Who can write this article?

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Mudder

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[profile]Randy_[/profile] came up with a great idea for a tutorial. Many times it has come up on the forum and we get many answers (and parts of answers) that it would be nice if someone (or a group) would take on the task of writing an all inclusive tutorial on how to troubleshoot and prevent out of round pens.

Anyone up for it?
 
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Mudder

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Why not ask for volunteers on the forum??

Might be able to recruit a budding "Steinbeck".

Since this is the Library Forum and everyone should be able to see it, I thought that's what I was doing ? :confused:
 
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M

Mudder

Guest
[profile]Randy_[/profile] came up with a great idea for a tutorial. Many times it has come up on the forum and we get many answers (and parts of answers) that it would be nice if someone (or a group) would take on the task of writing an all inclusive tutorial on how to troubleshoot and prevent out of round pens.

Anyone up for it?
Now back to our regularly scheduled programming.


I'm looking for some folks who would like to tackle this article.

Anybody??
 

iowacobb

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I've been thinking of getting more involved with some writing. Perhaps this will be a good start. Would someone be able to help with photos and diagrams?

Do you have guidelines that I should try to follow? Timeframe?

Thanks,
Tim McGill
5-17-09
 
M

Mudder

Guest
I've been thinking of getting more involved with some writing. Perhaps this will be a good start. Would someone be able to help with photos and diagrams?

Do you have guidelines that I should try to follow? Timeframe?

Thanks,
Tim McGill
5-17-09
Tim,

I can help you.

There are no real guidelines or time frame, however there is an excellent tutorial in the library that will help to get you started.

http://content.penturners.org/articles/2007/writingatutorial.pdf
 

Kaspar

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Possible topics:

Crud on the bushings, Morse Tapers, etc... (Solutions: clean things up)

Poor barrel trimming. (Solutions: Sharpen the trimmer blades, Carbide trimmer blades, trim off bulk of material with saw, reducing to a bare minimum the amount of material the the trimmer must mill, even pressure when trimming, rotate as you go to assure consistency of cut.)

Over-tightening the knurl on a mandrel. (Solutions: eighth to quarter turn past tight, anything more is too much. If that's not enough to hold the piece, something else may be wrong.)

Over or under tightening the tail stock. (Solutions: same as above.)

Dull tools requiring increased lateral pressure on the mandrel. (Solution: sharpen them.)

Doing both barrels at the same time resulting in OOR at the tail stock end. (Solutions: Do one barrel at a time, close the to head stock. Use B mandrel whenever possible. The 8mm mandrel has something like 35% more interior volume of the 7mm mandrel so it take lateral pressure better without bowing. Mandrel-less turning.)

Variegated densities in wood blanks. (Solutions: sharp tools, light consistent cuts at the denser sections.)

Poor quality lathe. (Solutions: Better lathe. I have noticed that many of you have big lathes, designed for bowl turning and such. My first was this. I have a ways to go before I can say that most of my pens were not made on that lathe. It served quite well, but because of its puny size, I suffered nearly every OOR problem you can have.

My solution was to accept an inevitable amount of imperfection, and to rotate the blank on the mandrel 3 or 4 times during the turn down, to round out the inevitable eccentricities. And save for a better lathe. When I finally got that, the difference was like night and day.)

Anyone else?
 
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CabinetMaker

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One thing to remember is that over tightening the keeper nut on the end of the mandrel *does not* cause the mandrel to deform. In fact, it will act to straighten the mandrel. The pressure from the nut is applied to the spacer(s). through the pen body and to the spacer(s) on the on the other end that rest against taper body. The effect is to put the mandrel in tension which has the effect of pulling the mandrel straight. Over tightening the tail stock can overcome the tension applied to the mandrel by the keeper nut and bend the mandrel.

Just a thought from an engineer who really enjoyed physics.
 

Kaspar

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We're just brainstorming at this point.

Yes, I understand. But over-tightening the knurl might manifest weaknesses in other areas, crud on the bushings, loose tolerances between bushing and tubes, etc. Of course, you want to know about those, so ...

I think there's a lot to be said for rotatiing the blanks on the mandrel now and then. If you have a dense section in a wood blank, the repeated "hits" the mandrel takes (unless you rotate it from time to time) could wear it out faster in that area.
 
