Still getting out-of-round with PSI Turn-Between-Centers Mandrel - Need some help

[jrista]

I've been turning pens...well, for almost a year, although there have been some largish gaps. The last couple of months I've really gotten into turning pens more, after watching some of the presentations at a pen turners virtual conference in May. Learned a LOT from that conference (sadly, all the content seems to be locked out and is no longer accessible for re-review, I'm sure I could learn so much more), which lead me to switch from boring blanks on the lathe to buying a new Jet free-standing drill press, pen blank vise, and using a more refined technique there. Also started painting my tubes when doing acrylic/poly pens to avoid coloration issues. These have helped refine the quality of my pens a lot.

Another change I made was to move from a shafted mandrel, to a turn-between-centers mandrel from PSI. This too, has helped a lot. The TBC mandrel is really great, and even though I can't turn a pair of blanks at once, applying some of the tips and techniques from the conference (such as marking the inside of the tubes on the sides of each half of the pen blanks that are supposed to match grain/design wise, and also drawing arrows and labeling each blank as to whether it is the top or bottom half, or pen or cap half, etc. has made the ability to turn only one at a time a non-issue.)

I am still struggling, however, to achieve that "perfect seam" where the blank is turned down to just exactly the right size at the bushings to seamlessly fit the pen kit parts. I've spent weeks recently trying to hone my skills there, and I think I've pretty much got it down. Sadly, I still have out of round issues, and it doesn't seem as though any amount of trying has resolved it so far.

I started to pay closer attention to the tools, the lathe, and the mandrel...and I am beginning to think that the mandrel I received from PSI may in fact not be entirely true. The shaft from the mandrel that fits into the head stock seems to be quite true, however the shaft from the free-spinning mandrel that fits into the tail stock, seems like it may be very slightly bent...ever so slightly. I think this is causing a vibration in the bushing, which is keeping me from turning that side of any given blank down properly. I seem to be able to turn it down just right on one side of the blank, but on the other I'm unable to turn it all the way down to the bushing.

It may also be partly the lathe as well. I have two lathes, a Wen 14x20 and a Laguna Revo 1524. The Wen is pretty nice, was a replacement for my original lathe, a Nova Comet 14DR (horrible lathe, started exhibiting problems within 6 months, if even, and took another 4+ months to get Teknatool to actually accept an RMA, fix it, and when they sent it back it still had problems...very souring experience!), and I've turned the majority of my pens on it. Its size just kind of fit pen turning better than the much larger Laguna. I did try turning some pens on the Laguna recently, however, and while I still had out of round issues, they seemed to be much less. Laguna has their Precise Point technology in the tailstock which allows you to very precisely align the headstock and tailstock/quill centering, and I think that may have helped as well. Despite dialing that in as perfectly as I could, it still seems as though there is a vibration in the tailstock side of the TBC mandrel.

Finally, I've occasionally had vibration in the bushing at the headstock side of things. Not in all cases, but sometimes I think some bushings don't perfectly fit the bushing shaft on the mandrel, and I'm wondering if that may also be allowing for some vibration...

Anyway. I guess my question is...has anyone else encountered vibration issues like this? If so, are there any tips or techniques I could follow to try and minimize these issues, so I can get that more-perfect turn and ideal fit at the seams when assembling my pens?

 

[KenB259]

Can't really address your issue but I have a set of that tbc mandrel system and it works very well. I use it all the time. My pens are not out of round and I get no vibration. I do put a small delrin washer on each end before the pen bushing goes on to keep the bushing from sticking.

 

[montmill]

Have you checked the alignment of the tail stock and head stock? You can also test for out of round. While there's more on the subject this is a start: https://www.gnhw.org/qaarchive/lathe-runout The fact that it's worse on one machine than the other is interesting. Is the morse taper clean? I use a 20 gauge shotgun cleaning brush to clean it once in awhile.

 

[jeff]

It may also be partly the lathe as well. I have two lathes, a Wen 14x20 and a Laguna Revo 1524. The Wen is pretty nice, was a replacement for my original lathe, a Nova Comet 14DR (horrible lathe, started exhibiting problems within 6 months, if even, and took another 4+ months to get Teknatool to actually accept an RMA, fix it, and when they sent it back it still had problems...very souring experience!), and I've turned the majority of my pens on it. Its size just kind of fit pen turning better than the much larger Laguna. I did try turning some pens on the Laguna recently, however, and while I still had out of round issues, they seemed to be much less. Laguna has their Precise Point technology in the tailstock which allows you to very precisely align the headstock and tailstock/quill centering, and I think that may have helped as well. Despite dialing that in as perfectly as I could, it still seems as though there is a vibration in the tailstock side of the TBC mandrel.

