The center of my pen is just not lining up? Any suggestions on getting it right?

[Joshua Dinerstein]

OK. This is bizarre. I bought 2 pen kits from CraftSupplies the other day at lunch. I have the wallet destroying "blessing" of working about 30 minutes away from those guys. :)

The first pen was an unmitigated disaster. I smashed the transmission in way way to far.

So 2 Rex and Kip videos, a conversation with Rex (who just happened to be in the lobby of the store that day), and a slower more careful approach later I thought I had succeeded.

So here are the particulars:
- I used CSUSA slightly more expensive slim-line kit.

- I cut one blank a little longer and didn't ream it down so that I could get rid of the center band and go for a larger diameter pen.

- I glued in the brass tubes.

- Once the CA had cured I trimmed the ends of both segments so that they were all flat.

- I turned the blanks such that I could put the center parts directly together with no bushing in between them, turned/twisted them so they fit tight together with the corners not in the way, so that I would be "guaranteed" to get the same larger diameter in the center of the pen.

- I checked the mandrel to make sure it wasn't being bowed at all. I actually had to loosen the headstock and turn it a bit to make this happen. Once that was done it centered perfectly.

With this setup I turned it down to a fairly thick diameter in the middle, as compared to a normal approach to a slimline kit and tapered to the nib and cap only at the very ends. The grain was off because of the twist for the corners but the fit was so good that there appeared to be no gap. I turned it down and all looked great!

I applied a simple finish of some Myland's friction polish. It was what was recommended at the time in CraftSupplies but I have since read that it doesn't hold up well so in the future I will try something else.

Anyway I then assembled the pen with my bench vise. Much to my disgust, once assembled the two halfs of the pen that were turned right next to each other are no longer "a good fit". If I twist the pen to the right place then there is no discernable gap or ridge to the touch. It is aligned and smooth and exactly what I wanted. But then twist it to open the pen and suddenly if feels like there is a 1mm or larger ridge. It is visible as well as something that can be felt.

How is that possible?!!? I mean honestly. I turned it down to round on the lathe. No chatter, not twisting or ridging occured. No excessive pressure was used. I took only the lightest cuts. But somehow it is like the center of the brass tube wasn't actually the center of the pen or something?!!?

I know that there are some major pen turners on here who have made literally hundreds of pens. (Ken, Bernie, Brian, etc...) Have you guys or anyone else run afowl of this kind of thing before? What causes it? And how do you deal with it? How do I correct it so that the pens actually look like they were made properly. It is the kit? Is it me? I think I might be cursed.

Any suggestions would be greatly appreciated! I am lost as to how this happened...

Thanks!
Joshua

p.s. Sorry no pictures at the moment but tonight if anyone needs to see this.

[Steve Mawson]

Not sure how you made the ends flat. If they are not perpendicular to the tube then there will be spots were the ends do not mesh flat. I used to use a sander and had the issue you describe. Then bought a pen mill and that has taken care of the problem. Hope that helps, others may have better ideas.

[Brian McDermaid]

I'm going to vote mandrel flex... tailstock too tight, the mandrel nut too tight or even a bent mandrel and you'll get a nice egg shape. I think without the center band it would be even more noticeable.

~Brian


PS. CSUSA.. Just as nice in-person as you'd expect! its great to be a local!

[Bill Stehman]

Joshua, two suggestions, first see if you can wrap scotch tape about 7/8 the way around your mandrel where the bearing are. Not all bearings fit all mandrels the same. Second, when sanding remove the center bearing and rotate each half 180 degrees on the mandrel. Then another 90 if you still feel the ridge. Keep rotating and sanding until the fit is acceptable.

[John Terefenko]

Boy if you have Rex or Kip there you have a wealth of info. You lucky dog.

There are some parts of your story you are leaving out but I will give you my ideas. First you do not tell us how you made the ends flat. You could have sanded them but what did you use to sand them.

Oh this is going to get long.

