I send you by this mail for your inspection one of the saddle bolts and one of the bolts taken out of the piston, and also the certificates of the engineer, boilermaker, and machinist who repaired the boiler. In justice to my fellow-farmers I ought to publish these certificates and the names of these boilermakers to the world, but, for the present at least, I refrain from so doing. These boilermakers will see this article and they will know, if the public does not, for whom it is intended. If it has the effect of making them exercise more care in the construction and fitting up of their engines and boilers, I have not written in vain.
D. FREEMAN.
Los Angeles, Cal., March 7,1884.
[The two bolts and the certificates above referred to accompany the letter of Mr. Freeman. We can only wonder how it was that, after having been treated as he relates in the first instance, he should have had any further business with parties who would send out such boilers, for the testimony of the engineer and workmen make the case even stronger than Mr. Freeman has put it.--ED.]
A THREADED SET COLLAR.
There are cases where a long screw must be rotated with a traversing nut or other threaded piece traveling on its thread a limited and variable distance. At one time the threaded nut or piece may be required to go almost the entire length of the screw, and at another time a much shorter traverse would be required. In many instances the use of side check nuts is inconvenient, and in some it is impossible. One way of utilizing the nut as a set collar is to drill through its side for a set screw, place it on its screw, pour a little melted Babbitt metal, or drop a short, cold plug of it into the hole, tap the hole, and the tap will force the Babbitt into the threads.
Insert the set screw, and when it acts on the Babbitt metal it will force it with great friction on to the thread without injuring the thread; and when the set screw tension is released, the nut turns freely. A similar and perhaps a better result may be obtained by slotting the hole through the nut as though for the reception of a key. Secure a key (preferably of the same material as the nut) by slight upsetting at its ends, and then thread the nut, key, and all. Place a set screw through the nut over the threaded key, and the job is complete.