Hard Facts on TBC, Mandrels, Centers and 60°

[leehljp]

Hard Facts on TBC, Mandrels Centers and 60°

There seems to be a constant confusion concerning TBC, (Turning Between Centers) and Mandrels as it concerns the live and dead centers and also bushings. I hope to clarify this and ask anyone to clarify if there are errors in my presentation here. AS people comment, I will edit in the changes.

(Premise for this: Constant mixing of information that is not technically correct and conveying erroneous perceptions, which causes some new people to have mixed emotions about the viability of TBC.)


1. Mandrels ARE metal and metal mandrels require a 60° Live Center (LC) to function properly.
Over the past several months, there have been posts here concerning vibration and Out Of Round/Eleptical pens. On several it takes the 2nd and 3rd page of replies before it is discovered that the person is NOT using a 60° live center.


2. 60° Live Centers are the industry standard for METAL, but NOT wood lathes.
Most people who buy their first wood lathe do not know the difference, and consequently run into problems as mentioned in number 1 above.


3. TBC, in contrast to using Mandrels - does not REQUIRE 60° LCs or 60° Dead Centers - when using the standard mandrel bushings.
It would be better to go to the same standard as used with mandrels (60°) but it is not necessary as an absolute for getting started.


4. COST: Except for Slimline series, getting started can be cheaper with TBC than with Mandrels - simply because most mandrels cost more than a Dead Center. Dead Centers can even be made at home on the lathe. Some wood lathe "centers" that cause problems on mandrels - can be used just fine for TBC. Check your lathe's stock "center" to see if it will work.

One advantage of TBC is the higher quality bushings available from JohnnyCNC, and while they cost a little more than standard, they are worth it. These do require a 60° LC-DC because the holes are chamfered to this. It only takes getting one or two sets of bad bushings from a commercial vendor to appreciate the bushings that John makes.


5. STANDARD MANDREL BUSHINGS OK for TBC in getting started. . . . UNLESS they are drilled Off Center. :hammer:
TBC began with many using the standard Mandrel Bushings, but due to some of these being drilled off center, John (JohnnyCNC) (and Paul in OKC for a short while I think) began to fill a void by offering custom precision bushings that once used, it is hard to go back to mandrel bushings again. Still, to get started, one can use what they have on hand. There may be (will be for most) some slippage due to the fact that the mandrel bushings do not have a chamfered shoulder for nesting in the DC and LC. But this it self will not hurt the precision unless the bushing is drilled Off Center.


6. SIMPLICITY IS AN ADVANTAGE of TBC
A. It uses LESS PARTS - eliminating the problems associated with the mandrel,
• Over tight tail stock,
• Flexing mandrel,
• Bent mandrel,
• Using wood lathe stock live center on mandrel;

B. It offers options of finishing without bushings . . . TO PREVENT:
• Bushing sanding dust,
• Glued in bushings,
• CA "lift" or "chipping" when separating the bushing from the blank

C. Using calipers to determine size extends the life of the bushings. On Mandrels, bushings are considered consumables (need to be replaced after sanding down or turned down with the skew/scraper.

If one were to check past problems that people have with vibration and OOR, a high percentage of those would be associated with mandrel usage. While long time lathe users do not have most of these problems (because their experience and skill have worked them out) new people often do.
When mentioning TBC to correct these problems, TWO PERCEPTIONS pop up regularly against the use of TBC: Cost and Complication! Both of these are more Perception Problems than real problems.


7. PERCEPTION VERSUS FACTS: TBC is not expensive to get started, but when it is mentioned that TBC Requires a 60° DC and LC, it does appear that it is going to cost more. When chamfered bushings are mentioned to beginners, Cost again comes to mind as well as complicated set ups for which most people are not ready. This is the PERCEPTION that people get . . . even though most people already have bushings and a wood stock live center and some kind of drive center on hand - that can be used.

NOT ADDRESSING THE FACTS when these perceptions pop up - as people refer to TBC - unintentionally leads to and spreads misinformation. That is what Perception does! I tried to address this with a fellow member who said he wanted to move to TBC. I thought he was speaking of it from a complicated point of view and wished to eliminate any complications. He took it in a straight forward way in which it was intended and not as criticism. In my trying to correct that perception, another veteran member took it as a remark against him, which it wasn't. Perception, Context, Facts. Dangerous but necessary!


The above is for Getting Started, Making The Transition from Mandrels to TBC. Below is for "moving on up".


CREAM RISES TO THE TOP! After getting started, and the speed and simplicity are discovered, many people will want to make modifications, buy more durable products such as carbide tipped/hardened centers, along with Johnny's bushings along with his and others delrin bushings.

TBC can start inexpensively enough, but there are plenty of options to climb to the top of precision turning with durable lasting products. TBC is what will help move to the $100, $250, $500, $1000 and more quality pen. To be sure, these can be accomplished with mandrels for sure but TBC can make the transition to this quality much faster for those just starting out. It is not a panacea, but it is huge.

For a tutorial, Here is a link to the most superb Tutorial on TBC to date:

http://www.penturners.org/forum/showthread.php?t=54760

 

[KenV]

was that the "bully pulpit' you have been standing on, or just a darn good soap box.

the challenge is that most come to the IAP having already been helped down one path by vendors -- and/or friends and neighbors.

