ft...Drivers &Mechanics
Page 19
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Send us an account of any special incident of your work or experance. If suitable, um mill edit your notes, snpply a sketch when required,
3" and pay you for everything published. Mention your employer's name, in confidence, as evidence of good faith. Address in The Editor, THE COM ME RC1AL MOTOR, ROSebery .4 Venue, London, E ,C.
Repairing Dies and Drills.
[13064 " (Cardiff) writes :—" I recently
had a in. Whitworth hexagon die-nut break through being strained on a bolt. Rather than throw the die on the scrap-heap I effected the following repair :---" I first tightened the broken haves of the die together in the vice, then forged up a piece of steel hexagon shape, drilled out the centre and filed it out a good fit over the die-nut, making the hole a slight taper. I entered the die and squeezed it home in the vice, filed the hexagon to spanner size, the result being quite a satisfactory repair.
"It sometimes happens that mechanics have a little time to spare when the work is not at high pressure. Upon these occasions I turn up your 'D. and M.' pages and often come across some useful tips. " I recently had a few broken twist-drills by me which had been saved up from time to time, and referring to your correspondent's letter No. 1067, I set to work to make a repair as there describe-A, and could not wish for a better repair to broken twistdrills. Had I not seen the letter, it is almost certain! that the drills would have been thrown on the scrapheap long ago."
When Welding Steel.
[I307] " W.B." (Finsbury) sends the following hint:—" Many drivers are rather scared if they have on occasion to weld steel. A very useful recipe for this job is made as follows :—
"Two oz. powdered chalk, 2 oz. common soda, 2 oz. burnt borax, 1 lb. silver sand, which should be used in the ordinary way of fluxes, when welding. It is also useful to know that this mixture is very serviceable for restoring steel which has been burnt or overheated in welding."
For Cutting Your Own Gears.
[1308] " HAL" (West Bromwich) writes :--" I send you a description and sketch tWe have had this redrawn.—ED.] of a rig for making gear-milling cut ters on a lathe, there being many drivers and mechanics who desire to make their own cutters for producing spare or replace gear-wheels. In the illustration is shown the cutter blank marked out ready for cutting away the clearance pieces. This is best done by first drilling * in. or .PGin. holes in the blank as shown, then slotting out or filing away the clearance, or the pieces may be, cut out with a hack-saw. For attaching the cutter blank to the face-plate of the lathe I made a shouldered pin as shown in the drawing. The forming tool should be carefully filed up to a gauge somewhat wider than the width of the toothspace so as to allow a certain amount of side movement to shape up one side of the cutter at a time.
" The lower half of the illustration shows the general arrangement of the rig, the operations for machining the cutter being as follow. A piece of
tool steel about 3 ins, diameter and in. wide is bored out and rough turned on. a mandril to nearly the required shape, it is then bolted to the lathe faceplate, a hole, having previously been drilled in the latter in a suitable position to accommodate the shouldered pin. The distance out of centre of the faceplate at which the blank is attached will vary according to the diameter of the cutter-blank and the amount of backing-off clearance required. For a 3 in. diameter cutter, in. above the centre is about the right distance, the cutting edge being level with the centre of the face plate. The cut is put on by the cross screw in the saddle, as in the ordinary method of turning, for this purpose the lathe belt is pulled to and fro by hand, first relieving one side of the tooth and then the other until it is completed. To ensure reaching the proper depth for forming each tooth, a gauge-stop is best fitted in one of the tee. slots in the lathe saddle. A cutting thrust stop should also be provided, so that when one tooth is formed,. the cutter can be revolved to the next tooth,"