If you sanded them using a disc sander you need to make sure the device holding the pen is straight on with the disc and is 90 degress to the disc. There are holders and some people have made their own. But probably the most used tool is the pen mill. Now there can be issues with this also so that is why a 6 cutter head is better than a 4 cutter head. If the cutter edges are slanted just a little bit from say the way it was shapened it can leave the outside edge of the blank shorter than the inside where the tube is. To get around that what I have done in the past ( now have a sander mill) Get close with the pen mill and the cutter head. Now take the cutter head and turn it around so now you have the flat side facing the tube and cut a piece of sandpaper to fit over the mill. I used stick back paper and a hole punch to make the piece. What this does gives you a blank where the tobes are 90 degrees with the outside edges.

Now if you did all this and you are still having fitting problems you should check if there is runout in the mandrel and it is bent because of overtightening the brass nut or thew tailstock. Or bending the mandrel by applying too much pressure when sanding. If this all looks good a way to combat such out of roundness is to rotate the blank about a slight ways say around 90 degrees. Loosen the nut rotate one side of the blank 90 degrees and the other side of the blank 180 degrees. If you put both blanks back together and everything was 100% right on then those blanks should line up again but I bet they do not and never will. So you sand till even again and at least now you have taken a percetage and made it work. Try it and you will be amazed.

I rotate a blank even if I am doing a Sierra which has only one blank. Because if not totally round it will show up when you press it against the ring on the pen kit.

I hope this all made sense. If not fire away.

[Phil St.Germain]

Another thing to look at is maybe the transmission is not straight into the lower barrel.

just my 2cents

[Don Carter]

Joshua:
You are so lucky to live close to CS. My wife is glad that we live so far away.;)
You have received great advice as to things to check for the dreaded OOR(out of round).
I have always used a pen mill to get the ends square to the tubes. I would like to see a pic of your pen. If no run out on the lathe and the mandrel was not bowed...?

All the best.

Don

[Don Orr]

Could it be that sanding of different grain patterns has made them oval ?
Hard to describe, but if the grain is lined up along both blanks with no bushing in between while turning so they meet at the join, then when sanding you are sanding different densiteis of wood. Edge grain where you see the longitudinal edge of growth rings, and face or side grain which is in between growth rings. The face grain is often softer and sands away more easily than the edge grain. If you have ever sanded pine or fir this is very noticeable. Sanding away more face grain than edge grain would cause the blanks to become oval and not line up when rotated ene to end with each other. Try to see on the pen if this the case. Just a possibility and I'm sorry but I don't have a good solution. Do you sand along the length of the barrels with each grit ? Maybe spend a little more time on the edge grain while doing this. Even go so far as to check diameters with an accurate dial caliper or micrometer.

I hope you figure this out. I don't do pens very often because I can't get them to come out as nice as I think they should. Mostly due to impatience probably. Good luck and let us know how you make out.

And I could NEVER live that close to such a cool toy store:eek::D.

[Joshua Dinerstein]

Sorry about the missing information. I had thought I was going all run-on and being too full of detail and then at the end there was too much missing.

To answer the questions I was asked:

1 - How did I make sure the ends were flat? To true up the ends of the wood I am using a woodcraft multi-tip pen mill. I am actually looking at it right here. I brought it into work to show a co-worker. The mill fits relatively tightly into the pen's cap. I just pulled it apart to test. So I used t 4 blade mill to ream it out and then get the end flat. It appeared to be so as when the wood was pushed together it snugged right up with none of the gaps I would have expected on my mandrel if it had been angled. I did not sand the ends flat. I have seen that in a video somewhere, especially using a large wheel and belt sander, but I just used the pen mill.

Are there problems here I am unaware of? Will the pen mill not always flatten the surface properly?

2 - I'm going to vote mandrel flex Hummm. I had thought about this in terms of the tailstock being too tight. I had read about that somewhere online. So I locked the tailstock hand-wheel so that it wouldn't move and then slid the whole tailstock up until it touched and then locked it down in place. I had expected that to prevent any flexing from over tightening. But then I had the nut on the mandrel tightened down pretty hard. I didn't want them to twist on me. It is quite possible that I had it too tight. I had no idea that that could flex the mandrel shaft.

I am embarrassed to admit it but I never thought to check the mandrel to see if it was already bent when I got it. I haven't dropped it so I wouldn't expect it be but it is easy enough to check.

