To turn by Center or Not to turn by Center?

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65GTMustang

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I am considering the purchase of new bushings to turn by center.
I was hoping to get some advice before I spend a bunch of money before doing so.
I have a few sets that came with a trade and I really like turning with them
I get a much better pen than if I use a mandrel.
I have 4 or 5 mandrels and I have checked to make sure my lathe is running true - for whatever reason I am getting a high / low spot on both ends of my pens (definitely not turning true)???
I have tried brand new mandrel shafts, adjusting the tightness of the brass nut, using the mandrel saver...etc... Even the best result I am getting is not very good and some adjustments are needed.
When I use a set of CTB I don't have a problem?
What would you do?
Thanks
Kevin
 
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Kevin,
Seems like you've answered you own question. :wink:

You have two choices: (1) Figure out why your mandrel turned pens are inferior or (2) bite the bullet and purchase the between center bushings.

I turn one barrel at a time with no out of round problems.
I use a Beall collet chuck to hold my mandrel and a 60 degree live center.

Sanding often makes a round pen oval because the different grain orientations. Wood on one side of a rounded blank is softer or harder than wood on another side and sands away at different rates.
Dull tools require more pressure to cut and can bow a mandrel.

But, from what you have said none of these problems seem to be plaguing you but only you can figure it out.

Keep looking or spend the money.:biggrin::biggrin:
Do a good turn daily!
Don

65GTMustang said:
I have a few sets that came with a trade and I really like turning with them.
I get a much better pen than if I use a mandrel.
I have tried brand new mandrel shafts, adjusting the tightness of the brass nut, using the mandrel saver...etc... Even the best result I am getting is not very good and some adjustments are needed.
When I use a set of CTB I don't have a problem?
Thanks
Kevin
Click to expand...
 
I had a set of cigar bushings that caused an out of round barrel. If you're having problems with different kits and bushings, best to start by adding each component to see what is causing the wobble. Switching to center turning doesn't necessarily mean you've solved your problem.
 
Don,
Thanks for the input - I think I will try chucking my mandrel in the Beal Colet before making the change over....
If that does not work, I already have my shopping basket loaded on PTP.
OUCH!!! That's a bunch of money but well spent - I turn daily and don't need the aggravation.
Plus I like the idea of the different finishing bushing. That will be another plus.
Thanks
Kevin
 
Kevin the finishing bushings are a smart investment, I turn between centers and wouldn't go back for a minute. But I cheat, I make my own bushings, Johnny's are the best you can get, and unless you just go nutz and buy the whole collection ;-) just get the ones you use the most, also like Don said just keep it short, the mandrels I have can be adjusted for about any length but unless I'm doing a bunch of Slim Lines for troop pens or something like that, I just turn one barrel at a time TBC or on a mandrel either way.
 
Another thing to check is if your tools are sharp. Trying to turn with a dull chisel can make you press more on the blank causing the mandrel to bow creating an out of round pen.
 
I thought it would be harder for some reason to turn between centers so I put off doing so for quite awhile. I finally got sick of trying to make my mandrels straight and not wobble on EVERY pen I tried to make. So I went on Amazon and bought me a Grizzly dead center for around 12 bucks. and turning life is much better. The only harder part about it is you have to measure all your final dimensions. I have not used my mandrel in months.
 
I watched a video a week or so ago on turning between centers. Looked like the turner was using bushing designed for a mandrel between centers. If so, is there a down side to this.
 
Robert Gill said:
I watched a video a week or so ago on turning between centers. Looked like the turner was using bushing designed for a mandrel between centers. If so, is there a down side to this.
Click to expand...
I have tried it with the bushings and still got wobblel and out of round blanks. Some say that the bushings you get with your for your kits are not drilled perfectly centered.
I do not know if he still makes them though I think he does bushings>>>http://www.penturnersproducts.com/
I just plug the live and dead centers right into the brass tube.
 
I have been turning betw centers with good success by using the standard bushings. It is not the complete answer, and some standard bushes are not as precise as others. I will eventually get the special bushes from PTP, but am getting decent results now. It is a MUST to accurately square the ends of the blank for this type turning, since the end of the blank is a reference surface for keeping everything aligned. You can try this with no additional $ outlay.
 
Once you start to turn between centers you will always wonder why you took so long to start. Your accuracy improves dramatically. Now you don't have to worry about over tightening the nut, pushing too had when your tools become dull or a number of many other things that are critical to turning on a mandrel. The other important key is JohnnyCNC's bushings.
 
I thought about my response (post #12), and wanted to add this. After turning down close to finish size using standard bushes betw centers, the final turning is completed with no bushings and calipers. This removes any OOR, etc. possibly introduced using the bushings. You can't get any better than centers directly in the tubes.
 
65GTMustang said:
I had considered turning without bushing and using my calipers to check dia. but don't want to be bogged down with the constant checking.

Thanks for your comments.
Click to expand...

Yea, the constant measurements can be a pain, a foot switch for the lathe helps a bunch for this. The bushings make things go a lot quicker, since you can get pretty close to size more quickly without having to check over and over, but like Steve said, I do the same, use the bushings to get close, then do final sizing, sanding and finishing without bushings. I also only bought TBC bushings for pen kits I do a lot of. Learn to TBC without bushings and it can cut your investment in low volume pen kits by not needing to have bushings for pens you may only do a couple of, or may only do once and a while. Invest in TBC bushings when you have a kit you like or want to do often.
 
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