Bike Timing Sprocket.

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Zadig:

mexican jon:
Nice work :thumbup: I have a couple of questions :lol: why didn't you bore to size when you had it in the 3 jaw chuck that most of the machining was done ? What was the logic in using a faceplate rather than a 4 jaw chuck ?

Zadig:
Firstly, thanks for the thumbs up, glad it amused you.

I wanted a good fit on the taper. If I had done as you said and cut the taper with the op in the first instance, I would have had to have left the large boss on to hold the blank to machine the reverse side. This would then have necessitated a further op to reduce the boss to the finished size. If you are suggesting that the whole of the front face could have been machined in one setup, then there would have been a danger of crushing the taper when machining the obverse side, plus this extra step would negate any advantage you were trying to gain.

Cutting the taper using the topslide was also made easier because the reverse side has the recess. It's quite a deep hole for a small boring tool, so any advantage in chip clearance because of the through hole, on this tough alloy steel was welcome. It gave me the advantage of not having to drill deeper than was necessary to give clearance for the taper thread, thereby potentially ruining the end of the remaining stock.

I see no logic in holding it in a four jaw to machine the rear. Clocking the back side of it would have been awkward to say the least. Then there are the holding marks it would leave on the diameter. The tooth thickness is only .188" thick, which would have needed some holding force in the four jaw.

You may think differently, but like all things in this game, you do what suits you.

mexican jon:
Firstly I was laughing at myself :scratch: as I knew there was a perfectly logical reason you had done what you had done :clap: I guess I should have studied the pictures more and realised that the spocket was going on to a taper :doh:

It was just as I was thinking of the questions I was giggling thinking when I read the answers " Jon you should have realised that" :) :)

Zadig:
It was a fair question and I had to think back as to why I did it that way. If you have the patience there is nearly always a few ways to get the job done. A four jaw could have been used, but setting it up would have taken a fair amount of time in comparison to the way it was done.

Thanks again for the comment, I'm still new here and finding my way around.

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