Cam-Gear

I have to make a gear wheel with a cam attached.Is it better to form the cam first and then cut the gear or vice-versa.

What equipment do you plan to use to cut the cam? Method/order will be machine-dependent. JD

In the photo it looks as though the cam and gear are separate parts that have then been assembled (pressed, loctite etc). If the timing between the cam and gear is at all critical then I think I'd be looking at doing the same, to allow for alignment on assembly rather than trying to line everything up exactly during machining. It may be easier that way even if the timing is fairly free.

Yes, two separate parts is the way to go.

Having access to a copy milling machine I would make two plates with dowels to locate on the gear teeth so that they are both in line then copy mill from the original to the new one. I do motorcycle cams this way.

If making as one piece, I'd make the cam first - on the basis (from personal experience) that I am more likely to make a mess of cutting the cam than the gear. However, as advised above, I would make in 2 parts. Assuming that the assembly is being driven by a pinion with half the number of teeth, the adjustment for timing is rather coarse. One way of overcoming this is to pin the cam to the gear with a selection of holes. In this example, the holes are spaced by n teeth plus 1/3 and n + 2/3.

The pins are actually 12 BA screws.

HTH,

Rod

I have made sevaral like this and the gear was cut first, then held in the rotary table to cut the cam. Quite common on a lot of teh hit & miss engines that supply the stock gears and you modify them by adding the cam