lathe vibration

[Rmartin]

I was out in the cold turning some pens today, hey, it's an addiction. I was making a couple of Berea's White coconut and Mother of Pearl ElGrande rollerball pens. I had the shorter cap blank on the shaft first and then the longer barrel blank. I turned down the longer blank first, very smooth, no vibration. When I went to do the shorter blank, as I got it roundish, I noticed some vibration. I figured if I switched the positions of the blanks on the shaft, the vibration would be on the longer blank I had aready turned now that it was in the position of where the vibration was and the cap blank would have no vibration. Wrong. I hope I'm making sense. Nothing was changed but the locations of the blanks, but the vibration stayed with the shorter cap blank.

Anyhow, what could cause this?

Could the problem be in the bushings? Sure seems that way.

 

[jaywood1207]

Not sure I follow but check to make sure there isn't any junk on your MT assuming you are using one and also make sure there isn't any on your bushings or mandrel. Also take the mandrel off and check it to make sure it didn't get bent.

 

[Rmartin]

Thanks Jamie. I was afraid I wasn't making myself clear. Let's see if I can confuse the issue more. []

I have two blanks on a B mandrel

The one closest to the head stock is vibrating

The one near the tail stock is not, it's smooth to the touch.

I switch the position of the two blanks

The vibration moved with the blank to the tail stock end.

 

[Grizzlyss]

Just a guess, but either one of your bushings is out of round, or your wood blank has a very dense side that is causing the vibration. But I would never had thought that a wood blank cold have that much of a density change. These are only guesses mind you on my understanding of your explanation.

 

[Rmartin]

I wasn't using wood. It was coconut shell embeded in resin. Very large tube, but also very light weight. I guess the tube could have been slightly out of round. The bushing haven't been used much, but I'll order some new ones just to make sure.

 

[Fred]

Take at look at this site for a possible solution to any vibration problems.

http://www.fholder.com/Woodturning/Glaser%20Tunable%20Blanacer.pdf

Also, try turning the offensive blank all by itself on your mandrel. Keep it close to the headstock end

Hope this helps ...

Fred_erick - "Fred"

 

[Jerryconn]

Does it vibrate all the time or just when you are cutting? If just cutting it could be your tools have gotten dull. I would take the mandrel and everything off the lathe and run it, if no vibration then add just the mandrel, if still no vibration then add the blank that originally did not vibrate, and so on and so on. In this manner you may be able to identify what is causing the vibration.

 

[Dario]

Is it possible that you are hitting the shell on one side and just resin on the other? The difference in density maybe causing one side to cut faster than the other.

 

[Rmartin]

Thanks for the advice. I'm sure I'm not going past the resin into the shell. I'll do as suggested and add on piece at time to get a better idea of what's causing the vibration. I'm afraid it may be my lathe. I remember turning some cigar pens which use different bushings and mandrel than the Baron, and I had was having trouble turning down to the bushing. When I turned the lathe off, I noticed I was flush with the bushing on one side and slightly proud of it on the other. Probably within tolerances of the inexpensive Jet mini I using. I don't know.

 

[ed4copies]

If you are going to turn those expensive blanks, might want to get an adjustable mandrel. I turn a lot of "stuff" embedded in PR blanks, it is the ONLY time I use the adjustable and bring it down to about 4" total length. Makes the whole process much more rigid. The ends of an "embedded" blank have VERY LITTLE resin left, covering the "stuff". It's easy to rip off the last bit of covering PR and be left with a "design opportunity".

GOOD LUCK!!![][][]

 

[Dario]

I seriously doubt it is the lathe since the other barrel works fine. It has to do with your barrel or bushing since the problem goes with it.