pens out of round

[scroller99]

Now I know this is an old question, but I have tried just about everything. Now my lathe has made a few pens 20 or so years worth and I really never had a problem before. I have checked my mandrel for straightness and have even retired my old Delta for a new Rikon. I know enough not to over tighten the mandrel and I still have an issue of the pens being just a little egged in the middle. I really am getting ready to go get an ax and start chopping. any advice would be greatly appreciated. thanks

 

[jttheclockman]

library/general_reference/Why-are-my-pens-not-round.pdf



http://content.penturners.org/library/general_reference/Why-are-my-pens-not-round.pdf

 

[leehljp]

That was one of the reason I started using TBC. Too many variables on mandrels when things go awry. And it is not always just one but sometimes a combination of two or more problems.

Took me a few minutes to find it John, but I hung in there.
More specifically here is where to find it:
library> second blue bar> techniques> first column (left side) second from the bottom.

There is one reason that quickly comes to mind that wasn't mentioned. Russ Fairfield use to comment on this on occasion: Sanding. two things can happen.
1. soft grain versus hard part of the grain. Soft sands away on one side more than the harder part on the other.
2. A similar problem with the same result: too much pressure when sanding - causes flexing and sanding the softer par of the grain away.

When I was starting out, it was not uncommon for people here to mention occasional bushing's mandrel hole being off center. I had one that was visibly so. I began to measure each bushing I ordered to make sure it was drilled properly. Use calipers.

 

[jttheclockman]

Sorry Hank. I fixed the link

 

[scroller99]

Thanks guys. Now you have me leaning towards my barrel ttrimmer, I need it could give me grief but not this much. Thanks

 

[mecompco]

Hope you find a fix! I would humbly suggest considering getting rid of the mandrel and TBC. I would further suggest perhaps eliminating the barrel trimmer and move to one of the sanding methods. Just things that have worked for me (in my relatively short time here), YMMV.

Regards,
Michael

 

[jttheclockman]

I do not believe you need to make any drastic changes but start eliminating one by one the possibilities. In the link I gave there are a list of them. Each one can produce the results you are seeing but in turn each one does not have to be the problem. I see so many times here that mandrels are to blame or bushings to blame but to tell you the truth many times it is operator error. I have never run into out of round bushings and i take care of my mandrels and pay attention as to what I sand if anything. Yes at times I do turn between centers but 90% of the time I do not. What I do practice is to turn one blank at a time. I am never in a rush to make a pen. I do finish between centers because I use a dead and live center for that and it totally eliminates the CA sticking to bushings which causes another set of problems. This has worked well for me. Good luck.

 

[low_48]

"Now my lathe has made a few pens 20 or so years worth and I really never had a problem before"
If your lathe has made pens for 20 years, how many years have you made them? LOL
What rpm are you turning at? Crank up the speed! What tool are you using? Learn to turn gently, I suggest a skew.

 

[Paul in OKC]

Don't remember how long ago I wrote that, but......... John, I still turn the same way as well. Standard mandrel and a barrel trimmer. Occasionally do a pen between centers. I still truly believe that most all 'out of round', or oval comes from wood grain. Concentric issues from unsquare ends, or loose bushings. I agree with only chasing one thing at a time. You may find your solution easily by just taking a step back and slowly looking at each step and how you do it.

 

[Imaginethat]

I did come across a set of bushings that were not true. Checked mandrill with dial indicator it was good, run dial indicator on bushings, not true. Trashed them, next set no problems.
I turn one blank at a time and as close to the headstock as possible. Use barrel trimmers works great if I put a small amount of oil on the trimmer end going into the tube, really helps.

At first it was about making pens now the fun is the motivation. Retired and relaxing.

 

[KenV]

Howard,

Ever note all the little differences when you get into a different vehicle and drive it? Lots of little things different and a few bigger ones. Those thing that were comfortable and automatic do not seem the same.

On a smaller scale, changing lathes has the same root issues.

Make sure tools are sharp, because you may have been able to get one more pen before sharpening. Pay attention to your presentation, because with more torque, you can be taking excessive cuts because what you hear is now different.

New equipment new challenges with changes in muscle/mental memory.

 

[scroller99]

Thanks Ken, the reason I changed lathes was because of this problem thinking my ol girl was done? Maybe I under estimated her. I am leaning towards my barrel trimmers because I have had problems with them in the past. I'll try one barrel at a time and chuck the trimmers, new set on order and see how things work out. Thanks to everyone who has been helping me I really appreciate it Howard

 

[nativewooder]

Why don't you sharpen your barrel trimmers? I sharpened mine and I quit having headaches! (Or was that when my ex left?!)

 

[jttheclockman]

Why don't you sharpen your barrel trimmers? I sharpened mine and I quit having headaches! (Or was that when my ex left?!)

You need to be careful when sharpening trimmers. It really should just be a honing if anything. You sharpen one side more than another and now your trimmer is out of round. This could come from the company that way also. Just something to look for.