Re: [CAD_CAM_EDM_DRO] turret tool post for lathe

Hi,

I have a turret on my Harrison which came with the lathe. When I took it
off, it was in the way all the time and only took 12mm square shanked
tooling or 16mm boring bars, too small for some of the cuts I make. I find
it easier to program stops in the code and change tooling with a
quick-change tool post, I couldn't resist taking it to bits.

The unit only indexes forwards, if the tool was @ position '2' and the next
tool needed was position '1' then it has to go through all eight to get to
it. When I was using the turret a little thought was necessary in loading
the tools to keep change time low. In practice there was little time between
changes. It consists of a large stepper running a worm and wheel to a trip
switch then reversing to a stop. The stop is spring loaded plate against a
wheel, the teeth of which are the tool positions. It has eight stations/tool
positions. The only thing that holds the tool position is the weight of the
components and the cutting forces from the tool as the whole rig run in the
vertical plane. I'm not sure if the stepper shuts down between moves, I
don't think so because the driver circuit is very crude.

The only advantage I can see in using a stepper over a DC motor would be
using the holding torque against the stop. It would be possible to use a
solenoid and a re-design of the indexing wheel to achieve the same ends. I
am thinking of designing a horizontal tool changer, using just this sort of
arrangement, and selling the Harrison one off for pot loads of cash.

Regards,

Terry

> > Why use a stepper? The only advantage would be that you could index the
> > turret both ways. However you would either need a huge stepper or some

form

> > of locking mechanism to hold the tool in place while cutting. This adds

a

> > lot to the cost and complexity.
> >
>
> I would think that the advantage of programming the tool used, would have
> advantages. If the stepper drove the turret back into the locking

position,

> wouldn't the holding torque keep it there?
>
> bill
>
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