AHilton wrote:
Now, ALL of this self-ejector talk is assuming something big. There have
been a couple of different self-ejector mechanisms that I've seen on lathes.
I'm mainly talking about the mechanism that fits into the female morse taper
in the tailstock. The female morse taper, as it is extended and retracted,
rides over/around the self-ejector which stays stationary deep inside. As
the tailstock-fitting device (live center in this case) is moving toward the
self-ejector, it hits it and causes the live center to stop ... but the
female taper of the tailstock keeps going back a slight bit depending on how
long the live centers' taper is. This process ejects the live center. Like
I said, there are a couple of other mechanisms that I've seen (albeit on
just a couple of older and fairly custom machines) so much of this talk may
not be relavent to your exact lathe. Just so there's no (or at least less)
misunderstanding in what we're talking about here.
Just to clarify, and simplify matters here--
1.) The "self-ejector" you speak of is nothing more than the end of the
tailstock's feed screw which hits the end of the morse taper shank when
the tailstock ram is retracted.
2.) If a tailstock center is hollow, and the hole is bigger than the
screw, then of course it won't eject.
3.) The extension at the end of many morse tapers is called the tang, it
fits in a slot inside the drillpress spindle to hold the shank from
rotating in the spindle.
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/
Comments inline below...
You probably have noticed, at least once, that the self-ejecting feature
is
an extension beyond the ~ 3/8 diameter portion of the #2 taper.
Well, actually, no. Some tailstock fitting devices have this extension,
which isn't part of the taper of that device, and some do not. The live
center that came with my Jet Mini doesn't have any extension, for instance,
and it ejects just fine. As long as the taper OR the taper/extension is
long enough, then it'll self-eject in a tailstock designed for it. It's the
design of the tailstock AND the length of the tailstock fitting device (just
the taper or the taper + any extension on the end of it) that determines if
a device is going to self-eject or not. If the tailstock isn't designed to
self-eject devices, then it won't no matter how long of a devices' taper or
taper/extension. So, the "self ejecting feature" is a product of the lathe
itself and not the device that fits into it. But, again and for clarity
(not to mention repetition), the tailstock fitting devices' taper or
taper/extension MUST be long enough to hit up against that tailstock
feature.
"Now, read carefully..."
Ohhhh, I do try to and ask actual questions (that I, amazingly, would like
answers to) when I don't feel like I have understood what was being said.
Otherwise, misunderstandings and personal attacks (see below) can ensue.
Now, read carefully - with some centers you can bore through the CENTER ,
not just the tailstock, gaining extra stabilization for the piece. I even
Absolutely. I'm with you here.
mentioned one of the type. This, unfortunately requires the center be
shorter to accommodate the hollow. I have already mentioned two ways to
You lost me here. Why must the center (I assume you mean the taper of the
live center) be shorter in that case? Do you mean that the taper must be
shorter so that you can crank the live center closer to the tailstock and
not be sticking out so far? If so, then why would that matter? In many
lathes, you're only talking 1/4" of an inch difference between either
ejecting the taper fitting device (in this case a live center with a boring
hole) and fully seating the tailstock to full retraction.
Or perhaps (and I think this is it) you're talking about a tailstock that
will allow 3/8" diameter boring, for example. If the taper of a center that
allows boring through it had an extra long morse taper on it, then it might
not allow a 3/8" hole to be through it. You could fit the 3/8" bit in the
tailstock but it wouldn't fit into the centers' hole. So, to overcome this,
the taper on the center is shortened up to allow that 3/8" hole through it.
Is that right? Assuming that that is what you're talking about....
So what? That's just a design mistake of the lathe manufacturer by
mismatching the boring hole of the tailstock to the size of the female morse
taper of it (having a 1/2" boring hole with a morse taper #1 for instance
g) AND the length of the morse taper before it hits the self ejecting
feature of the tailstock when it's fully retracted if that's a feature of
the lathe (to make this more relevant to this thread). If the manufacturer
gets their design right, then any tailstock device with a boring hole that
matches the tailstock boring hole (say 3/8" for both) will both fit the
female taper of the tailstock AND the tailstock fitting device will self
eject (given that the tailstock itself has that feature in the first place)
AND be able to use the full boring diameter of the tailstock and the center.