Rule out the mandrel as the problem. Do you have a dial indicator and a mag base? If not they're pretty cheap. Check the runout on the live and dead centers. Check YouTube for setup and use of a dial indicator on a lathe. Are you over-tightening perhaps?

Here's a good article:

http://content.penturners.org/library/general_reference/Why-are-my-pens-not-round.pdf

 

[MPVic]

I think most of us started out using the 7mm mandrel & consequently learned about non-concentric blank results. Taking the many, many recommendations here, I abandoned the mandrel setup, EXCEPT for roughing blanks only, & started turning between centers which greatly improved the finished product. And yes, I did try the so-called TBC bushings but there is still the risk, albeit reduced, of non-concentric barrels.

 

[rherrell]

I agree with Jeff, watch this short video I made on how to check runout.

 

[leehljp]

The PennState mandrel system requires bushing even to finish the blank. Custom made bushings came into being due to the minuscule imperfections of commercial bushings.

ARE the bushings snug - once placed on the PennState Between Centers Mandrel, or is does it have a tiny bit of "play," and easy sliding on it? One aspect of the original TBC was that for finishing the sizing and adding the finish, the bushings were taken off of the TBC live center and dead center and the "almost finished" blank was put directly onto the live center and dead/drive center and then turned or sanded down to its final size - measured with calipers

IF there were any out of round at this point it would be because of headstock-tail stock alignment problems (or CA build up on the live center or dead center.

Not using bushings in the final "finishing in sizing, and finishing with CA" (or other) eliminated the majority of problems and brought the problems down to one or two conclusions. This was a tremendous boost in getting perfect rounds.

For your and other recent members information, the TBC system was begun by a few others outside of the IAP years ago (in my understanding) and originally came to be used here because of CA cracking and lifting off of the blanks when separating the blanks from the bushings - especially on oily woods such as ebonies. It was quickly discovered that the TBC without bushings for final turning and finishing, provided a number of other benefits such as MUCH LESS OOR and more perfect fitting. There were a few other benefits also.

When you get a chance, try turning between centers with a dead/drive center and a live center. Use the bushings to get it to near size, then take the bushings off and place the blank directly between the dead center and live center. Finish turning or sanding to the correct size and measure with calipers every few seconds. Do the same with adding CA and turning/sanding the CA round and or finish polishing or waxing.

 

[drise]

I agree with Jeff and Rick. I had one of the PSI mandrels. Pens were always OOR some worse than others. Finally checked the runout and was surprised how bad it was. After that I got a live center and dead center and just put the regular bushings between them. It works fine, no more OOR.

Dave

 

[jrista]

Rule out the mandrel as the problem. Do you have a dial indicator and a mag base? If not they're pretty cheap. Check the runout on the live and dead centers. Check YouTube for setup and use of a dial indicator on a lathe. Are you over-tightening perhaps?

Here's a good article:

http://content.penturners.org/library/general_reference/Why-are-my-pens-not-round.pdf

Jeff, thanks for the link.

I like his terminology...non-concentricity seems to fit better than out-of-round, as I think my blanks do turn round, just off-center basically.

I have found that some bushings don't seem to be snug enough on the shaft, and I've suspected that could be part of the problem. I've never trued turning just between a normal tapered dead and live center, though...I'll have to try that and see if it helps.

 

[jrista]

I agree with Jeff and Rick. I had one of the PSI mandrels. Pens were always OOR some worse than others. Finally checked the runout and was surprised how bad it was. After that I got a live center and dead center and just put the regular bushings between them. It works fine, no more OOR.

Dave

What kind of dead center did you use? Actually also what kind of live center? I don't think I have any dead centers that would work, as they all have teeth. Most of my live centers have a very short tapered point.

 

[jrista]

I think most of us started out using the 7mm mandrel & consequently learned about non-concentric blank results. Taking the many, many recommendations here, I abandoned the mandrel setup, EXCEPT for roughing blanks only, & started turning between centers which greatly improved the finished product. And yes, I did try the so-called TBC bushings but there is still the risk, albeit reduced, of non-concentric barrels.

Are there a particular set of centers you use for pens?

