oor problem

[danroggensee]

Hi all I have a problem with oor on my sierras and i am turning on centers with a set of johnnycnc bushings and am still getting the oor problem can any body tell me what im doing wrong. The tips on my lathe lineup right on the money and i do not have the problem with my slimlines and they are turned on johnnycnc bushings also.

Thanks for the help.

Dannie

 

[KenV]

First thoughts as an easy check is to assure that the ends are indeed square with the center line of the tube.

dial calipers are needed here and a dial indicator is good to have.

Mount and turn a blank to round -- about 5/8 to 3/4 inch tube. Take it off

The outside turned cylinder is concentric with the tube and should be at 90 degrees to the ends all the way around. Canting of the ends with tend to skew the mount and lead to an eccentric turning that should show up now. Use the dial calipers to measure the thickness around the blank. If you are getting OOR, it shoud be showing up now if it is mounting or gear related.

The dial indicator (mine has a magnetic base) allows me to set the banjo and hook the dial indicator to it and check the variation as the tooling is rotated by hand. Headstock through to tail stock. I check at about 1/8th points on the locations checked. start at the headstock and move to the tail stock checking each piece of the gear (headstock bushings tube, other bushing, live center. Write the numbers down.

If these check out, the answer is likely your technique/tools. dull tools and pushing tools into the turning will cause the OOR also.

let us know what you find.

 

[leehljp]

Something I learned a few weeks ago: You can line the tips up perfectly, however when separated by 3 inches due to the blank and bushings, the alignment can be off.

Do you feel ANY vibration in the blank as it is spinning fast? A hint that alignment is the problem that the centers will be turning smoothly and the bushings will be turning smoothly, but there seems to be a vibration at some point on the blank.

I noticed that I was locking it down while it was out of alignment and was getting OOR with Johnny's bushings. Once that was corrected, everything worked fine.

This may not be your problem but I did want to offer it as a suggestion.

 

[danroggensee]

But if it was a alignment problem would it not do it with the slimline also and i do not have the problem with them just the sierras. But will check it all out when i get the chance.

Dannie

 

[johnnycnc]

If you have no problems with the slimlines, just
the Sierra's, my thoughts would be that you need to look carefully at how
you are squaring the ends of the Sierra's.
If they aren't squared to the inside of the tube,you will have problems, as with any pen.
Are you using a barrel trimmer?

 

[danroggensee]

Hi John I am using a disk sander and jig to square the ends just as i do with the slims and i check them with a square to be sure that they are square but will check smoe more.

Dannie

 

[johnnycnc]

Hi John I am using a disk sander and jig to square the ends just as i do with the slims and i check them with a square to be sure that they are square but will check smoe more.

Dannie

Ok, just wondering though, does your jig have a rod that goes into the tube, and square to that? or does it reference off the outside of the blank?

 

[danroggensee]

it has the rod that you square it to and i am going to check it to be sure it is square to the sander. I Have a pen mill to might try that the next time and see what happens.

Dannie

 

[KenV]

Sounding more and more like alignment - another trick as you near desired size, stop, loose the nut and turn the blanks bushing 1/4 turn compared to the blank. Your next cuts will uncover the excentric nature as you will be cutting a little air and a light pass and a good close look will tell you where you have a "kink" in your tooling.

 

[danroggensee]

Well it was the disk sander the table got lose and they were not real square the one that i posted today was squared with the pin mill and no problem with oor. Guess i wll have to rework the sanding table. LOL

Dannie