That puts TBC into a conversion process -- and that gets to sunk costs and leaving what I first learned to go in a different direction.

Nice explanation ---

 

[leehljp]

was that the "bully pulpit' you have been standing on, or just a darn good soap box.

the challenge is that most come to the IAP having already been helped down one path by vendors -- and/or friends and neighbors.

That puts TBC into a conversion process -- and that gets to sunk costs and leaving what I first learned to go in a different direction.

Nice explanation ---

Agreed! on all accounts. :biggrin: Over the past couple of years, There have been a few people (relatively new folks) who asked why TBC was not taught at the beginning. As you said, the commercial ventures catch folks unaware!

One thing that I did not mention concerning perception is that the opposites are true: Mandrels have the image and perception of entry level and therefore easier and cheaper. TBC has the image of high end and therefore expensive and complicated. Since mostly experienced users are doing TBC, that further fosters the wrong perception of being for the experienced high end user instead of for the beginner.

 

[altaciii]

I'll be the first to raise my hand. I was sucked into the commercial vendors trap with my initial purchases. Not that it didn't and works for me still. I have adjusted and have had moderate success in selling enough of my pens to help increase my tool inventory and in turn the quality of my work. Newbies usually want to enter into this madness with the least possible cost to them, albiet most of us have our own CFO'S at home to help us curb our spending. I have purchased at least 7 mandrels since I started and just last week contacted johnnycnc to order the proper tools for tbc turning. I can't wait to see the difference. Hank, thanks for the soap box and the link, to me it was a great read and I now have saved it for prosperity.

 

[Mac]

Very good ,I want to move on up to the east side too.

 

[jbmauser]

I am a relative newcomer to the hobby but I have some comments to add.
Item # 1 is no longer correct. The new PSI catalogue includes a center open live center where the mandrel slides freely into the live center and is retained by the bushing itself. It is designed to have no end pressure to bend the mandrel.

You have completely lost me with your TBC. In my understanding to turn between centers cannot be done with a traditional mandrel. A mandrel is driven by either a 3 or 4 jaw chuck, a Morse taper arbor or a drill chuck. None of these are "Centers" a center is a point, as with a metal lathe the stock is held between centers or 60 degree points and the power is transmitted to the stock with a dog and faceplate. In a wood lathe the power is transmitted via gripping teeth attached to the center. The live center or dead center in the tailstock are for support and axial position.

I can only conclude that you use the term Center loosely. I have made a crude Pin mandrel that seems to work well, I run it with a metal lathe chuck and no tailstock center. It is a mandrel by definition.

I also do not understand how out of round or not too concentric bushings are going to mess up my barrel. I am turning a barrel on a shaft and that will cut true to the axis of the lathe. The bushing could be egg shaped and my barrel will still be concentric. If my tool touches the bushing as I cut to the edge my tool may shave some metal from the high spot but my barrel should remain true. If my mandrel is bent because the tailstock pressure is to great or it is out of alignment then I will turn an egg.

I have learned a bit and left a bit of rubble behind with bent mandrels, burned dead center tips, homemade bushings, and crude pin mandrels. Trial and error can be a bit expensive over time but lessons are rarely free. I hope to learn more here but I am confused . JB

 

[Smitty37]

TBC vs Mandrel

When I came to this hobby I had never turned anything on a lathe. If I wanted to take up the hobby (and I did) I had to go commercial or go looking to find someone to teach me how. I bought a couple of books got a video from PSI then bought a starter package from PSI which included a Mandrel. I have turned a couple of hundred pens now, but in the month or so since I was invited to join this group, is the first I had ever heard mention of TBC New pen turners who don't find this (or a similar group) could go their whole life an never know that pens could be turned without a mandrel.

 

[leehljp]

I am a relative newcomer to the hobby but I have some comments to add.
Item # 1 is no longer correct. The new PSI catalogue includes a center open live center where the mandrel slides freely into the live center and is retained by the bushing itself. It is designed to have no end pressure to bend the mandrel.

JB,

It is not available at this time and looks like it will eliminate some of the problems associated with mandrels. At least they are acknowledging that there is a problem with standard mandrels. Still it is more complicated to setup than TBC. Imagine you are working on a pen that is commissioned for $400 - $500 or more. With that in mind, most people will be very conscientious and will want to observe (remove, inspect, replace) the blank during the process two or three times or more. I know that I do remove and inspect blanks for the cheapest pens 3, 4 or 5 times in the turning process - and I know others have too as they mention their habits. This is not something fun to do with bushings and spacers.

Dang it, I hate it when I drop a spacer! With TBC, I can have a blank off in less than 5 seconds and back on in less than 5 seconds. It takes me 30 seconds on average with a mandrel. That is not much, but if one does want to inspect the blank closely, having it on a mandrel discourages doing it several times. I hate to even remove the mandrel from the head stock for inspecting the blank(s) as I have had dust get in the taper or something did not go back just right. I don't have that problem with TBC.

You have completely lost me with your TBC. In my understanding to turn between centers cannot be done with a traditional mandrel.

