A solution of sal-soda mixed with lard oil is a lubricant I have seen used on copper in turret lathe work with good results. S. H. Sweet.
A mixture which will permit hard steel or iron to be drilled with ordinary drills is made by using 1 part spirits of camphor and 4 parts turpentine. Mix well and apply cold, letting It remain a few minutes before applying the drill. Run the drill slowly with fine feed. C. E. Mink.
Syracuse, N. Y.
Gasoline is an excellent lubricant. In our shop we have used it as a lubricant for cutting copper with very good results.
Rockford, Ill. George C. Nash.
The best "dope," so-called in shop parlance, that I have ever seen used for making pipe connections, is composed of 1 pint of "black strap" machine oil, ½ pint graphite, ¼ Pint of white lead, and a tea-spoonful of flour emery. These proportions are not exact, but they are substantially what are used. The object of the flour emery is to polish the threads as they are being screwed together. The graphite, white lead and oil make a fine lubricating mixture, which has enough consistency to stop incipient leaks. I have seen many large pipe radiators made up using this mixture, and they never leaked a drop when the steam was turned on. M. E. Canek.
Altay, N. Y.
Mineral oils should never be used in thread cutting and tapping, as they do not generally flow freely enough. An excellent solution for this purpose can be prepared by dissolving 1% pound of sal-soda in 3 gallons of warm water, then adding 1 gallon of pure lard oil. This is known as a soda solution. Pure lard oil is the best for fine, true work. T. E. O'Donnell.
Those who have had to turn copper in the lathe have generally wished they had let someone else do the work, and that they could stand by and jeer when it was being performed, or else criticise it after it was done. Soap and water do not help; turpentine is a delusion and a snare; but milk does the trick "with neatness and dispatch." ROBERT GRIMSHAW.
To make a good lubricating mixture for cutting thread in hard tool steel, use equal parts of turpentine and benzine or kerosene. For cutting in soft tool steel mix equal parts of kerosene and lard oil. These mixtures always flow even and keep just about enough moisture at the cutting point.
Kearney, N. J. Everett Kneen.
Zinc shells should be clean and free from all grit and should be immersed in boiling hot soap water. They must be redrawn while hot to get the best results. On some shells hot oil is sometimes used in preference to soap water.
For redrawing aluminum shells use a cheap grade of vaseline. It may not be amiss to add that the draw part of the redrawing die should not be made too long, so as to prevent "too much friction," which causes the shells to split and shrivel up.
For redrawing copper shells use good thick soap water as a lubricant. The soap used should be of a kind that will produce plenty of "slip"; if none such is to be had, mix a quantity of lard oil with the soap water on hand and boil the two together. Sprinkling graphite over the shells just before redrawing sometimes helps out on a mean job. C. F. Emerson.