Out-of-round finished pen...

[killer-beez]

What is the cause of an out-of-round finished pen? When I assemble the pen, the edge on one side of the finished pen sticks out beyond the kit, yet the other side is flush. Mandrel bent? Bushings out of round? Sure does trash an otherwise great looking pen....

 

[sbell111]

Overtightening of the tailstock?

 

[Petricore]

There are many many many threads covering this. I'll tell you the 2 things I did to fix it for me. I switched to mandrelless turning (turning between centers) and I also built a little sanding jig as I found the premade barrel trimmer just wasn't making them perfectly square. Now I'm close enough for me being a perfectionist

 

[RussFairfield]

The first question you have to resolve is - Was the pen out of round when you finished turning, and before you started sanding on it??

If it WAS round before you started sanding, then a differential in wood removal because of the differences in wood grain is the problem. If this is the problem, you need to concentrate on making a smoother cut while turning so you can sand less and with a finer grit.

If it WAS NOT round before you started sanding, then there was something wrong with your turning, or the mandrel was wobbling.

Turning the wood can make it out of round because of the same grain differences that affected sanding.

If the problem is the lathe and mandrel, it could be anything from tightening bushings too tight against ends that aren't square with the insides of the tubes, to dirt between mating metal surfaces, to a bent mandrel, to misalignment in the lathe or the adapter.

You can isolate the problem further by running the mandrel without wood. If it runs smooth and true by itself, then the cause is something you did after you put the wood on the mandrel; and trimmed ends that aren't square to the tubes is the most likely culprit.

 

[donwae]

What type of pen is it? The first time this happened to me the bushings for the blank I was turning were a 'B' size and I had them on an 'A' size mandrel.[:0]

 

[donald19]

I had that problem O of R. Use your original head stalk ( >--< ) and line it up with your tail stock as shown in between the brackets. If they don't line up within 1/16"+- your lathe is OUT OF ROUND You may have to use some kind of shim to align the H & T stock.

 

[Brewmeister35]

A couple more ideas for you to check.... after you follow Russ's advice. If your blanks aren't trimmed square, when the nut is tightened on the mandrel, it will bend slightly causing an out of round condition. When you first cut the square corners off the blank, check the mandrel nut and make sure it hasn't over-tightened itself. You can loosen it and re-tighten. Another thing to look into is turning between centers which will eliminate the problem IF it's related to the mandrel system. You also need to make sure you have a good 60' live center.

 

[Rudy Vey]

The main reason for out of round is that ends of the barrels are not perfectly square to each other and/or to the bushings (assumed your head and tail stock are in alignment).

 

[brez]

I use to have this problem often. While there can be several reasons, that have all been mentioned, I have found that by loosening the mandrel nut after rounding the blank, it is no longer a problem.

Mike

 

[redfishsc]

I used to fight this tooth and nail and could not, for the life of me, get it right. So here is what I learned.

1) I do not used the black mandrels from Woodcraft- I use the silvery ones. They, for whatever reason, seem to have a lot less flex. I can turn dozens upon dozens of pens on one of the silver colored ones.

2) Careful not to tighten the nut down TOO much.

3) Use sharper tools and make lighter cuts. This does two things: reduces the amount you are pressing on the mandrel (that force can cause an out of round pen in and of itself), and it leaves a cleaner cut which makes sanding easier and more accurate, just as Russ said.