Bushings acting like Drunk Monkeys!

[Hayseedboy]

Hey All,

Another newbie question. I have turned 3 cigar pens one I was actually kinda proud of and two of the three have turned out to be out-of-round on the cap side. Watching this last night as I started to turned another I finally saw that the bushings seem to be wobbling. Enough that the cap is out of round by probably almost a finger-nails difference on one side.

Tried another mandrel thinking maybe I bowed this one and found the same thing on a brand new mandrel. Don't think I have applied to much pressure to the mandrel's or tighted them to tight as I always have to stop and tighten a little more after I start.

Could the bushings themselves be out of round? The headstock and live centers neither seem to have the wobble....

Thanks in advance for your help!
lr

 

[ed4copies]

Could they? Anything is possible - you'll learn that.

The hole could be drilled off center, too.

IF only one spot is out of round, move the bushing to the other end (reverse the pen) and see. OR, the hole COULD be too large and create slop. (fix this with tape on the mandrel) Best answer, buy new bushings and test, but not on Christmas Eve (stores closed)

Run the mandrel with nothing on it, just held in by the two ends. If IT is out of round, this will show it.

Good luck!

 

[gwilki]

LR

Please don't be offended, but are you using the right mandrel. Cigar bushings come in both A and B mandrel sizes. If you are using B mandrel bushings on an A mandrel, the bushings will wobble and your pens will definitely be out of round.

 

[redfishsc]

You should also try to rule out your lathe turning out of round. Sometimes your live center won't mate up with your mandrel properly, and sometimes your headstock is a bit out of round due to a bad bearing.


To check if your lathe headstock is out of round, put the mandrel on your lathe without any pen or bushing. Turn it on. Lay a chisel or your knockout bar on the mandrel very close the headstock and hold the other end and see if you feel vibration. You should feel NO vibration other than the metal on metal fee

Do the same for your tailstock joint. It should be buttery smooth.

 

[leehljp]

You mentioned "finger-nails difference" which suggests you are not using calipers. If you want good consistent turnings, you need to look into getting a good pair of calipers. Calipers can tell you things that your eyes and words can't.

In this case, it is obvious you don't need calipers to tell what happened, but if you did micro measure them and post it here, it would be easy to determine if the bushings were A or B bushings. Besides, with calipers, you could measure them and tell how much out of round by yourself.

As to too tight - that is a VERY subjective "feel". With woodworking tools and adjustment, I have learned that one person will say something is "just snug" when the next person won't be able to budge it. It could be that you are tightening it too much and that does happen. Tightening too much will cause out of round on a mandrel. Either the end stock too tight or the mandrel nut too tight can cause the same.

 

[johnnycnc]

Larry,
You ask "could the bushings be out of round?",
the direct short answer is a positive YES.

But,if I may,could I suggest you consider some other areas first?
There are several other issues that can cause out of round.
I'll presume you have the correct A or B mandrel for your bushings.
I won't address head and tailstock wobble,as you say they are good.
If you eliminate some other things,it's easier to say bad bushings.
I'll ask the same questions I had to work thru,
on some not-so-obvious issues that seem small,but can cause trouble.

A.)are your lathe tools truly sharp?
>even if so,they don't stay that way for long.
this can cause a lot more trouble than imagined.
>A dull tool has to be pushed,which can bow a mandrel
under tool pressure;can cause out of round.
>dull tools don't often cut evenly,and tend to chatter
and bounce on a small scale;can lead to out of round.
Sharpening can be a steep learning curve,at least it was for me.

B.)Are the ends of your blanks square,to the inside</u> of tube?
note:square to the outside of blank doesn't necessarily count.
&gt;if not,it can push the bushings out of alignment and
you could see the wobble you describe,and out of round issues.
(out-of-square also causes a poor fit to your kit parts !!)

C.)What live center are you using?
&gt;does it have a groove worn in it from mandrel?
&gt;mandrel ends are supposed to have</u> a 60 degree hole to mate
with the live center tip.(no guarantees,some look good,others awful)
&gt;If you are running the factory center tip,odds are it is not</u>
60 degrees.
If it's not,it never seats properly in mandrel end and soon chews a groove;
that groove is mechanical damage,and alignment and trueness only get worse with time.
Many here recommend this one,it's fine for the price: http://www.littlemachineshop.com/products/product_view.php?ProductID=1189&category=1

D.)Is your mandrel nut overtightening while you are roughing down?
&gt;Stop after you get roughed at least to round,and check.
Mine always over-tightened theirselves during roughing,
and an overtight mandrel nut will bow a mandrel,which in turn
will cause wobbles and out of round.
&gt;Loosen and re-snug after roughing,then carry on.

I hope there is something here to help,as I know it's
frustrating to have a poor,out-of-round fit spoil your work.
This exact</u> issue is what almost turned me away from turning pens.[:0]
Have a nice evening!

Originally posted by Hayseedboy

Hey All,

Another newbie question. I have turned 3 cigar pens one I was actually kinda proud of and two of the three have turned out to be out-of-round on the cap side. Watching this last night as I started to turned another I finally saw that the bushings seem to be wobbling. Enough that the cap is out of round by probably almost a finger-nails difference on one side.