I will admit that while it is not that clear, it is as clear as I could get it in a short succinct statement.
. . . Here is what I said with a little alteration: - 3. TBC, in contrast to using Mandrels, TBC does not REQUIRE 60° LCs or 60° Dead Centers when using the standard mandrel bushings. TBC does not require specific 60° centers when using "mandrel BUSHINGS" as opposed to "TBC bushings".

It is a regular posting here by several who write that TBC REQUIRES 60° live centers and dead centers to work. It does not. Every time it gets written like that, that information is picked up an passed on. In My Opinion, It is better to go ahead and go this route (60° centers) for TBC, but it is not an absolute necessity when using bushings that are made for mandrels.

A mandrel is driven by either a 3 or 4 jaw chuck, a Morse taper arbor or a drill chuck. None of these are "Centers" a center is a point, as with a metal lathe the stock is held between centers or 60 degree points and the power is transmitted to the stock with a dog and faceplate. In a wood lathe the power is transmitted via gripping teeth attached to the center. The live center or dead center in the tailstock are for support and axial position.

I agree with that and I didn't think I gave the impression of anything different. I apologize if I made it sound different from that.

I can only conclude that you use the term Center loosely. I have made a crude Pin mandrel that seems to work well, I run it with a metal lathe chuck and no tailstock center. It is a mandrel by definition.

Centers: The two metal points supporting the blank in the picture in the link below:
http://www.penturners.org/photos/images/940/1_Dead_drive_1.jpg

Those two center above also work with bushings that I had previously used on Mandrels.

I also do not understand how out of round or not too concentric bushings are going to mess up my barrel. I am turning a barrel on a shaft and that will cut true to the axis of the lathe. The bushing could be egg shaped and my barrel will still be concentric. If my tool touches the bushing as I cut to the edge my tool may shave some metal from the high spot but my barrel should remain true. If my mandrel is bent because the tailstock pressure is to great or it is out of alignment then I will turn an egg.

This one gets tricky as different people label different problems differently. And I could use help at defining this portion.

Basically several things happen and no "one" explanation defines all of the different problems that can happen. In recent weeks we have had a fellow with wobble, another with vibration and another who said the tail stock blank was not round or shaved to near the tube on one side and high on the other. All of these are thrown sometimes erroneously into the same "Out Of Round" label. Of Center drilled bushings which cause the similar problems.

My first pen almost 5 years ago is here: http://www.penturners.org/photos/images/940/1_1st_pen_photo.jpg
On the nib end (technically by some it is not a "nib" on ball/rollerball pens) there is a high spot on one side and is visible, the other side is flat against the nib. How you describe it technically would be appreciated. But in the end, we still have this common problem that occurs on mandrels for one reason or another.

Some of these high/low spots are caused by Off Center drilled bushings. Some are caused by wobble/vibration on the tail stock end when using a Live Center made for wood lathe - that is placed into the dimple of a mandrel. The dimple hole of the mandrel and woodstock live center do not fit correctly, causing wobble, vibration or what ever that is not normal. Too much tool pressure against the spinning mandrel also causes this problem at times.

As to your question about Of Center:

I also do not understand how out of round or not too concentric bushings are going to mess up my barrel. I am turning a barrel on a shaft and that will cut true to the axis of the lathe.

Edited in:. YOU ARE CORRECT! I stand corrected!
But something I learned today - loose bushings in the tubes causes all kinds of problems. OC bushings can introduce vibration; Loose fitting bushings can cause vibration and movement - and combined with OC bushings the non-concentricity can be introduced. I do know that I have had non-concentric blanks turned even with TBC. But they were with commercial bushings. If you try one set of John's (JohnnyCNC) bushings - slide them into the end of a tube and then slide a commercial bushing into the other end - feel the play difference. I used to think my bushings were tight fitting until I got some of John's. Then I though John's were a little too tight! :biggrin: :wink: I figured out that what I thought was "tight" (commercial bushings) was actually loose by comparison. This combined with OC vibration will cause the elliptical shapes. By Elliptical, I mean that when I measure a turned blank and have 12.04 at one point and 90° from there I will get a reading of 11.98 or 11.99.

I have learned a bit and left a bit of rubble behind with bent mandrels, burned dead center tips, homemade bushings, and crude pin mandrels. Trial and error can be a bit expensive over time but lessons are rarely free. I hope to learn more here but I am confused . JB

JB, I hope I didn't confuse you and I certainly have a lot to learn myself. One thing that I do learn is that different regions and areas use different terms for the same thing! I try to understand that when writing.

Thanks for the questions. Please feel free to post your experiences. This is a great learning experience for all and for me too. It makes me think and my brain is almost too full to do much more.

