View Full Version : turret tail stock question

02-18-2005, 07:08 PM
Can any one explain just how or where to find info on turrets? I want to know how they index automaticly. Used to run a Hardinge, it always interested me; and I just can't stand not knowing how somthing ticks!

Mike Burdick
02-18-2005, 09:38 PM

If you don't get any information here, Ill take one apart and photograph it for you. They're pretty neat!

- Mike

Milacron of PM
02-18-2005, 09:53 PM
Even more interesting is the Geneva mechanism of a Burgmaster drill which indexes the turret under power. To see the details, look in the books "Ingenious Mechanisms" or go the the US Patent Office website and search patent owner, Fred Burg for patents.

02-19-2005, 04:53 AM
..........I don't know if you mean a fancy power one or a more mundane manual operated bed mounted unit. Maybe both? If so, I hope I can explain this intelligently enough for you to visualize.

I just got done taking my 11" Logan's bed mounted turret apart, cleaned and painted it and put it back together. It's a manual one, with the carriage powered via a capstan wheel turning a gear in mesh with a rack on the turret carriage.

The 6 sided turret rides on a circular machined surface on the carriage and rotates on a substantial spindle. This spindle extends through the carriage and on the underside also carries a circular plate which rides on a machined surface. Via a 'T' handle on top of the spindle, the turret itself and this plate can be tightened together.

The underside plate has 12 pins, 2 for each position which extend downward. The central spindle extends below these pins and carries a bevel gear. There is a shaft from the back where the limit stop screws are located. The shaft carries another bevel gear to mesh with the one on the spindle shaft.

After retracting the turret, there is a springloaded arm pivited on the fixed base, which is the part clamped to the bed that the carriage moves back and forth on. As the underside plate with the pins moves back, the nose of this arm contacts one of the pairs of pins.

At the same time, there is another arm like a seesaw. One end has a tapered plunger which extends up through the carriage and into a mating hole in the turret to lock it in position. As the carriage moves backward, the opposite end of this seesaw arm contacts an inclined fixed surface of the base. This tilts the rear of the arm up to retract the tapered pin and unlock the turret.

The other arm contacting a pin on the plate under the turret actually stops it, and forces the turret to rotate. The 2nd pin of the pair rotates also so as to push this arm out of the way, as the turret is positioned. In the meantime the seesaw arm has over-ridden the angled surface and drops down under some healthy spring pressure. This allows the tapered pin to raise and lock the turret into it's next position.

While the turret is rotating, the bevel gears rotate the shaft carrying the limit stop screws, so the next one is brought into line with the stationary stop. Each may be independently adjusted to stop the turret at some distance in it's travel.

In the case of my particular unit (Logan Engineering part number LA-70) the carriage travel is 8".


02-19-2005, 09:18 AM
Thanks! so far, so good.....The turret in question is the manual type. but any thing that awnsers a question is helpful, I found a pretty neat site last nite too.