned on large format scanners, computer restored (which is no small effort), and saved on discs.
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