Our shop's excello style 602 mill has a problem that I need some help
solving. We bought the machine recently and just got it hooked up
electrical-wise and started working with it. We noticed that the quill
spring was broken and when we opened up the housing the spring was
missing. We took out the hub and got another spring from excello.
When we went to install the new spring, we noticed that the 3/16"
hardened dowel pin that the end of the spring normally hooks around is
completely sheared off. The hole is not a through hole (it would go
into the quill area) but we were able to push the remains of the pin
into the back of the hole. We tried using an extractor set but the
hardened steel is hardly dented by the drill bit. There is about 5/16"
of open hole that we can insert a new pin. We milled some slots into
the cover plate to hold the spring so permanence isn't an issue. Here
are our questions:

1. Is there a drill bit that can drill this hardened pin to use an
extractor to pull it out and insert a new pin?

2. Failing removing the pin, what kind of temporary replacement would
hold the load of the very powerful spring. We only need it for a few
minutes but this an issue where personal safety could be in danger. We
were considering a roll pin or even the shaft of a 3/16" drill bit cut
to the right size.

3. Has anyone had this problem before, more the removing a hardened pin
issue rather than the quill spring issue?

Thanks in advance,
woodworker88
Los Altos High School Robotics Team
Los Altos, CA
www.lahsrobotics.org

On 31 Jan 2006 21:53:22 -0800, "woodworker88"
wrote:

Our shop's excello style 602 mill has a problem that I need some help
solving. We bought the machine recently and just got it hooked up
electrical-wise and started working with it. We noticed that the quill
spring was broken and when we opened up the housing the spring was
missing. We took out the hub and got another spring from excello.
When we went to install the new spring, we noticed that the 3/16"
hardened dowel pin that the end of the spring normally hooks around is
completely sheared off. The hole is not a through hole (it would go
into the quill area) but we were able to push the remains of the pin
into the back of the hole. We tried using an extractor set but the
hardened steel is hardly dented by the drill bit. There is about 5/16"
of open hole that we can insert a new pin. We milled some slots into
the cover plate to hold the spring so permanence isn't an issue. Here
are our questions:

1. Is there a drill bit that can drill this hardened pin to use an
extractor to pull it out and insert a new pin?

2. Failing removing the pin, what kind of temporary replacement would
hold the load of the very powerful spring. We only need it for a few
minutes but this an issue where personal safety could be in danger. We
were considering a roll pin or even the shaft of a 3/16" drill bit cut
to the right size.

3. Has anyone had this problem before, more the removing a hardened pin
issue rather than the quill spring issue?

Thanks in advance,
woodworker88
Los Altos High School Robotics Team
Los Altos, CA
www.lahsrobotics.org


If that dowel pin is in a hole ..ask yourself how it was drilled. Was
it drilled from the inside of the casting..or through from the
outside.

If it was from the outside..its probably covered up by bondo and
paint, and should be relatively easy to drive back out, and then put
in a new one. If it was drilled from the inside..simply move a few
degrees, drill and ream another hole, and install a new dowel pin

Im being sort of generic here as Im not particularly familiar with the
excello. But the Bridgeport quill spring is held by a dowel pin hole
that was drilled from the outside of the casting.

Gunner

"Deep in her heart, every moslem woman yearns to show us her tits"
John Griffin

--Not totally clear on the picture but if possible I'd grind the
sheared-off flush and drill a new hole somewhere else for a new dowel pin.

--
"Steamboat Ed" Haas : I can make damn near anything
Hacking the Trailing Edge! : ...except money, sigh.
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

Is it is kind of loose and would come out if you could get a good yank
on it? If so, you could start an arc on it with a TIG, then bury the
tungsten into the puddle. Let it cool and pull it out with your
electrode. Probably need to let it cool until the pin is the same temp
as the casting, or it will be oversize and that much more stuck.

I have used junk 1/8" carbide ball mills for drilling out broken drill
bits and taps. It ususaly takes a few. Unless the dowel pin spins I
suspect you could put a hole in it. Then you'd have a pin with a hole
in it, but I don't know if an extractor would bit into it.

Thanks for all your advice. After some fiddling I managed to get the
pin pretty far back into the hole. Apparently it hadn't been fully
inserted originally. I inserted a 3/16" roll pin, which is about 15
thou oversized. I used a pin punch to hammer it in and fill the hole.
I tried unloading the spring tension on the pin and it held, so we went
ahead and slipped off the retaining clip. With someone holding tension
on the quill handle to prevent uncoiling of the spring, we put on the
cover and reengaged the quill (it is disengaged to allow the handle to
move freely). Everything seemed to work great. The quill moves down
easily and if you let go of the handle it slowly moves back up. Now we
can start making some chips!
Thanks again
woodworker88
www.lahsrobotics.org