 

[KenB259]

One thing we all know, but I rarely see it addressed is the fact that everything has a tolerance, even those custom made TBC bushings we hear about. I must have gotten a really good set from PSI, because I don't have any OOR issues or vibration issues. Just because you personally have had bad results with any given tool or method does not mean that said method or tool is bad. That's a major part of woodworking, figuring out problems. Most of the time when something's not working out for me, that answer is staring back at me in a mirror.

 

[Paul in OKC]

Good advice given. On centers they both need a 60 degree point. The ones that come with most wood lathes are sharper and the point can hit the bottom of the 'dimple' in mandrels, and not fit the chamfer well on TBC bushings. Also good square ends can make a huge difference.

 

[jrista]

The PennState mandrel system requires bushing even to finish the blank. Custom made bushings came into being due to the minuscule imperfections of commercial bushings.

ARE the bushings snug - once placed on the PennState Between Centers Mandrel, or is does it have a tiny bit of "play," and easy sliding on it? One aspect of the original TBC was that for finishing the sizing and adding the finish, the bushings were taken off of the TBC live center and dead center and the "almost finished" blank was put directly onto the live center and dead/drive center and then turned or sanded down to its final size - measured with calipers

IF there were any out of round at this point it would be because of headstock-tail stock alignment problems (or CA build up on the live center or dead center.

Not using bushings in the final "finishing in sizing, and finishing with CA" (or other) eliminated the majority of problems and brought the problems down to one or two conclusions. This was a tremendous boost in getting perfect rounds.

For your and other recent members information, the TBC system was begun by a few others outside of the IAP years ago (in my understanding) and originally came to be used here because of CA cracking and lifting off of the blanks when separating the blanks from the bushings - especially on oily woods such as ebonies. It was quickly discovered that the TBC without bushings for final turning and finishing, provided a number of other benefits such as MUCH LESS OOR and more perfect fitting. There were a few other benefits also.

When you get a chance, try turning between centers with a dead/drive center and a live center. Use the bushings to get it to near size, then take the bushings off and place the blank directly between the dead center and live center. Finish turning or sanding to the correct size and measure with calipers every few seconds. Do the same with adding CA and turning/sanding the CA round and or finish polishing or waxing.

Thanks for the detailed reply, Hank!

Regarding bushings...I think it depends on the bushings. Some seem to be pretty snug, others just a bit of play.

I tested the Wen, and it, too, seems to be pretty well centered between the head and tail stock. I can hardly tell if there is any misalignment, although I think that there is some slight play in the tailstock that can allow the whole thing to rotate just slightly, and that might cause some mis-centering if not locked at just the right angle. The Laguna with its precise point capability is dead on between the centers.

I haven't tried just turning the final size between a normal dead and live center. (I say normal, as the TBC system I have isn't a toothed or tapered center, but more of a morse taper with a shaft, and a live center with a shaft, and the bushings go on the shaft.) But I can see how using just tapered dead and live centers could help, as it would eliminate any chance of bushings being loose.

 

[rherrell]

What kind of dead center did you use? Actually also what kind of live center? I don't think I have any dead centers that would work, as they all have teeth. Most of my live centers have a very short tapered point.

Dead center... https://www.ebay.com/itm/301993591201?hash=item46503881a1:g:8mMAAOSwcwhVLLBy

Live center... https://www.ebay.com/itm/353606021359?hash=item52548fb0ef:g:BGUAAOSwDSxhCkiS

I'm not endorsing these two vendors, just using them for pics.

 

[drise]

What kind of dead center did you use? Actually also what kind of live center? I don't think I have any dead centers that would work, as they all have teeth. Most of my live centers have a very short tapered point.

I got both of my centers from amazon. The live center is a PSI. I liked the PSI between center mandrel but I may have dropped it once and got the bearing out of whack. I should try to take it apart and replace the bearing.

 

[mgoetzke]

Noobie here. I turned I think 3 pens maybe 15 years ago then got interested in bowls. Haven't turned for a while but am now ready to turn 15. I did some homework here and had a long conversation with Ed at Exotic-Blanks and decided to try the PSI between centers system instead of my adjustable mandrel and mandrel saver. One of the first things in the PSI kit manual says to check alignment. I have a PM3520B and it's been in the same spot for years so was surprised when I found my centers off a bit. I lifted the lathe and adjusted one of the feet and got it perfect to my eyes.

For these practice/give-away pens I bought some Legacy Cigar pen kits at TheWoodturningStore. We will see but the bushings slide in the blanks pretty easily. They don't seem to have radial movement but just slid into the first pen tubes easier than I expected. Don't know if this is typical or not.

