Pen12b

Clean the inside tapers in both spindle and tailstock BEFORE doing anything else.

These internal Morse Tapers must be clean. The thickness of a piece of dirt or wood shaving is enough to throw the tapers out of alignment.

A piece of paper towel that is damp with Kerosene or WD-40 will clean both of them.

Wipe them dry with another paper towel.

Blow them out with an air hose if you have one.

Plastic "Taper Cleaners" are available from the woodturning stores for this purpose. However, I would recommend making one of them, rather than buying one. It is good practice for using a skew or spindle gouge, and it will work just as well. Use a piece of soft wood such as Pine. Wrap it with a small piece of soft paper towel if the fit isn't too good.

Cleaning the internal tapers BEFORE putting anything into them is a good habit to form.

The 1st check for alignment between the head and tail stock.

Put a center point in each of them. Use whatever you have.

Bring them together until they almost touch.

Do the two points match?

If they don't, we have the first indication that something could be wrong. I say "could" because I

would expect some mismatch between them in the quality level of the lathes that most of us are using to turn pens. The question becomes one of how much is OK?? If I were to make a statement on this, I would say that anything less than 1/64" may not hurt us, and anything over 1/64" is an indication that something may be wrong. There are several "IF's" that can be applied.

IF it is only that the two centerlines (spindle and the tailstock) are "offset" but "parallel", then we can tolerate a little offset. I made pens for years on a lathe that had a 1/16" offset.

IF the two center lines are not "parallel", the spindle is at an "angle" to the tailstock, and the "offset" will increase the farther the two centers were apart. This one can be a problem. It is a common problem with any lathe that has a swiveling headstock, but it can be corrected. If the lathe is fixed, the problem was created when it was machined.

The proof is in the turning.

Always do some turning. If everything can be made to work towards an acceptable pen, then everything is OK. IF there are always problems with the pens, then this can be the source of all problems.

Put the adapter and the mandrel rod into the lathe. A slight "pop" from about 1/2" out is all that is necessary. We only need enough grip that it doesn't slip when we are turning.

Run the lathe at somewhere between 500 and 1000 RPM.

Lightly grip the mandrel rod between the finger tips.

We should feel no wiggle in the rod. Impossible?

Remember that sheet of paper that was only 0.003" thickness? We can easily feel that much movement here. Just barely touch the rod.

I would be surprised if there was any movement detected. These adapters are usually very good in their machining. But if there is, tighten the rod in the adapter. If there is still a detectable movement next to the adapter, it would indicate that the centers of either the adapter or the rod are not the same as that of the lathe spindle.

If this is a new adapter, there may be some surface imperfections that are causing the problem. Polish the taper on the adapter with a piece of 320-grit wet-dry paper. Use either Kerosene or WD-40 to lubricate the sandpaper. Wipe it clean, put it back in the lathe and try it again. Go to the next step if there is still a problem.

Mark a line on the adapter and on the lathe spindle.

Loosen the adapter, rotate it 1/4 turn, and "pop" it back into the spindle.

Run the lathe again and do the same "feel" test next to the spindle.

Do this four (4) times, and return to the starting point.

If there was any improvement in any of the other positions, go back to that spot again.

Give it the "spin test" just to make sure.

Mark a new line on the lathe spindle to line up with the one we put on the adapter.

This will be the "Home" location for every time we remove and replace the adapter in the spindle.

If mandrel rod passed the "feel" test at the spindle........

Go out to the end of the rod and check it again.

Any movement here would be caused by either a bend rod, or either the adapter or the rod being at a n angle to the lathe spindle. In either case we can correct that problem, provided that nothing else can move.

Bring up the tailstock.

Leave the tail-center back so there is a small gap. We are using it only as a reference point.

Rotate the mandrel. Watch the end to see if it makes a circle around the center point.

We are going to bend the rod, so it will run "true".

Now comes the tricky part....

Grip the mandrel rod so that any bending is confined to where it is attached to the adapter.

Bend the mandrel in the direction to REDUCE the circle that it scriped around the reference point.

It doesn't take much pressure. A slight "bumping" application of pressure is better. Do it several times in small steps and there should be no problems.

Do the "feel" test again.

Run the lathe at about 1000 RPM, and feel along the entire length of the mandrel rod. When only the slight friction of the rod between the fingers is felt, then it is straight and on the same centerline as the spindle.

Make sure that the adapter and lathe spindle are marked so we can always return to this "Home" position.

Bring up the tailstock again and lock it in place. Then advance the tail-center.

Look for any misalignment or movement of the rod as the center is pushed into the centered hole in the end of the mandrel rod. This misalignment is the angular difference between the center-lines of the head and tail stocks. How much can be tolerated?? If it is more than a 1/64", tightening the tail-center can put a "bow" in the rod, making it difficult if not impossible to turn an accurate pen.

Go back to the spindle. Loosen the adapter. Move it 1/4 turn in the spindle. Do this four (4) times until we have returned back to "Home". If there was any improvement in any position, this should be marked as the new "Home" location. If there was no change, we can assume that the centerline of the spindle is at an angle with the centerlines of the lathe bed and the tailstock.

Bring up the tail-center again.

Use just enough pressure that the live-point will not slip when the spindle is spinning at about 1000RPM.

Check with the "light touch feel test" along the length of the mandrel rod. If any vibration is almost imperceptable to the touch, is running within 0.002. That is close enough to make a perfect pen.

Conclusion

This discussion and our little "tweekings" should have solved most of our problems with eccrenticity and runout in making our pens. If not, there is probably a larger problem than what we can find in our shop. We will also need measuring devices that are more accurate than "feeling" with our fingers.

As I noted in the Introduction to these pages, turning a pen is a relatively precision activity. Unfortunately, not all lathes are up to the task.

I said that I wouldn't make any comments about the lathes and which ones were the better for turning a pen. Of the many Jet "Mini" lathes that I have used, seen, or heard about, all but two of them passed my "feel" test with flying colors. Of the two that didn't, one was marginal but acceptable, and the other was so far out of alignment that it was replaced by the manufacturer. The Jet "Mini's" reputation for quality is deserved. I would expect the same from the Vicmarc V-100. I cannot say that same thing about any other lathe in the same price range.