Berea "A" mandrel, not happy.

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stevers

stevers

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Bullhead City, Az., USA.
Hi All,
Last Friday I received my Berea precision mandrel in the mail. It's this one;
200732742534_mandrelA.jpg


I noticed a small wobble in the center of the mandrel. I mounted my dial indicator on the lathe bed (Jet 1014 vsi) and measured. It is under a thousandth on the head stock end, about 2 1/2 thousandths on the tail stock end, and when I went to the middle of the mandrel (half way between the head and tail stocks) it was over 5 thousandths off. The tail stock was moved up to the mandrel but not pressing with enough force to flex it. It was basically just tight enough to hold the end of the mandrel true. I also have a 60 degree LC. And it is right on the money. There was, of course, no nut or tubes on it.
When they shipped the mandrel, they shipped it in a soft envelope with bubble wrap inside. (like a cushion envelope)

Shouldn't this mandrel be more accurate than this??? The wobble in the center is noticeable with the fingers, let alone with a dial indicator.


Edit; Another thing. When I ordered this mandrel, I felt like the lady on the phone was trying to get me finished and hang up. I had called Woodturningz a few minutes earlier, and the guy I spoke to there took the time to talk to me. He even knew several of you folks. We talked for at least 15 minutes. Now I didn't expect the lady at Berea to talk to me for that long, but I felt quite rushed.
Just wondered if thats the norm at Berea? This was my first order from them, and first impressions are very important to me.
 
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I wish I could help, but the ones I bought from AzSil have the rods strapped to heavy cardboard and are shipped in a priority box. Sorry, I don't have a dial indicator to take measurements, but I feel confident they are alright.
 
It is possible to get defective mandrels, from Berea and others. Many on the market are Bereas sold by companies we are all familiar with. Be careful who you do business with, some will happily take care of you, others stop being nice when a problem arises.
 
I asked about a longer mandrel on another topic and jcollazo made one for me for $5, including shipping. I used it last night and I have to tell you, it was the best one I have ever used. He drilled a 60 degree concave hole in the threaded end that fit perfectly with my 60 degree live center. The rod was nice and snug to the live center. My other rods don't fit snug and my live center does not go in very far. I like doing both tubes at the same time and have always gotten wild vibration way out on the second tube. I would say the vibration was cut down by 95% with his rod. I was standing there thinking, what's missing? Oh yeah all the chattering and vibration.[:D]
 
Stevers,

How would Berea or anyone else know how to respond to you when you use a 'coded' name? Have you contacted Berea directly?


Frank (Rifleman 1776),

You are about to be become quite embarassed if you continue to claim that defective mandrels are intentionally shipped to customers.

BB
 
No Bill, I haven't. Thats sort of what I was getting at. Am I being to particular about this mandrel? Is this something they may consider within tolerances?

Bill, I misunderstood your reply, so I deleted my earlier post.
 
Steve - Call Berea and ask to speak to Larry. Explain the problem to him and he will likely help solve it. My experience with Berea and their re-sellers has been outstanding.
 
Originally posted by Bill Baumbeck

Frank (Rifleman 1776),

You are about to be become quite embarassed if you continue to claim that defective mandrels are intentionally shipped to customers.

BB
Click to expand...

Maybe I'm missing another post somewhere, but i didn't see any editing in his post and from what I can see he is just saying that there can be a problem with a mandrel, any mandrel. (you can't possibly inspect every single one to the thousandth when you are only charging $8 for a mandrel) I do believe that he's saying when you deal with a company, some will help you out more than others when a problem arises. I have also noticed that and I will deal with those companies who treat me right.

-Mike
 
Originally posted by Mikey
<br />
Originally posted by Bill Baumbeck

Frank (Rifleman 1776),

You are about to be become quite embarassed if you continue to claim that defective mandrels are intentionally shipped to customers.

BB
Click to expand...

Maybe I'm missing another post somewhere, but i didn't see any editing in his post and from what I can see he is just saying that there can be a problem with a mandrel, any mandrel. (you can't possibly inspect every single one to the thousandth when you are only charging $8 for a mandrel) I do believe that he's saying when you deal with a company, some will help you out more than others when a problem arises. I have also noticed that and I will deal with those companies who treat me right.

-Mike
Click to expand...

Did I mention names? Answer: No.
Jeff, this person has threatened me on forum. He needs moderation.
 
Steve,

When you say 5 thousandths is that the full indicator reading?
When we measure the straightness of shafting here at work it's done on a surface plate with a laser height gage. When using an indicator on a full rotation then you have to cut your measurement in half because on a complete rotation you are measuring both above and below the centerline.

