# Computer fried and 60 deg. Live Center



## turff49 (Apr 12, 2006)

Man, there are a lot of postings generated here. My hard drive decided to fry itself Friday so I've been sorta out of touch. Just checking emails when I could snag the wifes computer(I'm using it now). But trying to catch up on all the postings here is almost impossible. That's probably a good thing. Anyway, should get the computer back tomorrow and hope to post pics of some of the pens I turned over the weekend. I'd like to thank whoever told me to give "The Little Machine Shop" a try on a 60 degree live center. That took care of the Out Of Round problem I was having. Thanks Again, Brian


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## wudwrkr (Apr 12, 2006)

Brian,
I know what you mean about emails.  It's tough to keep up sometimes.  

I was one of the few who mentioned the live center.  I'm glad it worked for you, it certainly made a difference for me.


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## Ron Mc (Apr 13, 2006)

Brian,
I love my The Little Machine Shop 60 degree live centers. Great price as well.


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## Johnathan (Apr 16, 2006)

Using those 60 degree live centers makes the world of difference. I don't know why people are still using the live centers that came with their lathes. They were not made to be used with the metal pen madrels.


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## redfishsc (Apr 16, 2006)

I got one too. When I needed to order it, it was out of stock, so I got the heavy duty version. Damn thing is almost as big as my fist, so I don't use it for pens but for roughing out larger, wobbly bowl blanks. 

BTW, did the instruction booklet have a bunch of butchered english like mine did? I laughed at it for nearly an hour.


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## turff49 (Apr 17, 2006)

Just got the computer back this weekend. It's going to take awhile to get everything loaded back on it. Brian


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## txcwboy (Aug 6, 2006)

I was just about to ask about MY cheapO live center when I Just decided to go buy the LMS one 

Dave


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## Dario (Aug 6, 2006)

Just for safe measure I bought two sets of live and dead centers from LMS [].  

I use the dead center as my driver for mandrel less finishing []


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## webmonk (Aug 6, 2006)

So as not to be left out of the club I just ran over and bought myself one too. Back when I started turning someone mentioned I needed to get one of these and I had totally forgotten about it until I came by this post.

Thanks!


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## GreggR (Aug 6, 2006)

You know what's annoying? That we have to do this in the first place! I had to touch the tip of my live center to a grinder, had to tweak the mandrel, etc, all the tricks. Some I have to do frequently. When I bought my lathe I checked the tailstock - put a 1MT in the spindle with a 0.0005 dial indicator in, then checked the out of round on the live center. It was 0.023 inches out of round. It was fine in height but was too far back. I pulled the live center and put another ground MT1 in the tailstock then swept it. Same results, so the live center was good. Thats when I went to a local store selling numerous mini-lathes... even the Jet and the Delta had runout. I pulled my tailstock, took it to work and machined another 0.025 off the casting. Now the headstock and tailstock are true. But the mandrel is 0.243 diameter (too far undersize)and made of soft material, so it always gets shoved out of round. I've designed a new mandrel and am having the shop machine, heat treat and grind it for me. I expect the problem to go away with a precision mandrel that is a little harder. The question is... why aren't any of the commercially available mandrels of very good quality?! The same for the lathes.... if I bought a metal lathe and the tailstock was out by more than 0.001 I would demand it replaced.    

If the mandrel works out, I'll post plans.


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## kenwc (Aug 6, 2006)

I assume that the LMS live center fits the Jet Mini?  It wasn't listed in their spot on compatible lathes.

Just curious...


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## Jim15 (Aug 6, 2006)

I have one for my Jet Mini. I dont remember the part nr. off hand. If you need it let me know and I'll see if I can find it.


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## txcwboy (Aug 7, 2006)

As long as you have MT1 or MT2 and order the correct taper it should fit any lathe with that same taper.

Dave


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## txcwboy (Aug 7, 2006)

Those with the LMS live center, do you have to take the point off it to work with the cone in the mandrel ?

Dave


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## txcwboy (Aug 11, 2006)

I got my LMS live center today.Am I going to have to file some off the point to make it work with a pen mandrel ?

Dave


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## Dario (Aug 11, 2006)

DO NOT file it...you should use it as-is.


