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Looking good Andrew...............Terry
This thread seems to be attracting a steadily increasing number of views, but no comments. I'm not sure if that's good or bad?Anyway, here are a few more gears, specifically the crankshaft pinions and final drive pinions. Here is one set of pinions, along with the arbors for holding them during gear cutting. On the right are a couple of ground arbors to check the bore size.On the left is a gear vernier. When I first started cutting gears I did a roughing and finish pass with the cutter and checked the tooth width with the verniers. It turns out I was wasting my time. I now cut gears in one pass; all that two passes does is wear out the cutter. Likewise the gear verniers weren't much use. For non-precision gears like these it is fine to touch off the cutter on the OD and then move the mill by the theoretical depth of the tooth and commence cutting. You live and learn. Unless of course you do something really daft and get a Darwin award. The final drive pinions are 5DP in cast iron and are straightforward mchining. The crankshaft pinions are 6DP in EN8. The horizontal mill cut the EN8 like it wasn't there:The crankshaft pinions as shown thus far have been scrapped. When I made the first set I was ignorant about machining EN8 and didn't get a good finish, as can be seen. I was also concerned about the fit of the splines and made the bore 10 thou bigger than specified for clearance. Sometime later, with more experience, I machined another set of EN8 gears for a mate, and got a much better finish. So I remade mine, and also reduced the bore to the proper size. I found that the key to a good finish on EN8 is surface speed. The new sets of pinions were machined at 800-1200rpm, using insert tooling.Once I'd made the crankshaft thoughts turned to cutting the internal splines in the pinions. I wanted them to look neat, so I puzzled about how to get the correct radius on the end of the tool to be used in the slotting head. Eventually I twigged that I could use the cylindrical grinder to grind a diameter that I could measure, and then cut the toolbit in half and grind the reliefs by hand:Here is a rather poor picture of the slotting in progress on a scrap blank (I cut the gear selector slot in the wrong place) as a trial. The pinion is mounted centrally on a rotary table. Relatively fine cuts were needed or the Bridgeport slotting head jammed:The pinions required some work with needle files to achieve a good fit on the crankshaft splines. Not least because the width of the crankshaft splines vary by a thou or two over their length, but that's another story. Finally here are the proper set of crankshaft pinions in place and one of the final drive pinions just visible at the bottom of the picture:Andrew
Likewise the gear verniers weren't much use. For non-precision gears like these