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the sender of the best letter which we publish on this page; all others paid for at the rate of a penny a line, with an allowance for photographs. All notes are edited before being published. Mention your employer's name, in confidence, as evidence of good faith. Address D., M, and F., "The Commercial Motor." 713, Bosebery Avenue. London, E.C.
Jig for Running White-metal Bearings.
The sender of the following communication has been awarded the Ws. prize this week.
[1765] M.M. (Fulham, S.W.). writes :—" Herewith is a sketch (Re-drawn by us.—En.) of a. jig for running white metal bearings. I have seen many jigs, but as a rule they are very crude, and a great deal of time is wasted and Unnecessary mess made by the use of fireclay or some other such things, and very often the fireclay cracks with the heat and causes the metal to run and the bearing-has to be run again, but by my
method there is no need to use fireclay or any other substance except cardboard asbestos, which can be used over and over again, and I can guarantee them to be metal-tight every time. The jig is very simple and inexpensive to make. It consists of the following parts. A piece of metal plate 3i ins. by 4 ins. by
in., drilled out and tapped in the centre to whatever size mandrill is required for the core. Then a hole is drilled and tapped I in. each side of the bearing and studs fitted. A plate the same size is made for the top, bored out in the centre tin. smaller all round than the extreme outaide diameter of the bearing. A piece of asbestos is placed both top and bottom of the bearing, so that when the top plate is clamped down both the top and bottom Joints are made tight and no metal will pass out. The top and bottom pieces of asbestos are left larger than the outside diameter of the brasses and the holes are made the same size as those in the top and bottom plates. The method of making the outside tight is as follows :—First of all, two pieces of saw blade are inserted between the brasses. The two blades should touch the mandril and be flush with the eutside.of the brasses. This will be a guide for getting the brasses central and will make it easy to split them after the metal has been run. The next thing to do is to place a piece of asbestos all round the bearing clamped on by two clips, similar to those used for water pipe clips. It is advisable to have the clips as wide as possible. I have found two clips better than one. After the above has been done, the bearing is ready for clamping down. The gas can then be played on the outside and the bearings run in the usual way. It is advisable to soak the asbestos in water before placing it on the brasses. All parfs used with the jig should be blackleaded, as this keeps the parts clean and prevents rust."
How to Get Free When Bogged.