 

[mickr]

you did a fine job here Mr. Lee (as usual) Newbies, trust this fella to know what he is talking about..he always does ...now just to throw a monkey wrench in this for you newbies with pen mandrels and people with no more $$$ to spend: when you turn your pen on a mandrel, you may find one side of the barrel is thicker than the other(OOR, or out of round) There is a very simple way to fix this with no more $ outlay. .When you are near completion of your barrel loosen the mandrel nut, spin blank one quarter turn and continue your turning of the barrel again..check the barrel and turn another quarter turn...this will get your blank to a pretty fair roundness...you aren't production turning, so the time is irrelevant... will save you some bucks now and later you can upgrade if you wish thanks Mr. Lee for this Terrific explanation

 

[dustmaker]

Hank,

First off, thanks for this. I am a TBC convert in principle...I ordered my centers yesterday and it looks like Johnny is already got them on the way. I have seen the OOR issues with the mandrel and experienced the vibration and effects of a damaged live center so I cannot dispute any of that and am looking forward to the TBC experience.

However, I too am having difficulty getting my brain around how off center bushings cause out of round. If we hypothetically assume a perfectly spinning manderl, perfectly on center, but only introduce off center bushings, I have to agree with JB...the wood you are turning should be perfectly round. When you encounter the off center bushing (like the cam you described) you will nick the bushing at its high spots. It seems to me in the end what you would end up with is a blank that is slightly proud of the kit, but not OOR. Isn't the blank and bushing spinning to fast for the chisel to follow the bushing? I ask with all due respect and humility, because you did mention that when folks started TBC with stock bushings they were still encountering problems, hence the confusion. Where is my reasoning flawed, or am I right about this?

 

[jleiwig]

Mandrels can get bent many ways, and I find this to be the cause of probably 75% of problems. I usually had to unscrew the mandrel shaft and roll it on a known flat surface every time to check for out of round conditions. After I started doing that, but before I switched to between centers turning, all my fit issues were resolved.

I think that one thing no one really harps on about between centers turning is how much more easy it is. Before with a mandrel if I wanted to pull a blank off the lathe to inspect it closer I had to move the tailstock, unscrew the brass nut, remove some spacers and then pull the blank off. Now I can just loosen the tailstock and pull the blank right out. When I'm done turning I again just loosen the tailstock and pop the bushings off and then put it back between the centers for finishing.

Soooo much easier than dealing with a mandrel, regardless of whether or not it's cheaper or I get a better finished product, the easiness is what sold me because from my younger days there is nothing I hate more than set up for production. I've always been an instant gratification wham, bam, thank you ma'am type guy anyway and I see turning between centers as a way to accomplish that.

 

[jleiwig]

Hank,

First off, thanks for this. I am a TBC convert in principle...I ordered my centers yesterday and it looks like Johnny is already got them on the way. I have seen the OOR issues with the mandrel and experienced the vibration and effects of a damaged live center so I cannot dispute any of that and am looking forward to the TBC experience.

However, I too am having difficulty getting my brain around how off center bushings cause out of round. If we hypothetically assume a perfectly spinning manderl, perfectly on center, but only introduce off center bushings, I have to agree with JB...the wood you are turning should be perfectly round. When you encounter the off center bushing (like the cam you described) you will nick the bushing at its high spots. It seems to me in the end what you would end up with is a blank that is slightly proud of the kit, but not OOR. Isn't the blank and bushing spinning to fast for the chisel to follow the bushing? I ask with all due respect and humility, because you did mention that when folks started TBC with stock bushings they were still encountering problems, hence the confusion. Where is my reasoning flawed, or am I right about this?

Try this experiement. Take a blank and mark the center on each end. Then mark another point 1/8" away from the center on one end. Make another point 1/8" away in the opposite direction of the first off center point. Put it on your lathe and put the tailstock end in one of the off center points. Turn that part round, then put in the second off center mark. You'll end up with an oval instead of a round. This is how you turn a hammer handle on the lathe, but it provides an extreme example of what we're talking about when your bushing is off center.

I take it from your description that you're used to working on a metal lathe. What you describe with nicking the bushing would happen with a metal lathe, but it will not happen with a wood lathe since you are not using a fixed feed in a perfectly co-planar alignment to the perfectly aligned mandrel. The mandrel does not provide the plane, the bushings provide the plane in which we are turning.

Think about it, you have a blank which has been drilled out and tubed, always 7 mm or bigger in diameter. You have a rod which is 5/32 or so in diameter. If both bushings are drilled perfectly on center, then your bushings, tube, and ultimately the blank are perfectly co-planar. If one bushing is drilled off center then the tube and blank are no longer co-planar to the mandrel, they are slightly off of co planar, and the end with the mis-drilled bushing will have more wood on one side of the tube and less on the other. When you insert your perfectly round pen kit fitting into the perfectly round tube, you will have one side with extra wood on it proud of the fitting and one side with little wood on it short of the fitting.

Hope this lengthy explanation helps. :biggrin:

 

[Sylvanite]

However, I too am having difficulty getting my brain around how off center bushings cause out of round. If we hypothetically assume a perfectly spinning manderl, perfectly on center, but only introduce off center bushings, I have to agree with JB...the wood you are turning should be perfectly round. ... Where is my reasoning flawed, or am I right about this?

It's a terminology issue. The term "out-of-round" (OOR) is used a bit loosely. What Hank is describing is really non-concentricity, not out-of-round. That is, the bushing hole (what the headstock/dead-center/tailstock/live-center lines up on) is not concentric with the bushing bearing surface (what the blank/tube lines up on).

