On Wed, 28 Mar 2018 09:41:43 -0700, Bob La Londe
wrote:
On 3/28/2018 7:53 AM, Jim Wilkins wrote:
"Larry Jaques" wrote in message
...
On Tue, 27 Mar 2018 12:05:09 -0700, Bob La Londe
wrote:
A buddy of mine called me yesterday saying he was having some
troubles
seating tools in his new bench top mill. I stopped by to see if I
could
help and I found there appeared to be only a thin ring of contact
surface very near the large end of the taper on every tool and
collet.
So little that tools tightened down HARD just fell right out when
the
draw bar was loosened. Its supposed to be an R8 spindle and came
with a
few R8 tools.
I'd check how and where the collet was pulling tight. Perhaps the
drawbar threads are too short, or a washer is missing?
-jsw
I actually lengthened the threads for my buddy on both of the draw bars
he had. I think they might have been right at the edge of hitting the
shoulder, but the problem remained that tightening up the tool in the
spindle (we tried both hard tools and collets) was difficult and they
only engaged on a very narrow ring near the large end of the taper. I
checked one tool by marking it up with a sharpie marker and tightening
it, but if you looked at the light scuffs on the various tools they were
all the same.
When loosening the draw bar I am used to having to give the draw bar a
light tap with a mallet to release the tool. On his machine if you
loosening the draw bar 1/2-3/4 of a turn it released the tool with no
tap. It just fell out. That was after putting the muscle on wrench
against spline wrench to tighten it. I didn't kill it, but I tightened
a 1/2 turn further than I normally would have thought was good enough.
Yeah, something is hinky there alright.
There was another issue I couldn't understand. With both of his
drawbars there was a little binding as you tightened them up. Enough to
cause that annoying wrench/no-wrench affect I hate. I cleaned the
threads on the draw bars (obviously since I lengthened them), and
cleaned the threads in the tools. Out of the machine they spun together
freely. It just made the whole experience of tightening a tool up in
the spindle that much more maddening.
That sounds like one piece going sideways. Was the spindle portion of
the taper burred or rusted, maybe? Pulled the spindle and look for a
sledge hammer mark in the middle?
In order to get a tool holder or collet to tighten up (his dog pin was
removed) I had to hold the tool up into the spindle with enough force
that my fingers were almost trembling. On other R8 machines I've never
had to do that. Just holding the tool in place normally was more than
enough.
The importer (normally very good which is why I have not named them) has
been doing the "find one thing in your description of the problem and
picking that apart" thing rather than trying to actually address the
problem. Either that or saying he doesn't understand the problem. The
day before yesterday we shot a video of tightening and loosening some
tools and showed the minimal contact ring. I don't know if my buddy has
sent the video to them or not yet. Its a brand new machine.
It was sold and marketed and documented as an R8 machine.
Maybe an R7 got through.
Just for the heck of it I took an empty collet, held it in place with a
block of wood and smacked the block of wood with a mallet. Several
times and as hard as I could swinging upward. Several attempts produced
the same result. The collet just fell out. THAT surprised me. Even
with a self releasing design that collet should have stuck.
My buddy had done most of this already. (Except lengthening the threads
on the draw bars.) I think he just wanted me to try it out and see if I
came to the same conclusions he had.
You certainly did.
--
"I have noticed even people who claim everything is predestined
and that we can do nothing to change it look before they cross
the road." --Steven Hawking