You can certainly have a center with a boring hole of, say, 1/2" fitted into
a (properly designed as per above) tailstock with a boring hole of 3/8"
where the center will be shorter to accomodate that larger diameter
through-hole. And it might not auto-eject, that's true. It's not the fault
of the tailstock. It's the fault of the person using the wrong center for
the lathe! If you're not going to use a properly matching center to your
lathe, then you can't expect everything to work out. The auto-eject feature
of the tailstock might be that failure. You're not going to be boring a
1/2" hole through the 3/8" tailstock hole even if the center accomodates it.
g
So, assuming that I deduced what you were actually talking about in the
quote from your email above correctly, your answer to my question of...
"Why would the ability to bore through the tailstock negate the self-ejector
feature of a piece of equipment (live center for example) inserted into it's
morse taper?"
would be that of length of the centers' morse taper. And considering the
statement just after the one quoted above by me....
"Or are you talking about the live center itself? I don't see where that
would be relevant either as that piece of equipment doesn't have anything to
do (except, obviously, it's length) with a "self-ejector" feature. Please
explain yourself."
Those questions of mine were directed to you as per your statement of...
"Nope. Think about it. If they're designed to be able to bore through
them, they'll lack the self-ejector."
Reading your last statement of: "used in one of the Taiwan drillpresses,
and therefore lacks the ejection tang" got me to thinking (and coming back
up here to insert this) that because you believe that a lathe tailstock
"auto-eject" feature is the same as found on some drillpresses, the live
center/Jacobs Chuck/whatever it is must be the one with the feature instead
of the tailstock, right? Perhaps this is much of the misundertanding.
So, the centers' that I have that allow boring through them won't self-eject
as per the above quote of yours? Hmmmm amazing! Let's take a quick and
easy example of a Jet Mini with the live center that came with it. It's
right in front of me and many people have one so I'll use that. I pop out
the sharp point and put the center into the tailstock taper. I then slide a
12" long, 3/8" diameter bit through the tailstock and through the center.
So far so good. BUT, will the center self-eject?
Yep. It does. Need a picture to verify? Not being mean ... just don't
want there to be any misunderstanding.
Should I try a few more lathes and centers? I have no doubt that I can
find a couple of combinations where it won't work. But, by and large for
the standard equipment lathes that I have access to, they'll work just like
the Jet Mini in my test.
So, it does appear that not all centers that are "designed to be able to
bore through them" will lack a self-ejector feature. Of course, as I
explained above, it's not the tailstock fitting device (live center or
Jacobs Chuck in this case) that has that "feature" although it must have
enough length for that tailstock feature to engage it..
overcome the (pun intended) shortcomings of such centers in this thread.
And those were fine recommendations.
You also use the hole in the Nova to knock out the various end appliances.
There are also solid tapers, I think most I've seen are the 60 point
degree
metalworking kind, with no self ejection which respond similarly to the
extraction methods I mentioned.
Yes, I have a few of those as well. No problems self-ejecting here.
Different models and lengths and tailstock designs are the culprits. As
long as they are long enough (taper or taper/extension on it) to hit that
self eject feature of the tailstock then it'll work.
"The chuck which was the subject of this thread - not Andy's offended sense
of importance -"
Yet more trolling by George. *sigh* My only sense of importance comes
internally from helping people and trying to give them the best information
possible whether it's from me or directing them to another resource. NOT
from just trolling newsgroups looking for a fight or lobbing personal
attacks and cowering away from real questions. If a person can provide
different opinions, evidence or experience then I am all for it. Just don't
expect to not get called on it. I am not easily offended and you've not
even come close. I've been through 18 years of Usenet, FIDOnet, Craig-soft,
GlassRoomnet, and other online forum trolls that were far far worse than
you. It still saddens me, though, that such things and people still exist.
I have nothing to prove and everything of myself to offer in what limited
areas of expertise that I have fought to learn. I have much to learn in
many many fields of study, not the least of which is woodturning. As much
as I wish the online forums to educate and inform me, I want even more for
those that are just starting out to have accurate and helpful information to
help them.
"was probably designed to be used in one of the Taiwan drillpresses, and
therefore lacks the ejection tang."
Perhaps this is where you are erroneously extrapolating your views from?
The ejection from most drillpresses is far different than from a
"self-ejection" feature on a tailstock. No need for that "tang" on the end
of some Jacobs Chuck morse tapers on a wood lathe tailstock. In fact, I'm
going to go cut the one on one of mine off because it's not needed on the
lathes I work on. It just makes the whole thing too big.
- Andrew
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----