Protecting Dead and Live centers when doing TBC?

[jrista]

Well, I started doing TBC in the fall last year. It solved numerous problems I had been having with mandrel turning, and has allowed me to get pretty much perfect seams between the blank and the kit parts. However, it seems that even with TBC bushings, I am having problems with both the dead and live centers, which are 60 degree, wearing...with grooves being carved into the metals by both the bushings, as well as the brass tubes when I take the bushings off for final sanding and finishing.

It seems that this starts happening within just a matter of a few pens, and by the time I've made dozens of pens, the marring of the surface of the centers is enough to throw off the centering of the blank, and I start getting non-concentricity issues again.

I'm curious what other people are doing to solve this problem. Is there a solution? I can't really afford to be replacing these parts every month or two...that would add a lot to my costs, not to mention with markets and shipping as it is these days, I may not be able to get replacements all the time. Does anyone know if there are any replaceable tips or something like that that could be attached to the centers, so that the tips can simply be replaced, without having to replace the centers? Or is there any other way to prevent marring of the center surface?

The dead centers usually last longer, as at least there is drive power behind them, and I can clean up the surface for a while. It is mostly the dead centers that become problematic, as they have a bearing and there is no real way to get them to spin so I can clean up the surface (I've just been using some fine grit sandpaper to smooth out the surface for a while, which is good for a little while, but not good enough to keep the centers viable for much longer than a couple months.)

 

[Curly]

I have considered carbide tipped centres. Dead centre ones are easy to find. Live is less but this one is cheap enough and with the carbide almost 1/2 inch in diameter would do for a lot of pen sizes. https://toolsmach.com/en/live-cente...live-center-morse-2-dma412-5904158701244.html That exchanges to under $40. You could contact them through their chat box and see if they would make one or two with bigger carbide tips, 5/8" would be enough, and get some dead centres too at the same time saving on shipping. If they need bigger quantities for bigger tips a group buy might be of interest to members of the forum. I'd go in it with you for a dead and live centre with .600/16mm or so tips.

Right now I can recut them on the metal lathe when needed but having carbide would probably eliminate that need for a long time to come as I only make pens occasionally.

 

[bradh]

I wipe a bit of bees wax on the center before use. I find this little bit of wax provides some lubrication and reduces wear on the center.
I buy small blocks of wax from the honey sellers at my local farmer's market. Keep a block of wax on my tool rack ready for use.

 

[PatrickR]

I'm not sure how it could happen. With true tbc bushings that have a 60* chamfer used on centers that have the same chamfer? With the tubes directly on the centers its brass vs steel. Steel should win. Think about upgrading centers and bushings.

 

[rherrell]

Try Delrin bushings, it's a type of plastic so you can make your own on a wood lathe.

 

[Mortalis]

Well, I started doing TBC in the fall last year. It solved numerous problems I had been having with mandrel turning, and has allowed me to get pretty much perfect seams between the blank and the kit parts. However, it seems that even with TBC bushings, I am having problems with both the dead and live centers, which are 60 degree, wearing...with grooves being carved into the metals by both the bushings, as well as the brass tubes when I take the bushings off for final sanding and finishing.

It seems that this starts happening within just a matter of a few pens, and by the time I've made dozens of pens, the marring of the surface of the centers is enough to throw off the centering of the blank, and I start getting non-concentricity issues again.

I'm curious what other people are doing to solve this problem. Is there a solution? I can't really afford to be replacing these parts every month or two...that would add a lot to my costs, not to mention with markets and shipping as it is these days, I may not be able to get replacements all the time. Does anyone know if there are any replaceable tips or something like that that could be attached to the centers, so that the tips can simply be replaced, without having to replace the centers? Or is there any other way to prevent marring of the center surface?

The dead centers usually last longer, as at least there is drive power behind them, and I can clean up the surface for a while. It is mostly the dead centers that become problematic, as they have a bearing and there is no real way to get them to spin so I can clean up the surface (I've just been using some fine grit sandpaper to smooth out the surface for a while, which is good for a little while, but not good enough to keep the centers viable for much longer than a couple months.)