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ed4copies

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Biggest thing, I believe, is to learn how to test for bend in your mandrel.

Set up mandrel with tailstock in place and put sharpie (or other felt-tip type) across the tool rest to just touch the mandrel. IF there is just a mark on one side of the mandrel, it is bent. You will not get a ROUND pen from a BENT mandrel.

Step 2: fix or replace???
 

ed4copies

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BTW Kaspar - I tried mandrel-less. It confirmed the "conversation" that had said the bushings were not drilled "on-center", which I had previously "poo-pooed" as near impossible. So when you start mandrel-less, if you appear to still be out of round, CHECK the BUSHINGS!! I threw out a bunch and went to the "professional" mandrel, slide it out just as much as I need to make ONE half of a pen. Then do the other half.

My pens are now ROUND!@!!!!
 

keithkarl2007

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yeah i've just noticed my bushings for the jr statesman are bored off centre, so i haven't even tried using them
 

iowacobb

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Scope of article

BTW Kaspar - I tried mandrel-less. It confirmed the "conversation" that had said the bushings were not drilled "on-center", which I had previously "poo-pooed" as near impossible. So when you start mandrel-less, if you appear to still be out of round, CHECK the BUSHINGS!! I threw out a bunch and went to the "professional" mandrel, slide it out just as much as I need to make ONE half of a pen. Then do the other half.

My pens are now ROUND!@!!!!
I think the discussion of mandrel-less should be in a separate article, but listed as a possible solution the "out of round" article.

Do you agree?

Tim McGill
 

ed4copies

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Hey Tim,

If you are brave enough to volunteer to write it, you certainly enjoy the privilege of selecting WHAT to write. If I can HELP, let me know, but I certainly do NOT want to HINDER!!!

I have, however gotten a couple emails asking whose bushings, so I want to clarify, these were "stock" bushings from PSI, CSUSA, etc.

I HAVE HAD NO PROBLEMS WITH BUSHINGS FROM JOHN (JOHNNYCNC)!!
 

leehljp

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One thing to remember is that over tightening the keeper nut on the end of the mandrel *does not* cause the mandrel to deform. In fact, it will act to straighten the mandrel. The pressure from the nut is applied to the spacer(s). through the pen body and to the spacer(s) on the on the other end that rest against taper body. The effect is to put the mandrel in tension which has the effect of pulling the mandrel straight. Over tightening the tail stock can overcome the tension applied to the mandrel by the keeper nut and bend the mandrel.

Just a thought from an engineer who really enjoyed physics.
CM,

You are correct on the "over tightening the keeper nut on the end of the mandrel *does not* cause the mandrel to deform.".

However, over-tightening the keeper nut can force the blanks to skew if they are not perfectly squared. On soft woods that are not stabilized, the over-tightening can force a slight crimp in the tube where it meets a bushing, which will then cause OOR.

A second problem with over-tightening the mandrel nut is HOW the result that is described. Most people (including me) over-simplified the conclusions and blamed it erroneously on "deforming the mandrel" . . . instead of correctly describing it as "warping the blank/tube". The cause is still over tightening the mandrel nut.
 

leehljp

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Subjectivity in following directions causes problems

A problem that is RARELY discussed: Subjectivity in following directions causes problems.

Over on a woodworking forum (flatwork), Something that I noticed loooonng ago was - subjectivity in application of directions caused lots of problems.

The woodworking forum is centered around a very light weight saw made basically from aluminum but is VERY accurate/precise in its cutting. The problem was that it would not stand abuse like dropping 2X4s on the table top or hauling it around in the back of a pickup-truck over a job site and then expecting accuracy.

The one thing I noticed consistently with this situation (and in a few other situations) was that a few 250 lb people detested the saw after a few months and then claimed they had the right to treat the saw any way they wanted. I use the "250 lb" because it would come up later about their size and ability to do certain jobs.

I am not criticizing large / heavy men, but what seems like "snug hand tight" to a very strong man would take channel locks to tighten that much by a 120 lb person. I have (and others too) have witnessed anger expressed at suggestions at over-tightening or applying too much pressure - or in the case of light weight people - not tightening it enough. I have also seen posts where people said they thought that they were over tightening when in fact they were not tightening something enough.

