Projects 5

Lathe Attachment

I've seen 4th Axis attachments for the X2 around, usually a modified rotary table. This
attachment will have 4th Axis abilities too, but I also want to use it as a lathe.
Since I'm in the process of making big changes to my Harbor Freight Mini-Lathe,
I have some extra parts lying around. I put them to use here. The base is a 3x22x5/8
ground steel plate. I made the headstock from aluminum to save some weight. The
original cast iron headstock weighs 8 lbs. The aluminum weighs 3.5 lbs. I used the original
lathe spindle and bearings, DC motor, control panel(modified) and toolpost.
I made an aluminum mount for the tooplost that will bolt onto the X2 spindle bracket from
an earlier project. The tailstock will an have M-2 taper and about 2 in. travel.
I tested the RPM and get 550 - 3100 with the current pulleys.
I have to order the 4th Axis components next, stepper and controller.
I plan to use Mach 3 Turn for post processing and Bob Adams' Cad2Lathe for creating
the toolpaths.

Click Image for larger view.

X2 lathe Headstock

X2 lathe spindle

X2 lathe progress 1

X2 lathe progress 2

X2 lathe progress 3

X2 lathe progress 4

X2 lathe progress 5

X2 lathe progress 6

X2 lathe progress 7 control panel 1

X2 lathe progress 8 control panel 2

X2 lathe progress 9 control panel 3

X2 lathe progress 10 control panel 4

X2 lathe progress 11 toolpost mount 1

X2 lathe progress 12 toolpost mount 2

X2 lathe progress 13 tailstock

X2 lathe progress 14

X2 lathe progress 15

X2 lathe progress 16

April 29, 2007

It Works!
The first tests of the lathe went well. I had to configure Mach 3 Turn to control the motors and Axis'
opposite of normal. The Z Axis on the Mill is the X Axis for turning and vise versa. Then I remapped
the keyboard keys and my Control Panel to jog the motors correctly. Made some test runs using
the wizards for Radius,Chamfer and Fillets. Now on to something bigger and more complex using
Cad2Lathe. Still need to make a new timing pulley for the motor. It doesn't have the XL pitch I need.
Must be metric, it's close but not quite right. I think I'll use my thermoformable plastic sheet to make
a shroud for the motor and belt.

X2 Lathe First Run 1

X2 Lathe First Run 2

X2 Lathe First Run 3

X2 Lathe First Run 4

X2 Lathe First Run 5

X2 Lathe First Run O.D. Radius

X2 Lathe First Run Chamfer

X2 Lathe First Run Chamfer Small

X2 Lathe First Run I.D. Radius

The stock torsion arm and spring limits the travel of the Z Axis and doesn't provide even support
of the head assembly. The Z motor was having trouble raising it to it's maximum height because
the torsion spring gives out at the top. I've seen Air spring kits like this one at Little Machine Shop
but opted for a counter balance system instead. Total cost to me was $0.00. I found I had an old
motorcycle engine timing chain and sprocket. Thought it would look cooler than a metal cable
and pulley. The track for the weight to ride up and down on is a piece of angle iron with a steel
guide roller on the inside at the top to keep it from popping off. I made the weight (about 38lbs.)
from a bunch of old rebar pieces welded together. Couldn't bring myself to waste a lot of perfectly
good stock on it. Prettied the weight up with some Bondo and paint. I can raise and lower the head
with one finger. The Z motor should have an easier time now.

Counter Balance Guide Track

Counter Balance Sprocket

Counter Balance Sprocket and Chain

Counter Balance Weight Construction 1

Counter Balance Weight Construction 2

Counter Balance Weight Construction 3

Counter Balance Weight Construction 4

Counter Balance Weight Construction 5

Counter Balance Assembled 1

Counter Balance Assembled 2

Counter Balance Assembled 3

Counter Balance Assembled 4

I added a 495 oz/in Stepper motor to control the lathe attachment as a 4th Axis. A single Servo motor would
be more efficient than the 2 seperate motors. I already had these so that's why I used 2. The stepper is a
1.8 degree per rev, 200 steps per rev motor. To get the spindle to turn 1 degree per step, I used a 15 tooth
timing pulley on the motor and a 27 tooth on the spindle. 15 x 1.8 = 27. To set up Mach 3 with my
Xylotex driver on 1/8 microstepping, I set the Motor tuning Steps per Rev setting at 2880 (360 x 8 = 2880)
and a Velocity of 200 with an Acceleration of 50. This will give a theoretical accuracy of 1/8 degree or 7.5 min.
If I ran in full step mode, the steps per rev would be 360 (1 step = 1 degree).
I ran several tests to check the torque and accuracy.
Following are pics and videos of Milling flats, timing pulley cutting, threading and OD engraving.