Turning Between Centers

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JBCustomPens

JBCustomPens

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Hey Guys,

I am about to turn to being a TBC convert!:biggrin: I've been turning for about 2 years now, think I am ready. My question is, what will I need to do this? I already have chisels, etc. Thanks.
 
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You are making things OVERLY complicated and this post is passing on mis-information!

You don't need to do ANY MODIFICATION to the mandrel bushings to start turning between centers. You don't even have to have a 60° dead center on those bushings!

THERE is NOTHING 60° about THIS dead center:

1_Dead_drive_1.jpg


To keep things on the up and up - JohnnyCNC's bushings are drilled to 60° and do require that on the dead drive center and live center to be 60°. John's bushings are far superior to the stock mandrel bushings.

But when using stock mandrel bushings, 60° is not needed. Chamfering them as you mentioned is not needed either. It won't hurt (unless you accidently do them off center) but it only adds an extra step and time to using TBC.
 
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Thanks Hank. I just got a live and dead center from Johnny. Does it work better with a 60 degree on the bushings? How well does it fit without 60 degrees? Thanks for answers!:smile:
 
I started between centers with stock bushings and the small edge of the thru hole is a poor excuse for a drive surface, in my opinion. think about it!
It works, but there is better to be had. The fit of the stock bushings is often so poor in the tubes, drilling the ends with a center drill is a step in the right direction, but likely to be of little help in the quest for accuracy.
As long as one is happy with the results he/she is getting, no reason to change.
But if you are not happy with the results,.. there is much room for improvement to be had. (Even without any of my bushings:wink:)
And I don't know what you make on the hour at your job, but I sure can't buy material and try to make a home-made dead center for what I can just buy the real McCoy.
The carbide tipped one I have in my lathe has been in use for 2-3 years, and still no wear. It may outlive me, only time will tell.
Similar standard steel ones lasted me just weeks before they were grooved and useless. A waste of good money, for my uses.
And I'll add that 60° is an industry standard, not some off the wall niche thing.It is a time tested and proven method for driving and locating
center work, and is works well, reliably, and repeatably across a range of standardized 60° products.
 
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I use John's for most of my pens and swear by them. However, the TBC is often questioned as being too expensive along the lines of "I can't afford that". And it comes from people looking at custom bushings.

Also, almost every time I see TBC, I see 60° in the same sentence, which also gives the wrong impression. I don't see people telling new turners "Welcome, you are new, get your 60° LC for your mandrel." A 60° LC IS a requirement for a mandrel, But it is NOT an absolute requirement to go TBC with regular bushings.

TBC is like pen turning itself. You can do it on a Nova or Powermatic or Jet, or Rikon or PSI and even a Drill Press. It is not relegated to one end of the "cost" spectrum.

When the focus of TBC talk is ONLY on the high end, fewer people are going to try it because of "cost" and complication perception, when in fact it is not. We will get tons of continuous questions about OOR & OC and when TBC is recommended, we get the "I can't afford to go to TBC yet" answer.

TBC can be cheaper than Mandrels to get started, and TBC offers much better precision, fit and finish. The difference with TBC is that TBC users can climb the expense ladder as they need and get finer bushings.

I did mislead on one item in my post. For that, I apologize to you and to John. John addressed that issue. There is less contact space when using a 60° (or dead center such as mine,) on standard bushings and I think that standard bushings will benefit from the chamfer as originally asked - IF chamfering can be done correctly. AS John said, 60° is the industry standard for the metal machining. However this does not apply to most wood lathes and their stock centers. A few people have made dead center drives from wood to use on standard bushings. I don't want people to think that as an absolute . . that "60°" is a necessity.

Concerning Standard bushings: Most of us who have been TBC for the past 2 to 3 years started with standard bushings and had a great improvement with just that alone. Early on, I never had a problem and I don't think that anyone else die either when using standard mandrel bushings for TBC - except for when the standard bushings that were drilled OC to begin with. IIRC, that is what gave birth to custom bushings, not the small shoulder connections. The chamfer of John's bushings is a bonus in that it stops the "digging in" ring on steel dead centers - that standard bushing can cause over time and with slippage.

That said, Johns bushings are the BMW/Porche of bushings and I don't mean the glitzy part but the accuracy and finely machined parts. AS I said, I use them but they are not necessary to get started. Once you do get started, you will want the finest and that would be John's.