I will report back my results of fit soon.

Mike

 

[rherrell]

Keep in mind that just because your tailstock and headstock centers "touch", it doesn't mean that they "line up". Try this, put your two index fingers together tip to tip so they "touch". With your fingers still "touching" move your right hand a few degrees. Your fingers are still "touching" but they don't "line up". This same thing can be happening with your lathe. The fix might be as simple as holding pressure on your tailstock to one side or the other as you tighten it. The other more complicated fix is adjusting your headstock so it lines up with the ways.

 

[mgoetzke]

Keep in mind that just because your tailstock and headstock centers "touch", it doesn't mean that they "line up". Try this, put your two index fingers together tip to tip so they "touch". With your fingers still "touching" move your right hand a few degrees. Your fingers are still "touching" but they don't "line up". This same thing can be happening with your lathe. The fix might be as simple as holding pressure on your tailstock to one side or the other as you tighten it. The other more complicated fix is adjusting your headstock so it lines up with the ways.

I somewhat checked this by testing the point alignment at the full extents of the quill travel - I know this isn't perfect. I also checked the runout of the PSI TBC kit of head/tail stock and head is within 0.001" and tail 0.002".

 

[jeff]

Jeff, thanks for the link.

I like his terminology...non-concentricity seems to fit better than out-of-round, as I think my blanks do turn round, just off-center basically.

I have found that some bushings don't seem to be snug enough on the shaft, and I've suspected that could be part of the problem. I've never trued turning just between a normal tapered dead and live center, though...I'll have to try that and see if it helps.

To at least eyeball concentricity, put a blank between centers (assuming you have a toothed drive center) and turn it round. If it looks concentric around the center dimple on each end, you've mostly eliminated the lathe as the problem. Make sure you're tightening the friction lock on your tailstock, too.

 

[leehljp]

I think it needs to be noted that OOR and Non-Concentricity are two separate problems. OOR/ Out of Round usually results in an oval or elipse shape and can occur on wood blanks that have large soft grain layers contrasted by a very hard grain layers. Heavy sanding will eat away on the sides that have softer grain and leave the area where the hard grain is prominent.

 

[randyrls]

Keep in mind that just because your tailstock and headstock centers "touch", it doesn't mean that they "line up". Try this, put your two index fingers together tip to tip so they "touch". With your fingers still "touching" move your right hand a few degrees. Your fingers are still "touching" but they don't "line up". This same thing can be happening with your lathe. The fix might be as simple as holding pressure on your tailstock to one side or the other as you tighten it. The other more complicated fix is adjusting your headstock so it lines up with the ways.

Rick; You know this so this is for those who want to see if their lathe points are exact. From metal working lore....
Bring the tail stock up until it is shy of touching the headstock point. Now insert a thin piece of metal (a feeler gauge leaf works well) between them. While holding the leaf, advance the tail stock and see if the lead twists and if so which way it twists and how much. This will tell you if the points are not exact and which way they are off. This test is VERY sensitive.

 

[Mortalis]

I will continue to argue that centers not being aligned with one another will not cause out of round. On a lathe with a fixed cutting tool and holder that runs parallel to the lathe ways it will result in a taper.
Out of round or concentricity issues are most likely a result of sloppy fittings of bushings, contamination (super glue buildup) on the points of the centers or contamination in/on the Morse tapers, inside or outside surfaces and/or uneven blank end faces. Of course worn out bearings, drive belts and a whole host of other mechanical issues will/can exasperate the issue.

 

[MJK]

I've been turning pens...well, for almost a year, although there have been some largish gaps. The last couple of months I've really gotten into turning pens more, after watching some of the presentations at a pen turners virtual conference in May. Learned a LOT from that conference (sadly, all the content seems to be locked out and is no longer accessible for re-review, I'm sure I could learn so much more), which lead me to switch from boring blanks on the lathe to buying a new Jet free-standing drill press, pen blank vise, and using a more refined technique there. Also started painting my tubes when doing acrylic/poly pens to avoid coloration issues. These have helped refine the quality of my pens a lot.

Another change I made was to move from a shafted mandrel, to a turn-between-centers mandrel from PSI. This too, has helped a lot. The TBC mandrel is really great, and even though I can't turn a pair of blanks at once, applying some of the tips and techniques from the conference (such as marking the inside of the tubes on the sides of each half of the pen blanks that are supposed to match grain/design wise, and also drawing arrows and labeling each blank as to whether it is the top or bottom half, or pen or cap half, etc. has made the ability to turn only one at a time a non-issue.)