This condition produces a turned blank that (in relation to the tube) is thin on one side, and thick on the other. When pressed onto a pen fitting, the barrel will be shy on one side, and proud on the other.

You are correct that if the bushing hole is concentric with the bearing surface, but the outside (let's call it a "guide surface") of the bushing is non-concentric, then you'll simply end up nicking one side of the bushing as you turn.

I hope that helps,
Eric

 

[dustmaker]

Justin, I appreciate the response and I think I am getting there, but you lost on me on this statement:

The mandrel does not provide the plane, the bushings provide the plane in which we are turning.

So if I put a slimline tube in a blank and use pieces of slimline tubes as spacers and turn down using calipers to 8mm (or whatever)....technically there are no bushings so what is then providing the plane if not the mandrel? Sorry, still confused :frown:.

 

[dustmaker]

It's a terminology issue. The term "out-of-round" (OOR) is used a bit loosely. What Hank is describing is really non-concentricity, not out-of-round. That is, the bushing hole (what the headstock/dead-center/tailstock/live-center lines up on) is not concentric with the bushing bearing surface (what the blank/tube lines up on).

This condition produces a turned blank that (in relation to the tube) is thin on one side, and thick on the other. When pressed onto a pen fitting, the barrel will be shy on one side, and proud on the other.

You are correct that if the bushing hole is concentric with the bearing surface, but the outside (let's call it a "guide surface") of the bushing is non-concentric, then you'll simply end up nicking one side of the bushing as you turn.

I hope that helps,
Eric

Ok, I think I am getting the error of my reasoning. The slimline example that I gave is no good since the tube will always be concentric with the mandrel. But with larger tubes the bushings provide an opportunity for non-concentricity (is that a word) because there are three surfaces involved: the inside surface that rides on the mandrel (or lines up with the centers in TBC), the surface that the tubes fit onto, and the top surface which you called the guide surface. Have I got it?

 

[jleiwig]

Ok, I think I am getting the error of my reasoning. The slimline example that I gave is no good since the tube will always be concentric with the mandrel. But with larger tubes the bushings provide an opportunity for non-concentricity (is that a word). Have I got it?

Good enough for guberment work! :biggrin:

 

[dustmaker]

Thanks Justin and Eric. I am more of a visual thinker and once I realized there are three surfaces (or circles) coming into play here, it started to make more sense.

 

[Mac]

I have first hand experience with out of round bushings , after about 3 pens in a row not fitting ,with the lathe running I turned a little off the outside of a bushing with a skew ,it touched on one side only (out of round) (trashed that one).
I know that some have a hard time turning from square to round using TBC method. Faster works better for me. The faster the lathe runs the more solid the piece acts like and is much easier to turn. Similar to turning a rectangle winged vessel ,and as always sharp tools.

 

[jbmauser]

Well, thank you Mr. Lee. your picture said 10,000 words. Your configuration in my lingo is a supported pin mandrel without the pin. The mandrel is the bushing in a way. You don't have a true "step" guide surface as with a tubular bushing. your ends are "wild". You have added an tremendous stiffness to your mandrel to eliminate bowing but you introduce the possibility of run out by driving it with a drill chuck which unless a high quality one is purchased $$$$ may not run as true as a three jaw chuck.

Don't you also run the risk of belling the ends of the barrel if you over tighten the tail stock? I am a reloader and I apply just a little pressure to the the mouth of a cartridge with a tapered point to flare the edge to accept soft lead bullets.

I just don't see why I would want to introduce pressure to the blank that was not squarely directly against the length of the tube. I understand what you are doing, and it is giving me other ideas but I am not sold. Some experiments must be run!! hobbies are great when they stretch your gray matter... JB

 

[dow]

Well, thank you Mr. Lee. your picture said 10,000 words. Your configuration in my lingo is a supported pin mandrel without the pin. The mandrel is the bushing in a way. You don't have a true "step" guide surface as with a tubular bushing. your ends are "wild". You have added an tremendous stiffness to your mandrel to eliminate bowing but you introduce the possibility of run out by driving it with a drill chuck which unless a high quality one is purchased $$$$ may not run as true as a three jaw chuck.

Don't you also run the risk of belling the ends of the barrel if you over tighten the tail stock? I am a reloader and I apply just a little pressure to the the mouth of a cartridge with a tapered point to flare the edge to accept soft lead bullets.

I just don't see why I would want to introduce pressure to the blank that was not squarely directly against the length of the tube. I understand what you are doing, and it is giving me other ideas but I am not sold. Some experiments must be run!! hobbies are great when they stretch your gray matter... JB

Hi JB. The picture that Lee showed you is what you'd see when finishing the blank, not turning. In turning, you have bushings put in the ends of the barrel and the points of the live and dead centers go in the ends of the bushings. As far as belling the ends of the tube, yes it's possible, but once again, the only time that the centers directly contact the tube is during finishing, when you need only enough pressure to keep the tube spinning, as you'll only be applying finish at this point (CA, Hut, whatever).

If you haven't already, take a gander at George's tutorial, which can be found here: http://www.penturners.org/forum/showthread.php?t=54760. While all of Georges tutorial is great, the steps that I think will be the most useful to you for this line of questioning begin with step # 10. From here you can see the blanks with the bushings during turning, and then without bushings for finishing.

