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Author Topic: Arcs in Turn wizards  (Read 8551 times)

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Offline TonyP

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Re: Arcs in Turn wizards
« Reply #20 on: December 01, 2007, 06:57:02 AM »
It won't let me attach two pix at once apparently
Re: Arcs in Turn wizards
« Reply #21 on: December 01, 2007, 07:42:24 AM »
Tony,

Yes, stepper was size 23. The turret spindle was mounted in two ball bearings with the toolholder plate bolted onto a flange. Worm wheel ratio was 30:1.
Your picture shows an additional microswitch, presumably to generate a position signal for tool number 1.

On  the Yahoo Mach group John Stevenson suggested using a rotary table with the ratchet mounted behind a toolplate. I though that it might be possible to use this idea,
but mount it directly to a stepper. The ratchet would take all the downward forces on the cutting tool and the side forces are very low on these little lathes. One of the Chinese 250 microstep drivers would give enough resolution with enough torque at low speed say, 12 rpm. Just an idea for discussion.

Ian
Re: Arcs in Turn wizards
« Reply #22 on: December 01, 2007, 07:50:16 AM »
Overloaded,

Very simple really, the stepper indexes the plate to the next ratchet position then backs up and stalls. Step singals are stopped and position is held by motor detent torque. No other locking pins are used. I just wrote a subroutine call to index the turret.

Ian

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #23 on: December 01, 2007, 10:16:40 AM »
Ian
I just tried a quick scaling exercise and it looks as though using the centre height for the scaling is incorrect. I can't get the same scale factor for the centre height & the stepper size. Looking at my turret1 pic I notice that the tool tips do not appear to lie on a line through the axis of the turret. Scaling from just the stepper gives me an axis height of 45mm above the cross slide & a possible toolplate dia of about 140 -160 mm. Does this sound about right?

Regarding the idea of using a rotary table, I think it would work well, but for a small lathe like the TCL it may be difficult to find one with a small enough centre distance. I've been thinking about the same sort of thing myself, but I'm sort of becoming resigned to having to make one from scratch.

Tony
Re: Arcs in Turn wizards
« Reply #24 on: December 01, 2007, 04:21:25 PM »
Tony,

On the TCL 125, the turret toolplate is 132mm diameter and the centre height of the turning tools from the crosslide is 35.25mm. The TCL 240 (pictured) is a very much bigger machinne.

Ian

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #25 on: December 01, 2007, 04:42:05 PM »
Ian,

ah! Thanks for that. I didn't know that there was a difference in capacity. I thought that they'd usedthe same basic mechanics with updated control layout & electronics. ( or was that just the 160 )

Tony