The two articles are based on enhancements to our machines.
The first is my ball turner and second is Johns Mill/Drill automated table
control.
I set the center of the ball with the triangle 'full over' - pointing to the center. I set the offset of the boring head against the height of the rod - for the size of the ball. This requires multiple movement of the cross slide and saddle. Simply stated, I'm setting up the two 90 degree final points on the side and over the top.
I then adjust the milling height for nominal depth of cut - trim and then lower the milling jaw for the next cut. During setup - I noted the setting of the mill for the intended final cut.
The block of iron that holds the boring head was sawed, milled, edged
and bored. It fits into the jaws shy of the top as to allow a length
of steel to take the pressure from the two mounting screws. It can be replaced,
the iron takes more time. I bought a 1" mandrel that threaded into
the head, made two bronze pressure washers Drilled and tapped the mandrel
- for the main shaft that the handle mounts upon. I chose the handle
as compared to a bat handle simply so I could use two hands in the process
of feeding the cutter in an arc.
Martin Eastburn oldtree@pacbell.net
I think there's a place for a mill-drill in every shop. Whether the
shop specializes in machine work, welding, auto repair or even woodworking
this versatile machine is an asset. It will do many more things than a
drillpress will do and most of the things a milling machine does. From
accurately locating holes to putting a flat surface on most any type of
material, a mill-drill is well worth it's price. Light Weight is one of
the best features of these machines, especially if it has to be put in
a basement shop. They are usually mounted on a roller cart and can be moved
around the shop. Although these machines are not suited for heavy duty
production work, I soon got
tired of turning the crank on milling jobs so I decided what was needed
was power feed. These are available from the machine dealers but are somewhat
pricey.
I bought a small DC motor that was equipped with a 140:1 gear reduction
from a surplus dealer for about $15.00. That seems to be the proper ratio.
You want torque rather than speed. To power the motor I used an electronic
speed control which can be obtained from most electrical equipment suppliers
for about $200.00. I made a coupling which was fastened to the output shaft
of the motor with set screws and the other end was a slip fit for the lead
screw. On the lead screw is a collar with 4 holes, one of which a pin projecting
from the
coupling goes into to transmit the power when the power feed is put
on the mill. On top of the feed motor is an arm mounted on a pivot and
is parallel with the motor shaft. The front end of the shaft has a ball
ended fitting that goes into a hole in the mill table. This keeps the power
feed from rotating. The other end of the arm is spring loaded and
if the torque on the arm exceeds a certain amount it activates a microswitch
which shuts the motor off. I hope the accompanying pictures will help make
this explanation clear.
John Taylor ENGINEMAN1@AOL.COM
As you can see, John got a new camera!
I left all of these large so it would be easier to see.
A Note on the format of this page. I left off the background and
frames for printing. I can print the background, but several of us
cannot print some of the frames. Perhaps this will make the page
easier to read at leisure. Martin