I am still struggling, however, to achieve that "perfect seam" where the blank is turned down to just exactly the right size at the bushings to seamlessly fit the pen kit parts. I've spent weeks recently trying to hone my skills there, and I think I've pretty much got it down. Sadly, I still have out of round issues, and it doesn't seem as though any amount of trying has resolved it so far.

I started to pay closer attention to the tools, the lathe, and the mandrel...and I am beginning to think that the mandrel I received from PSI may in fact not be entirely true. The shaft from the mandrel that fits into the head stock seems to be quite true, however the shaft from the free-spinning mandrel that fits into the tail stock, seems like it may be very slightly bent...ever so slightly. I think this is causing a vibration in the bushing, which is keeping me from turning that side of any given blank down properly. I seem to be able to turn it down just right on one side of the blank, but on the other I'm unable to turn it all the way down to the bushing.

It may also be partly the lathe as well. I have two lathes, a Wen 14x20 and a Laguna Revo 1524. The Wen is pretty nice, was a replacement for my original lathe, a Nova Comet 14DR (horrible lathe, started exhibiting problems within 6 months, if even, and took another 4+ months to get Teknatool to actually accept an RMA, fix it, and when they sent it back it still had problems...very souring experience!), and I've turned the majority of my pens on it. Its size just kind of fit pen turning better than the much larger Laguna. I did try turning some pens on the Laguna recently, however, and while I still had out of round issues, they seemed to be much less. Laguna has their Precise Point technology in the tailstock which allows you to very precisely align the headstock and tailstock/quill centering, and I think that may have helped as well. Despite dialing that in as perfectly as I could, it still seems as though there is a vibration in the tailstock side of the TBC mandrel.

Finally, I've occasionally had vibration in the bushing at the headstock side of things. Not in all cases, but sometimes I think some bushings don't perfectly fit the bushing shaft on the mandrel, and I'm wondering if that may also be allowing for some vibration...

Anyway. I guess my question is...has anyone else encountered vibration issues like this? If so, are there any tips or techniques I could follow to try and minimize these issues, so I can get that more-perfect turn and ideal fit at the seams when assembling my pens?

I'm a newby here so sorry if this comes off wrong but how perfect does it have to be?

I see all my microscopic flaws but when I give the pen to someone they are amazed at how nice it looks.

Granted I don't sell my pens, but the ones I've seen for sale aren't perfect either.

I'm a wood worker, not a machinist.

 

[philipff]

My method defies all the laws of turning. First of all, I only turn on a dead center/live center combo- - no mandrel. I only measure with a caliper and do not use bushings - -I have a draw full but leave them there. I sand and polish on the lathe and before all this I clean and square the ends with a round nose scraper for a perfect fit. end of story. P.

 

[jrista]

I'm a newby here so sorry if this comes off wrong but how perfect does it have to be?

I see all my microscopic flaws but when I give the pen to someone they are amazed at how nice it looks.

Granted I don't sell my pens, but the ones I've seen for sale aren't perfect either.

I'm a wood worker, not a machinist.

I guess that is it right there...I see a lot of pens for sale, for not very much, that have those little flaws...out of round or non-concentricity, non-flat ends so you see gaps between pen parts and the blanks (I still sometimes get this, although setting my sanding disk with a square each time before I sand has helped a lot), scratches from the clip where it met the blank when putting the pen caps on, etc.

I would like to sell my pens for higher prices. I feel that if I don't eliminate these flaws, then I really wouldn't have a right to ask for more premium pricing. I haven't started selling yet, and I don't really want to until I can be sure I am able to produce a truly professional quality, high grade result. Maybe most customers wouldn't notice...but there is that class of customers that would. I would like to cater to those who really appreciate the work that goes into a high quality pen. (At the same time, these days, all it takes is one unhappy person with with a big enough twitter following to destroy a business. Sell a pen for $100+ that has all these little flaws...sooner or later someone is going to set out to destroy you.)

I started with slimline pens, which I think due to their very small diameters, are harder to get perfectly round and concentric. I've moved on to higher end pens though, the nice quality rollerball and fountain pens, and I don't want to be selling them for $35 a pop (heck, I've seen some higher end pens, where between the kit and a quality blank could COST $60, $80, $100 just in the kit (i.e. Rhodium+Gold) and blank (i.e. TruStone) costs, sold for well under cost...not entirely sure how or why people do that...but its kind of sad.) Many of these kits, paired with the right blank, are just beautiful. I don't want to waste a good quality pen, on a poorly turned blank either.

