E. For those who would like even more head room between cutter and cross slide I
am confident that another 50 mm would have negligible effect on the head's capacity
to make a cut. How I wish I had not cut my original columns down!
F. Make the spindle mount thicker, say 12 mm. The extra thickness would then require
an equal reduction in the length of the spacers D6.
As indicated above there is a difference between feeding the workpiece along the
length of the bed and feeding it across. In the latter the cutting forces are attempting
to twist the spindle mount and there is more evidence of vibration, even though the
system still performs well.
I suppose it was my experience as an electrical drive systems engineer that made
me question what could be done to dampen out the vibration. Greater mass at the spindle
end of the spindle mount seemed likely to improve the situation. To achieve this,
I took a 250 mm long piece of 32 mm square steel and clamped this vertically to the
end of the spindle mount, about 125 mm above and below. As expected, the vibrations
were noticeably reduced. However, in terms of cutting efficiency there seem to be
little improvement. I am not suggesting that this is an acceptable modification but
just an interesting experiment with the laws of physics in mind.
Having made these suggestions please do not read into them that the milling head
is inadequate as drawn. As will be seen in my pages regarding the stationary steam
engine it is capable of some very interesting projects. In comparison with using
a vertical slide it is a little less capable in terms of metal removal, but its ease
of use due to the horizontal worktable makes it win hands down. The larger worktable
surface and increased lengths of traverse are also major advantages.
I have left to last the question of guarding the belts against accidental contact
with them whilst they are running. For example, if whilst running you bend down to
take a closer look at the workpiece, it would be easy for your hair, at least for
some, to become caught up between belt and pulley. I feel therefor that a guard at
this point is absolutely essential.
Guarding the belt at the rear of the column may not be quite so important but still
preferable. This particularly if you have a lathe with a clutch that is operated
close to the belt, such as a Myford series seven.