Out of round HELP!

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Hi all,

I know this is an old problem and i have used the search function both here and on Pen Turners Paradise to no avail...

This is my problem.

I have the dead centre in the headstock - Runout is less than a thousandth.
The live centre is in the tailstock and runout is the same as the headstock dead centre.
I line up the centres and lock the headstock so that the points are aligned.

Then when i turn something it is not round...
Turning is done between centres so no mandrel to bend.

I tried using a blank brass tube mounted on the bushings and that is where all the runout is happening!
On both bushings the runout is almost a hundredth of an inch!!
This is also translated to the brass tube.
Do i need new bushings??
Or is it time to try without the bushing??

I am going to glue up a tube in some useless wood and turn it without bushings to see what i get.

Any help appreciated!!!

Andrew
 
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Knight

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If the ends of the brass tube are not square, you will have the runout.
Also, what bushings are you using?
 

skiprat

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How are you squaring up the blank once you have glued in the tube?
It sounds like the sloppy fit of the bushes combined with the possible non perfectly squared blanks is the problem.
 

mbroberg

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You should be using 60 degree live and dead centers. If you are using stock bushings that are meant for a mandrel then that may be your problem. For between center turning you should be using bushings that fit the 60 degree live and dead center. Check out Penturnerproducts.com John (IAP name JohnnyCNC) has everything you need for perfect between center penturning.
 

wdcav1952

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Good ideas have been offered. I was having the same problem and was using stock bushings. Since I have two collet chucks already, I went back to a mandrel held by a collet and turn one tube at a time. My out of round problem is no more. If I didn't already have the collet chucks, I likely would have gone with custom between center bushings from Johnny.
 
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Thanks for the answers!!

At present i am using the bushings that come with the kits.
Some sort of alloy, not the 60 degree ones. Will have to look into the ones johnnycnc sells.
I have also noticed that my pen mill does not cut very cleanly anymore. The edges it leaves kind of wavy looking. Time for a new one!

I need to investigate a higher quality pen mill, any suggestions?
And look into bushings.
I might turn my own on my metal lathe, just need to get some good bar stock for turning. Only have Alu at the moment.

Thanks for all the help and the food for thought!!!!

Andrew
 

skiprat

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Shame on you!!!:mad::biggrin: ( Just kidding ) but if you have a metal lathe, then you SHOULd be making your own bushes, pens, mandrels etc etc.
A facing cut on your ML is a perfect way to square a round tubed blank too.:wink:
 

Paul in OKC

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If you have a way to 're-center' drill the ends of the factory bushings, that may help. These bushings are generally good enough for mandrels, but if the chamfer on the ends (if there is one) may not be true to the diameter the tubes ride on.
 

JBCustomPens

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Thanks for the answers!!

At present i am using the bushings that come with the kits.
Some sort of alloy, not the 60 degree ones. Will have to look into the ones johnnycnc sells.
I have also noticed that my pen mill does not cut very cleanly anymore. The edges it leaves kind of wavy looking. Time for a new one!

I need to investigate a higher quality pen mill, any suggestions?
And look into bushings.
I might turn my own on my metal lathe, just need to get some good bar stock for turning. Only have Alu at the moment.

Thanks for all the help and the food for thought!!!!

Andrew

Check these out, they are of very high quality.

http://www.penturners.org/forum/showthread.php?t=59097

Hope this helps!
 

jskeen

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I've not turned a pen with bushings in ages. I got tired of taking the turned blanks off the bushings and mounting the tubes themselves between centers and them being out of round. So... I just started turning blanks from square to round and then to final shape and size just between the centers. I use a dial caliper to sand down to final size (read directly off the part that end of that particular blank is going to fit). I also usually don't bother too much getting the ends of the blank exactly square before turning. I use an old countersink bit that is about 80 or 85 degrees to open up the ends of the blanks and clean up the inside edge of the brass tube, then just face them with a thin parting tool on the lathe between centers.
 
