Newbie Mandrel Question

[maxwell_smart007]

Tried making my first pen today...

the blank drilled nicely, and I managed to get the tubes glued up without gluing myself to anything..

Put it on my adjustable PSI maxi mandrel, and every time I'd go to put the gouge to the blank, the blank would just spin...I guess I need to really reef down on the mandrel nuts, is that it?

I don't want to wreck anything, so I thought I'd try asking before I destroyed something...

Andrew

 

[Blind_Squirrel]

You do NOT want to over tighten that nut! You can bend the mandrel! Make sure you are not being too agressive with your gouge. If you get a catch and the blank stops rotating, stop the lathe and give the nut a SMALL (e.g. 1/8th turn or so) snug up.

 

[leehljp]

NO, don't "reef" it down, but you probably need to tighten it a tad more. This is a VERY subjective part of learning. If it is a nut, then maybe "maybe" a <b>little</b> more than hand tighten. IF you have a knurled brass nut, then hand tight. If you have strong hands, then hand tight can be too tight on the knurled nut. I know people with little strength in their hands and some with lots of strength. Strong handed people will say something is barely snug while weak handed people will say the same thing is too tight. Try experimenting. Too tight will cause the mandrel to flex minutely' when turning (and it can even bend the mandrel) and you will get an out of round blank at the least.

Another part to this - is taking too much of a bite, which will stop it from turning. In the first turnings, you need a SHARP edge and little bitty bites across the blank to knock the edges off. The key here, and on the first few pens, is to get the "feel" of turning. Consider the first few pens to be the bonus to learning and getting the feel.

 

[Fred]

Definitely DO NOT OVER TIGHTEN the nut. Just make a bit less aggressive cuts till the blanks start rounding out. If the blanks continue to spin on the mandrel I would suggest you setup and turn then one at a time. Here is where a good collet comes into play. []

 

[Russianwolf]

And it may not be the tightness at all.

when I started out I was trying to use cheap CA glue to glue the tubes in the blank. I wasn't getting good contact so the glue bond would break and the blank would spin on the tube.

It's easy to check. pull the blank off the mandrel and check to see if the tube is loose inside. If it is, you'll need to reglue it (I've switch to gorilla glue and don't have this problem anymore).

If the tubes are still glued then it's the mandrel tightness. Make sure the collet at the headstock is tight, then adjust the nut per what the others have already said.

Also, make sure your mandrel is seated in the morse taper on the headstock (when the blank stops spinning, the entire mandrel will be stopped in this case).

 

[drayman]

andrew, also make sure your tools are sharp. good luck and let us know. regards colin.

 

[maxwell_smart007]

I'll try again tomorrow and let you know what the problem was - guessing a combination of everything above!

 

[maxwell_smart007]

OOps, not tomorrow - going Muskie fishing for my bday - hope I catch a big one!

I'll try out your suggestions on Tuesday...thanks for all the advice!