I use a piece of wood (2" - 3" piece of dowel works) between the dead and live center to drive the live center. I turn the live center end down to within an 1/8in of the point and that way I can get into the live center with a very fine file and/or sandpaper and remove the glue build up. that way I have a clean concentric surface to contact the ID edge of the tube when I turn TBC. The small portion that I cant get to doesnt effect the turning as it doesnt touch anything.

 

[Todd in PA]

I put blue painters tape on both the live and dead centers to protect them and give them some grip. The tape actually lines up perfectly for one layer, no overlap. I use 3 layers. I have to put on new tape every 5 pens or so.

 

[Curly]

I'm not sure how it could happen. With true tbc bushings that have a 60* chamfer used on centers that have the same chamfer? With the tubes directly on the centers its brass vs steel. Steel should win. Think about upgrading centers and bushings.

Patrick in this instance we turn without bushings, measuring with callipers to reach the size needed. The contact is direct with the brass tube and the 60º cone of the centres. The brass eventually, from slipping a bit now and then while turning, wears a grove in the centre. Brass being a soft material can cut the steel because any small amounts of abrasive imbeds into the brass and cuts. Same kind of action as when sand and small rocks gets stuck in the soles of your shoes and you walk across the floor of the living room. You scratch the floor and after quickly cleaning up, blame the dog.

 

[SteveG]

Pete, your explanation is so nice, and the illustration makes it so clear to understand what is happening. It triggered a memory of my instruction pursuing my engineering degree 50 years ago. The prof, who was a real world experienced engineer, pointed out the process of using a "lap", where fine, loose abrasives (usually in a slurry or paste) are introduced to a softer metal surface, and then that is used by rubbing the work, typically a harder metal against the lap, to yield a nice, precision flat surface. We inadvertently introduce a lap in our pen turning process, but the result is to deform the smooth surface of the centers being used, rather than the typical machinist use that improves the surface. That learning experience for me, way back then, was also a situation where I had inadvertently introduced a lap on building a design project, causing it to be not quite right. Now that same affect is happening all over again at the pen turning lathe!

 

[RunnerVince]

I use a piece of wood (2" - 3" piece of dowel works) between the dead and live center to drive the live center. I turn the live center end down to within an 1/8in of the point and that way I can get into the live center with a very fine file and/or sandpaper and remove the glue build up. that way I have a clean concentric surface to contact the ID edge of the tube when I turn TBC. The small portion that I cant get to doesnt effect the turning as it doesnt touch anything.

I admit that I am often too lazy to do this, but if your issue is glue build-up, you can simply put a half-inch or so of acetone in a narrow glass jar (I find 1/2 pint mason jars work well if you have them, but small jam jars would do the trick) and soak the dead center/live center point down in the acetone. As long as the acetone doesn't come up above the level where it can seep into the inner workings of the live center, you'll have no risk to your hardware, and you'll be using the perfect solvent. When I remember to do this at the end of a session, the centers are clean by the next day, although I'm sure it doesn't take more than an hour or so.

 

[jrista]

I'm not sure how it could happen. With true tbc bushings that have a 60* chamfer used on centers that have the same chamfer? With the tubes directly on the centers its brass vs steel. Steel should win. Think about upgrading centers and bushings.

I'll see if I can get a picture...but, the TBC bushings DO have that 60º chamfer, which contacts the centers along that entire surface. That seem to very quickly start marring the surface, leaving it uneven, and eventually it wears even worse than that.

Patrick in this instance we turn without bushings, measuring with callipers to reach the size needed. The contact is direct with the brass tube and the 60º cone of the centres. The brass eventually, from slipping a bit now and then while turning, wears a grove in the centre. Brass being a soft material can cut the steel because any small amounts of abrasive imbeds into the brass and cuts. Same kind of action as when sand and small rocks gets stuck in the soles of your shoes and you walk across the floor of the living room. You scratch the floor and after quickly cleaning up, blame the dog.