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## Randy_ (Aug 12, 2006)

Dario is absolutely correct!!!  You should not need to file any material off the end of the live center unless the LC is poorly ground or the dimple in the end of the mandrel is not right.  In 99 of 100 cases, it will be the mandrel that is the problem and in 1 case out of a hundred, it will be the mandrel that is the problem.....get the idea??  Chances are minuscule to none at all that there is a problem with the live center.


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## Ron Mc (Aug 12, 2006)

Dave,
Just put it on your lathe and start turning! You shouldn't have to do anything to it at all.


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## dozer (Aug 12, 2006)

> _Originally posted by Dario_
> <br />
> I use the dead center as my driver for mandrel less finishing []



I know this sounds like a noob question but how do you use the dead center as a driver???


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## Dario (Aug 12, 2006)

> _Originally posted by dozer_
> <br />
> 
> 
> ...



Check this thread http://www.penturners.org/forum/topic.asp?TOPIC_ID=16594


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## kenwc (Aug 31, 2006)

Like Redfish stated above, I too ordered and received the heavy duty live center from Little Machine Shop and this thing is all there and heavy.  Is there any reason to not use this beast on my Jet Mini for pens?


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## GreggR (Sep 2, 2006)

I see some senior members don't like the idea of touching the point of an LC. As a machinist and ME, I can promise everyone that the cone in the end of ANY mandrel does NOT come to a point (unless it's burned in by an EDM machine, and then only the first cone burned would be pointed!). I found only one mandrel that had the LC end properly spot drilled with a #1 spot drill. Yup, I bought it! So, for most mandrels, why would we want to put the pointed end of an LC into a cone that does not have clearance for the LC point? I've looked at six brands of mandrels. Only the one had clearance for a pointed LC. And it helps to remember that most spot drills used on metal turning lathes (used to make the mandrels) have an 82 degree included angle, and most LC's have a 60 degree included angle. See the problem? The LC wants to sit deeper in the mandrel, adding to the problem of little or no point clearance. And since the mandrel is usually more than .240 inches in diameter, why would it be important NOT to touch the tip of the live center to a wheel or file? What are we using the very tip of the LC for? My mandrels are bearing on the LC at about 0.18 diameter, so having a point past that diameter is useless anyway. I haven't found any use to have the tip pointed. I still turn between centers for non-mandrel operations, but any hole I drill larger than the smallest diameter of the LC centers just fine! And before I touched the point off the LC I had plenty of chatter from the mandrel wandering all over the point.


Or, I could be wrong. Please condisder this nothing more than food for thought. Just playing the devils' advocate, not trying to make enemies!


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## PenTurnerJohn (Sep 2, 2006)

Gregg, you've raised an interesting point.  Until I heard about the LMS 60 deg LC I was having more than a little out-of-round problems.  Now that I've bought the LMS LC I have far fewer problems.  I'll be interested to read what those with more experience with the LC from LMS think of your point grinding suggestion.


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## alamocdc (Sep 2, 2006)

Very interesting indeed. Since I have two LCs and one of them is all but useless unless I can find new bearings for it (I'm looking for ceramics), I think I'm going to give Gregg's idea a try and see what happens. I'll let you know, but it may be a few days.


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## Randy_ (Sep 2, 2006)

> _Originally posted by GreggR_
> <br />.....Or, I could be wrong......



Gregg:  What you are saying makes a lot of sense.....<b>IF</b>.....the comments about the configuration of the "dimple" at the end of the mandrel are correct.

We have some members here who are pretty good machinists.  I wonder why they haven't already discussed this possibility?  Is this something that everyone has missed to date or is there something more to the story that Gregg is missing?  Paul, Bruce, Fred, Rudy, Ken and any others I may have missed......where are you.

Gregg, don't take this post as a negative response.  I think it is great that you have tossed out this idea....never can have too many ideas.  [^]It is always good to keep us on our toes; but I would like to hear what some of our other members have to say who have experience in this area.

I'd like to know which manufacturer made the mandrel that was to your liking as well as those who made mandrels that you were not happy with.  It is commonly accepted that there are only 3 pen manufactures/importers in the US and everyone else is a reseller so some of the mandrels from the "6" companies had to have been made by the same manufacturer.  Was the "good" mandrel the only one you saw or were all of the mandrels offered by that company properly machined?  If you don't feel comfortable naming names publicly, you could email me the info if you care to; but I suspect a lot of folks are going to be interested in this same information.  Thanks.

