Pen Turning Questions

[Carver238]

I am new to this site and some what new to pen turning. I have turned about 60 pens, mostly slim line. I am having a little problem when I turn pens. It seems to be very hard (for me at least) to get the pen mandrel on center on the right side. When I finish and press everything together, I can feel an edge where the point of the pen and the wood meet. This edge is not all the way around but, only on one side. Also, does anyone have a method or procedure for taking the pens apart to refinish. I am using a Jet Mini lathe.
Bill

 

[barrels]

Hey Bill,

Welcome...... from what you explained it sounds like the pen is out of round. And this is the obvious..... is your mendral rod out of round? or from what you expained that you can not line up to your tailstock is the mendral placed in your headstock correctly?
As for disassembly the regular pen suppliers sell tools for that, I use a punch(closest size to match interior of pen) and rubber mallet.

Eric

 

[kent4Him]

You have a bent mandrel. You will probably now get a ton of information about this, but you can do a search and find many threads. Here is my list of things that will help:

Get a Beall Collet Chuck
Get a 60 degree live center
Get a new mandrel
You are probably tightening the ring too tight.
You may also be putting too much pressure towards the bar when turning.

 

[Rifleman1776]

Bent mandrel is a possibility. Some come that way new or the threaded hole on the MT is not perfectly straight. Another possibility is that the lathe is not perfectly in alignment. Put a spur drive in the headstock, and a live center in the tailstock. Then bring them together, the points should touch exactly. There are some complicated varibles to this, but if, visually, they meet, you should be OK. Another possibility is that the mandrel just flexes. My pens improved dramatically when I went to an adjustable mandrel and did only one half at a time. Shortening the mandrel eliminates 99% of the whipping flex. Check out discussions on the 'no mandrel' method of turning pens. I highly reccomend this. What you are experiencing is not a new problem and you are not alone.

 

[Monty]

Bill,
First off, welcome to the insanity.
In addition to the advice already given, check to make sure that the headstock and tailstock line up. To do this, put a dead or drive center in the head and the live center in the tail and bring the tail up to the head. The points should touch. If they are off, you may need to shim the head.
As for disassembling pens, the 28 piece transfer punch set from Harborfreight, http://search.harborfreight.com/cpisearch/web/search.do?keyword=transfer+punch&Submit=Go
is your best bet, and it's under $10.
Do a search on pen disassembly and you'll find lotsa info. If you need more info, email me.

 

[Rudy Vey]

Very important: make sure your blanks are square!! This seems to be mostly the problem when all other things are ok.

 

[leehljp]

One thing I noticed two or three times in the past couple of year - when I was not paying close attention, I overtightened the tail stock live center just a smidgen too much. It turned fine but had a minute' and almost unnoticable wobble that made the wood proud on one side. I have never measured it, but I bet the difference between perfect and too loose or too tight on the live center would be no more than .006 or .007 inch. It takes a little practice and experience to do it perfect.

IF this is the problem (or even if it isn't) it is good to practice for several minutes tightening and loosening the live center onto the mandrel to get the feel of what is just right and what is too loose or too tight.

 

[JimGo]

I think Rudy meant to make sure the ends of your blanks are square with respect to the tube. If an end is crooked, the bushing can be pushed out of alignment.

Everyone has given you really good advice. One thing I'll add, though, is that there's a no-cost way to help remedy the problem. Try this:
1) turn close to the bushing height (1/32" or so over)
2) stop the lathe
3) loosen the brass nut - if it's overtight (which can happen naturally as part of the rounding process), it can contribute to misalignment problems
4) hold the bushings still and rotate the blank 1/4 turn
5) hand tighten the brass nut just enough to keep everything from slipping
6) touch up the ends of the blanks with VERY light cuts
7) repeat steps 3-6 two more times

You should now have pen barrels that are much closer to round than you've been getting, and you'll be pretty close to the bushings, too. Mic the parts and the barrels to ensure everything will line up, and you're good to go.

