Dial Gauge: Logan, 1883

John Logan of Waltham, Massachusetts, patented this dial gauge in 1883, US 283,627. A gauging bar slides lengthwise through guides in a case with a graduated dial. A chain fixed to the bar is wound round the arbor that carries the pointer, so when the bar moves the chain unwinds and turns the pointer. The pointer's end moves much further than the bar, which makes the reading very delicate. A spring on the arbor winds the chain back and returns the bar to zero. A jaw on the case and a jaw on the bar make it a caliper; a slender rod beside the bar's other end makes it a depth gauge.

上級者

Workshop process

手順

Case and dial

Make the case with the graduated dial, with tubular guide projections at opposite sides for the gauging bar.

このステップの材料:

目盛板付きダイヤルゲージケース1 個

Arbor, chain and bar

Pivot the arbor carrying the pointer at the dial's centre. Pass the gauging bar through the guides and connect it to the arbor by a chain fixed to the bar and wound round the arbor.

このステップの材料:

指針軸と指針1 個

測定棒1 個

細鎖1 個

必要な工具:

精密ピンセットセット

ドライバーセット

Return spring

Connect a spring between the arbor and the case so that it turns the arbor to wind the chain and draws the bar back to the zero position.

このステップの材料:

アーバー戻しばね1 個

必要な工具:

精密ピンセットセット

Jaws and depth rod

Fix a jaw on the case and a matching jaw on the bar; when they touch, the pointer reads zero. Fix a slender gauging rod beside the guide at the other end, in line with the bar's end at zero, for measuring depths.

このステップの材料: