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Jacobs Chuck on Jet Mini Lathe

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.

Comments inline below...

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.

Absolutely. I'm with you here.

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 ) 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.

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..

And those were fine recommendations.

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

Reply to
AHilton
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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

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Coulee Region Woodturners AAW chapter
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Ken Grunke SW Wisconsin

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Coulee Region Woodturners AAW chapter
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Reply to
Ken Grunke

Well, sort-of The way I read your description of 1 and 2 below is yet another version of a self-ejector mechanism. Your description suggests that the only part of the tailstock "screw", as you call it, that hits the end of the live center (I'll just use this example from now on to make it easier) is at the center (of whatever diameter) of it's end shank. Is that a correct reading of your comments below? If you have a hole in the bored live center that's bigger than that mechanism, then I can certainly see the live center passing right over it. This, of course, doesn't mean that every live center that has a hole bored through it will not self-eject as George blanketly stated.

What I'm talking about is what's most often found these days and that's where the self-ejector mechanism acts very much the same but makes contact with the outermost ring of the live center end shank. It doesn't matter what size hole is bored (within reason ... you *could* have a 1mm sliver of metal ring and it might slip past the mechanism a little but eventually the taper would catch up to it and hit the mechanism anyway ) into that live center as long as the shank is long enough to reach that self-ejector mechanism when retracting the whole thing.

The essence of it is the same (retracting causes what's inside the morse taper to stop retracting with the rest of the female morse taper) but it's the details that matter most and affects what will and what will not self-eject. Can you provide a picture or drawing of the exact mechanism? I'll do the same of at least one version of self-ejector tailstock mechanism that I've worked with on wood lathes and post it on abpw. Then we can compare.

- Andrew

Reply to
AHilton
****** the Backcutter, and """""'"' the Shearscraper (names deleted to protect the guilty) in the 9th inning of a tied Morse taper game at rcw stadium.

*****: What ejects the tail center?

"""""": No: What's screwed on the ram

*****: No! Which is screwed on the ram, What is centered into the end of the blank.

""""": Can't be, Which is in the Barrel.

*****: I told you, What goes into the barrel!

""""": You are plumb out of the chuck, The ram screws on the barrel!

*****: Nah, you have too much runout, rams screw old U gouges.

""""": No V's on that old bowl gouge eh".

*****: The bevel you say, a Ram actually prefers a female taper.

""""": I just hope they take precautions to self eject.

*****: A dignified turning ng is listening to us and I'm not gonna go there.

""""": Well, what does the hand wheel do?

*****: Now really, """"". You should be ashamed. Next you'll bring up the tailstock.

"""""": You know that dead center has a hollow ring, you dull spur.

*****: No worse than a short tang!

(the game was tied til the 17th when the umpire found that *****'s spindle had been plugged with carnauba and """"'s bowl blank had been soaked in LDD. Both turners were ejected along with the revolving center. )

Your correspondent was later arrested for sniffing acetone by a ng moderator. A very sad end to a civil thread with so much promise early on. :( Arch

Fortiter,

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Reply to
Arch

Tsk... A good one but nothing about CA glue?

Reply to
Mark Hopkins

I just posted a picture on ABPW of one type (the most common found on todays' lathes) of tailstock design with the self-ejection feature. I'm just using the common bored-through live center design in these pictures. If needed, I can easily put a Jacobs' Chuck in there or anything else to show what's going on. Also, I can do a drawing of some other tailstock designs (that have the self-eject feature of course) to compare and contrast.

The more I think about George's statement of "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." the more he's describing a completely different tailstock design. And this statement of his ... "Nope. Think about it. If they're designed to be able to bore through them, they'll lack the self-ejector" really suggests that he's just thinking of that one kind of tailstock self-ejection feature design. He's expecting that "tang" to be there on the end of the male morse taper to hit the center-hitting device in the tailstock to knock it out. In my mind at least, he's confusing that tang as the self-ejection feature in wood lathes.

Hopefully, George will respond in order to clarify what he said and answer my questions. I hate to assume but without a response, I am forced to until then.

Anyway, if anybody has a problem with viewing or understanding the picture, let me know. Also, like I said above, if there's some clarification needed on other tailstock designs and/or different centers (jacobs chuck, etc.) let me know and I'll whip up some pictures.

I have had to get some woodturning video editing done this weekend and earlier this week so I was delayed in getting the picture done and posted. Sorry about that.

- Andrew

Reply to
AHilton

I'm describing the taper. Look at the overall length of the same, on the Nova I mentioned, and you'll see that the entire is not long enough to butt against the end as you retract the quill in a lot of tailstocks. Seems like it needs about an extra half inch in length beyond the point at which it is

3/8 or so in diameter.

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still haven't the foggiest notion of what you're trying to prove. I'mmerely noting that shorter tapers, including those which come with Chaiwanbenchtop drill press chucks, like we have at school, might be the reasonthey didn't self eject for the original poster, not his lathe. The metallathes at school also have short live centers which require help. I also gave two easy ways to eject such types.

Reply to
George

Yep, I'll grant (for the upteenth time in this thread) you that some tailstocks and devices designed to fit into those tapers just don't go together or are simply poorly designed in the first place. Some of those devices' tapers just aren't long enough to hit the self-ejector in the tailstock. That's why I mentioned to Mike originally.... "That must be a pretty short live center taper! Good point though. How long is that taper you're talking about?".

I'm trying to get the point of the self-ejector mechanism discussion as clear as possible to those turners out there that might be having problems buying and using their centers and tailstocks. Poor and misleading information is not good. I'd hate for someone to read your "Nope. Think about it. If they're designed to be able to bore through them, they'll lack the self-ejector." statement and think that if they buy a live center with a boring hole in it, that their tailstock self-ejector feature will be negated in all cases. I was confused in what you were actually trying to say and wanted clarification so that those that might still be following this thread could have the facts and opinions of those of us posting in it clear. They can make up their own minds, then, as to what they want to buy or try in order to fix their problems.

When you came up with those statements of having the self-ejector mechanism as part of the live center, for example, and of having a bore hole in any live center, again as an example, will negate the self-ejector feature, had me wondering what you were talking about. You still haven't directly referrenced your statements on those points, by the way. Do you still stand behind them? If so, are you willing to clarify those specific statements? Now, you're saying that it's the shorter tapers that might be the problem. Which, of course, is what was being talked about before you started in with these other statements.

I'm always willing and interested in learning and maybe you've run across why those statements are true? Please help us to understand those statements of yours.

Yep. And as I've said before to you in this thread, they are good ways. They're also useful on some lathes' headstocks when a taper fitting device is stuck in there too.

- Andrew

Reply to
AHilton

I have dignified your boorish "challenges" and accusations more than enough through my previous answer.

Those who purchase chucks for their tailstock should be aware that if they don't eject, it is not necessarily the fault of the lathe, nor is it reason to panic. The length of the taper may not be sufficient, for which there are two easy workarounds.

Reply to
George

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