3 - How did I sand it? I will post up a picture later tonight. It has lovely grain. It is a piece of Cocobolo that I got from a friend. But the grain does run down the length of the pen rather than across. I sanded pretty lightly, I thought, but I am a bowl turner so it is possible that I am to used to that and sanding to hard. I am not sure.


I will be trying it again and I will both try rotating on the mandrel mid-turning to see what I can get and sanding much more lightly.

BTW the problem isn't one of getting something like this:

__________
____/\_____

when I turn the pen to open or close it. I am not creating a gap that way. I am shifting around the center. So that this:

______
___|___

becomes, with great exaggeration, this:



____
____|-----
|-----


when set just right the 2 halves line up perfectly. When twisted say half way around they are off like the lower text picture above. You get an edge you can both see and feel. Though to be clear it is no where near as off as the drawing would indicate. It is just annoying as I try to figure this out.


Thanks for the help. Any further ideas? I will check the mandrel tonight. BTW, how tight do you make the nut on the mandrel? I am only hand tightening it but I did get it pretty tight so that things wouldn't slip.

Thanks!
Joshua

[Bernie Weishapl]

Joshua I can't add much more. I have to say ditto what John T. said. I had the same problem when I first started but I found I was getting a little heavy handed tightening the brass nut. On the tailstock I bring it up and just start it into the mandrel then I turn the lathe on at slow speed and crank the livecenter up to where it just makes solid contact then lock it down. I use a disc sander squaring the pen blank ends and use a machinist's square to make darn sure the blanks hit the disc perfectly square. For me it works better that the pen mill. I am going to order and try a six blade one if I can find one.

[William Payer]

Joshua,

I would go with the mandrel being bent or tightening the tailstock and mandrel nut the most likely problem. I have found that when running the tailstock to the mandrel end, do not exert too much handwheel pressure as it will induce a bow inthe mandrel. Secondly, only tighten the mandrel nut after the tailstock is locked and tightened.

Another issue no one has yet mentioned is the mandrel is cone shaped on the end that receives the tailstock center. Both the mandrel and the center need to have the same 60 degree cone machined in them. Often tailstock centers are not ground to a true 60 degree angle, and can often be made of softer metals (need hardened centers) that distort with use. If the fit between the center and mandrel tip has any slop in it due to these issues, it can cause non circular rotation.

[Joshua Dinerstein]

Ok. So here are the promised pics. I turned another one tonight. Just to see what would happen.

The first 3 pics are of the pen that is the worst. It was the one I was talking about here at the start of this thread. The photos aren't great. I fear I have no particular skill at taking photographs of anything much less my turnings. But hopefully you can see it when it is opened and when it is set to be aligned. It is kind of funny how it fits.

The last 2 photos are of the one I turned tonight. It is made from Padauk as the LOML loves red. I thought a red pen might really do well for her.

I did all of what I was mentioned here and a few other things. I came home and turned on the lathe on slow without the tailstock to see what the mandrel did. It spun true. Basically no visible wobble at all. I checked the mandrel and it seems to be perfectly straight. I put the blanks on with a spacer this time as that was suggested that it could be the problem. I checked the gap between the brass tube and the mandrel and there wasn't one. I brought up the tailstock before tightening the nut on the mandrel. I did everything I could think of. The pen was "better" but still off when I turned it. So I wound up turning it by about 90 degrees and then doing more sanding, and again and a forth time just in case. It is better. Much better. But not perfect. So I will keep working on it. But if anyone should happen to have any more thoughts then please feel free to share them with me.

Thanks!
Joshua

[Ken Fitzgerald]

Joshua,

Here's a simple check to make. Pull the pen apart and look at the end of the pen. Is the wood even all the way around the brass barrel? It should be. If any place is thicker than the rest....there's the problem.

In theory, you drill a hole and glue in a brass tube. Then you place the brass tube over the mandrel As long as the mandrel remains straight during the turning process and sanding process, the pen should assemble without the problem you are displaying.



I put the pen blanks with the glued in tubes on the mandrel and loosely adjust the brass thrumb nut. Then I place the mandrel into the headstock. Then I bring the tailstock up and lock it down and slowly turn the handle until the live center engages the mandrel. Turning the lathe on at a slow speed, I place a couple of fingers on the live center and see if a slight amount of friction with my fingers stops the live center from turning. If it does, I tighten it just a little more and lock it down. Then I shut the lathe off, and just snug up the brass thumb nut on the mandrel. Very light pressure on the thumb nut.