BTW, since I bought my 60Â° LC, my problems have gone away.  Maybe I got lucky and got a good mandrel??(Berea)  To be honest, I have never looked that closely at the "dimple" in the end of my mandrel; but your post has spurred me to get out the jeweler's loupe and take a close look when I get back in the shop after the holiday. And as long as we are here, what is the correct technical name for that little sucker in the end of the mandrel, anyway??


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## alamocdc (Sep 2, 2006)

Randy, it almost sounds like you are saying that you don't think Gregg is a good machinist, but I don't think that's what you meant. If all will read his post carefully, you'll see that he is not only a machinist, he's a mechanical engineer. And I'm certainly not saying that our other machinists aren't good... nothing could be farther from the truth.

Okay, so I have two 60 degree LCs and both have been used with a mandrel(s). However, I have also noticed a wear pattern on the point of both LCs that seems to indicate what Gregg is saying is in fact true.

So, I will round the point of one w/in the next few days and let everyone know if I can tell the difference.


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## Randy_ (Sep 2, 2006)

> _Originally posted by alamocdc_<br />Randy, it almost sounds like you are saying that you don't think Gregg is a good machinist.....



If it sounded that way, it certainly was not intentional.  Fact is that good people miss stuff, too.  Either Gregg has missed something or Paul, Bruce et al have missed something.  I'm not experienced enough to know what the situation actually is so I'm just asking.


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## jjenk02 (Sep 2, 2006)

What does LMS stand for??


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## jjenk02 (Sep 2, 2006)

Never mind, I figured it out.....


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## GreggR (Sep 2, 2006)

All,
I'm glad we have "counter-point" (pun?) responses to my post! We only benefit from differing opinions and observations. The mandrels; two were from PSI - one was the MT1 collet setup, and the other the threaded headstock adapter. I bought the collet setup after not liking the threaded model because I know threads make very poor centers because they are rarely straight and concentric to the shaft. I'm speaking of the threads on the mandrel shaft where it threaded into the headstock adapter. At .250 diameter and sticking out 3/4", even supported by a tailstock, it's very hard to thread stock such there is no deflection and the threads remain true in total indicator runout to the shaft. Especially since there is no shoulder on the shaft for the threading insert to exit the cut - which relieves the tool pressure. With no shoulder the insert necessarily touchs a larger surface area at the end of each pass - which tends to deflect the shaft among other undesirable things. So a collet, assuming it is ground concentric ID/OD, is far superior to holding a shaft true to the spindle taper than a thread screwed into an adapter could ever be. 

One mandrel was from my local wood store where I compared the Delta and Jet, it was made in China, but didn't look like either of the PSI mandrels. Another from the same store was a mandrel that looked suspiciously like the pSI mandrel setup. You are right.. probably eevrything is made by two or three suppliers. Two more were ones I looked at in the Denver WoodCraft store. One was a copy of the PSI (or same one branded differently). It was sold under another name. The other was branded "American Turner Systems", which is the one I bought. Made in Indiana (it didn't say what town). But it WAS properly machined in my opinion. It had less than .003 inches TIR and was much harder than any Chinese version. It had a beautiful centerdrill feature on the tailstock end of the shaft. No burrs, no chatter, no material smudging. Just done right, the American way.

I've attached a centerdrill gif. The one I liked and bought had a profile that looked like this, the drill diameter was clean and truly reflected this profile. The others all looked like they were done with an 82 degree included angle drill, and not a very sharp one at that. In the bottom of the PSI mandrel that came with their "starter kit" (threaded headstock adapter), the cone went to a surface, then a positive "bump" of material came back upwards near the center. This feature was caused by a chipped or damaged tool. I've seen careless lathe operators make thousands of parts with damaged tools and not notice it. This also happens on unattended screw machines. Anywho, you can see how the minor (drill) diameter, if deep enough, leaves room for most any LC pointed tip - regardless of angle. The problem comes when we have no minor diameter for the point to clear. Do you gents have this profile in the tailstock end of the mandrel you use? If not, you're letting an inferior product affect your outcome.