FWIW: the industry standard for precision ground shafting of a diameter tolerance of +.0000/-.0002" is .0003"/in. Or 3 ten thousandths per inch. This can easily compound itself when the bend extends over several inches. It is kind of hard to understand but if you have a .0002" bend it can cause the shaft to seem much further out at the end because of what we refer to as the "triangle effect".

See attached screen shot (exaggerated for clarity)





200733016462_part1.jpg


If you have a .100" bend over one inch it grows to .200" at 2" and so on BUT when the next inch also has a bend in the same place It grows considerably as the shaft gets longer.

Take into account that there is also a tolerance in the threading of both the shaft and the taper and we can easily explain the run out that you see.

&lt;edit in&gt;

I do not work for any supplier, I'm just trying to explain the best I can from a Quality Control Supervisors viewpoint.
 
This is an example of how "shtuff" gets out of hand. Most of us are quite articulate and, therefore, very exacting in what we write, albeit some can't spell or won't spell-check [:D]--but that's a different story.

It is very clear <b>to me </b>that Frank is saying:
1. Manufacturers can have defective products slip through their QC controls.
2. Lots of resellers offer the Berea mandrel. I interpreted the fact that Berea is named because the OP did so.
3. Some resellers stand behind the products they sell, some do not. Be careful who you buy from because of that.

No different than selecting one GM or Ford reseller over another.
Case in point: MY FIL had an oil change done at X's Ford. They forgot to tighten the plug. Oil leaked out.
Upon his return to the dealership to get things taken care of, they tried to blame him for what happened.
I will never visit that dealership for anything, even if they have a vehicle I'd prefer.

Bill, you should apologize to Frank so that your potential customers like me don't perceive you as a hot-head. [;)]

Regards,
Gary
 
Bill, you should apologize to Frank so that your potential customers like me don't perceive you as a hot-head.


Hello Gary,

You may perceive me in any manner that you wish.[:D]

BB
 
Hi Scott, Thanks for the info. From what I understand, that would make my mandrel under 3 thou off. Which is not too bad in industry standards.

Peter, Gary and Frank, I didn't mean to start a fight here. What I meant to do is just what Scott (Mudder) did for me. To help me understand how much is common and acceptable in the industry.

And Mikey, you are absolutely correct. and I don't expect them to test every one. Especially when, like you said, the mandrel is only an $8.00 part.

Thank you all for the input.
 
Just to let you all know. I used Russ Fairfield's tutorial on tuning and truing a mandrel. It worked quite well. Now it is no more than a thousandth off on full rotation. I have yet to turn anything, but the wobble is completely gone.
 
Steve, check that mandrel often. If you start bending steel, it will soften at the point you bent it and it will be easier to knock it back out of round the next time. I would perform a checkafter every few pens if your indicator base sets up easily.
 
Originally posted by Mikey
<br />Steve, check that mandrel often. If you start bending steel, it will soften at the point you bent it and it will be easier to knock it back out of round the next time. I would perform a checkafter every few pens if your indicator base sets up easily.
Click to expand...

Mikey,

I agree that Steve's mandrel should be checked after every few pens but I have to disagree with your reasoning as to why. Please allow me to explain.......

I an not a metallurgist and I'm sure there might be some metals that will soften when bent but I think that you are confusing "plasticity" with work hardening. Most steels will harden as they are worked making them more brittle and prone to breakage. It is the "plasticity" effect that might allow it to come back to it's earlier form.

http://en.wikipedia.org/wiki/Work_hardening

http://www.engineersedge.com/material_science/work_strain_hardening.htm

http://matse1.mse.uiuc.edu/metals/c.html

Where I work we manufacture an assembly that requires extremely straight 1/8" shafts and the material that we buy is cold formed in what is called a rotary hammer from 3/16" steel rods. they are very straight and surprisingly wear resistant, but they are also more brittle and break more easily than the rods they were manufactured from. One thing that surprised me at first was the 3/16" raw material starts at 12" long but since steel does not compress very well the 1/8" rod that comes out the other end of the hammer is longer than 12"
 
Mudder, I am not a mettalurgest either, but do know that once a piece of steel is bent and you bend it back, the chance of it bending again in that same exact spot is greater than anywhere else along that part given the same stresses. (it can possibly break the next time, but it can also just bend again in the same area.) The processes that are described in your link deal with some of that, but also deal with heat and other tempering or annealing techniques.
 
After turning a few things this weekend, it turned out very well. More of what I was looking for. Very accurate, smooth and well balanced.

Thanks for all of your input and ideas.
 
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