This is correct. Pete nailed it, the mechanism of wear and all.

After I get my blanks turned most of the way, I take off the bushings, and put the blank directly between centers. This means the brass IS in contact with both, which does cause a groove to wear. This is the biggest problem, as that groove, even when very thin, acts like a stop, or otherwise throws the bushings off-center on the next pen.

 

[jrista]

I admit that I am often too lazy to do this, but if your issue is glue build-up, you can simply put a half-inch or so of acetone in a narrow glass jar (I find 1/2 pint mason jars work well if you have them, but small jam jars would do the trick) and soak the dead center/live center point down in the acetone. As long as the acetone doesn't come up above the level where it can seep into the inner workings of the live center, you'll have no risk to your hardware, and you'll be using the perfect solvent. When I remember to do this at the end of a session, the centers are clean by the next day, although I'm sure it doesn't take more than an hour or so.

I've been using acetone on a cloth, but this seems like a better way.

 

[jrista]

I put blue painters tape on both the live and dead centers to protect them and give them some grip. The tape actually lines up perfectly for one layer, no overlap. I use 3 layers. I have to put on new tape every 5 pens or so.

This is interesting! I figured tape like that, might introduce its own issues with non-concentricity. Do you find that it keeps everything nice and centered and concentric?

I'm also curious...do you only turn with bushings, or do you take the bushings off for final sanding and finishing?

 

[Todd in PA]

I haven't had any significant issues with the tape. I typically have used regular bushings, which I'm sure you know are a little hinky to TBC. It wears through the tape in a pen or two. So I'm replacing the tape frequently.

I recently got some TBC bushings for sierra's and they perform much better. The angle matches the centers, rather than cutting into the tape. My first centers went in the trash relatively quickly because without tape they became grooved and no longer produced a round result.

I typically put the barrels back on the mandrel with plastic bushings to apply my finish.

 

[Todd in PA]

Here you can see what happens to the tape after one barrel.

 

[jrista]

I haven't had any significant issues with the tape. I typically have used regular bushings, which I'm sure you know are a little hinky to TBC. It wears through the tape in a pen or two. So I'm replacing the tape frequently.

I recently got some TBC bushings for sierra's and they perform much better. The angle matches the centers, rather than cutting into the tape. My first centers went in the trash relatively quickly because without tape they became grooved and no longer produced a round result.

I typically put the barrels back on the mandrel with plastic bushings to apply my finish.

Thanks for the details, Todd! Gonna give the tape a try. Thanks for the photo, too...was starting to wonder how to wrap the tape without it kinking or anything like that...but I see what you did now.

 

[jrista]

Well, I'm back at the task of trying to protect my centers! I gave the tape approach a try. Its great, when I'm just using the bushings, and it has stopped the marring of my current set of centers. When turning with bushings, I probably get three pens out of a set of tape before I have to replace. The last pen might have some slight concentricity issues...

The problem I have run into, is when I remove bushings and put the brass tube and blank directly between centers, the brass cuts right through the tape, and starts marring the centers again. I am able to use less pressure to hold the blank thanks to the tape, but it still seems to cut through each time.

So, I am wondering...anyone with a 3D printer out there, would you be interested in helping me trial a new idea? A set of 3D printed 60 degree angle cones, maybe a millimeter or so thick, that I could glue (with some kind of temporary glue, or maybe double sided tape or something) to both my dead and live centers. The cones, being a plastic or resin, should be more durable than the tape, should last longer than the tape, and when they start to wear out and cause concentricity problems, I can simply print a new set and replace them.

I would trial it all myself, but I'm all tapped out at the moment money wise, and cannot afford anything for a while. I can handle replacing my centers a couple more times, as each set (at least until the next price hike) is about $40 or so plus shipping. Still, I'd rather replace a set of printable cones to cover the centers, than replace the centers themselves...seems so wasteful to throw away centers due to gouging (and I already have several sets I've kept for normal wood turning projects!)