Tried another mandrel thinking maybe I bowed this one and found the same thing on a brand new mandrel. Don't think I have applied to much pressure to the mandrel's or tighted them to tight as I always have to stop and tighten a little more after I start.

Could the bushings themselves be out of round? The headstock and live centers neither seem to have the wobble....

Thanks in advance for your help!
lr

 

[workinforwood]

Lots of great advice for sure. You have to figure, if your tools are sharp, the rod is straight, then out of round bushings shouldn't matter at all, or so is my theory. you would possibly have a pen that protrudes on one side of the bushing if the bushing was out of round, but the pen itself would be round and you'd know if it was the right diameter by using a caliper. I've had these problems come and go. Using my Johnny centers and just turning one barrel at a time using the bushings between centers has really increased the success rate. If I was a business, well time is money and one barrel at a time takes a bit longer, but if you are trashing your pens because they aren't round, you are losing time and money. Hopefully mr cnc will create me a rotisserie for finishing my pens and then I'll actually be ahead in time as I can finish more than one pen at a time and maybe cook a chicken on the side []

 

[CHICAGOHAND]

Well let me say that i just got an order for 10 pens and 5 letter openers and I had to figure out quick how to solve my wobble.
My pens would have a lip on one side where the nib met the blank and if I rotated the pen it would be flush on the other.
I tried different mandrels different live centers everything i could think of.
I measured for runout at the head stock,etc. then i started talking to"johnnycnc".
I bought a dead center a live center and a set of bushings for three items i needed to turn.
Let me say that johnny was right when he and my next door neighbor told me that the only way to turn something like pens is to get a set of bushings that have one end that fits into the tube and the other end sized to the outer diameter of the item you are turning. with both bushings having a female taper at 60 degrees that will match your live and dead centers.
my wobble is almost gone but maybe now is the time to discuss the play in some of my pens between the tube and the blank.I use a brad point drill but when drilling some acrylics it seems that when the material is trying to clear the hole i start to get alot of slop.I have tried cleaning the hole after every 1/8 inch of drilling but i am still getting some play between the tube and blank.Is this where i am still getting some problems boys?
johnny brought up a point about squaring up the blank by checking from the inside of the tube.
That might be hard for me because the ATLAS is a big tube and I had to make a sleeve from corian with a 7mm tube on the inside turned to the same outer diamiter on the outside as the ATLAS tube is on the inside and then use my barrel trimmer.I am still getting a slight ridge and on the ATLAS pen fron woodcraft but nothing like I was before.I have even checked and fixed my alingment center to center as best as I could.It has been very frustrating for me because I have always wanted perfection especially now that others are buying my pens.
Here is the finished product thanks from the help of "johnnycnc" and "Firefyter-emt" for the lathe part he gave me.
Thanks boys.




Hope this helps "Hayseedboy".
Talk to johnny about purchasing some bushings he's got my vote.

 

[loglugger]

Some bushings will fit loose on the mandrel and will cause a wobble.
Bob

 

[Firefyter-emt]

Dave, nice looking batch, I am sure that banjo made life a little eaiser to make that many pens in one order! You hit the nail right on the head though, if your bushings don't fit, them it don't matter what you have for a lathe, you will not have centered pens.

I make my own bushings, but in my view, the only way to go it with the "between center bushings" that John makes. Between the precision, the ability to quickly remove the blank for measurement easy CA application, it's hard to find fault other than you need to slow down a hair and turn one blank at a time. I turn for prefection, not speed, so I am happy

 

[johnnycnc]

I'll agree with you gentlemen;poor fitting bushings
just don't do us any favors.
I've skirted around this as long as I can stand it,
so I'll just say it:
All of the several sets of factory Cigar bushings I have
fit so poorly that it is really not surprising to have problems with them.
I have up to .005 slop where these fit inside the tube.
This will not likely run true enough to satisfy anyone.
Both diameters are not always concentric,either.
These issues can cause random out-of-round.period.
It's like you are turning lobes on a camshaft!
The Sierra factory ones can be just as bad,also,in my experience.
While this may suit some folks just fine,it just doesn't cut it for me.
That's why I make what I make.
I just hate to point the finger at bushings right off the bat,
because there are other factors that need to be looked into,
and I just don't want to seem pushy.

 

[loglugger]

I have had slimline bushing .004 slop on the mandrel.
Bob

 

[johnnycnc]

Bob,that .004 makes it somewhat difficult to
turn out a decent piece of work on a barrel that thin.
I have noticed this same issue,as well.
And the answers I've seen that suggest using scotch tape
to shim things just don't work for me. &gt;sigh&lt;
I have some new things in the pipeline for next year,
and I'm looking at mandrel use also.
A mandrel CAN make good pens,it just needs everthing
else to work with it.The factory bushings just aren't always
on the same page.
4-6 bucks just doesn't mean quality guaranteed.
Have a great evening.