As for Hank's dead center in a jacobs chuck instead of a three or four jaw chuck, I do know that Hank made his own dead canter, and that his method works very well for him. If you'll refer back to George's tutorial, you'll see what a dead center looks like with a MT2 taper on it. Hope this helps you visualize.

Dow

 

[TellicoTurning]

Agreed! on all accounts. :biggrin: Over the past couple of years, There have been a few people (relatively new folks) who asked why TBC was not taught at the beginning. As you said, the commercial ventures catch folks unaware!

One thing that I did not mention concerning perception is that the opposites are true: Mandrels have the image and perception of entry level and therefore easier and cheaper. TBC has the image of high end and therefore expensive and complicated. Since mostly experienced users are doing TBC, that further fosters the wrong perception of being for the experienced high end user instead of for the beginner.

That and I think the TBC idea is a relatively new idea.. an evolution of the process as we learn and try new things... I started on the mandrels with the wax finishes because that was "the norm" when I started and what most pen turners were doing at the time... it was later that other finishes and methods began to be developed.... I think it's a natural progression as we learn.

 

[dogcatcher]

This is what I use, instead of a dead center in the headstock I use my collet chuck. No mandrel, just the 2 bushings. One end is fit for the collet chuck and the other for the live center. 40 years ago when I started making game calls there was no chucks and mandrels. I used something like this made out of wood and used the spur drive and the tailstock dead center to turn the calls. Sorry about the photos, but I wasn't going to set up the fancy stuff for this.

The parts/bushings

The parts/bushing with the brass tube put together, The left side goes into the drive/collet chuck and the other end fits the live center.

 

[workinforwood]

I have tried turning between centers using mandrel bushings and that is not a great idea. The Center of the mandrel style bushing is often a bit off center, but the biggest issue is the hard corners in the hole..those hard corners will eat up even a decent live or dead center. Sure a dead center is not that expensive, but if you eat one up after every 10 pens you make, that's expensive. Best stick to using a bushing made for center turning or at least chuck up the factory bushing and chamfer the sharp edges away with a 60 counterbore bit.

 

[wdcav1952]

That and I think the TBC idea is a relatively new idea.. an evolution of the process as we learn and try new things... I started on the mandrels with the wax finishes because that was "the norm" when I started and what most pen turners were doing at the time... it was later that other finishes and methods began to be developed.... I think it's a natural progression as we learn.

Dang, Chuck, you are OLD!!!!!!!! :biggrin::tongue::biggrin:

 

[leehljp]

Hank,
However, I too am having difficulty getting my brain around how off center bushings cause out of round.

I finally got my brain around that and you are right. THANKS! However, we have to ask the question: What shape happens when vibration is introduced from a bushing that is off center and there is no counter balance for the off centeredness? So, Mix minute' vibration - that is caused by an off center drilled bushing, and you may have a blank that is not perfectly round.This is my "thinking" and I am not an engineer by any means.

I am religious at using calipers 5 to 8 times per end, per blank, as it gets close. IF at any point in pen making I could be considered obsessive by my own admission - it is here. And what I found with off center bushings is that the wood is elliptical by .004 to 006 or .008. According to the theory of it being perfectly round, just OC, . . . this doesn't hold true. The only thing I can figure is that the off centeredness is causing vibration to introduce the ellipticalness/eccentricness.

LAST and Probably the Most IMPORTANT to this discussion: John (JohnnyCNC) pointed out one thing to me something related. As I thought about his statement - it made logical sense that OOR occurs rather than OC in many many cases. John said that quite a few commercial bushing do not fit as tight as they should in the tubes, and as a result cause many problems. "Most" of my commercial bushing fit reasonably tight, but not nearly as tight and fine as John's. The minute' vibration from an off center bushings can cause more looseness between the bushing and tube, which will throw it Out OF Round. IF a bushing is not tight fitting and there is vibration or Off Centered hole, OOR will occur IMHO.

By the way, except for one pen type, I have not used a commercial bushing in a year. Only John's bushings. If any of you have any of John's bushings, slide the in the tube and notice the fit. Then slide a commercial bushing into the other end and feel the "play".

RE-Capping - IF the bushings is drilled off center, the blank should be round too, just the hole/tube will be off center from the pen fittings. However, if vibration takes place, and it effects the bushing/tube fitting - all bets will be off!

 

[Texatdurango]

Hank,

I was going to hold off mentioning this until I got an email last night from a turner who was very confused. She read several of the threads currently floating around right now and asked me... "I visited your web pages and your pens look so pretty, how do you make them so nice looking without using the new bushings, how do you overcome the bushings being out of round, what is your secret? I thought I had it figured out but now am more confused than ever"

What ever gave her the idea that all the bushings were out of round?

While the bushings Johnnycnc sells are nice, they are not required to make a decent pen. I even tried a set or two but got to adding up the number of kits I make and at over $20 per set, some nearly $30, I figured I would have hundreds of dollars in bushings alone so chose to drill my own $3-$4 "factory" bushings with a $2 center drill and I have had no problems whatsoever with any of them and I am just as much a caliper user as the next guy!

