An Improved Tail Stock Ram for the Craftsman 109
The taper in the original ram on my 109 is pretty gouged up, and I also
don't have an adapter to use a
drill chuck in the ram. They are tiny #0 MT
jobs, and I'd rather just have a solid
ram that is tapered and threaded
on the end for chucks and turning between centers.
This tail stock ram is similar to the one Taig uses on their lathes,
and one I'm
used to since I have one of their machines too.
All the steps are simple turning jobs.
First step is to drill center holes in the ends of a piece of stock so
a center can be
used for accurate turning of a long work piece. I
started out with a 7" long piece
of 3/4" dia 12L14. I did this step in
the Taig lathe, since I have no way of
mounting a drill chuck in the
Craftsman (yet). The center hole could also be
drilled in a drill press after using a center finding square to find
center of the piece.
Then the piece is moved to the 109 and the long end of the ram is
There will be a chuck register on the ram, and the end
register is 3 1/2" long, finished length. This portion of
the ram is turned down
to .500 diameter.
Once the long end is finished, the piece is flipped end for end and
dialed in. Then the
short end can be turned down. I left the register
ring at .2" thick, and the portion to
be threaded at 1 1/2" long at
this point. It will be shortened later when the taper is cut.
Once the diameter of the short end is finished, it's threaded for
1/2-20, (or for what
ever thread you would like, depending on the drill
chuck you use).
After threading to nearly the complete depth, a die is run over the
threads to finish them off.
They could be threaded just using the lead
screw to cut them, but running the die over them
just before final cut
depth is reached makes a nice finish on the threads.
The last step is to cut the taper and cut off the waste at the end of
the shaft. I started
the large end of the taper at 3/4" from the register face and turned it
to get down to what is seen
in this picture. The last bit
is cut off with a hack saw. You probably don't want to cut
it to the
completed length while it's got pressure from the tail stock center
against it. If
you do, when you get to the last few thous that are
holding the piece together, it will probably
separate and the part will
ride up over the cutting edge of the tool, spoiling the job.
The taper was finished after backing off the tail stock and took many
light cuts to get it
down to finished length. It's hanging out of the
head stock chuck nearly four inches, so a
light touch is needed prevent
chatter. Lock any gibs not in use.
The correct overall length was determined by threading the drill chuck
onto the tapered end.
When the drill chuck seated down nicely on the
register, it was done. The drill chuck I'm
going to use has a small hole completely through
its' body, and that allows the tapered end
a place to protrude into it
a bit while still leaving plenty of threads to attach the chuck.
The chuck I'm using also has a two thread rebate just inside the hole
in the back of the
chuck to allow it to seat. If you use a chuck without a rebate,
you will need to cut down
the last couple of threads next to the register to allow the chuck to
The next thing is to drill and tap the long end for a left
hand thread. I chose
1/4-20 LH since that's what I had handy. The
thread of the original piece was 5/16-24,
which is not very good for
calculating ram travel if you're trying to do it in your head. At
point I'll add a mic dial to the end of the ram screw, and it will be
easy to determine
drilling depths, since the 20 pitch of the new screw
gives .050" per turn.
The end of the ram screw is made of a built up piece, one end of which
will thread into
the ram, and the other end will take the hand crank on
the end of the tail stock. A small
stub is turned to a similar shape
and length of the original, then flipped in the chuck and
tapped for 1/4-20 LH. Dimensions of the piece are as follows;
Small end, .312" dia for a length of .875".
Large end, .440" dia for a length of .250".
Tap 1/4-20 LH 3/4" deep in large end.
This is the finished stub, and a piece of 1/4-20 LH threaded rod has
been screwed in and pinned.
The pin goes in the small hole, which can be at any convenient location
in the stub where it will go
through the threaded rod inside the stub. The
larger hole is for the pin that holds the crank to the
ram, screw, and the little stub must be assembled and inserted into the
to find the location of the larger hole. Once it's in the
tail stock, the handle is slipped over the end
and a transfer punch
used to mark the hole. If you have the original pin, it's
it's diameter about mid point and choose a drill bit of that diameter
for the hole and the taper pin
should work as it's intended when put to use.
The last step is to mill the slot in the ram. For this
it's a handy 1/8" wide
and .062 deep. Make it about three inches long and it will
Clean it up and it's ready to go.
I just happened to have a brand new Rohm chuck in 1/2-20 mount that was
needing to be used.
Until I got the 109 lathe, I had nothing to use it with. Now it
has a home.
The new ram sticks out of the tail stock about 1/2" farther than the
which is how I wanted it. It gives just that little bit of extra
length for holding a work
piece that is being turned between centers.
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Copyright Dean Williams