Problems with Turning

[Johnathan]

Being pretty new to this, I have probably turned 100 or so pens, this week I found myself surprised to see that a pen I was turning was not center to the bushing. Is this a bent mandrel? I've used the same bushing before with no problem. Please don't think I'm stupid, I'm sure I can figure it out, but I'm sure there is somewhere that has experienced this and can save me a lot of time. Thanks

Johnathan[:I]

 

[JimGo]

Johnathan,
At 100 pens, you're more experienced than many of us! And your question isn't dumb; it's a common question in fact. If you use the search feature, and especially if you check the search the archives box, you'll find an extensive discussion on this. Search terms to try include "bent mandrel", "eccentric", "off center", and "oval". You can also check out Russ Fairfield's site; he has a great discussion on this topic:
http://www.woodturnerruss.com

 

[Skye]

Center to tbe bushing while it's still on the mandrel?

 

[Dario]

If all else failed, you may want to read the following threads. It fixed my problem.

http://www.penturners.org/forum/topic.asp?TOPIC_ID=12120
http://www.penturners.org/forum/topic.asp?TOPIC_ID=12099

 

[Dario]

Oops

 

[Randy_]

Is this a new kit(which one) that you are doing for the first time or an old kit and bushings that you have done successfully before. If this is a first time kit with new bushings, perhaps you got some bad bushings. If these are bushings and a mandrel that you have used before, maybe there was some junk in the spindle and you didn't get the mandrel arbor centered properly?? There are all sorts of other possible problems; but I would expect they would not be a problem for someone who has already done a hundred pens.

 

[stilgar]

A problem that I found with my Delta is that the tailstock was so sharp that it was pointing into the mandrel at different locations. I switched to a different live center and it grabed the mandrel the same every time.

I am also in the process of having a new piece machine for the lathe to help reduce the amount of slop in the tail stock. This is to help with the alignment of the tailstock to the headstock. My headstock is fine but I found out the alignment of the head/tail stock and the problem with the livecenter was causing me to get some pens right and others misaligned.

If it was simple, then we wouldn't be enjoying it.

 

[knottyharry]

Do you have a 60 degree live center for metal?
If you have the original wood center that came with the lathe
that could be part of your problem.
Since the mandrel is metal you need a center for metal, and the end of the mandrel is designed to accept the 60 degree metal center.
Also watch your pressure on the tailstock....too much will bow the mandrel...just run it up to where the live center starts turning, snug is all.
Harry

 

[GBusardo]

I have learned that if I put too much presure on the mandrel , just as Harry said, the mandrel wobbles a little. You can almost see it, and certaintly feel it. I back off a little and I havent had many problems since. You did notices I didn't say any problems, just not as many []