DIY Lathe Turret

[PEU]

Im trying to make a 4 or 6 position lathe turret for my small Syil C6 CNC Lathe, but I want to avoid if possible pneumatics. So I made this drawing, it looks like a fail-safe brake operated by dowel pins instead of a braking disk:


Here is how it should work: when I apply power to the electromagnet, the yellow plate, wich has dowel pins attached to it retracts and allows the stepper motor to turn the turret, once the location is reached, power is stopped and the springs moves the yellow plate towards the turret locking it again.

BUT, there is always a but I didn't research about electromagnets before doing this drawing, and when I started asking they where: EXPENSIVE and the stroke they allowed was around 1mm (like eletromagnetic clutches and brakes)

So I was about to scrap the idea when I tought, why not ask, maybe someone more experienced than me can suggest a simple way of moving the clamp plate 10mm.

Im all eyes


Pablo

[phomann]

Pneumatics is how most do it.

Have a look at; http://www.issintl-inc.com/latheturret/

Cheers,

Peter.

[PEU]

I know... thats why I asked about electromagnetics
I saw that site and also found its plans here at CNCZone.

Initially I researched about fail-safe brakes, but for a small sized one, the holding torque is around 30Nm and Im not sure if this can keep the cutting tools securely in place.

I know nothing regarding pneumatics, maybe not wanting to use pneumatics is a case of fear to the unknown, so here is my question to someone that wants to educate me:
what do I need to be able to use pneumatics in a basic turret setup?

Thanks


Pablo

[Guldberg]

You still have pneumatics, but it uses a simple cylinder

[PEU]

It comes from this page It looks like the turret posted here: http://www.cnc-projects.de/ also a very nice page.

I see it uses an inexpensive air cilinder like this one but what else does one need to assemble the pneumatics?

Thanks!


Pablo

[Guldberg]

A tube supplying air:-) Thats about it, the turret locks by springs. The cylinder only pushes to release the turret

[PEU]

But you need some kind of air interruptor? I mean how do you activate the air cilinder?

I don't quite understand how it works, so I made this file, maybe you can explain how does it work:



I see in the video this sequence:

Piston is activated, D) moves towards C) compressing the H) springs and then B) tuns the whole assembly A) using the stepper.

I dont understand how B) C) or D) are attached to A) since when the piston is activated they don't move forward.



Pablo

[Guldberg]

They are "attached" with one of these http://thumbs2.ebaystatic.com/pict/3...89364040_1.jpg that rides inside a groove in A), cant remember the english term. This way they can slide back and forth

[praetor]

I think that pic you posted, Guldberg, is called a keystock, isn't it?

[NEATman]

peu-
I've sent you a private message about some electromagnetic brakes.

Also, I'm planning on making a turrett for a lathe I'm converting, and I too don't want it to be pneumatic. My plan is to make it as simple as possible. The turret rotates in one direction to change tools, and a ratchet locks it in the other direction to take the tooling forces. I've recently picked up a great Formsprag 300 ft-lb rated clutch with built in bearings for $9! The electronics surplus store in Manchester NH, has a few left.
http://www.warnernet.com/smartcat/ht...df/FSO_HPI.pdf

You could also make your own ratchet mechanism. Simply rotate the stepper past the ratchet then drive it back into the ratchet and stall the stepper to ensure that it is locked. It won't hurt the stepper at all. Also, it dosen't matter when you loose steps, as you'll know how many steps there are between the ratchet positions.

NEATman
Keith

[PEU]

Im interested in knowing how these formsprag clutches work, and at $9 Im willing to purchase one too

Can you explain how it works? Thanks!


Pablo

[NEATman]

Pablo-
It's a toothless ratchet. It can rotate one direction, but will grip in the other direction and won't slip until you exceed 300 ft-lbs. I haven't tried it yet, but I plan to build something in the next few months. The toothless version will allow me to stop at any point and apply torque, perhaps I can squeeze more than 8 tools into the turret this way. Plus, I'm thinking that the radius of the tool will not exceed 4" (1/3rd foot) so the clutch will hold 900 lbs of tooling force before it slips.

Keith