 

[mmayo]

My 2 cents

I have my PSI faux tbc system away. In short, it sucked and so did the stock bushings

Bite the bullet!
True up your headstock carefully looking from all sides. Tighten well and check again.
Buy or use a dead center in the headstock
Buy or use a live center in the tail stock
Buy real TBC bushings from Brian Nikitas
Never look back

 

[jrista]

My 2 cents

I have my PSI faux tbc system away. In short, it sucked and so did the stock bushings

Bite the bullet!
True up your headstock carefully looking from all sides. Tighten well and check again.
Buy or use a dead center in the headstock
Buy or use a live center in the tail stock
Buy real TBC bushings from Brian Nikitas
Never look back

I actually bit the bullet a few days ago. Bought a proper dead and live center, just the 60 degree ones. They should be here next week. It makes sense, that the cones would eliminate any issues with the bushings. The PSI "TBC" kit has those little pins on them that the bushings slide onto, and the bushings don't always fit snug. I think the live center pin is very slightly angled/bent as well, which I'm pretty sure is why I am having trouble turning down to the bushing on that side of each blank.

I did try something on the latest pen I'm working on...I pulled the bushings and the blank off the PSI TBC, flipped the whole assembly around so that the end that was at the live center was now at the dead center, and finished it that way. I think it worked, or at least worked better. I got sidetracked rearranging my workshop to better support pen making, with a new little 4x2" pegboard mounted on a simple 3-step ladder, with all my pen making supplies right there. So I haven't gotten back to the pen yet. Hopefully the little flip-it-around trick worked, I guess I'll see. Not sure how well that might work on other kits, though.

Regarding the Brian Nikitas bushings...are those absolutely necessary? I've got quite a lot of bushings now...would hate to have to replace all of them just to be able to turn between cone-type centers...

 

[PatrickR]

if the stock bushings are not a slip fit onto a mandrel they are out of spec and will cause problems. I've seen this with PSI bushings especially.
A dial gauge with magnetic base is indispensable.
The TBC Bushings are the best, worth every penny (as long as you will be turning enough pens in that particular kit)

 

[foursquare]

Lots of great input here. One thing I have discovered with the TBC mandrells is that your trimmed ends need to be square to the tubes. If they are not, then when you apply tailstock pressure ic will force the tailstock mandrel sideways and cause an out of round issue.

 

[Todd in PA]

Relative newbie here. Couldn't this be as simple as something in the tube? A bit of glue or a chip of wood at the exact edge to cause the vibration to appear between centers but not on the mandrel bushings. How is the OP cleaning his tubes?

 

[TonyL]

You can try simply turning a pen or just round it down WITHOUT any bushings. Just square it off and place the tubed blank between your centers. I would inspect each end every few millimeters to see when/if the OOR starts to appear. Assuming your centers are true, you should be fine. If not, then you know it may be your centers/lathe.

Every once in a while, I will get an OOR. It is usually a some speck in the tube or something that has adhered to centers or inside the dimples of my TBC bushings. Usually because I and rushing - just impatient.

 

[Alchemist]

I wanted to touch on this a bit. Like I, mostly, use a live and dead center with a lot of different www.tbcbushings.com bushings to go between them. Some days I use a mandrel. Personally, I notice that the quality of bushing is one of the most important things. Nikitas has a TBC adapters that I use for bushings that I don't regularly use.
The reason I bring this up is because, if you turn one or two specific pens consistently, then it's good have the highest quality bushings. The adapters allow for the use of other bushings.

This leads me to this: Even TBC can lead to non-concentrical ends. I have had it happen. Why? Sometimes, like hybrid blanks, you have two different materials so they can cut differently, just slightly enough to throw off the roundness. I have noticed this as I turn more and more. That's why I have become careful with my finishing cuts and sanding.

So, as suggested, check your dead to live center points and adjust as needed. You can check for run out as well.
One last thing! If you are using a chuck to hold your tbc mandrel instead of directly into the drive, see if it is running true.

 

[jrista]

Relative newbie here. Couldn't this be as simple as something in the tube? A bit of glue or a chip of wood at the exact edge to cause the vibration to appear between centers but not on the mandrel bushings. How is the OP cleaning his tubes?

Every once in a while, I will get an OOR. It is usually a some speck in the tube or something that has adhered to centers or inside the dimples of my TBC bushings. Usually because I and rushing - just impatient.

This is an interesting thought. I use epoxy to glue my tubes, rather than CA glue (story there, I tend to have near-deadly reactions to CA fumes, in particular, and dust...so I try to avoid CA in general whenever possible), and I usually get a little bit on the inside of the tube. I do try to clean it out before I turn the blanks, but maybe i'm not doing a good enough job.

I'm curious now, how do most of you clean the inside of your tubes? I switched to using a sanding disc to true up the ends of my blanks and trim them down to the tubes, so I'm not using one of those pen trimming drill bits. It never really seemed like those cleaned up the inside of the tubes much anyway, although they would chip off any big glue chunks.

 

[sorcerertd]

I could re-iterate a few things here, but will just say this: Take your existing non-tbc bushings and put them between centers. Spin up your lathe and see how "well" they are machined. The results will speak for themselves. That should give you an idea of why I only use bushings to cut down maybe 95% of the way. Even without the bushings, the ends have to be perfectly square with no glue or burrs for the end product to be concentric. As far as what to put those bushings on, mandrels are okayish for roughing, but I usually use Brian Nikitas TBC adapters instead. Just remember that you still have the cheap bushings on those well machined adapters, so remember what you found when you tested them between centers. Mandrels aren't a total waste. I do like them for holding the barrels securely when polishing on the buffer.

 

[leehljp]

This is an interesting thought. I use epoxy to glue my tubes, rather than CA glue (story there, I tend to have near-deadly reactions to CA fumes, in particular, and dust...so I try to avoid CA in general whenever possible), and I usually get a little bit on the inside of the tube. I do try to clean it out before I turn the blanks, but maybe i'm not doing a good enough job.

I'm curious now, how do most of you clean the inside of your tubes?

First thing I do is use plumber's putty - or some use wax, or dental wax, or Play Doh - and plug the ends before gluing and inserting.

2nd - IF I have glue inside, (and I, by habit, inspect every tube I glue into place after the glue has set) I use a rat tail file to get most out and am careful not to dig into the metal tube other than a surface scratch. Lastly - I have some round wire brushes that are used for cleaning guns and do a few twists and turns to finish cleaning the inside. Don't go overboard and increase the inside diameter with too much scraping, but do get the glue out. Minuscule amounts of glue inside the tube are responsible for many many cracks in finished blanks.

 

[jrista]

I could re-iterate a few things here, but will just say this: Take your existing non-tbc bushings and put them between centers. Spin up your lathe and see how "well" they are machined. The results will speak for themselves. That should give you an idea of why I only use bushings to cut down maybe 95% of the way. Even without the bushings, the ends have to be perfectly square with no glue or burrs for the end product to be concentric. As far as what to put those bushings on, mandrels are okayish for roughing, but I usually use Brian Nikitas TBC adapters instead. Just remember that you still have the cheap bushings on those well machined adapters, so remember what you found when you tested them between centers. Mandrels aren't a total waste. I do like them for holding the barrels securely when polishing on the buffer.

First thing I do is use plumber's putty - or some use wax, or dental wax, or Play Doh - and plug the ends before gluing and inserting.

2nd - IF I have glue inside, (and I, by habit, inspect every tube I glue into place after the glue has set) I use a rat tail file to get most out and am careful not to dig into the metal tube other than a surface scratch. Lastly - I have some round wire brushes that are used for cleaning guns and do a few twists and turns to finish cleaning the inside. Don't go overboard and increase the inside diameter with too much scraping, but do get the glue out. Minuscule amounts of glue inside the tube are responsible for many many cracks in finished blanks.

Thank you both for the tips. I agree, the mandrels are handy for roughing.

This thread has been great, and thank you everyone who has responded! I have refined my techniques a good deal thanks to all the tips and helpful info provided here. I think my process is going to be as follows:

1. Measure and Cut Blanks
2. Drill, with regular cooling to avoid expansion/contraction
3. Scuff and glue tubes with epoxy (plug tube ends to avoid getting glue inside)
4. Clean inner tubes (light filing & round wire brushes; do not change tube thickness)
5. Trim tubes with well-squared sanding disc (Mark Dreyer style!)
6. Rough blanks to general shape and size with PSI TBC mandrel
7. Turn blanks down to final size using proper TBC with cone dead and live centers (carefully measuring with calipers until optimal size, measured from that actual pen kit's parts for that blank, is reached at either end)
8. Sand through all grits, sand tube ends (temporarily swap out normal bushings for slimline, or perhaps CA bushings, to allow sandpaper to reach ends of blank)
9. Finish with finishing compound of choice; Acrylic, Poly, etc. use polishing compound for final glass-like finish
10. Assemble, using GREAT care not to put too much pressure on blank ends to avoid cracking