Reading through this thread, I see a lot of discussion about how bad, how out of round, how sloppy the factory bushings are and I can't help but wonder how many new turners are being discouraged from even trying turning between centers?

In my opinion, way, way, way too much emphasis is being placed on the kit bushings being unusable or a poor choice and I am seeing references to making $100, $250, $500, $1000 and more quality pens…. as if turning between centers or selecting the correct bushings is going to make the difference, give me a break!

Good grief man, thousands of turners have made millions of pens using kit bushings and I'm sure at least a dozen or two have turned out OK! Now you make it sound like the kit bushings aren't worth the metal it takes to make them and if one does, he is doomed to failure or a life of lousy pen making

I think these bushing discussions are sending the wrong message and confusing the hell out of everyone!

 

[jleiwig]

I agree with George. I haven't used JohnnyCNC's bushings simply due to the price. I know they are nice, I can see the quality, but I know I'd never be able to swing $400 worth of bushings. For $3.99 a set, I can try about 6 or 7 sets of factory bushings before I equal a set of John's bushings.

Sometimes having the highest quality items are important to some turners, but don't confuse that fact with the fact that factory bushings can be found that are near enough drilled and near enough dimensioned.

I didn't say perfect, because as we all know, what's the point in having perfect bushings if the findings on the pen kits vary as much as the bushings from the factory!

 

[rjwolfe3]

George, would it possible to see the end of a factory bushing after you drill it? Also which center drill do you recommend?

 

[leehljp]

Hank,

I think these bushing discussions are sending the wrong message and confusing the hell out of everyone!

Of course people are going to be confused because they are not reading the whole thing. The only thing we can do is present the full information and when someone mis-reads it that is their misunderstanding. You know that happens! But that should not stop you, me or others from posting informative information even if it is overload for those just starting out. It is just like your post and tutorial on TBC and the followup questions concerning not being able to turn 2 blanks at the same time on TBC. I commend you for such a great tutorial. It is super, but because some people have questions and don't see the simplicity of it, that should not prevent you or me from bringing it out to the open and making posts about it.

THAT is what this forum is about! CA is far more confusing than bushings and TBC can ever be, but it sure helps to have as much information and tutorials out there as possible. A lot of people are certainly appreciative of Jeff for having such an open forum for expanding ideas and information, not holding back because some people are getting confused.

Pen turning is simple but it is also complicated. TBC is much simpler than mandrels but it also carries through to the high end with the same efficiency that is on the lower end. Far more flexible. No use hiding it. Extol its virtues.

Reading through this thread, I see a lot of discussion about how bad, how out of round, how sloppy the factory bushings are and I can't help but wonder how many new turners are being discouraged from even trying turning between centers?

George, you know that is not true because you know that the problems of those bushings apply to MANDRELS as well as TBC. And I have stated that too. I have also stated that on the low end you can use the mandrel bushings but you can also move up to the high end bushings of Johns where this is eliminated. His can't move up to his for mandrels, unless he has changed the design. If you want to keep this quiet and not mention it because it discourages people, then we will be answer lots and lots more questions from people asking "why am I getting blanks turned proud on one side. Let the know up front! That is what the wisdom of this forum is all about.

ONE thing left out here is that Mandrels are related to more problems than bushings themselves, so again, I will interject a clearing of the issue. I always mention that mandrels present more problems for the beginner than TBC does. We are on the same side here. And I am not on the TBC bandwagon because that is my method, but because it works and there are a lot less problems (I didn't say none) than with mandrels.

You are a great guy and did a super tutorial. I appreciate your comments, but in disagreement with the "confusion" part, just because one or two said it, I would rather give more information than hold back. But that is just me. Thanks again for your wonderful insight!


Justin, in the past, I when I ordered a set of commercial bushings, I did just as you said, I ordered two sets and sometimes three. I would check with my calipers, measure them for off center drilling. Particularly with Sierras early on there was considerable OC and quality control problems with those bushings. Being in Japan, it was expensive to return and get another shipment, so it would order two sets at least and measure. It was my experience that one in 5 or 6 would be outside of tolerance for me - or enough to be smooth on one side and proud on the other.

 

[Texatdurango]

.......
Can I suggest that we take these personal differences off line? I posted on the other post about the misunderstandings between us - I was not addressing to you in that post. I also sent you a PM to that effect. It would be better to take this off line.... .

Good idea, I just sent you a PM and won't post again on this topic since it would serve no purpose.

 

[johnnycnc]

deleted by author.
really don't care anymore... sorry if I hurt anyone's feelings.

 

[PaulSF]

So can someone confirm for me, is this item from Penn State Industries qualify as a "dead center"?

http://www.pennstateind.com/store/LCENTSS21.html

 

[skiprat]

Yes Paul.
A dead centre is a solid chuck of metal while a live centre has bearings and spins freely. Dead centre in headstock, live centre in tailstock.

