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US Patent: 125,823
Improvement in Gauges
Butt Gage
Patentee:
John A. Marden - Veazie, ME

USPTO Classifications:
33/44

Tool Categories:
layout tools : marking gauges : butt gauges

Assignees:
None

Manufacturer:
H. Chapin - Pine Meadow, CT

Witnesses:
Fred H. Coombs
Horace S. Smith

Patent Dates:
Granted: Apr. 16, 1872

Patent Pictures: [ 1 | 2 ]
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Description:
The Marden's Patent gage was the first one to really solve the problem of hinge mortise layout. The key to this patent is a sliding "tongue" attached to the face of the head, which moves a marking point such that the distance from the end of the arm to this point is a tiny bit greater than the distance from the head to the fixed point. This difference will automatically make up for the "gain" needed to keep the door from binding in its rabbet.

This comparatively simple design dramatically simplified the error-prone task of hinge layout, and almost all butt gages from this point on used a variation of Marden's idea.

Chapin-Stevens showed two varieties of gage referred to as Marden's Patent in one of their catalogs: one that looks almost exactly like the patent drawing, and another with a sliding fence on the back of the bar. Current research indicates that the second gage is not in fact based on the Marden patent, but is instead a Thompson's Patent of 1900 (658,881) which shares many of the Marden features.

Another gage with very similar characteristics that is often mis-identified as a Marden is the LeFrancois Patent (435089). The LaFrancois gage adds a scribing point in the side of the head, and also uses a solid brass head.

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