"Straight" slimlines and "inward bowing" in turned blanks...

[jrista]

I've been trying to turn the last of my slimline kits. Its what I started with, which is probably how most turners start. I've recently been turning larger kits, and have found them far, far more satisfying than the slimlines (of any variety), with more consistent results, small errors are, in relative terms, less impactful overall. I have had a good number of slimline kits laying around for a while, though, and I need to finish them.

I know there is a lot of theory about that bulging lower half of the pen, and most of mine are turned that way...but I've also turned pens that are just strait, without any bulging, or any other flare or other stylistic features. For some reason, with slimlines, I really like them that way, and I've had a number of other people say they like them that way as well.

I have run into an issue turning pens that way, though. Once I pull the turned and finished blanks off the lathe, where they appeared to be perfectly straight, once I actually assemble them with the pen kit, I notice that the ends of the blank actually turn up just slightly. I've been looking for this when at the lathe, and for some reason it doesn't seem to look that way when the blank and tube are on the mandrel. I just assembled a copper slimline that I thought I had perfect, yet once assembled, I noticed this same problem. I'd turned the blank exactly down to the size of the slimline bushings, then sanded with 320, 400 abranet, then the full sequence of micromesh.

Is it possible that sanding is the problem here? That I'm sanding away more of the middle of the turned blank than the ends, which is leading to the inward bowed appearance once I get the kit assembled? Is there a trick to avoiding this problem? I've tried to leave the blank slightly thicker than the bushings (by, oh, at most 1/64th I'd say) before I sand, but that usually means that the blanks even after extensive sanding (and polishing for acrylics, polys) end up just a bit too large for the kit parts. Heh, seems to be a loose loose proposition.

 

[qquake]

It is certainly possible, and has happened to me. What I usually do, especially when turning slim pens, is leave a slight "bulge" in the blank before sanding. That way, if the sanding does remove material, it will leave it relatively straight.

 

[jrista]

It is certainly possible, and has happened to me. What I usually do, especially when turning slim pens, is leave a slight "bulge" in the blank before sanding. That way, if the sanding does remove material, it will leave it relatively straight.

Ok...I just tried this on a copper slimline kit with some "copper haze" blanks. Left it just very slightly bulged (for the top part anyway, ended up turning a slight outward bow in the lower part), and then sanded it. I myself can tell there is a very slight bulge...but, I wonder if most people would notice...

The top one is what I turned before I started the thread, the bottom since your reply:

The top half of the top pen exhibits more if the inward bowing. Its not as bad as I've had in the past, but when you are looking at the pen in your hand, it does kind of show. In this picture, I'm now also seeing that it looks like the pen is a little crooked...not sure how that happened.

The bottom pen, I left the top just ever so slightly bulged. I can tell myself, but its very slight.

(Note, the tubes for both of these were painted slightly differently, the top was painted a lighter colored copper Krylon, the bottom a darker...the top ended up more reddish and translucent, which wasn't intentional, while the bottom has a closer match to the copper tone of the kit itself. I may try mixing the two paints a bit next time and see if that gives me the best result, as the bottom pen is a bit too dark, I think.)

 

[qquake]

I do like the shape of the upper body in the lower pen. Not a fan of the big bulge in the lower body.

 

[jrista]

I do like the shape of the upper body in the lower pen. Not a fan of the big bulge in the lower body.

Yeah, not really a fan of bulges in slimlines... This one is smaller than bulges I've made in the past. I tried to get it to flow more naturally from the nib into the lower blank.... I do like the slimlines with this "Copper Haze" blank, though.

 

[1080Wayne]

Do you have a digital caliper ? Makes it easy to measure the amount of bulge you like , and ensure some consistency between pens . My guess would be that you have a 12-15 thou bulge on the diameter of the upper barrel of the second pen . I prefer 8-10 thou on an upper slim barrel , but use 12-15 on a Sierra style pen .

 

[keithbyrd]

I use a 3" piece of an old ruler - lay it on the blank until I see that the middle is slightly thicker than the ends. I mean slightly! Then sand and finish. I start with 400 grit and don't over sand. AN ever so slight rise in the center is much better than an ever so slight dip in the middle! I only use 400 grit and the n 4/0 steel wool before applying CA.

 

[RunnerVince]

What an annoying issue. I have two thoughts:
1. Get yourself some digital calipers so you can measure the diameter across the length of the pen. Your ruler could have a slight warp, you could be slightly non-concentric, etc.
2. If you have a dead center (I got mine for around $15 off Amazon) and a 60 degree cone revolving center (~$30 from I don't remember, probably PSI), dispense with the bushings. Put your barrel in between centers and take your measurements from the pen parts themselves. For me, turning between centers solved so many issues, and my gut says it might solve yours too. It does take a little more time because of constantly stopping to check with calipers and also having to finish each half of the pen separately, but for me it has been 1000% worth it.

 

[Bope]

When making a straight tube use a sanding block. My turning is not as good as I would like it to be so when making a straight tube it is not perfectly level after turning. Using a flat sanding block you can see the high and low spots. Keep sanding until it is level. With a block that spans the length of the blank you wont sand more in the middle than on the ends. This also works well with the slight bulge just rock the sanding block from end to end.

 

[egnald]

I have had similar experiences with the Slimline. My resolution was to buy center bands for Comfort pens and convert my Slimline kits into Comfort kits (sorta). The only difference is the diameter of the center band. In my opinion, the larger Comfort center band permits more of a gentle gradual shape between the band and the nib and between the band and the finial versus the straight flat area on a Slimline. It makes a slight bulge look a little more natural to me.

Slimline bushings at the nib, center, and finial are all 0.333 inches in diameter (nominal). Comfort bushings are 0.333 inches for the cap and finial, but are 0.420 inches (nominal) for the center band.

Dave

 

[penicillin]

I turn mostly straight pens. Why? Because I prefer them myself. I like the way they feel in my hand when I use them.

My trick to making straight pens is to keep a 4 inch double square at the lathe. I use the blade (ruler) to check for straightness.
https://www.google.com/search?q=4+inch+double+square&tbm=isch

When done turning, I use the popular cone-shape plastic non-stick bushings for sanding and finishing. The bushings expose the ends of the turning(s), so you can keep checking with the square's blade as you sand.

P.S. My friends teased me so much about the straight pens that I made some seriously curvaceous pens for them. They thought I couldn't turn curvy shapes on the lathe. Not true.

 

[qquake]

I like your double square idea, but with my setup, a 4" straightedge won't fit between the collet chuck and knurled nut on a lot of shorter bodies. It would with this body, but only because it's longer than usual. This straightedge is a little over 4" long.

 

[PatrickR]

I'm to sure if it has been mentioned but urning under power can easily cause this. Once you have the shape you want only sant with the lathe off going in the direction of the blank. I only sand under power to shape the blank. It removes material very quickly.

 

[leehljp]

There are some very good helps above. I too had that problem, but on a few larger pens. Over sanding was not noticed while it was on the lathe, but it became noticeable when assembled. That means that you have a good eye. Some people don't notice that. Jim Lane has a good photo above that shows what happens when we over-sand. I have dozens of steel straight edges and squares of all sizes. I keep two or three near the lathe at all times but don't usually think about it until it is too late. Using them during turning IS a great help. After a while, the ration of it being a problem diminishes.

As to "why," I am not 100% sure. My thoughts are that a shiny finish will accentuate the mistake, whereas the matt surface of an unfinished pen masks the minuscule mistake, and it is unseen until polished/shined. Again, I have done that and wondered why I didn't see it until after finishing it.

That said, with experience there is another way to overcome it. I don't apply CA with paper towel, but use flat applicators that I make from margarine tops or other nylon/plastic bowl tops, or foam applicators purchased from crafts stores. It applies a thicker layer. Through considerable experience with CA, I can build the CA up along the length of the blank until it is more than needed, (by about .01) and then sand or turn back until perfectly straight. This build up of CA does not reveal an over-turned or over-sanded blank, but makes it look like it should. One caveat: if building up a thicker CA thickness, it does require 10 minutes to an hour or so for it to be ready for sanding or turning. I have built up the thickness of the CA and let it set over night.

 

[jrista]

I've been working on my turning problems with pens. I think a lot of my sanding problems come from the vibrations I experience while the blank is spinning, and as I'm trying to clean up the ends of my blank with sandpaper, I end up just ruining them. But, I think it all stems from vibrations, notably at the live center end of things.

I've been trying a lot of the things you guys have been sharing (from this thread, and another about out of roundness/non-concentricity), and also found a PDF file from these forums that explained a TBC technique. I followed most of the instructions in that PDF, which starts with turning the blank round, then down to just a bit above the bushings, with whatever system you prefer. Once you have mostly turned down the blank, you ditch the mandrels and bushings altogether, and just put the brass tube with the blank between two centers. No bushings, just the tube and the blank.

From there, you re-true the blank. If you have vibration problems like I do, this is necessary. I think, now that I've been digging into this problem for a couple weeks now, is due to several issues with...all of my mandrels and centers. Once I've have the blank trued up, and at this point for me this is the first time I'll hear the tool cut the wood cleanly without many vibrations or continual chatter or anything like that, then I can turn it down to the appropriate size by measuring with calipers. This is slower for sure, takes a lot of checking, and you have to take really fine, light cuts as the thinner the blank gets over the brass tube, the harder it is to avoid ripping it to pieces. There is still a small amount of vibration at the live center end...but, more on this in a moment.

If I am extremely careful, once I'm turning sans bushings and just between centers, I can get the blank turned pretty accurately. In some cases, with some kits, I was able to turn a bit smaller than the bushings, as the bushings weren't really sized right...the bands on two kits I turned recently have convex aspects to them, and when turning just down to the bushings, the blanks have a hard right-angle edge that butts up against these convex shapes, and it doesn't look good. On the second of these two kits, I did this sans-bushing TBC turning, and turned the blank down to about ~0.445", while the bushings were ~0.46". The second kit looks better. The wood ended up quite thin doing this, however, so its very very delicate work! I have picked up some Mercury Flex CA to try CA finishing again...I have always been worried that adding CA will expand the diameter of the pen (well, at least in my experience, it does, making the blank thicker than the bushings). I think with sans-bushing turning, I will be able to thin the blank out a bit more, giving me room to build up some layers of CA without that worry...hopefully.

----------

I have a lot more practicing to do, but this may be what solves most of my pen turning problems in the long run. I believe ALL of my centers have problems that are leading to my issues. So I'll also have to resolve that. I have the PSI TBC system, a PSI fixed shaft mandrel, and a normal pen turning mandrel from my original slimline starter kit, as well as some standard live centers, including a very common 60 degree live center:

Buy WoodRiver 60 degree Ball Bearing Live Tailstock Center 1 Morse Taper at Woodcraft

WoodRiver 60 degree cone live centers are perfect for pen turning mandrels weed pots or general turning projects These heavy duty ball bearing centers can also be used for hol

www.woodcraft.com

The vibrations prevent me from turning the blank down to the proper dimensions. As a little test, I can put my fingernail up against a bushing while it is spinning. If my fingernail touches without any ability to "see through" the bushing and my fingernail, then the bushing is likely turning true. This is usually the case with the bushing at the headstock end. When a bushing is vibrating, my fingernail cannot actually be fully pressed into the bushing, and there will be (at high speed) what looks like an air gap between the bushing and my fingernail. The thickness of that gap, is usually the amount of non-concentricity or out of round that I'll end up with on the blank at that end. I've tried flipping the blank around, but, once I've turned it down enough to identify the problem, flipping it around usually means the non-concentricity remains, and if I turn the edge that is higher than the bushing down, the other edge ends up smaller than the bushing...so non-concentricity, once it is there, doesn't seem correctable unless you get rid of the bushings and just put the blank directly between centers (which is then a much more meticulous process.)

First, both my pen mandrels have bent shafts! Including a rather expensive one from PSI. The PSI one is actually worse than the classic kurled brass nut type with the adjustable shaft. The PSI one has become rather useless, as the vibrations are completely untenable. I bought that a while back, months ago, so I may not be able to return it...although when that didn't actually fix any problems when I first bought it, I stopped using it as I ordered the PSI TBC mandrel system. So its hardly had any use, mostly still looks like new, and is still in its original red container. Anyway...

The TBC mandrel also has problems. It seems like it has a slightly bent shaft on the live center part, but I don't think it is actually bent, or if it is, its not all that much, or maybe just circumstantial. The dead and live center both have about a 1" shaft on them, or "pin" I think its properly called. Anyway, I was experimenting with that earlier, and I found that the bearing is very "soft"...its not a tight fit, and just a bit of twisting the live center with relatively mild force with my fingers can twist it a bit, and the pin will move around (change angle). I think depending on exactly how the bushing seats onto the live center, it will shift the angle of the live center on the bearing, and then the pin would effectively be wobbling once the lathe is turned on. I've had plenty of vibration problems with this, and I believe those can all be traced back to this "soft" bearing. I tried to tighten that up, but I don't have any tools that seem sufficient to allow me to try and tighten the plate that covers the bearing...so, this tool may also be useless.

(I've tried contacting PSI several times about this through their contact form, but over the last week and a half I've received no reply. I'll be tryin to give them a call next week, to see if I can get these items replaced...but, ATM, I'm extremely dismayed at the quality of these tools. They came right out of the box with these problems!)

I also found issues with my 60 degree live center...it is not actually truly tight in the bearing either, it is soft like the PSI TBC mandrel. It also seems to settle into a position where when I bring the tailstock up so I can have my 60 degree dead and live center points almost touching, then rotate the live center, I can tell that it does not in fact spin entirely true! The tip of the live center wobbles slightly around the tip of the dead center. At speed, this wobble is about the magnitude of the vibrations I've experienced with bushings between these two centers, and about the size of the non-concentric shift to one side I end up having with blanks I turn that way (maybe, half to two thirds of a millimeter.)
This is one of those very common live centers, the type I linked above, I see almost every turner I watch on YouTube using one of these, except those that use the Robust/OneWay/EWT type modular live centers (which are a lot more expensive.)

Oh, I also have two different kinds of "Mandrel Saver" type live centers. One I picked up at the local Woodcraft, I think it was around $30 or so, and the other I bought from Craft Supplies USA. Both also have soft bearings, where you can wiggle the live center on the bearings. The "Apprentice Live Center" I picked up from Craft Supplies has a VERY loose bearing! It only stabilizes once its got quite a lot of pressure on it...a lot more pressure than I'm comfortable putting on a pen blank and brass tube. That one I may still be able to return, I'll have to see.

So it seems every tool I have to turn pens, has an issue that causes vibration. All told, the cost of all of these tools is something like $180 or so. I find that rather depressing, that so many tools all have manufacturing issues like that. I'm not entirely sure what to do, either... If anyone has any highly reliable options they could recommend, I'm all ears. Even with just pure TBC without bushings or anything, my 60 degree live center still has its wobbling problem, and without any bushings you cannot put much pressure on the tube, otherwise you risk expanding it and preventing tight compression fit for the pen parts, or even cracking the blank. So the live center still causes a slight bit of wobble at the far oh, 1/3rd of the blank. Less than when using bushings, but...its still not ideal.

I have also experimented with the tailstock on my wen. I've tried locking it down in different ways...pushing it back in the track, pulling it forward, angling it left or right. The difference each of these adjustments make is minuscule, barely detectable. I've also tested bringing the live and dead center points together with the quill retracted and fully extended, and in both positions the points seem to come to the same place (the 60 degree live center obviously has its wobble problem, but I'm not noticing that there is actually a difference in the position it comes to when I bring the points together.) I'm checking the point locations both from the side and the top, and they are darn close to each other. The Laguna is currently out of commission awaiting a motor repair, so I haven't tested anything on that yet.

Anyway...the few couple of days (well, in total probably a couple of weeks) have been very revealing, and extremely disappointing! I'm amazed at how poor quality most of these tools are. Just floored. I now understand why I've had so man problems...but, I'm at a loss as to what to replace all of these with. Its a huge waste of money for the most part...I may only be able to return one or two of these items. What a journey. At least I understand the core of the problem, though...so hopefully I can find the right tools from the right brands, and put these issues behind me.

 

[jrista]

I turn mostly straight pens. Why? Because I prefer them myself. I like the way they feel in my hand when I use them.

My trick to making straight pens is to keep a 4 inch double square at the lathe. I use the blade (ruler) to check for straightness.
https://www.google.com/search?q=4+inch+double+square&tbm=isch

When done turning, I use the popular cone-shape plastic non-stick bushings for sanding and finishing. The bushings expose the ends of the turning(s), so you can keep checking with the square's blade as you sand.

P.S. My friends teased me so much about the straight pens that I made some seriously curvaceous pens for them. They thought I couldn't turn curvy shapes on the lathe. Not true.

I recently picked up a small little square. I don't think it is 4" long, maybe 3" or thereabouts. ITs small, and its pretty much perfect to measure pens. I picked it up for a different reason, but that same day I used to to check pens. Its quite useful, and immediately shows any curvature.

I also started taking the blank and brass tube off the bushings, and just putting them directly between centers for final turning and finishing. I tried using the plastic bushings, but they would still wobble on the mandrels, and got completely chewed up when I tried them just between centers. So I'm just finishing between centers now. So far, seems to work pretty well.

I hear ya about overly curvy pens! For some pen styles, like Sierra, I think a bit of a curve fits...but, on the slimlines, most rollerball and fountains, etc. I really like a straight look better! Or, maybe a very slightly curved pen body, and a straight cap. I've done a number of curved pens (I see a LOT of those for sale for some reason), and I have even tried some of those more oddball shapes...multiple bulges, or even angled cuts, stuff like that. I think I could do some thin grooves or maybe ridges in the lower part of a lower blank for grip, and maybe some decorative grooves or ridges, but the crazier shapes...well, not a single one I've made so far feels good in my hands, for one! They just lack effective ergonomics, and for some reason I can't bring myself to really make non-ergonomic pens.

 

[jrista]

Do you have a digital caliper ? Makes it easy to measure the amount of bulge you like , and ensure some consistency between pens . My guess would be that you have a 12-15 thou bulge on the diameter of the upper barrel of the second pen . I prefer 8-10 thou on an upper slim barrel , but use 12-15 on a Sierra style pen .

I do, yes. I've tried using it, and the last few pens as I described a couple posts up, I'm using calipers now to carefully measure my final turnings bushingless between centers.

I haven't actually measured the bulge on the most recent Sierra style I turned...but, I would say its probably around 15 thou. The curve follows fairly nicely from the nib, but I feel it may be slightly too thick. I have some non-concentricity with that one, and have thought about disassembling it, putting it sans-bushings between centers, and do some final turning to see if I can true it up. The finish was rather light on it as well, and I am thinking it might be worth trying to take off 2-3 more thousandths and then finishing with CA. I picked up some Mercury Flex to try.

 

[jrista]

What an annoying issue. I have two thoughts:
1. Get yourself some digital calipers so you can measure the diameter across the length of the pen. Your ruler could have a slight warp, you could be slightly non-concentric, etc.
2. If you have a dead center (I got mine for around $15 off Amazon) and a 60 degree cone revolving center (~$30 from I don't remember, probably PSI), dispense with the bushings. Put your barrel in between centers and take your measurements from the pen parts themselves. For me, turning between centers solved so many issues, and my gut says it might solve yours too. It does take a little more time because of constantly stopping to check with calipers and also having to finish each half of the pen separately, but for me it has been 1000% worth it.

Thanks for the tips! I started another thread on these forums, about out of round, and I received the same recommendations there. So with my most recent pens, I did just that. I received a 60 degree dead center a couple weeks back, and had a 60 degree live (although, read my post a few posts up to see that the 60 degree live has problems), and it was an improvement.

Eventually I learned even just turning with bushings between centers like that wasn't quite working, and I was still having out of round/concentricity problems, so I ended up ditching the bushings entirely like you've recommended here (and some other people as well, plus there is an old 2015 article (actuall, I think older than that even) from these forums that recommends the same thing). For the final bit of turning and finishing, I just put the brass tube and blank directly between centers, and use my digital calipers to turn it down to exactly the dimensions I want.

I think this is indeed the long-term solution...although I still have some other issues to resolve (see post above).

Picked up some Mercury Flex today, both thin and medium. I've tried CA in the past, but I may have a 60-pen order (first large order!) Coming through, and I think for those pens I'll need a more durable finish than the friction polish or pens plus friction+microcrystalline wax I usually use.

 

[jrista]

I have had similar experiences with the Slimline. My resolution was to buy center bands for Comfort pens and convert my Slimline kits into Comfort kits (sorta). The only difference is the diameter of the center band. In my opinion, the larger Comfort center band permits more of a gentle gradual shape between the band and the nib and between the band and the finial versus the straight flat area on a Slimline. It makes a slight bulge look a little more natural to me.

Slimline bushings at the nib, center, and finial are all 0.333 inches in diameter (nominal). Comfort bushings are 0.333 inches for the cap and finial, but are 0.420 inches (nominal) for the center band.

Dave

Interesting. I hadn't seen the Comfort bands before. So you basically have a pen that bulges a bit in the center, then tapers towards the ends?

It looks like WoodTurninz has some comfort bands. I may have to give that a try...I still have a few slimlines to turn.

 

[leehljp]

. . . Once you have mostly turned down the blank, you ditch the mandrels and bushings altogether, and just put the brass tube with the blank between two centers. No bushings, just the tube and the blank.

If I am extremely careful, once I'm turning sans bushings and just between centers, I can get the blank turned pretty accurately. In some cases, with some kits, I was able to turn a bit smaller than the bushings,

I also found issues with my 60 degree live center...it is not actually truly tight in the bearing either, it is soft like the PSI TBC mandrel. It also seems to settle into a position where when I bring the tailstock up so I can have my 60 degree dead and live center points almost touching, then rotate the live center,

Oh, I also have two different kinds of "Mandrel Saver" type live centers. One I picked up at the local Woodcraft, I think it was around $30 or so, and the other I bought from Craft Supplies USA. Both also have soft bearings, where you can wiggle the live center on the bearings. The "Apprentice Live Center" I picked up from Craft Supplies has a VERY loose bearing! It only stabilizes once its got quite a lot of pressure on it...a lot more pressure than I'm comfortable putting on a pen blank and brass tube. That one I may still be able to return, I'll have to see.

If anyone has any highly reliable options they could recommend, I'm all ears. Even with just pure TBC without bushings or anything, my 60 degree live center still has its wobbling problem
. . . and without any bushings you cannot put much pressure on the tube, otherwise you risk expanding it and preventing tight compression fit for the pen parts, or even cracking the blank. So the live center still causes a slight bit of wobble at the far oh, 1/3rd of the blank. Less than when using bushings, but...its still not ideal.

A general truth: the more items needed turn a pen, the problems that you have to deal with, kind of like taking 5 or 6 meds, it takes a while to figure out which one is interacting with a different one that is causing as much problem as they solve. It is hard to figure out which two out of 5 or 6 are the cause.

I noticed and highlighted several spots in your post. PSI followed by a few others have caused a problem in perception in the last few years among those new to pen turning. TBC has nothing to do with mandrels; Listing Mandrel savers are a form of TBC greatly distorts and complicates explanation for something that is, or was simple. Mandrel Savers are not true TBC.

Here is a pict of TBC, pure and simple.

Custom Bushings on TBC setup

Custom Bushings on TBC setup

www.penturners.org

1. Notice the bushings on it but no mandrel;
2. I simply take the bushings off at final sizing and finishing with CA.
Some people do not use bushings with TBC and they do well, but many do use the bushings with TBC. NO MANDREL at any time, nor since about 2007. I do have some from back then, just don't use them as there is no need.

IN that set up, if there is vibration, it is either bad bushings or drive (dead) center or live center/tail stock alignment. With bushings eliminated as the problem, it is easy to figure out if it is the head stock or tail stock.

Hope this helps. If you have more questions please ask.

 

[jrista]

A general truth: the more items needed turn a pen, the problems that you have to deal with, kind of like taking 5 or 6 meds, it takes a while to figure out which one is interacting with a different one that is causing as much problem as they solve. It is hard to figure out which two out of 5 or 6 are the cause.

I noticed and highlighted several spots in your post. PSI followed by a few others have caused a problem in perception in the last few years among those new to pen turning. TBC has nothing to do with mandrels; Listing Mandrel savers are a form of TBC greatly distorts and complicates explanation for something that is, or was simple. Mandrel Savers are not true TBC.

Here is a pict of TBC, pure and simple.

Custom Bushings on TBC setup

Custom Bushings on TBC setup

www.penturners.org

1. Notice the bushings on it but no mandrel;
2. I simply take the bushings off at final sizing and finishing with CA.
Some people do not use bushings with TBC and they do well, but many do use the bushings with TBC. NO MANDREL at any time, nor since about 2007. I do have some from back then, just don't use them as there is no need.

IN that set up, if there is vibration, it is either bad bushings or drive (dead) center or live center/tail stock alignment. With bushings eliminated as the problem, it is easy to figure out if it is the head stock or tail stock.

Hope this helps. If you have more questions please ask.

Hi Hank. Thanks for the response.

FWIW, I am aware of the differences between a normal pen "mandrel", the PSI TBC Mandrel (their particular product) and just TBC (turning between centers, no mandrel). I've tried to be accurate with my terms. When I say "mandrel", I do mean a mandrel (a normal one, or the PSI TBC mandrel...i.e. something with a rod that you put the blank on..or, pins that stand in for the rod) and when I say "TBC mandrel", I am specifically referring to the PSI product. PSI sells a particular component, and I bought it, and it has problems. I've ALSO done just plain old TBC, just between two 60 degree centers, no mandrels, with and without bushings. I agree, "true TBC" is better, and no bushings seems to be the best, but it only really seems to be viable when doing final turning down and finishing.

With "true TBC" with bushings, I have still had problems with vibration. I actually have problems even without bushings, but its less. The 60 degree live center I have is apparently a piece of junk (I think it came with my very first lathe, a Nova Comet 14DR, which is also a piece of junk. ) So even without any mandrels of any kind, turning just between centers, with bushings, I've had some fairly significant problems with vibrations in the bushing a the live center end. That, in turn, seems to have lead to a groove being turned into my live center itself, which just made it all worse. I managed to turn that groove out with a bit of care, and kept the angle and surface of the live center, but it still has the bearing problems.

As far as I can tell, I don't have either headstock, tailstock, or dead center problems...the problems stem from all the looseness in all of my live centers, and possibly also bent mandrels (real mandrels...i.e. the shaft you put bushings on attached to an MT#2.) The problems come from the live center. I tried with the live center I got with my Wen lathe. It is a tighter live center, it doesn't spin completely freely, but, it also has ZERO wobble or looseness in the bearing. I think Wen is over-compressing their live center tips into the bearings, and they could stand to be just a smidge less tight, spin more freely, but still not have any wobble... It took a little bit more pressure with the wen live center, but, it seems to spin true... It is not 60 degrees, but I'm not sure that is going to matter. I haven't completely turned anything with it yet, that's my next task.

 

[leehljp]

Hi Hank. Thanks for the response.

FWIW, I am aware of the differences between a normal pen "mandrel", the PSI TBC Mandrel (their particular product) and just TBC (turning between centers, no mandrel). I've tried to be accurate with my terms. When I say "mandrel", I do mean a mandrel (a normal one, or the PSI TBC mandrel...i.e. something with a rod that you put the blank on..or, pins that stand in for the rod) and when I say "TBC mandrel", I am specifically referring to the PSI product. PSI sells a particular component, and I bought it, and it has problems. I've ALSO done just plain old TBC, just between two 60 degree centers, no mandrels, with and without bushings. I agree, "true TBC" is better, and no bushings seems to be the best, but it only really seems to be viable when doing final turning down and finishing.

With "true TBC" with bushings, I have still had problems with vibration. I actually have problems even without bushings, but its less. The 60 degree live center I have is apparently a piece of junk (I think it came with my very first lathe, a Nova Comet 14DR, which is also a piece of junk. ) So even without any mandrels of any kind, turning just between centers, with bushings, I've had some fairly significant problems with vibrations in the bushing a the live center end. That, in turn, seems to have lead to a groove being turned into my live center itself, which just made it all worse. I managed to turn that groove out with a bit of care, and kept the angle and surface of the live center, but it still has the bearing problems.

As far as I can tell, I don't have either headstock, tailstock, or dead center problems...the problems stem from all the looseness in all of my live centers, and possibly also bent mandrels (real mandrels...i.e. the shaft you put bushings on attached to an MT#2.) The problems come from the live center. I tried with the live center I got with my Wen lathe. It is a tighter live center, it doesn't spin completely freely, but, it also has ZERO wobble or looseness in the bearing. I think Wen is over-compressing their live center tips into the bearings, and they could stand to be just a smidge less tight, spin more freely, but still not have any wobble... It took a little bit more pressure with the wen live center, but, it seems to spin true... It is not 60 degrees, but I'm not sure that is going to matter. I haven't completely turned anything with it yet, that's my next task.

It does seem that the problem is in your live centers, but as an after thought have you cleaned the (senior moment) tail stock that the live center fits into? Another thing, and I am reading into your answers that you are fairly meticulous that this next suggestion doesn't apply to you, but is your lathe "ways" clean? Does your tail stock slide smoothly and lock into place in alignment?

I still think you have narrowed everything to the live center. I have the same one I got about 12 years ago from Grizzly. The same one now costs $55!!! Seems like I paid $25 or $30.

Live Center - MT2 with Taper Bearings

Perfect for just about any turning requirement, these dust, chip and oil proof live centers feature 60° included angles and pre-loaded taper bearings. Type: MT #2.

www.grizzly.com

 

[jrista]

It does seem that the problem is in your live centers, but as an after thought have you cleaned the (senior moment) tail stock that the live center fits into? Another thing, and I am reading into your answers that you are fairly meticulous that this next suggestion doesn't apply to you, but is your lathe "ways" clean? Does your tail stock slide smoothly and lock into place in alignment?

I still think you have narrowed everything to the live center. I have the same one I got about 12 years ago from Grizzly. The same one now costs $55!!! Seems like I paid $25 or $30.

Live Center - MT2 with Taper Bearings

Perfect for just about any turning requirement, these dust, chip and oil proof live centers feature 60° included angles and pre-loaded taper bearings. Type: MT #2.

www.grizzly.com

Hi Hank! Thanks for sticking with me!

Regarding the quill, I have cleaned it a couple of times. I've felt around inside with my pinky, and I haven't felt anything in there, but, I can only get it in so far as well. My lathe is usually clean. I am constantly blowing, brushing, or otherwise cleaning it off, even as I work. I know a lot of people let everything build up, but I can't seem to do that myself. Now, I don't constantly clean the insides of my spindle or quill, but, I do try to clean them out fairly regularly. Lately, I have been checking those, though. In fact, I found that on the Wen, the spindle hole had a bit of a ridge, and that was digging into some of the morse tapers I was putting in there. I have these tiny little gouges on two sides of the MT on some of my dead centers. I've cleaned those up, and then I polished down that sharp edge on the spindle. I haven't had the problem with that edge catching since, and dead centers still seem to seat just fine and turn true.

