A Versatile Pen-Holder for Chart Recorders Many scientific instruments use strip-chart, drum, or flat-hed recorders for data display. A minor yet very annoying problem is occasional pen failure. This is especially true of older recorders that use rather complicated liquid inking systems. Most newer recorders use Nylon-tipped pens with a built-in ink supply. When a pen fails t o write, it is easier to replace a self-contained Nylon-tipped pen than t o clean up an entire inking
Raundhead Screw 16.32 x 1%")
6 No. 6 Washer [bent-edge down)
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The pen-holder described in this note can be installed on most recorders. I t allows use of an inexpensive pocket Nylon-tipped pen and requires only a small hole for mounting an the pen carrier. A little ingenuity generally provides a suitable method of attachment; some recorders have a pointer that can be used. The drawing shows all of the individual parts and how they are assembled. TwoNo. 6 flat washers are bent along one edge t o a right angle by placing a small segment of the washer in a vise; a few blows with a hammer will bend the edge to 90'. A roundhead screw (6-32 X 1%in., or 1% in.) is inserted through one washer with the bent edge downward. ___...~ With the screw outside the back of a small binder clip (Industrial Precision Products Co., Pen Carrier Chicago, Illinois, size No. 2, Small Binder Paper Clip,' or equivalent), the bent edge of this washer is hooked over the hack of the clip a t the top. The other washer is placed on the . ..Nut 16.32) screw with the bent edge up so as t o hook on the back of the clip a t the bottom. One nut is used to tighten these parts together. The bottom of the screw is placed through a hole drilled in the pen carrier and the whole assembly tightened together with another nut. Insertion of a Nylon-tipped pen inside the binder clip completes the installation. If the screw is too long, disassemble and cut to the required length with a hacksaw. Before sawing, thread a nut on the screw so that damage to the threads will be repaired by removing the nut. This pen holder has a number of advantages. It is assembled from common, readily available inexpensive parts and does not require any machine-tool work for construction. The binder clip securely holds a variety of pen types from different manufacturers; the best for the purpose can be selected. Costa can be reduced if ordinary pocket pens are psed rather than the more expensive pens made especially for chart recorders. Nylon-tipped pens are available in many colors and, because it is so easy to change pens, several scans can he made on the same chart using different colors for identification. This can be advantageous for sample comparisons, or time studies and, of course, also saves chart paper.
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Northern Regional Research Center Agricultural Research Service U.S. Department of Agriculture Peoria, Illinois 61604
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H e n r y J. Nieschlag
The mention of firm names or trade pmdurts d w s not imply that they are endorsed or recommendpd hg the U.S. Department of Agrirulrure over orher firms or atmilar produrts not mentioned.
542 1 Journal of Chemical Education