 

[Rmartin]

Try installing your mandrel without any blanks. Turn the machine on and run your finger or a tool along the mandrel. Is is smooth, or do you feel vibration?

 

[Carver238]

Thanks for all of the comment and suggestions. [^] I have tried to be carful tightening the nut on the mandrel however, after reading your comments, I know I have over tighten the live center. [] I don't know why I did not equate that to the same thing as tightening the nut too much. I will check the tail stock to the head stock and make sure they are in line then, I will run the mandrel without a pen blank to see if it is smooth or has a wabble. I will let you know how things turn out. You have given me several other items if the above does not correct it. I have replace the mandrel with a new one but I suspect I am tightening the tail stock too much trying to keep it on center.[B)][:I][B)]
Thanks, Bill

 

[bjackman]

Also, you mention you use a Jet mini, but you don't mention that you have replaced the stock live center with one that has a 60 degree angle point. The stock live center will usually work ok for a while (maybe 60 pens or so... [] ) but then wear on the point will begin to get worse and worse.

 

[Rifleman1776]

Originally posted by Rudy Vey
<br />Very important: make sure your blanks are square!! This seems to be mostly the problem when all other things are ok.

Huh? 'scuse me, blanks can be almost any shape. That's what the lathe is for, to turn chunks of wood into round things. I've started out with branches.

 

[Rudy Vey]

Originally posted by Rifleman1776
<br />

Originally posted by Rudy Vey
<br />Very important: make sure your blanks are square!! This seems to be mostly the problem when all other things are ok.

Huh? 'scuse me, blanks can be almost any shape. That's what the lathe is for, to turn chunks of wood into round things. I've started out with branches.

What I meant is that the end of the blanks have to be squared so that the tubes are square to bushing resp. mandrel. Some using a squaring tool, aka "Barrel Trimmer", others use a disc sander. I had no idea you didn't know that, even branches must be square to the tubes....
I guess JimGo understood what I said.

 

[Rudy Vey]

Originally posted by Rudy Vey
<br />Very important: make sure your blanks are square!! This seems to be mostly the problem when all other things are ok.

OK, the blanks must be squared to the tubes. There are different methods, like using a barrel trimmer or a disc sander. Now, to avoid the next smart remark, the standard shaft for trimmers are for the 7 or 8 mm tubes, if one is using larger tubes, a liner has to be made. This is easy to be done. Glue a tube that is matching your barrel trimmer into a piece of wood, Corian etc and turn it round so that it fits snug the inside of the larger tube. I have made liner sets for all type of pens, like Sierra, Baron, Gent Jr, El Grande etc.and use the same 8 mm barrel trimmer for for all.

 

[GBusardo]

Bill, One other thing to check. It dont take much gunk, either on the live center point, the mandrel or the morse taper to make your madrel wobble a little. Some acetone can clean things up in a hurry.

 

[Scott]

Hi Bill! Welcome to the IAP!

In your description of the problem, you mention that the out-of-round problem always occurs at the end of the pen, at the nib. While you have received excellent advice above, I have to think the problem may lie in the live center you are using. The taper in the end of the mandrel is 60 degrees, but the taper on the point of the Jet mini live center is not 60 degrees. As Bill Jackman mentioned above, it will work for a while, but about where you're at right now it will tear up the point of your live center, the taper in the mandrel, or both. That would throw things off at one end of the pen like you describe, rather than in the middle of the pen, which is where you would more likely see out of round if you tighten too much or have a bent mandrel. Of course, not squaring the ends of the blank properly could also throw things off at one end. I recommend you get an inexpensive live center with the 60 degree taper, and a new mandrel.

As for disassembly tools, I highly recommend the punch set from Harbor Freight mentioned by Mannie above.

I hope this helps! Remember to have fun!

Scott.