For the live center...I was even thinking, if I can figure out an optimal design for the model...it might be possible to print some extensions with little right-angle clips at the end, so it could just clip right over the back of the live center. Not sure if that would work in the long run or not...it might allow slip if the cone isn't actually glued in place somehow.

 

[mmayo]

Try Delrin bushings, it's a type of plastic so you can make your own on a wood lathe.

Try these. They are not delrin but Delrin is actually my least favorite plastic to turn.

 

[jrista]

Try these. They are not delrin but Delrin is actually my least favorite plastic to turn.

Have you done any turning with those? Any risk with part of them sheering off during turning (due to the layering)?

 

[mmayo]

Have you done any turning with those? Any risk with part of them sheering off during turning (due to the layering)?

They just work. If you heat them to over 120 F there might be an issue. When I sand or buff they just work.

 

[jrista]

They just work. If you heat them to over 120 F there might be an issue. When I sand or buff they just work.

Hmm... Is there any chance I could commission a couple sets from you to try them out? I've been turning a lot of cigar, baron and triton kits lately... I'd pay you for the service!

I've taken to swapping out sets of centers lately. I use one of the new sets for turning with the TBC bushings. Then I pop the bushings off, put on my older set of centers which were already marred by the brass tubes, and use that for final sanding and finishing direct between centers. I spend a bit of time adjusting the fit of the tube to the centers so that any decentering is minimized, and this has been working pretty well for the final finishing part (and since these centers are already marred all over the place, its not a big deal). The TBC bushings are still eventually going to create enough marring of the new centers that I'm sure I'll run into concentricity problems eventually...they are creating this rough band where the 60 degree negative cone of the bushings rests on the centers. So the idea of a 3d printed set of bushings made out of plastics is really appealing!

 

[michaelperez]

Well, I started doing TBC in the fall last year. It solved numerous problems I had been having with mandrel turning, and has allowed me to get pretty much perfect seams between the blank and the kit parts. However, it seems that even with TBC bushings, I am having problems with both the dead and live centers, which are 60 degree, wearing...with grooves being carved into the metals by both the bushings, as well as the brass tubes when I take the bushings off for final sanding and finishing.

It seems that this starts happening within just a matter of a few pens, and by the time I've made dozens of pens, the marring of the surface of the centers is enough to throw off the centering of the blank, and I start getting non-concentricity issues again.

I'm curious what other people are doing to solve this problem. Is there a solution? I can't really afford to be replacing these parts every month or two...that would add a lot to my costs, not to mention with markets and shipping as it is these days, I may not be able to get replacements all the time. Does anyone know if there are any replaceable tips or something like that that could be attached to the centers, so that the tips can simply be replaced, without having to replace the centers? Or is there any other way to prevent marring of the center surface?

The dead centers usually last longer, as at least there is drive power behind them, and I can clean up the surface for a while. It is mostly the dead centers that become problematic, as they have a bearing and there is no real way to get them to spin so I can clean up the surface (I've just been using some fine grit sandpaper to smooth out the surface for a while, which is good for a little while, but not good enough to keep the centers viable for much longer than a couple months.)

Hello, the live center I checked at Axminster has replaceable tips.
Live center

Axminster Woodturning Deluxe Live Revolving Centre

For professional woodturners and dedicated home turners, our heavy duty live centre is designed to meet all your needs. This centre is both robust and versatile, whatever your project or ambitions this centre has it covered. It’s manufactured in our...

www.axminstertools.com

replaceable tip

Axminster Woodturning Standard Tip For Deluxe Live Revolving Centre

This is a replacement standard steel tip for the Axminster Deluxe Live Revolving Centre. It has a 60° tip angle and fits directly into the revolving centre's aluminium cone. CNC machined from stainless steel.

www.axminstertools.com

 

[michaelperez]

Well, I'm back at the task of trying to protect my centers! I gave the tape approach a try. Its great, when I'm just using the bushings, and it has stopped the marring of my current set of centers. When turning with bushings, I probably get three pens out of a set of tape before I have to replace. The last pen might have some slight concentricity issues...