I do have some standard bushings that are OC by .004 and that is just enough to make me want to through them away but too close to accurate to let go. You will not find that with John's. His is dead on.


Bottom line on TBC, the cost is far more flexible for the accuracy that you get than with mandrels. TBC - it can be cheaper and it can be more expensive, but either way, it is more accurate overall.
 
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leehljp said:
You are making things OVERLY complicated and this post is passing on mis-information!.......
Click to expand...

Since I am the only one who has responded to JBCustomPens so far other than jleiwig who just linked to a tutorial I did and I'm the only one who mentioned 60 degrees, I will assume that I am the one who is passing on all the miss-information causing JBCustomPens to make things overly complicated and I take personal exception to that remark!

To begin with I don't see where I am passing along any false or misleading information. Here is what I have said in the past and what I say now, I want YOU tell me specifically what is miss-leading!

In the simplest way of putting it, in order to turn between centers, you need two centers, one dead center in the headstock and one live center in the tailstock. Nothing miss-leading about that.

It just so happens that 99% of all the dead centers I have seen readily available on mt-2 shafts just so happen to be tapered to 60 degrees as do 99% of the center drills readily available! That is the ONLY reason I mention 60 degrees when talking about turning between centers! Nothing miss-leading about that.

In my opinion, the simplest way to mount a blank between two centers to quickly turn it to kit dimensions is to use the kit bushings that are sold by various vendors for $3 or $4 a set. You don't have to spend $28 on a set of custom bushings, that just overly complicates the issue! Nothing miss-leading about that.

The ONLY reason I drill my bushings with a center drill is to allow the bushings to run truer between the centers and to afford more contact surface area between bushing and centers. Nothing miss-leading about that.

The easiest and most accurate way I know of to drill a set of bushings is to use a center drill. A set of 5 center drills are readily available for $6, probably cheaper if you shop around. Nothing miss-leading about that.

Based on the above, I would recommend to anyone asking "What do I need?" that they get a dead and live center and a set of bushings and drill (or chamfer) the bushings with a center drill to match the centers. Nothing miss-leading about that.

So tell me, where is all this miss-information I am spreading? And as far as making things overly complicated, If YOU choose to spend $23, $25 or $28 on a set of custom bushings, that's YOUR business but it's NOT required so I don't appreciate you accusing me of giving people bad advice (miss-information) just because I don't mention them.

 
Hey George, ! I wasn't replying to you!


I am about to turn to being a TBC convert! I've been turning for about 2 years now, think I am ready. My question is, what will I need to do this? I already have chisels, etc. Thanks.
Click to expand...

Can you drill out the ends of your mandrel bushings with a #6 center drill to make them accept TBC? Thanks.
Click to expand...

I was replying to those quotes/questions above. AS to 60°, it is a standard and requirement for mandrels as I said, but it is not that big of a deal for TBC except for Johns bushings. IF you read ANY of my statements on TBC over many a post over many days and months, you will notice that I almost always mention that, whether anyone else does or not! Kind of my trademark in explaining TBC. I did NOT mention it in reply to you, but I mentioned it to keep the facts straight and simplify the process as I always do!

"Drilling out the ends of the mandrel bushings" that is not necessary and overcomplicates the situation for someone just starting out. It is their choice, yes, but still not necessary for just starting with TBC. Even the standard non 90° tail stock centers on wood lathes can be used on those mandrel bushings. That is what that I was referring to concerning overcomplicating things! NOT YOU!

Have you NEVER added something to a question before that was not asked but the context did need explaining? OF course you have. And that is what I was doing. The world is not out to get you, at least not me! I tend to agree with your concepts as much as and more than most around here. You just took my post wrong and read it as though I was talking about you! NOPE, I was not.
 
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Count me as one who misunderstood what it takes to start TBC. Thanks to everyone for this post as it has cleared up some of the questions and mis-infomation (pre-conceived on my part) about the subject. I may give it a try sometime myself.
 
OK men but we still don't have any sort of answer as to what to use to drill the 60 degree chamfer? Is a normal drill the right angle for it? Do we need to get a chamfer tool? Give us a link to what we need to turn a 7mm mandrel bushing into a TBC bushing? We understand that these bushings are not a accurate as $25 bushings, I would not expect them to be. As I need to replace bushings I will get the better ones but for now I have to use what I have.
 
mikespenturningz said:
OK men but we still don't have any sort of answer as to what to use to drill the 60 degree chamfer?
it's in this thread, just read back a few posts. 60° center drill.

