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Bob La Londe[_7_] Bob La Londe[_7_] is offline
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Default Cutting Off Those Darn Dovetails

I've acquired some cast iron bits of a medium size bed mill. The base,
column, and table. Since they are heavy and cast iron I was thinking of
lopping off the dovetails and mounting linear rails on the remaining flats.
The head, and saddle are not present so just throwing it back together is
not an option.

All the pieces are a little big to throw on my Hurco mill table. It can be
done, but its a chore requiring the removal of my vises and my enclosure I
suspect. Probably also have to use my cherry picker to place them on the
table. I could do it, but its not really necessary if I can figure out a
simple way to just whack those dovetails off. The flats that would remain
aren't perfect, but with the use of my granite square and some shim stock I
bet I could mount linear rails pretty darned straight and flat.

I considered laying a piece of metal sheet on the flats and using a Sawzall.
A portable bandsaw a buddy has doesn't have enough throat to do the job. If
I had a big vertical metal cutting bandsaw I might mount the pieces on a
large right angle plate and use that, but such a saw is very far in my
future. Of course there is the hammer method, but cast iron doesn't always
break the way you want. LOL. I don't think I want to use an OA torch for a
couple reasons. Fear of explosions is one since these are used pieces, and
of course warping is another. Also I never cut cast iron with a torch. Not
sure how it would go.

Of course somebody might suggest trying to find a match head and saddle, but
I really want to go with linear rails. In fact I already have them.
Accumulated as new overstock from various sources. Several sets of NSK, a
couple THK and even some HiWin. Bearings and rails. I've got three small
CNC mills that do a pretty good job for high speed milling aluminum, but I
really need a bigger machine, and I don't want to mount a companion or worse
completely convert the Hurco to high speed. Its fine the way it is for
heavy milling. Two of my small machines have all linear rail axis. The
third is dovetail constructed, and its ok, but the other two are better.

I figured by using these cast iron pieces I already have an easily trammable
column and base. And it should be heavy enough for the light high speed
milling I want to do with it. It will be heavier than my smaller machines
for certain. I just need to remove those pesky dovetails so the bearings
have room to go on. Then figure out how to build my saddle. The head will
be pretty much dead easy... after I get those stupid dovetails out of the
way.

I am hoping for some ideas I hadn't thought of, and I just can't wait for
the tangents some folks will go off on. LOL.