 

[mmayo]

I actually bit the bullet a few days ago. Bought a proper dead and live center, just the 60 degree ones. They should be here next week. It makes sense, that the cones would eliminate any issues with the bushings. The PSI "TBC" kit has those little pins on them that the bushings slide onto, and the bushings don't always fit snug. I think the live center pin is very slightly angled/bent as well, which I'm pretty sure is why I am having trouble turning down to the bushing on that side of each blank.

I did try something on the latest pen I'm working on...I pulled the bushings and the blank off the PSI TBC, flipped the whole assembly around so that the end that was at the live center was now at the dead center, and finished it that way. I think it worked, or at least worked better. I got sidetracked rearranging my workshop to better support pen making, with a new little 4x2" pegboard mounted on a simple 3-step ladder, with all my pen making supplies right there. So I haven't gotten back to the pen yet. Hopefully the little flip-it-around trick worked, I guess I'll see. Not sure how well that might work on other kits, though.

Regarding the Brian Nikitas bushings...are those absolutely necessary? I've got quite a lot of bushings now...would hate to have to replace all of them just to be able to turn between cone-type centers...

Yes you need Nikitas bushings. I only use the stock bushings to make delrin sanding and buffing bushings.

 

[MJK]

I guess that is it right there...I see a lot of pens for sale, for not very much, that have those little flaws...out of round or non-concentricity, non-flat ends so you see gaps between pen parts and the blanks (I still sometimes get this, although setting my sanding disk with a square each time before I sand has helped a lot), scratches from the clip where it met the blank when putting the pen caps on, etc.

I would like to sell my pens for higher prices. I feel that if I don't eliminate these flaws, then I really wouldn't have a right to ask for more premium pricing. I haven't started selling yet, and I don't really want to until I can be sure I am able to produce a truly professional quality, high grade result. Maybe most customers wouldn't notice...but there is that class of customers that would. I would like to cater to those who really appreciate the work that goes into a high quality pen. (At the same time, these days, all it takes is one unhappy person with with a big enough twitter following to destroy a business. Sell a pen for $100+ that has all these little flaws...sooner or later someone is going to set out to destroy you.)

I started with slimline pens, which I think due to their very small diameters, are harder to get perfectly round and concentric. I've moved on to higher end pens though, the nice quality rollerball and fountain pens, and I don't want to be selling them for $35 a pop (heck, I've seen some higher end pens, where between the kit and a quality blank could COST $60, $80, $100 just in the kit (i.e. Rhodium+Gold) and blank (i.e. TruStone) costs, sold for well under cost...not entirely sure how or why people do that...but its kind of sad.) Many of these kits, paired with the right blank, are just beautiful. I don't want to waste a good quality pen, on a poorly turned blank either.

I finish every grit with the lathe off, sanding with the grain. If the wood is flush with the bushing it should make a nice fit.

I harden all my blanks with CA as I sand.
Thin soaks in the best. Kind of a sanding sealer. This helps with the nicks and dents.

I too wonder how some sell pens for cost.
Maybe they just want to break even.
But I also wonder who is buying them.
You're correct in thinking a higher quality should fetch a higher price. But again who's buying them?

As far as I know, the only people making money are the hardware sellers .

I may try to sell my work someday but right now it's a fun hobby. And I turn lots of other small stuff that don't require hardware.

Keep riding the bevel. ✌

 

[KenB259]

This is an interesting thought. I use epoxy to glue my tubes, rather than CA glue (story there, I tend to have near-deadly reactions to CA fumes, in particular, and dust...so I try to avoid CA in general whenever possible), and I usually get a little bit on the inside of the tube. I do try to clean it out before I turn the blanks, but maybe i'm not doing a good enough job.

I'm curious now, how do most of you clean the inside of your tubes? I switched to using a sanding disc to true up the ends of my blanks and trim them down to the tubes, so I'm not using one of those pen trimming drill bits. It never really seemed like those cleaned up the inside of the tubes much anyway, although they would chip off any big glue chunks.

As soon as I get the tube where I want it, using epoxy, I clean the inside of the tube with a q-tip. Easy to do before the glue starts setting up.