Is a normal drill the right angle for it? NO
Do we need to get a chamfer tool? NO

Give us a link to what we need to turn a 7mm mandrel bushing into a TBC bushing?
Magic Fairy Dust

We understand that these bushings are not a accurate as $25 bushings, I would not expect them to be. As I need to replace bushings I will get the better ones but for now I have to use what I have.
Click to expand...

And you don't need to drill them at ALL. you CAN, but it's completely un-necessary to get started.
It's not going to help matters that much.
Maybe even more harm than good, depending how far off center you manage to get that new center seat.
I'm not saying it can't be done, just that I wouldn't recommend it on a wood lathe.
 
johnnycnc said:
mikespenturningz said:
OK men but we still don't have any sort of answer as to what to use to drill the 60 degree chamfer?
it's in this thread, just read back a few posts. 60° center drill.

Is a normal drill the right angle for it? NO
Do we need to get a chamfer tool? NO

Give us a link to what we need to turn a 7mm mandrel bushing into a TBC bushing?
Magic Fairy Dust

We understand that these bushings are not a accurate as $25 bushings, I would not expect them to be. As I need to replace bushings I will get the better ones but for now I have to use what I have.
Click to expand...

And you don't need to drill them at ALL. you CAN, but it's completely un-necessary to get started.
It's not going to help matters that much.
Maybe even more harm than good, depending how far off center you manage to get that new center seat.
I'm not saying it can't be done, just that I wouldn't recommend it on a wood lathe.
Click to expand...

Yes I read that it needs to be a 60 degree center drill but then it was added that some use a #4 and others use something different. I found that on your site and will order later on this evening. As far as the fairy dust I don't know much about that stuff so I ordered one of each, maybe you can tell me what you do with that when it comes in. :smile:
 
JBCustomPens said:
Hey Guys,

I am about to turn to being a TBC convert!:biggrin: I've been turning for about 2 years now, think I am ready. My question is, what will I need to do this? I already have chisels, etc. Thanks.
Click to expand...
I turn between centers and do Not use bushings of any kind. I measure the dia. of the component to be turned, set a caliper to that level and turn. Why bother with bushings? The components are the most accurate, and required end result.
 
I'm confused why you need to drill bushings that already have holes in them. I TBC the larger kits. slimline, etc I still turn on a mandrel. Using the stock bushings works just fine between centers.
 
crokett said:
I'm confused why you need to drill bushings that already have holes in them. I TBC the larger kits. slimline, etc I still turn on a mandrel. Using the stock bushings works just fine between centers.
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David, You don't!

Posts number 20 & 21 also say the same thing.
 
I think I'm finally getting it! I'm starting to think that if you live long enough, you eventually you wind up with various bushings and adpapters, collets, 4 jaw chucks, Jacob's chucks, drive centers, live centers, pin collets, and who knows what else and then make up your mind as to what works best with what project when TBCs. and for that matter, when segmenting, drilling, assembling, etc. The advice on these pages is awesome, but it always seems way too enticing, thinking, "I wonder if it would be a juuusst a little better if I did it 'that' way instead of 'this". For me, as a beginner, that's what keeps it exciting and interesting (as long as you spend your money slowly). Thank you to all the contributors to this topic and this forum!
 
You can also use plain-old mandrel bushings with 60 degree centers and turning a barrel that appears centered (may actually be centered).
However, in general, stock mandrel bushings can be sloppy. About 3/4 of the way through my turning, I stop the lathe and turn on bushing a quarter turn clockwise, and the other bushing a quarter turn counter clock wise (then I throw some salt over my shoulder and kiss my rabbits foot :-)). If I like the kit, I have 60 degree TBC bushings made for me.

Naturally, the less hardware between your centers the less likely you will turn something that is out of round. This also assumes:
  • Your centers are have no to little runnout
  • You removed any glue or debris from within the tube
  • You drill a clean/straight hole
  • And your tools are sharp where you are not applying too much pressure to the barrel.

If you don't mind checking your dimensions often, TBC without bushings should give you the best chance of turning something "true" .

This is just my opinion based on my experience. I yield all to the machinists and more experience turners.
 
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