Pen turning - PSI Mandrel and mandrel saver

[bobgroh]

Just off a big push to actually make items for Christmas and that included my first serious attempts at making pens with my SS 510. I am using the Penn State Industries (PSI) pen mandrel (#PKM-CL) along with the PSI mandrel saver (#PKMSTS2V2) and have some comments and thoughts to pass along.

Mandrel

MandrelOnSS_B.jpg (114.99 KiB) Viewed 15399 times

This picture shows the mandrel mounted but not inserted into the mandrel saver. PSI says to NOT use the nut and just to insert the end of the mandrel rod into the mandrel saver and 'squeeze' it to tighten up the blanks. I think that is wrong! I think it is far better to use the nut to tighten up the blanks and then to insert the mandrel into the saver and apply just the slightest amount of pressure. That guarantees that you won't bend the mandrel rod.

Any comments on this point??

[wa2crk]

BOB
You will not bend the mandrel if you do it the way Penn State says to.
The pressure is on the pen blank and the bushings and they are in compression between the quill and the mandrel saver and the mandrel is actually floating in the mandrel saver.
People bend mandrels when they have a pen blank mounted in the conventional manner and the brass nut is used they use too much pressure against the tailstock thinking they are tightening up the workpiece. The only way the workpiece can be tightened when turning conventionally is to tighten the nut. The mandrel should only be tightened enough against the tailstock to hold it so it doesn't move. Too much pressure against the tailstock will bend the mandrel.
Bill V

[kenbu]

Bill is right: Put pressure on the pen blank, not the mandrel, by using the mandrel saver without the nut.


Ken

[bobgroh]

You are both absolutely right - my 'world' picture was a bit skewed. I was ok in that I was putting the pen blanks only in compression by using the nut (which only puts the rod in tension) and only 'nudging' the nut against the mandrel saver. OK but not great. Much better to just not use the nut and just squeeze up the pen blank stack between the headstock and the mandrel saver. Since the compression is through the pen blank stack and NOT through the rod, all is good.

Thanks for your comments.

[benush26]

Bob,
If you are uncomfortable with the pressure fiddling (adjusting the quill to what you hope is correct), you might try what I do and that is slip a small nylon washer over the threaded rod between the mandrel saver and the pen bushing. It still allows the live bearing to work well but gives a bit just in case you press adjust too firmly. It also reduces the squeal if I happen to cut too quickly / press too hard near the bushing.
I initially bought large diameter washers as an early warning system that I was getting too close to the end, but quickly noticed that I would snug up the quill and spend less time fiddle farting with pressure.

Be well,
Ben

[thpalex555]

Thank you, the information was much helpful to me.

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[Jeepmiller09]

what was your results? I had this come with my ER and have yet to use it.

[bobgroh]

The PSI mandrel works great. The PSI Mandrel Saver is a good addition - it has a MT 2 so it fits the tail piece (at least for the Mark Vs and I suspect the 10ER has same setup). The Mandrel saver means that, when you mount your pen blanks on the mandrel, you don't have to put any pressure on the mandrel's rod - you just 'squeeze' the pen blanks and spacers between the drive end and the tail stock. No bending of the mandrel rod!

[tomsalwasser]

REALLY looking forward to making some pens!

[bobgroh]

Yeah, pens are fun. If you have the Nova scroll chuck, I heartily recommend Nova's optional pen blank drilling jaws. Those plus a drill chuck in the end mount make a nice way to drill the pen blanks! I made a simple wood 'miter box' to cut the blanks to length - uses the pen tubes to set the length and then you just use a fine tooth saw to cut the blank to length. I do a number of pen blanks and then mount the mandrel on the SS and start making pens! I have tried a number of finishes but have settled on the use of CYA as the best for me.