Decided I have tripped over the old mill for the last time.
So after months of sitting around in pieces I started cleaning and cleaning and
cleaning… and more cleaning. The old swarf tray had been patched and welded and
bumped and bent so much that it looked a little tired. It was also the one
thing that looked a little out of place given all the nice round curves on this
machine. So I welded up a new one and used the old to transfer all the holes I
planned to re-use. The base also had a section used as a sump for flood coolant
and as I don’t use full flood coolant in the home workshop decided to leave out
the drain holes. This also reduced the machines footprint by a lot.
After that there was a lot more cleaning and taking
everything apart for cleaning. Stripping paint and painting and slowly
reassembling. Cleaning the spindle revealed that the original was a little
battered and worn and bearings needed replacement. As luck would have it I
found a spare spindle on a local trade site which I bought some time ago.
Sourced new spindle bearings. Installed new oilers. Replaced some thrust
bearings and straightened the knee screw. Welded up some castings. Ordered new
v-belts. Rewired a new single phase motor with a magnetic contactor switch and
finally all up and running
Here is a photo before fitting the motor:
With the gib adjusted in the centre the table binds a little
with it reaching the end of travel to the right. That was expected given most
work is done on the right hand side of the table feeding to the right. I will
need to source a surface plate, long enough straight edge and some marking
fluid so I can scrape it in.
One thing I have not addressed is the table feed mechanism.
This mill was heavily modified to use a sprocket chain to power the feed
gearbox. Some parts were since lost or broken and what was there was horribly
cobbled up. One sprocket was crudely welded to the end of a drive shaft which I
ended parting off on the lathe. The drive worm that feeds the worm gear on the
leadscrew is missing along with part of the telescoping drive shaft and the
bracket allowing for it to be disengaged. Research revealed the specifications
for a replacement worm though the remaining missing parts complicate the
rebuild. At this point the machine is not original and later models replaced
this mechanism with a servo powered solution allowing ease of change in
direction and finer speed control. I am tempted to give the table feed an
independent drive motor. This allows the feed to be disengaged and the feed
motor turned off when not needed, reducing wear. However it requires most
missing parts to be built.
Alternative is a more compact stepper or servo driven
solution fitted directly to the table with a basic control panel off the side
of the machine. This may end up being more elegant without detracting from the
machines appearance. One benefit of the original setup was that it was driven
off the spindle making it in tune with the spindle speed. That means feed would
adjust with the spindle allowing for 3 basic adjustments on that speed. An
independent drive mechanism would not offer that without adding some feedback
from the spindle. Which would mean a little guesswork to get the feed ration
dialled in. However this can be achieved by adding a sensor to the spindle and
using a stepper driver to control step speed in relation to spindle speed. This
all warrants a little thinking. In the meantime the machine can be operated
manually.
No comments:
Post a Comment