Too much pressure will cause the mandrel to bow.

Good luck Joshua!

[Randy Schaffer]

Sorry I don't have anything to offer here in regards to the problem....

But I must say that is a much much much more attractive Slimline design than the wasp-waisted kits. It looks like a very comfortable and attractive pen.

Once you figure the issue out, you will have one of the most attractive slimlines I have ever seen.

[John Terefenko]

Take the pen and see if there is play side to side with the top and the bottom. Slimline trannys are not the best kits. Make sure when you press the tranny in you do it straight. Is your live center on the tailstock a 60 degree live center or is it the one that came with the lathe??? You do need a 60 degree live center because what will happen that small margin of space in the end of the mandrel where the center goes will cause the mandrel to spin off center. This is why alot of people have abandoned turning with mandrels and going to turning between centers. Of course you would need different bushings but you take out one aspect and that is any bent mandrel or slop in the mandrel. Good luck and keep trying.

[Steve Trauthwein]

What tool do you cut with? How much pressure do you use to cut? What grit sandpaper do you start sanding with?

Regards, Steve

[Jeff Nicol]

Joshua,

No one so far has addressed if the extra wood left for the removal of the center band is causing the trouble. I have not done this yet but I was reading about it in the new Woodturning designs. But is the extra length of wood mirrored with the brass tube? I was wondering if the brass is the original legnth of the kit and there is no tube glued all the way to the end it may give the wood there an extra area to dry (generated heat etc. from sanding) and change shape. If this is true there is a small gap between the mandrel and the wood where the extra wood was left. It may let you shift that enough to get and oval spot like mentioned before. I see that a lot of guys that do this put a small accent ring where the break is, this way you can drill the hole in the accent piece a little smaller than the 7mm for the tube. This will give you support at the joint.

Lots of information to absorb, but with all of it you should be able to find the problem.

Good luck,

Jeff

[Brian Brown]

Oh thanks Joshua! Other than visiting with my broker this morning to find out how much broker I am, I thought I would have a very relaxing day sitting by the fire sipping hot cocoa. Now I will spend the entire day trying in futility to wrap my feeble mind around the concept of why your pen shafts are off center. :D I myself have always been off center. But alas, that is a matter for the shrinks and philosophers of the world, and way beyond the expertise of those on this forum.

As to the pen problem at hand, I think your solution lays not so much in your equipment or technique, but your physical location. It's a gravity issue. The solution is to find and position yourself (and your lathe) in the exact physical center of the city of Atlantis. Most psuedo wild haired scientist-like-folk agree that Atlantis is the exact gravitational center of the universe, and that nothing there is ever off center, bowed, skewed or dimpled or dappled. As a side note, intense study is underway to determine why in Atlantis, tools never get dull. So, I am currently arranging a pilgrimage to Atlantis. For all who care to join us, send me your travel fee of $3,000.000 (US dollars only) and we'll stop by and pick you up. Just think Giant cruise. Don't forget your skew.

Other than the answers that you have already gotten, I think humidity may play a role here. Your weather is similar to ours, and we have had some real extreme changes in humidity lately. This will cause some movement in the wood, and not equal in all directions. Of the three different directions that the wood can move, it will move in differing amounts in each direction, and that can cause a round shaft to become oval. In other words, your wood (much like me) is not stable before you started to turn, and the heat and/or removal of slight tensions in the wood during turning have caused the wood to move after you so meticulously rounded it. It’s a conspiracy I tell you. The wood is out to get us. Probably revenge for using their families and friends to create our art. Well, gotta go. There are two guys in white jackets knocking at my front door. Looks like they are selling coats with long sleeves auugggggggggggg…………….. hellllllllllllllllp………

[Joshua Dinerstein]

Here's a simple check to make. Pull the pen apart and look at the end of the pen. Is the wood even all the way around the brass barrel? It should be. If any place is thicker than the rest....there's the problem.
Hummm. An excellent thought. I have a very nice pair of digital calipers. I will check it when I get home tonight and see if I can find a deformation in the width of it at various around the ring. Would be interesting to see what is really going on.

