What did I do?

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jakoop

Member
Joined
Nov 29, 2016
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51
Location
Carson City
OK, I think there is a combination of things but would like some help diagnosing what I did wrong, please.

As you can see I am off center a wee bit. Now, it looked centered when I drilled it on the lathe. And this was my first attempt at drilling a blank on the lathe. I also used 7mm bushings which were too small, according to the directions. And I am guessing there is no way to fix this and just to consider it a loss and chalk it up to lesson learned. Thanks for any input, have a great day!

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Oh and I used a 7mm barrel trimmer also...... which was to small! LOL! This is a cluster :)
 
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If you used small bushings that were loose where they should be tight inside the tube, as soon as you put pressure on the blank with the lathe tool it moved off center if it wasn't already off center when you mounted it (in the mandrel).

Other possible causes too, but that is my first thought since you mentioned small bushings.
 
I agree with the small bushing hypothesis.

Remember you can turn bushings!! Make something that wil, at a minimum, hold the blank equidistant from the mandrel. THEN you can see if you have other problems.
 
Sorry I guess I didn't read the post close enough. If you used the wrong bushings that would cause the same problem. Since the tube is off center after turning that means something's out of alignment from the mandrel or the cutting tool.
 
Yup, just turned me another pen for personal use: a Jr Retro Black T roller. It has naked eye visible radial rings either from turning or from application of CA - or both. Didn't notice them until after I had assembled pen and was showing it to my wife.
Over the tears I've become quite adept at dis-assembling all manner of pens. However, the Jr series from Dayacom has that big tight-fitting black plastic union for attaching center band to cap tube. Short of really messing with that union, I've got no idea of how to get it out. Doesn't look like I'll be able to take that tube back to the lathe nor will be able to hand sand, so, it will become my daily use roller.
 
1shootist said:
Bent / warped mandrel rod would be my first suspect.

You can put it back on the lathe between centers and it should straighten it up....use a dead center in the headstock and a live center in the tailstock, this will completely elimate the need for a mandrel.
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I'll check my mandrel and see if I bent it. :-(

But my question is about TBC (Turning Between Center, yes?) I have a liver center tailstock and If I get the dead center headstock, would I need bushings still? Sorry for the rookie question. Appreciate all the help, Thanks again!
 
You don't have to use bushings...you can bump up the centers against the brass tube, just dont over do it..it may flare out the ends a little but it doesn't hurt anything. If you have bushings that are the same size as the tubes you can use them with any kit they fit to get the blank turned down nearly to pen kit specs, then remove bushings and use calipers to get it to size...
 
Who says I kant type? Years yes, tears, also yes.

As to the mandrel, it is entirely possible to flex the stuffing out of it by really torquing down on the end nut, and forcing the tail stock up waaaay too tight - don't ask me how I know - without permanently bending the mandrel. Most likely you will never know for sure what you did, and there is an important lesson here for all - experienced and beginner. Take your time, be sure of the bushings, use a light touch in setting things up on the lathe, spin it up and make light adjustments as necessary.
 
jakoop said:
I'll check my mandrel and see if I bent it. :-(

But my question is about TBC (Turning Between Center, yes?) I have a liver center tailstock and If I get the dead center headstock, would I need bushings still? Sorry for the rookie question. Appreciate all the help, Thanks again!
Click to expand...
It doesn't have to be just a bent mandrel. "Bent" is one of a plethora of things things that can cause that on a mandrel.
1. Bent
2. Too much pressure/tightening from the tail stock can cause that
3. Using a non-60° live center in the tail stock.
4. Applying too much pressure to the tool while turning (on a mandrel)
5. Slightly dull tools can cut but need more pressure which pushes the mandrel minuscule amounts into a bow.
6. OOR bushings. Use your calipers, measure the distance from the outside to the center with calipers from several spots. I have an old old set of bushings that are obvious to the naked eye OOR.

I left the mandrels behind 12 - 13 years ago and went to TBC. Mandrels require too much maintenance, and adjustments and have too many parts that can cause problems such as you have.

TBC: A few people manage to get by without bushings, but most people do use bushings to get the blank to "near" size and then switch to no bushings for the final sizing and finish. That process of changing from bushings to no bushings takes roughly 10 literal seconds, so it is not a real drawback.
 
I checked the mandrel. It's straight. So I am learning towards wrong bushings. I also maybe be a tad guilty of tighting things a bit much. [emoji3525]

Sent from my G6 using Tapatalk
 
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