Pressure, tight, loose, snug - these are VERY subjective words and each person reasons that their perception is the standard! Any suggestion to the contrary is sometimes taken offensively.
 

Kaspar

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Hey Tim,

If you are brave enough to volunteer to write it, you certainly enjoy the privilege of selecting WHAT to write. If I can HELP, let me know, but I certainly do NOT want to HINDER!!!

I have, however gotten a couple emails asking whose bushings, so I want to clarify, these were "stock" bushings from PSI, CSUSA, etc.

I HAVE HAD NO PROBLEMS WITH BUSHINGS FROM JOHN (JOHNNYCNC)!!
Thanks for clarifying that. Your post made it sound like you were having these troubles even with custom mandrel-less bushings.
 

Randy_

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.....You are correct on the "over tightening the keeper nut on the end of the mandrel *does not* cause the mandrel to deform.".

A second problem with over-tightening the mandrel nut is HOW the result that is described. Most people (including me) over-simplified the conclusions and blamed it erroneously on "deforming the mandrel" . . . instead of correctly describing it as "warping the blank/tube". The cause is still over tightening the mandrel nut.
[justify]Hank: I'm not so sure the above is completely accurate.[/justify][justify]

I fully agree with your basic point that a problem can arise if the nut is over-tightened (whatever that may be) AND if the blank end is not accurately squared. I don't have any way to measure it or prove that it exists; but it seems to me that if there are unbalanced forces that are strong enough to "warp the blank/tube", it is very likely that some of those forces will be transferred to the mandrel and cause some deformation of it as well.[/justify]
 
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leehljp

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[justify]Hank: I'm not so sure the above is completely accurate.[/justify][justify]

I fully agree with your basic point that a problem can arise if the nut is over-tightened (whatever that may be) AND if the blank end is not accurately squared. I don't have any way to measure it or prove that it exists; but it seems to me that if there are unbalanced forces that are strong enough to "warp the blank/tube", it is very likely that some of those forces will be transferred to the mandrel and cause some deformation of it as well.[/justify]
Randy,

I am all for finding the root problem, even if stating it wrongly or missing the point - prompts someone else to take a better stab at it.

Simply stating that "over tightening the nut doesn't cause the mandrel to deform" seems to imply that over-tightening the nut does not cause any OOR.

However, Over-tightening the nut does result in something being out of kilter and resulting in OOR - from my experience with mandrels and being a novice in turning pens. :eek:

Your input is greatly appreciated! And anyone else's input is appreciated if they can help pinpoint what happens when the nut is over-tightened.
 

Randy_

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All inclusive might be kind of hard. There are so many ways to screw these things up. DAMHIKT
Eric:

I couldn't agree more!! And that is one of the main reasons I suggested the need for such an article.

Whenever the question is asked there are a few or quite a few responses. The most common remedies are mentioned; but rarely are all possibilities covered in a single thread. Without doing a forum search and reading many threads, one never gets a full answer to the question. Hence my thinking that it would be helpful to have a comprehensive discussion with all of the information compiled into a single article.:cool:
 

CabinetMaker

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CM,

You are correct on the "over tightening the keeper nut on the end of the mandrel *does not* cause the mandrel to deform.".

However, over-tightening the keeper nut can force the blanks to skew if they are not perfectly squared. On soft woods that are not stabilized, the over-tightening can force a slight crimp in the tube where it meets a bushing, which will then cause OOR.

A second problem with over-tightening the mandrel nut is HOW the result that is described. Most people (including me) over-simplified the conclusions and blamed it erroneously on "deforming the mandrel" . . . instead of correctly describing it as "warping the blank/tube". The cause is still over tightening the mandrel nut.
I agree. I tighten the nut just enough to keep the blanks from slipping while I am using the roughing gouge to get the blanks round. That seems to do the trick.
 

Paul in OKC

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I have pm'd Scott, and am going to give a shot at this. It will come somewaht from a machinist point of view, as that is what I do, so....... I am going to put some thoughts together and send them to Scott. We may shoot them to another for more opinions, but I didn't throw that at him, yet. So, anyhoo.......
 
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