The problem I have run into, is when I remove bushings and put the brass tube and blank directly between centers, the brass cuts right through the tape, and starts marring the centers again. I am able to use less pressure to hold the blank thanks to the tape, but it still seems to cut through each time.

So, I am wondering...anyone with a 3D printer out there, would you be interested in helping me trial a new idea? A set of 3D printed 60 degree angle cones, maybe a millimeter or so thick, that I could glue (with some kind of temporary glue, or maybe double sided tape or something) to both my dead and live centers. The cones, being a plastic or resin, should be more durable than the tape, should last longer than the tape, and when they start to wear out and cause concentricity problems, I can simply print a new set and replace them.

I would trial it all myself, but I'm all tapped out at the moment money wise, and cannot afford anything for a while. I can handle replacing my centers a couple more times, as each set (at least until the next price hike) is about $40 or so plus shipping. Still, I'd rather replace a set of printable cones to cover the centers, than replace the centers themselves...seems so wasteful to throw away centers due to gouging (and I already have several sets I've kept for normal wood turning projects!)

For the live center...I was even thinking, if I can figure out an optimal design for the model...it might be possible to print some extensions with little right-angle clips at the end, so it could just clip right over the back of the live center. Not sure if that would work in the long run or not...it might allow slip if the cone isn't actually glued in place somehow.

Sorry I forgo to mention that Also there are this options:

Axminster Multi-Head Live Revolving Centre & Additional Tips

We think that this is the best universal centre available today. There are two sealed bearings in the body and the working end has a taper for mounting the various interchangeable tips, guaranteeing that they run perfectly concentric. The centre is...

www.axminstertools.com

Axminster Woodturning Multi-Head Live Revolving Centres

We believe that this is the most universal tailstock centre available today. There are two sealed dust proof bearings in the body and the working end has a taper for mounting the various interchangeable tips, guaranteeing that they run perfectly...

www.axminstertools.com

 

[mmayo]

Have you done any turning with those? Any risk with part of them sheering off during turning (due to the layering)?

They just work like stainless steel ones. I've spent many trials to get the size right. I use them for sanding and buffing, but have used them in turning pens instead of my Nikitas SS TBC and they just function perfectly. I have used several brands of filament and settled on Hatchbox performance PLA. Matte, but strong and very smooth. They don't separate at the layers if you use the right 3D printer and the right settings.

Shortly, I'll start selling them at very reasonable prices.

 

[mick]

NEVER MIND THIS, I'M STUPID! AND CANT DELETE THIS! I

 

[mmayo]

Hmm... Is there any chance I could commission a couple sets from you to try them out? I've been turning a lot of cigar, baron and triton kits lately... I'd pay you for the service!

I've taken to swapping out sets of centers lately. I use one of the new sets for turning with the TBC bushings. Then I pop the bushings off, put on my older set of centers which were already marred by the brass tubes, and use that for final sanding and finishing direct between centers. I spend a bit of time adjusting the fit of the tube to the centers so that any decentering is minimized, and this has been working pretty well for the final finishing part (and since these centers are already marred all over the place, its not a big deal). The TBC bushings are still eventually going to create enough marring of the new centers that I'm sure I'll run into concentricity problems eventually...they are creating this rough band where the 60 degree negative cone of the bushings rests on the centers. So the idea of a 3d printed set of bushings made out of plastics is really appealing!

Sent several sets for your approval.

 

[jrista]

Sent several sets for your approval.

Yup, I received them! I apologize for not responding yet...I've...had a hell of a summer... I'm still picking up the pieces of the last month here. I have several pen projects I have to work on soon here, and I'll definitely be using your bushings! I'm looking forward to it!