On Mar 11, 2:12*am, wrote:
On Thu, 10 Mar 2011 13:31:44 -0800 (PST), Jim Wilkins



wrote:
On Mar 10, 11:58 am, wolfgang wrote:
...
I do most cross drilling of round parts in the lathe with a motorized
drill spindle that fits the QCTP at lathe centre line height.

The spindle is aligned parallel to the chuck face with a 123 block and
is driven by a windshield wiper motor at 30VDC or so, developing about
1/4 HP....
Wolfgang-

Similarly I made a Dremel tool holder from an upright rectangle of
aluminum plate thicker than the compound slot.

The lower edge was stepped to fit snugly into the slot. A vertical
hole near the right edge takes the hold-down made from a carriage
bolt.

I set the compound parallel to the ways and bored a snug hole at
center height for the Dremel nose. If the hole had been a looser fit I
could have slotted the block to let the carriage bolt clamp the
Dremel. The compound feed screw runs a drill bit straight in or a
grinding wheel at the compound's angle.

My next project of that type is to adapt a laminate trimmer to the
larger lathe.

I have been looking at the similar arrangement and have not ruled it
out completely:

1) Do it on the Taig. Make a divider plate which should be relatively
simple and the spindle lock is easier to make than on the 9x20. Adapt
one of the toolholders (or make a brand new one) for the Dremel flex
shaft. The only thing that put me off that is the 1/8" or so limit of
the Dremel. In fact the whole concept started me thinking along the
lines of buying a new Taig headstock and adapting it as a dividing
head - then I could also mill etc. on the X2.

2) Do it on the 9x20. It should not be difficult to make a clamp for
the Dremel flex shaft here either. The cons are no spindle lock and
the drill size limit as above. I am not sure that I grasp the concept
of the "spacer pin". However, if I found a way to lock the spindle in
any position one could use a magnetic protractor gauge which I have
found eminently useful in other applications to set the angles.

3) Do it on the *wood lathe* - that one has not only a spindle lock
but an in-built dividing plate with 72 positions. Again the Dremel
holder should be easy to adapt to the tool rest banjo, but the above
limitations apply. Also would have to get a new chuck for the 1"-8
spindle. OTOH how easy would it be to get one of those MT2/plain
adaptors and cut *3/4"-16 thread on it and use it with the Taig
chucks?

BTW I have been looking around at the spin indexers: Somebody on
another forum posted pictures of the indexer which he adapted for ER40
collets! I thought it was a particularly smart move but could not find
a description of how he did it.

Many options could result in paralysis by analysis :-) However, as the
job is not imminent, it is good to explore them.

Michael Koblic,
Campbell River, BC



Mike,

Today there are more options than there were when I built my tooling.
I found the dremel tool speed too high for effective drilling of
steel.

The spacer pin (or bar) is a length of rod that I place between the
bottom edge of the horizontal chuck jaw and the flat of the lathe
bed; this makes for quick-and-dirty indexing. By careful choice of
this spacer you can get 6 divisions quickly depending on your lathe's
design. Certainly 3 div's are easy and a cross hole is a cinch.

Cross drilling does not impose a rotational force on the work piece
and I found that clamping of the lathe spindle, for this operation, is
not necessary. If you are concerned simply hold the spindle, by hand,
against the spacer pin mentioned above.

My drilling spindle runs on 2 ball bearings of 3/8" bore and mounts a
threaded 1/4" capacity drill chuck. It is driven by a windshield
wiper motor through a 3-1 reduction timing belt.

Built into the lathe bench is a variable AC and DC power supply
controlled by a Variac auto transformer. This is a permanent set-up
as I use this for other work and experiments. The variable AC is fed
into a step-down transformer, rectified and smoothed with big
capacitors. This transformer can handle up to 40 Amps or so and can
supply up to 30 volts DC. Most wiper motors are very robust and
reliable and can handle this easily. In the last decade or so really
powerful radiator fan motors have become available and I would use one
of these if I were to do this again.

Once you have this device you will be amazed how easily you can carry
out what is otherwise a tedious operation.

For a small lathe a flexible shaft driven hand piece held in a
dedicated QCTH would be the way to go. Take the time to make a nice
tool that will provide use and enjoyment for a life time.

As a guide to the tool holder simply look at the commercial
toolholders that carry a fixed drill chuck. Extend the back side of
this holder by some measure and drill & bore it to take 2 ball
bearings or the hand piece, where the drill chuck is mounted.

By planning ahead this tool can be used for cross and axial offset
drilling ie holes in a bolt circle. For this though a lathe spindle
clamp is advisable.

Wolfgang