 

[tntwoodcrafts]

Originally posted by Rifleman1776
<br />

Originally posted by Rudy Vey
<br />Very important: make sure your blanks are square!! This seems to be mostly the problem when all other things are ok.

Huh? 'scuse me, blanks can be almost any shape. That's what the lathe is for, to turn chunks of wood into round things. I've started out with branches.

Was one of the branches from your family tree!!

 

[dalemcginnis]

Originally posted by JimGo

3) loosen the brass nut - if it's overtight (which can happen naturally as part of the rounding process), it can contribute to misalignment problems

[]
Why'd you have to mention that the nut can tighten naturally?[?] Ever since I read that I've been having that problem. [] I'm having to loosen the nut with a pair of pliers. And no, it's not me over tightening it. [] I tested it on two pens this morning. After I had turned the blanks to a round shape, I would loosen the nut (with pliers) to where it's not even touching the bushing. Turn the lathe on and watch it tighten itself against the bushing and then do some more shaping of the blank. After a couple of minutes I would check the nut and it would be so tight I could barely loosen it by hand.

So, now I'm stopping every couple of minutes to loosen the nut so it doesn't get too tight. Never had to do that before.[]

 

[loglugger]

If the blanks are true at the ends, the mandrel and bushings are clean, it does not matter how tight the nut gets. I tighten the nut tight, bring the tail stock up close to but not toching the end of the mandrel and turn the lathe by hand, if the mandrel does not stay true then find out why. It is usually ca or dust or a burr on a tube or bushings. I have read that some of the bushings fit loose on the mandrel and can cause out of round but have not checked it out.
Bob

 

[cdcarter]

Originally posted by kent4Him
<br />You have a bent mandrel. You will probably now get a ton of information about this, but you can do a search and find many threads.

Don't know about Carver, but I was having the same problem and replaced my mandrel, and it fixed it.

 

[Carver238]

I put new bushings on the mandrel and I now put on my blanks and the nut. Next I get my tail stock close to the end of the mandrel and then turn on the lathe. when the mandrel is spinning true on center, I tighten up the live center to the mandrel. Next, I turn the lathe off and tighten the nut on the mandrel to keep the pen blanks from sliping. I have turned five pens this way with no problems described in my orginal post. Thanks for all of your help and suggestions.
Bill

 

[its_virgil]

I must respectfully disagree with this statement. Two common mistakes made are (1) tightening the brass nut too tight. If the brass nut is too tight, the blanks will bow in the middle as the blank gets smaller and cause out of round blanks and (2) tightening the live center too tight. This will cause the mandrel to bow and out of round pen blanks will occur. If (1) and (2) are both done, then they compound each other...bowed blanks and bowed mandrel. I don't think the brass nut will get too tight to cause problems on its own. But I was using pliers to tighten the brass nut and the tail stock when I first started. I thought they had to really be torqued down... They both should be just tight enough for sound support. I routinely stop during turning and rotate the blanks a quarter turn or so several time while turning and sanding. Just my thoughts ... take 'em or leave 'em.
Do a good turn daily!
Don

Originally posted by loglugger
<br />If the blanks are true at the ends, the mandrel and bushings are clean, it does not matter how tight the nut gets.

 

[loglugger]

I have a hard time with this typing bit, there is a limit as to how tight anything should be tighten and was not thinking about cranking things down with pliers, although I think if you are cafeful you could do that. I will put the dial indicator on one without the wood and find out what happens when you realy crank it down. Everyone is welcome to try this as every set up is a little different.
Bob

 

[Carver238]

I need to explain a little better. When I tighten the live center, I bring it in until the live center begins to spin. When I tighten the nut on the mandrel, I just snug it up to the pen blanks. I don't think I am tightening too much but, if you think this method is bad, I should change now. Thanks for your comments, I like the feed back, good or bad.
Bill

 

[loglugger]

Bill, my thoughts are if it is working for you that is what maters. []
Bob