Randy, it's all good; I never personalize statements of skill, so I don't know about being a good or bad machinist; it depends on the tolerances, the capability of the machine, and the consistency of the material. A good machinist is one capable of meeting the expected quality and standards with at least two of the caveats being true. In the last 10 years this would not consistently describe my abilities because I spend almost all my time on the engineering side. So you may be right. I hope I always accurately describe what I observe. And my observation is we have a pile of Chinese crap to choose from. [] I think that's an accurate observation, yes? []    

Gregg




<br />


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## Randy_ (Sep 4, 2006)

OK. I'm home.  Assembled my loupe, Berea mandrels(both "A" and "B" versions) and a very bright light.  It was not real easy to see; but both of the mandrels have a cone shaped hole in the end with a relief hole at the bottom of the cone.....the precise configuration one would expect from the center drill sketch posted in Gregg's message.  I don't have the instruments to measure dimensions and angles to confirm that they are correct; but at least the holes are the correct general shape.

As to Gregg's original post, whether he just ran into a batch of bad mandrels or maybe some manufactures do a better job than others of machining the centering dimple.....who knows??  An improperly configured dimple will cause problems even if you do have a 60Â° live center and the problem won't be apparent without looking very closely.  Although it should not be necessary, I don't see a problem with knocking off the tip of a 60Â° live center if you are missing the relief hole at the bottom of the centering dimple.  However, removing too much material will create an obvious problem so you must be careful.  Alternative solutions would be to purchase a centering drill and re-drill the hole or return the defective mandrel to the seller for a replacement.  

A good thing that came out of this discussion for me is as follows.  In carefully examining the centering dimple on my mandrels, I found that both appeared to be drilled properly; but one had a small burr on the lip of the cone probably caused by being dropped sometime during its lifetime.  That burr was situated such that I'm sure the live center did not ride exactly in the center of the dimple.  Probably wasn't off by more than a few thousandths; but was certainly off by enough to make my barrels slightly oval.  I have had a number of barrels that did not measure to be perfectly round; but were not off by enough that you could see or feel the discrepancy......maybe I now know why?  I dressed up the dimple and got rid of the burr.  It will be interesting to see if my barrels are now rounder!!  In the future, I intend to put some sort of protective cap on that end of the mandrel when it is not in the lathe and handle it a little more gently than I have in the past.


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## alamocdc (Sep 11, 2006)

Just thought I'd reply to this now that I've done as Gregg suggested and rounded the "point" of one of my 60 degree LCs. It "appears" to have made a difference in how it seats in the mandrel. It also seemed to run with less vibration. The bearings are still bad and it got hot to the touch after just one pen, but I was happy with the modification.


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## btboone (Sep 11, 2006)

I've never had to file a live center and mine come to perfect points.  Center drills, different from spot drills, normally have a 60 degree included angle that precisely matches the live center.  The tip of the center never touches the part because of the protruding drill part on the center drill.  A spot drill is simply a very stout drill that starts a hole for later drilling.  It's beefy to prevent walking.  They are common in 90 degree included angles as well as 80 degree.  They are not designed to be used with live centers.

I'm not that familiar with the pen mandrels out there.  I make my own mandrels when I need to turn on center, so I can't say exactly what they are doing.  I do sometimes make an aluminum insert with a centerdrilled end and a straight plug end opposite it to keep the live center from splitting my wood part as I machine it in a rotary axis mill.


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## alamocdc (Sep 11, 2006)

I just ordered new bearings. I couldn't find ceramics that I wanted to risk the money on since I'm not 100% positive it's the bearings. I'll let everyone know if this effort was worthwhile.


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## Randy_ (Sep 11, 2006)

Billy:  How do you plan to extract the arbor(Morse taper) from the bearing??  With the tapered configuration, it is going to be tough to grip without damaging it.


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## alamocdc (Sep 11, 2006)

Unnecessary, Randy. The back of my LC screws out and the bearings are held on the arbor via split ring.


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## Randy_ (Sep 12, 2006)

That's real handy!!  Who made the live center??  The one I have from the Little Machine Shop is all pressed together.


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## alamocdc (Sep 12, 2006)

PSI


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