Sneaking up on tyres

I may have been a trifle optimistic about finishing the learning phase before 20 hours are out. I’m still discovering how to hit a given diameter with a form tool. It seems to be equal parts art and science.

My approach is pretty much to make each tyre individually. Sure I take note of where the flange was cut completely on the first tyre and expect the others to be in the same place. However, it seems to be more effective to stop short of the final diameter, note where I am, and then figure how much further I need to sneak up.

At least the chatter’s mostly gone.

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2 thoughts on “Sneaking up on tyres

  1. This may be a dumb question, but are you using only the form tool? If so, stop!
    On the size of lathe you have, you need to use a standard tool to do most of the work, creating an extremely crude flange shape – all right angles and overwide flange width – and get as close as you can to removing most of the unwanted metal, then apply the form tool with the lathe running at the slowest speed you can manage.

    I am assuming here that you have a quick change tool post, so that once set up in their holders you can swap between tools and they will go back where they were. If not, then whilst I can’t speak for the costs in Canada, but a quick change tool post and holders didn’t cost much more than the replacement form tool I would have otherwise have had to buy.

    1. Actually, I’ve been only using the form tool, Simon. When I was learning to control chatter, I found the amount of the tool didn’t seem to really matter. The tool cost less than $4 because I made it myself. When I get to the P87 tool, I plan to do as you say (although the P87 profile is so fine, there isn’t much of a flange to rough in!).

      This morning, I cut a bunch of tyres with the sides of the tool relieved with a few cuts from the cutoff tool. This did, as you suggest, seem to result in more accuracy, although still required sneaking up.

      Thanks!

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