View Full Version : Denford Starturn Turret

09-09-2013, 07:54 AM
My little Denford Starturn (slantbed) is currently running on a standard Dixon Toolpost and a tooling block.
I would like to make a manual tool carousel, operating off the slantbed with the same axis as the lathe spindle and say, eight positions. That could be simply manually clicked around on programmed tool change notifications.
Has anyone faced this design, on this, or similar small lathe.
I am preparing to design it in 3D CAD. But thought It might be interesting to seek comments if possible from anyone who has tackled it already. I do have 3D CNC milling so design complication. e.g. castellated taper locking, as in some commercial applications would not be too much of a problem.
But just wondered if there is a simpler method out there.
Pleased to do a design/make collaboration with any interested party.

09-09-2013, 06:21 PM
I'm guessing you've looked at the turrets on turret lathes?

10-09-2013, 07:40 AM
I'm guessing you've looked at the turrets on turret lathes?

Yes. I have a Myford capstan tail stock. Also fairly familiar with commercial auto types.
There are restrictions in the design process due to the physical placement on the Starturn. I am reasonably capable of designing to it. But I was interested to explore the forum for ideas.
My first designs are very complicated. I could proceed with that. However it is more than I need! So just began to simplify it and wondered if perhaps I was not the first person engaged in such a project.
My simple design uses a block with a carousel sprung loaded on and off four commercial taper dowels and bushes. But not sure if the tool forces will move off the tapers? So will probably need a "square" interface of some kind to react to them. Begin to edge back to the complicated multiple taper castellation design. I determine to find a simple solution!!!!!

10-09-2013, 08:33 AM
the original rotating turret that is often supplied with this lathe, has a sprung pawl design which drops onto a ratchet, quite easy to make and works well.
Here's a diagram of Boxfords toolchanger which uses the same method.

Boxford Spares System (http://www.boxford-software.com/spares/250240TurretCam.html)

10-09-2013, 09:18 AM
Thanks! That has solved one of my problems.

10-09-2013, 05:06 PM
i2i beat with the basic ratchet and pawl system.
Lots of the smaller CNC lathes with basic tool changers use a ratchet and pawl, with the turret driven by a stepper motor. To change position it turns the turret for a pre-programmed amount of time (I don't think the basic ones use any kind of detent/position detection), then reverses the stepper motor and relies on the motor stalling once the ratchet and pawl lock.

It's a pretty crude system, but effective. The biggest downside is you can only change tools in the one direction, and they are relatively slow to rotate. Iknow there's at least one video on youtube of a Conect lathe with a tool changer operating.

Personally, if you're going the length of designing and building your own turret, I'd design in a stepper motor/drive system. All it would take to operate is one extra stepper drive, and a little bit programming.

11-09-2013, 07:36 AM
My desire to do this manually is derived from a slow moving unit previously experienced on an Emco. I am grateful for the input and have on the current design file extended the mainshaft so that I can drive it at a later date if desired.
Just addressing tool height adjustment at the moment. Will post when completed.

11-09-2013, 08:36 AM
you can get the ratchet/pawl method quite quick with a reasonable stepper, the slow ones use a dc motor/gearbox to rotate and are pretty slow.
With a stepper you can control exactly how far the changer turns and returns to lock, and of course the speed of the change.