Slimline Assembly - Alignment Issues

[Fulmaduro]

I love the slimline. It is aesthetically pleasing to the eye and hand. I have turned about 50. But they don't all end up being beautifully concentric in-line straight pieces of beauty. Why do some come align properly and others do not?

I use an arbor press and take extra care to align the pieces before pressing together. I have had problems with both slimline kits and funline kits from Woodcraft, PSI, and Woodnwhimsies. Out of round after assembly. Am I doing something wrong?

Do I need a specific assembly press if I want to ensure alignment other than by arbor press? Do more accurate set-ups exist? Can I make my own? Just want to avoid all the "seconds" I weed out of my production, which seem to be 1 out of 4 (slimlines). I want to start selling locally at a gallery.

Thanks in advance for any help.

Tony Z
KCMO

 

[its_virgil]

Tony,
I too am a big fan of the slimline for several reasons.

Out of round after assembly means out of round before assembly.

I see no way assembly can cause a pen to be out of round. You need to figure out what is happening. I read that not all of your pens are out of round. Is that correct?

If you search the site for "out of round pens" or "OOR pens" you will find much information on the topic and hopefully find a solution.

Do a good turn daily!
Don

I love the slimline. Out of round after assembly.
Tony Z
KCMO

 

[1080Wayne]

I would generally agree with Don , in that the brass should expand uniformly as the insert is pushed in . However , if it is badly misaligned (say 15-20 degrees off) , it may be possible to get local distortion at the end of the blank on one side , and farther into the blank on the opposing side . I have certainly cracked both wood and plastic blanks by doing this , but I was always too irritated with myself to check for added out of roundness .

You have taken special care to ensure the above doesn`t happen . The only other possibility than out of round before assembly is out of round inserts , which is not an impossibility . My money would be on out of round before assembly , probably coupled with 1 in 4 inserts being slightly smaller .

 

[its_virgil]

I'm surprised the "turning between centers" crowd hasn't responded to this. They must all be watching football. :biggrin:Here are some of the possible problems but not all are valid since not all of your slim lines seem to be out of round: bent mandrel, miss alignment of the head and tail stocks of your lathe, bad bushings (but not so much for slim lines), blank ends not squared properly, brass nut too tight, tail stock cranked too tight, not having a 60 degree live center in the tail stock, dull tools, and sanding. And what Wayne had to say above.

My thought is sanding. Aggressive sanding and grain orientation can cause one side of the blank to sand more than the opposite side removing more wood on one side than on the other. This will cause the blank to be out of round. Some woods are more susceptible to this problem than others. This is possibly your problem since (as I read the OP) not all of your slim lines are out of round.
Do a good turn daily!
Don

 

[hilltopper46]

When I was just starting out, the biggest thing I did to eliminate out of round pens, was to start using a 60-degree live center with my mandrel in place of the center that came with the lathe. Just like Fulmadaro, some pens would come out OK and others would be out of round when assembled.

 

[CREID]

Hilltopper, Hilltopper. You there?
You never finished, you ok?:biggrin:

Curt

 

[CREID]

I must have been typing while you were fixing?:biggrin:

Curt

 

[Mr Vic]

Tony, can you post some pics of what you are describing. Look at the sections where you press together. Is the material thicker on one side of the tube then another? Kind of oval shaped. If that's the issue then either the mandrel is bent or your headstock and tail stock aren't aligned. If it was other then a slim line it could also be the bushings. If your head and tail stock are aligned then turning between centers could be a fix.

 

[TonyL]

Hi Tony. I used to call myself thet mandrel-bender. You will continue to get great advice on your/this thread, but for information and laughs, see my woes/posts between March 2014 and Jun 2014. Oh yeah, I TBC now, and I am not embarrassed to admit that ever 2 dozen barrels or so, I will get one that "flunks" my standards. Sometimes I don't use bushings at all (because I keep losing them). When I get an out of round barrel (usually only on one side for some reason), I tighten-up my lathe - insert screws, belts, etc. I guess the vibration loosens them..not sure.

As many said above or will say:
There can be a little paint, glue, debris in a tube or on your centers.
I have found the CSUSA Patriot bushings to be very sloppy. I usually rotate all of my bushings a 1/4 turn in opposite direction during the turning process.
The bushings can be bent where the shoulder meets the sleeve that fits inside the barrel.

As I mentioned above, sometimes I do all of the above, even say a few Our Father's, light a few candles, throw some saw dust over my shoulder, and I still have to throw one out - or give it to my poor wife (who now knows how to find all of the flaws LOL).

Please share what you discover. It is likely to help us all...okay, probably just me .

 

[flyitfast]

I'm surprised, no one mentioned making sure the morse taper hole in the head stock and tail stock might have some debris inside causing the centers or mandrel MT to be out of line. It probably wouldn't cause it to be off too much but anything inside is too much.
Gordon

 

[Fulmaduro]

Thanks for all the suggestions and tips. At this point I believe the problem may lie in my assembly prep of the pen tubes. I might not have been quite as diligent as needed at removing any excess epoxy out of the tubes before assembly. I do plug my tubes at each end with potato plugs and trim them square after drying. But there might have been some thin residue remaining to cause the fittings to be slightly askew. My turnings are all very round and even. This is the only reason I can think of. I should take the slimline pens I have that are improperly aligned (2 halves not in the same plane at the centerband) and disassemble to see if there is residue. My headstock/ tailstock align and are checked before turning.