A Barth Journal

2016-05-31: Main Cams

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When I apprenticed on the Thompson Type Caster, I found that the main cams were they key to understanding the machine. On the Thompson, and also on the Barth, they simultaneously provide power to all of the mechanisms of the casting apparatus and control the timing of these mechanisms.

It's a bit harder to see what is and isn't relevant on the Barth camshaft when compared with the Thompson. On the Barth, there are several components of the driving (power input) system which are either on the main camshaft (e.g., an elliptical gear) or coaxial with it (the flywheel, the primary drive pulley, the clutch mechanism). There's also a countershaft linking the camshaft proper to the drive components on the left. For now, ignore all of these things - they just make the camshaft turn.

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There are six main cams on the Barth (at least on the Size No. 3 1/2, and also on the machine described in the Barth & Lietze patents, so I assume on all Barths). They are all fixed rigidly to the main camshaft and turn at the same rate. The direction of rotation is such that the top of each cam goes away from the operator.

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I've numbered the cams from one to six. (There's no indication that Barth, Lietze, or ATF did so.) I've given them descriptive names here. These may change when I develop the parts list for this machine.

Cam 1 guides a follower in a channel on its periphery. It controls the motion of the large slide on the top of the machine (Barth and Lietze call this, at times, the Mold Covering Slide). So, basically, it moves something left-and-right.

Cam 2 controls the Choker Valve. As such, it moves something (the Choker) forward-and-backward (or in-and-out).

Cam 3 moves the Matrix Carriage in-and-out.

Cam 4 moves the Mold Body Piece up-and-down.

Cam 5 controls the mechanism which pulls the type down into the delivery channel.

Cam 6, finally, is the Pump Cam. It raises the Piston against the pressure of a spring and allows it to fall abruptly.

There's much more to these cams and the mechanisms they control, of course. But the first step is to memorize what they are.