Stepperhead

[jackary]

Hi All
I have started this new thread now that I have found out how to do it
to avoid overlapping (Hijacking) an existing thread called "Lathe build part 2".
I apologize for any confusion caused.
Over the past few years I have been designing and building a variation
on the Metalmaster. It is made from solid cast iron blocks and
standard mild steel sections to avoid making castings. The essential
difference to the Metalmaster is that the bed remains stationary and
supported at each end and the head and tailstock can be raised or
lowered relative to the bed. A secondary vertical column is
incorporated in the integral tailstock to avoid an unsupported overarm
and tailstock. The machine uses stepper motors to drive each axis. A
separate stepper motor is dedicated to driving the headstock for indexing
the mandrel when required (Stepperhead)
A 430 watt 3 phase inverter controlled motor is mounted on the lower end of the raising column.
Using the polyvee pulleys and inverter give speed range of 15 to 3200 rpm.
The headstock can be moved up or down to change the centre height which can vary between
80 mm to a max of 220mm for large diameters and allow it to be also be used as a milling machine.
The axes can be operated either manually, power driven
by the stepper motors or CNC operated via the lap top computer. I
entered this machine in the Model Engineers Exhibition in 2008 at
Ascot UK where it was awarded a Gold Medal and The Bowyer-Lowe Trophy.
I have written an article which will be printed in the Model Engineers
Workshop soon. I have added a couple of photos under Stepperhead. I
have also added some dodgy videos on utube

http://www.youtube.com/watch?v=Yiug1F8XCME&feature=user

http://www.youtube.com/watch?v=yMxv1jU-R_A&feature=user

http://www.youtube.com/watch?v=FDNTeuojC78

http://www.youtube.com/watch?v=wNxgWhizX54

http://www.youtube.com/watch?v=DMmDCHkff0c&feature=user

http://uk.youtube.com/watch?v=sCsZN8Spbq8

http://www.flickr.com/photos/32647007@N02/sets/72157610446872607/

Regards
Alan

[Doc Nickel]

That's still amazing. Very nice work.

Doc.

[dp]

How is it realigned after raising/lowering the head and tail stocks? How do you avoid the "round post mill" curse?

The cross slide details are quite interesting, in particular, the diagonal feed screw.

[BillH]

Very nice!! When you made the tailstock, did you bore it out with the headstock in situation?

[jackary]

How is it realigned after raising/lowering the head and tail stocks? How do you avoid the "round post mill" curse?

The cross slide details are quite interesting, in particular, the diagonal feed screw.

The main column has a triangular gib strip as in the original Metalmaster (see yahoo groups "Metalmaster") The horizontal overarm has a secondary vertical column built in the tailstock. These two vertical columns and the overarm can all be locked together and add up to stiffen and align the whole assembly. The diagonal feed screw rotates a central wormwheel to move the cross slide the full cross slide length.
Regards
Alan

[jackary]

Very nice!! When you made the tailstock, did you bore it out with the headstock in situation?

The tailstock barrel is a close fit into the mandrel bore. The long tailstock barrel was inserted in the mandrel and tailstock sleeve to align the finished components, then the whole assembly was Loctited together. This was the only way I could think of to get it all aligned.
Regards
Alan

[Evan]

I have started this new thread now that I have found out how to do it
to avoid overlapping (Hijacking) an existing thread called "Lathe build part 2".
I apologize for any confusion caused.

Thank you Alan. I meant what I said when you first posted it. That is a beauty of a machine. My issues were mainly with John for reasons that go back a while. I in turn apologize to you for any upset this recent nonsense may have caused you.

What size of steppers have you used, particularly on the spindle? Also, what drivers?

[jackary]

Thank you Alan. I meant what I said when you first posted it. That is a beauty of a machine. My issues were mainly with John for reasons that go back a while. I in turn apologize to you for any upset this recent nonsense may have caused you.

What size of steppers have you used, particularly on the spindle? Also, what drivers?

Evan
No apology needed. I have used Nema size 23 stepper motors, 56mm long on the cross slide and headstock and 76mm long on the saddle drive the motors , drivers and power supply are all from Motion Control. They seem to supply adequate power. I have set them so that they will stall if the axes are overloaded.
They are all geared down about 1:10 by worm drives so they are not as fast as production CNC machines but fast enough for me.
Regards
Alan

[Evan]

Sorry, but by size I meant the holding torque rating.

[Rigger]

Alan,
That machine is amazing, in the time I have been on this forum I have never seen anything that looks so purposeful.
Building a machine is one thing but building one to look as well designed as this is another.

Short of Steve's CNC lathe which is also a work of art this has to be the best home build presented here.

I struggle to make bike fittings look as they should, that you won a Gold medal and a trophy speaks for itself.

After the initial misunderstanding I hope you stay around to put a fresh perspective on posts and views.
Contrary to what Evan thinks others are willing to accept alternative views.

Rigger.

[jackary]

Sorry, but by size I meant the holding torque rating.

FL57STH56-3008B Holding torque 1.24 NM

FL57STH76-2808B Holding torque1.85NM

MSD542 Microstepping Driver (4.2A Peak)

All by Motion Controls

Regards
Alan

[Peter.]

Superb piece of engineering Alan hopefully one day I'll get to see it in the flesh too.

[lazlo]

FL57STH56-3008B Holding torque 1.24 NM

FL57STH76-2808B Holding torque1.85NM

For the cretins like myself, who think in Imperial units :

1.24 Newton Meters = 176 ounce/inches
1.85 Newton Meters = 262 ounce/inches

Alan, that is a simply gorgeous build! I realized it was inspired by the Metalmaster multimachine when I saw the distinctive horizontal overarm. Does the headstock elevate like a horizontal boring mill?

For those who aren't familiar with the quirky but brilliant "Metalmaster" designed by W. D. Urwick, Tony's got a great page on it here:

http://www.lathes.co.uk/metalmaster/

There's also a Yahoo group of folks dedicated to making modern variants.

How do you avoid the "round post mill" curse?

Urwick received a patent in 1950 for the Triangular Gib Key -- there's a triangular notch milled into the round column, and a triangular gib key wedges into a positive lock:

http://www.lathes.co.uk/metalmaster/page4.html

[jackary]

Does the headstock elevate like a horizontal boring mill?

Yes the head ,overarm and tailstock can move up or down relative to the bed
Regards
Alan

[Spin Doctor]

Very nice piece of work Alan. It certainly looks far more useful than a 3-in-1 combination machine. I wonder just how rigid is the bar bed for the tailstock and what size are the bars. By the way the Flickr link isn't working.