Thanks for the advice and suggestions!
Joshua

[Joshua Dinerstein]

Take the pen and see if there is play side to side with the top and the bottom. Slimline trannys are not the best kits.
There does not seem to be any. It is quite solid feeling and with as much pressure as I am willing to use it doesn't move at all. I watched the transmission and did my best to press it in straight. I could perhaps build a better jig/press block that would help it all go in straight. That might make a pretty big difference.


Is your live center on the tailstock a 60 degree live center or is it the one that came with the lathe???
It is a PSI 60 degree cone center. I bought it after the live center that came with my lathe started to wobble. Terribly. I checked it again last night. I am getting a good seat with the tail stock in the end of the mandrel. It has scored the live center a bit but not badly.


This is why alot of people have abandoned turning with mandrels and going to turning between centers. Of course you would need different bushings but you take out one aspect and that is any bent mandrel or slop in the mandrel.
Oh now that is interesting. How is it done turning between centers? Is there a web page that discusses this different technique. I would like to read up on it for future reference.

Thanks!
Joshua

[Joshua Dinerstein]

What tool do you cut with? How much pressure do you use to cut? What grit sandpaper do you start sanding with?
Hi Steve, cut with my 1" HF spindle/roughing gouge until I get close to the final dimensions. I do this very lightly and I get the smallest seeming chips but I wanted a hefty tool to try to help dampen all of the movements. Mine and that of the lathe/wood. I then at the end switch over to a 3/8ths " Bengamin's Best spindle gouge. This makes it easier to to match to the nib and the cap diameters.

I start sanding with 150. Then I go up from there through all of the normal grits. I didn't start at 60/80 as I didn't want to dramatically change the shape I just wanted to smooth it down to a nice finish.

Joshua

[Joshua Dinerstein]

No one so far has addressed if the extra wood left for the removal of the center band is causing the trouble. ... But is the extra length of wood mirrored with the brass tube?
It is the original tube from the basic slimline kit. I just left the wood hanging out longer over it. But I filled the gap between wood and brass tube with thick CA glue. I had hoped this would keep it from moving/shifting but perhaps it is part of the problem. I hadn't thought much about it. The pen blanks I bought are seriously dry. So I would not expect much more, any honestly, drying to be occurring. But the heat going for a friction polish finish could indeed be warping or otherwise deforming the wood in that point. I will take the calipers to the outside of the worst of the 2 pens tonight and see if I can figure out if it is warped.

Thanks Jeff,
Joshua

[Don Carter]

Joshua:
Have you made pens without the extra wood, that is, with the brass tubes flush with the ends of the blanks. If so, have you had this OOR condition? In other words did this only happen when you tried the pen with no center band?
All the best.

Don

[Joshua Dinerstein]

Joshua:
Have you made pens without the extra wood, that is, with the brass tubes flush with the ends of the blanks. If so, have you had this OOR condition? In other words did this only happen when you tried the pen with no center band?
An excellent question. You know I have not actually. These are the first 2 pens I have ever turned. Well I made a third but it was a comedy of errors from the get go and was a total train wreck. I put the transmission so far into the pen that you can't retract the ink tip at all. I should try that. I just didn't care for the super thin pen or the center band. So on my first real try I decided to try getting rid of it.

I guess I am just surprised that a little overhang in the wood could cause so much troubles. Perhaps I should just try to make a center ring that complements the wood and matchs the diameters. Something like an acrylic could look good and would mask this problem... I just don't like things I can't explain or correct. :)

Joshua

[Don Carter]

Joshua:
I have made several "unorthodox" pens over the years. I have many without the center band or a band of some contrasting color or material. I often use small cutoffs from other pens or projects. You know, don't ever throw anything out.:rolleyes:

You could use larger bushings in the center to get the diameter at the center line that you want. Sloping the pen from each smaller end to a larger one in the center. I have even done some closed end pens with the slimline and PSI's comfort pens. The sky is the limit.

One problem with the longer wood is that your pen mill may have wobbled some, since the hole would be a little larger without the brass tube there to keep it straight. Just a thought.

Try a pen the "normal" way and see it you get any problems. At least, you will have a starting point.

All the best.

Don