Re: [CAD_CAM_EDM_DRO] Re: Electronic Lead Screw Drive Article ? | Threading Ratios ?

Vaso wrote:

>This PLL circuit fixes the speed of the lead screw to some ratio of
>the the spindle speed. The circuit as it stands has a fixed "table"
>of ratios, but it seems to me - with microprocessor control - any
>ratio between spindle and leadscrew speeds is possible, so this
>circuit could cut any metric or English threads - even non-standard
>threads.
>
>The problem of releasing the half nuts and traversing back manually to
>pick up the thread would still remain, but the half-nuts need not be
>released - the traverse direction can simply be reversed...
>
>Am I missing something ?
>
>

Yes. Reversing the leadscrew, unless the program has some arrangement
to only allow direction changes at the spindle index, for instance, will
throw
the "gear train" out of sync. This is the same reason you can't reverse
the gear
train on an all-mechanical thread cutting lathe, either.

Jon