I should try to take a short video for you. I did a test, and it is the part of the live center that rotates that is rotating out of true and wobbles. I'll see if I can do that.

I have been looking at the....I think it was the Robust live center. Well, honestly, I've looked at Robust's, OneWay's and Easy Wood Tool's. They are all largely teh same thing, modular and capable of handling multiple cone attachments, and all use a multi-bearing system. The EWT is ridiculously expensive (almost $200!!), the OneWay and Robust are also expensive, but not as bad as the EWT. I've had some people warn me away from the OneWay, saying the bearings don't seat well (Which seems to be a rather broad problem across many centers...) I've heard good things about the Robust...so far nothing negative. I may give that a try.

Live and Drive Centers

Robust Drive and Live Centers Made right here in the Robust shop, Robust ring, or cup-style drive centers are a proven way to safely turn between spindles. We feature the largest radial thrust bearing used in any commercially available woodturning live center. To adjust or remove the tip...

www.turnrobust.com

Before I dive in and spend that money, I may try to just get a cheaper live center, similar to what I have, and see if the bearing is better. The one I have is just junk. It came out of the lathe box rusted, which kind of surprised me at the time, but...I'm starting to wonder if some of my problems turning in the past have been related to that live center. But, when I get the cones and the live center, the total cost of the Robust will be something like 5-6 times as expensive as just a normal 60 deg. live center...

 

[PatrickR]

If your live center is questionable replace it with a quality one. Don't waste money on another budget tool. i think PSI tools are a crap shoot. A live center needs to be precise. I have a Nova that's probably 20 years old. Buy once, cry once.

 

[leehljp]

Hi Hank! Thanks for sticking with me!

Before I dive in and spend that money, I may try to just get a cheaper live center, similar to what I have, and see if the bearing is better. The one I have is just junk. It came out of the lathe box rusted, which kind of surprised me at the time, but...I'm starting to wonder if some of my problems turning in the past have been related to that live center. But, when I get the cones and the live center, the total cost of the Robust will be something like 5-6 times as expensive as just a normal 60 deg. live center...

I know that this is not being used on a mandrel now, but some of those those live center cones are not 60°. But even the custom made TBC bushings, and all mandrels require 60° cones. There are a few instances in which 60° cones are not necessary but that is speciality situations. However it sure helps to standardize on 60° cones for pens. The reason is: if a mandrel IS used, all mandrels require 60° cones to fit correctly in the dimple in the end of the mandrel, AND custom made TBC bushings are turned to accept 60° cones. And the reason for those two situations is that the mandrel rods are metal, bushings are metal . . . in the metal world 60° has become the "basic" standard for metal to metal points. Can't argue with machinists!

Back to your question, a simple and normal 60° live center just might clear up your problems. Even buying the best and highest quality tools and equipment does not prevent one or two getting through with defective parts. This type of problem pops up on this forum with quality equipment a couple of times a year. Most of the time, the manufacturer replaces the defective part without cost. BUT it takes troubleshooting and finding specifically where the problem is. In some cases it takes buying a replacement and finding that the original was defective.

 

[jrista]

Alright, success! It was indeed all the vibrations, and that 60 degree live center was definitely causing problems for pure TBC.

I was digging around in a drawer for a bushing, and found another 60 degree live center in a container. I don't remember when, or why, I put it in there, but....I think this is the original live center I received with the Nova Comet 14DR lathe back in Feb. 2020. That lathe....well, its a joke, and has had so many problems since I bought it. I eventually sent it in for repair at Teknatool, which took months...when it was finally sent back, they had included more tools and another dead and live center. I think the live center I've been using is the one they sent back after the repair, and it really is a piece of junk. I don't think it was supposed to be sent back, the thing was rusted and well used...somewhere along the line, I put my original live center in a drawer and forgot about it, thinking the returned one was all I had...

Anyway. The other live center was much better. A bit beat up...it was my first live center, I think, and when I first started turning I didn't know how to keep the tool off the centers. I cleaned it up a bit, smoothed out some of the scratches, and tested it out. Rock solid, no wobble in the bearing, totally true spinning. Turned a PSI version of a trustone blank on it, and it went really well:

Turned

Dry Sanded with Abranet

Wet sanded with MicroMesh, right down to the bushings

Assembled

First time I've been able to actually get this level of precision. At least now I know it is possible.