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Shame on you!!!:mad::biggrin: ( Just kidding ) but if you have a metal lathe, then you SHOULd be making your own bushes, pens, mandrels etc etc.
A facing cut on your ML is a perfect way to square a round tubed blank too.:wink:


It is just a small Sherline lathe....:biggrin:
I need to get some good SS round stock to make some bushings and such...
 

bitshird

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Andrew; Not to sound like I told you so but...............................check out this thread http://www.penturners.org/forum/showthread.php?t=59523. I recall I mentioned that as your problem way back when!

Mack; yes you did and that was on another forum.
I posted the same question here to get a variety of answers so that i can explore each one individually and then decide what works best for me.
That is just how i like to do things...
johnnycnc bushings will most likely help and solve the problem, but before i splash out a lot of cash for all the bushings i want to see if i can solve it with what i have.

Thanks again for the reminder, it is bookmarked!!:biggrin:

Andrew
 

randyrls

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You don't necessarily want Stainless Steel stock, a piece of O-1 tool steel will cut much easier and two pieces one 1/2 in and one 5/8ths will get you buy for most everything but Lotus, and Emperors. try http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=408-0029&PMPXNO=943418 pretty decent price for a 3 ft. piece.


Hi Ken; I tried using the 0-1 tool steel, but didn't like the surface finish. I tried 12L14 and that works much better. I have some 1018, and I may try that.
 

Paul in OKC

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Hi Ken; I tried using the 0-1 tool steel, but didn't like the surface finish. I tried 12L14 and that works much better. I have some 1018, and I may try that.

Randy, getting a finish on 1018 sucks. The 12L14 will finish much nicer and easier because of the 'L', lead in the mix. The few I have made are from O1.
 

bitshird

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Hi Ken; I tried using the 0-1 tool steel, but didn't like the surface finish. I tried 12L14 and that works much better. I have some 1018, and I may try that.

Randy 12L14 is freemachining steel it also contains a minute amount of lead alloy which makes it softer, 1018 cold rolled is also pretty easy to cut, but I'm surprised you had difficulty with 0-1 it cuts easy until it's hardened, I've never worked on a Taig or Sherline lathe, but I sure put my Taig Mill through hell. The 12L14 might leave a nasty residue when you sand near it, Enco also carries Delrin Rods cheap.
 

jocat54

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Leakey, Texas
Hi all,

I know this is an old problem and i have used the search function both here and on Pen Turners Paradise to no avail...

This is my problem.

I have the dead centre in the headstock - Runout is less than a thousandth.
The live centre is in the tailstock and runout is the same as the headstock dead centre.
I line up the centres and lock the headstock so that the points are aligned.

Then when i turn something it is not round...
Turning is done between centres so no mandrel to bend.

I tried using a blank brass tube mounted on the bushings and that is where all the runout is happening!
On both bushings the runout is almost a hundredth of an inch!!
This is also translated to the brass tube.
Do i need new bushings??
Or is it time to try without the bushing??

I am going to glue up a tube in some useless wood and turn it without bushings to see what i get.

Any help appreciated!!!

Andrew



Just a thought-I was having some out of round issues and it was only on the headstock side. It turned out that my morse taper in the headstock neede to be cleaned, made all the difference in the world.
 

randyrls

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Randy 12L14 is freemachining steel it also contains a minute amount of lead alloy which makes it softer, 1018 cold rolled is also pretty easy to cut, but I'm surprised you had difficulty with 0-1 it cuts easy until it's hardened, I've never worked on a Taig or Sherline lathe, but I sure put my Taig Mill through hell. The 12L14 might leave a nasty residue when you sand near it, Enco also carries Delrin Rods cheap.

Steven; I have made bushings from 0-1, but it seems to have a rough finish like cats tongue. I believe that my tools are not sharp enough. Can O-1 be work hardened?? Like Stainless?

I make my bushings .005" undersize so I don't hit them with the sand paper.

I'm going to have to try 1018, but right now I am working on remodeling the rec room; slightly larger than a pen! :) Staining oak trim pieces now.
 
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