 

[Paul in OKC]

I wouldn't take it personally. Johnny. I know the quality you make, and what it takes to make them, having made a few myself. Personally, I think what you get for the price from you with the delrin bushings in the package is a pretty good deal.
That said, I also agree with George. I still turn lots of pens on a mandrel with factory bushings. If they were that bad, you would not be able to make pens on or off the mandrel that didn't have off center problems. Looser in the tubes, yes they are, and that can be some issue.
Hank, good stuff. I have tuned between centers with the drive center that came with the lathe and the factory live center. Had to be careful because of the sharp edges on the drive end, but................!

 

[PaulSF]

Ya know, I'm a professional picture framer, and I get people go nuts over price all the time. Yesterday a woman came in and freaked over $60 to frame a set of Bruce Springsteen guitar picks, and $60 is pretty darn low. I've got frames that cost more per foot wholesale than that. Quality costs, but so does the time and care to get something done. When you have a factory in China or Mexico churning out thousands of bushings an hour, using cheap labor and lots of machinery, the retail for a set of those bushings can be low, $3-$5. Contrast that with someone here in the US, doing these a set at a time. You get what you pay for. If you don't see the value in it, don't buy it. But others may.

P.S. The guitar pick lady told me she had just lost her home and was homeless. Well, what the heck are you doing getting something custom-framed when you are homeless???

 

[Texatdurango]

.....Well, George since you have made a personal attack on my pricing twice now, I will address you.

Well that was certainly nice!

First, get a sense of reality, I was not attacking you or your pricing. Since I did a tutorial recently on turning between centers and since Hank brought up your bushings rather frequently the two facts sort of intertwined since I am getting a boat load of PM's and emails asking me why I don't use your bushings if they are so good and how am I dealing with all the problems from the kit bushings.

I was just using the thread to answer multiple questions over and over via PM's and emails since this thread is the one that triggered most of the PM's to begin with.

Here is probably the section from my post that got you all upset so le't walk through it calmly.........My comments will be in blue!

While the bushings Johnnycnc sells are nice, they are not required to make a decent pen. Your bushings are nice and they are not required to make a pen so both of those comments are a FACT not an attack!
I even tried a set or two but got to adding up the number of kits I make and at over $20 per set, some nearly $30, I figured I would have hundreds of dollars in bushings alone Notice the "I" above, that means I meant ME not someone else. If memory serves I did buy two sets from you last year, a Sierra and Jr Gent but now I mainly make Statesman, Emperors, Imperials/ Lotus and El-Grande kits with other kits only by request so the prices taken from your website for the sets I use are indeed $27, $25, $28 and $28. Simple math tells me that the sets I would use the most frequently would run over $100 so with a few more sets for oddball kits I make the total cost would indeed run into the hundreds so again my comments are FACT not an attack!
so chose to drill my own $3-$4 "factory" bushings with a $2 center drill and I have had no problems whatsoever with any of them and I am just as much a caliper user as the next guy! So here we are on the final segment. I do drill my own kit bushings with a center drill purchased in a $6 set of 5 from Little Machine shop so I just estimated that it cost $2. I haven't noticed any "out of round" or other problems with the kit bushings and trust me I use my calipers several times on every pen so I'm afraid that all of the above comments are based on FACT and not an attack on you!

I sorta got lost in your rant when you started talking about what lathes I have, how much they cost me or how I drill the bushings or how far you drive to work everyday so I won't reply to any of that. I hope that me explaining the FACTS to you isn't considered another attack! And just because someone doesn't endorse your bushings isn't considered an attack either, if people want to use your bushings... good for them, I NEVER told anyone not to buy them, I just saide they weren't required!

 

[Paul in OKC]

Ya know, I'm a professional picture framer, and I get people go nuts over price all the time. Yesterday a woman came in and freaked over $60 to frame a set of Bruce Springsteen guitar picks, and $60 is pretty darn low. I've got frames that cost more per foot wholesale than that. Quality costs, but so does the time and care to get something done. When you have a factory in China or Mexico churning out thousands of bushings an hour, using cheap labor and lots of machinery, the retail for a set of those bushings can be low, $3-$5. Contrast that with someone here in the US, doing these a set at a time. You get what you pay for. If you don't see the value in it, don't buy it. But others may.

P.S. The guitar pick lady told me she had just lost her home and was homeless. Well, what the heck are you doing getting something custom-framed when you are homeless???

Excellent point. We could go off in any direction with the 'needs' of pen turning. One thing I remember is our good friend Eagle used to aks me regularly 'Why do I need a vise that cost $XX to drill a stinkin' hole in a piece of wood?" You don't, but if you want quality, it is worth it.

 

[johnnycnc]

Right on, Paul.
I really try to avoid these sort of topics.. usually.
Making pens is a lot more fun than typing!

I wouldn't take it personally. Johnny. I know the quality you make, and what it takes to make them, having made a few myself. ..........

 

[PaulSF]

Best are the ones coming in now, they need it by Christmas, AND they want a discount. Ummm, no. Be glad I don't charge you extra. And don't bother shopping around, I won't suffer if you don't have anything to put under the tree!

 

[leehljp]

So can someone confirm for me, is this item from Penn State Industries qualify as a "dead center"?

http://www.pennstateind.com/store/LCENTSS21.html

As said above, it qualifies as a "dead center" but the one used for pens in TBC can be seen
here and here, and there are other places.