"Steve Lusardi" wrote in message
...
Bob,
I assume you bought a used Chinese Mill/Drill. They normally have at MT3
Quill taper or some of the newer ones have an R8 spindle. I assume you
have the MT3 variety. In Europe the tool for these machines use am M10
thread. In the US those tools use a 3/8-16 UNC thread. The purpose of the
drawbar is to prevent any helix in the cutter from pulling the tool holder
out of the quill. I too had to make a draw bar. It is no problem to do. I
used a 3/8 rod. threaded one end and pinned a piece of 3/4 hex stock
drilled for the rod on the other end. Be sure to use two pins, not just
one. Tighten lightly or you will shear the pins. It just needs to be snug.
those mill drills are incredibly handy. I wouldn't be without one, but
like everything else from China, there are good ones and bad ones.
Steve

Thanks Steve,

Its actually an MT2. I got an MT2 - ER25 collet chuck for it. The draw bar
that came with the machine does not fit my collet chuck so I assumed it was
metric. All the other screws on my other Chinese tools were metric. I
guess I better go double check my collet chuck before I make a draw bar for
it that doesn't fit. LOL.

I don't understand the hex and pins bit. I figured I would just take a
piece of 1/4 rod and thread both ends. Then thread a 1/4 x 3/8 bushing on
one end, and thread a hand knob on the other end. Use red Loctite and a
butted tight shoulder on the bushing to keep it from coming off. The mill
does not have a motor reversing circuit.








"Bob La Londe" wrote in message
...
I need to make a draw bar for a garage sale piece of equipment I picked up
cheap recently. Its got a drill chuck and a metric draw bar, but it won't
work for the collet holder I want to use instead of the chuck. The collet
holder has the right taper, but uses a 3/8 draw bar. There is only about
1/4 or maybe 5/16 passage through the spindle for the draw bar.

I figured to get a piece of rod, thread both ends with some standard
threads, and make a theaded bushing to loctite onto one end to go in the
collet chuck. Then make a knob to go on the other end to make it easy to
loosen if I ever want to take the collet chuck out. Something easy to hit
with a hammer instead of slipping of and smacking a pulley.

(The draw bar holding the drill chuck taper was similarly configured
except metric and just had a nut.)

I can't think of any reason to get overly obsessive compulsive over it,
but I thought I'ld ask you guys if there was any reason I needed to go
ape over balancing it or getting my bushing highly accurately concentric?
This machine spindle is relatively low speed. Top speed is 3840, but I
don't see me using it at that speed very often. I just plan to use it
for the occassional manual milling operation that I can do faster by hand
than to write a snip of code for one of the CNC machines, or for when I
have a project going on the machines, and have something else I want to
try.

With it basically going through the axis of rotation it would take a
pretty significant imbalance I am thinking to cause any vibration. That
and it doesn't have anything holding it EXACTLY centered at the top end
anyway. I suppose I could make the knob with a slight taper to do that if
I wanted to, but I think I would rather have a flat washer in between to
protect the surfaces. Speaking of washers, Since the taper is actually
holding the chuck. Any reason to need a spring washer under the knob?