paulg wrote:
Actually there are 2 sizes of mandrels for the Berea pens. If you
look at the Arizona Silhouette pen list some of the kits require a
bearing with a B after the number. Those require the larger mandrel.
Though if you are looking for accuracy you should use a micrometer to
check the pen kit parts. There can be a big difference from 1 kit to
the next. The bearings are just a rough guide. You can always make
your own out of scrap stock there is no mystery to what they are. Also
the bearings do wear out.
Runout problems can be caused by a bent mandrel, putting to much
pressure on the mandrel with the tailstock, bent tube etc.
All of those suppliers are well known. They do not all carry the
same Berea kits though and not to confuse the issue to much some of
them call the same kit by different names.
For a less intense group of penturners check out the penturners
group on yahoo.
Paul
snip snip snip
I also know about the two different shafts for the Berea and Rockler mandrels.
The one set that I am talking about is from Rockler with a Rockler pen kit and
Rockler mandrel (the "A" mandrel).
Regarding runout, I don't think a bent mandrel is my problem and is another
topic of discussion. One of them might be juuuuust a smidgeon bent now since I
tried a little tweaking on it, but the others I think are straight. I cleaned
off the flattest surfaces that I have (my table saw and bandsaw tables) and the
shafts roll on them smoothly. If there was even a small amount of bend in the
shaft, they wouldn't roll smoothly.
As for pressure from the tailstock, I have moved the tailstock in only far
enough for the threaded end of the shaft to stop wobbling and tightened it down.
At that point the two ends of the shaft will be running true (unable to feel
any vibration in the shaft), but I can still feel a little bit of wobble in the
middle. Even with a bare shaft with no pen blank or bushings etc. BUT, if the
shafts are straight to begin with, why doesn't the shaft turn true without a
tailstock in place?
This is why I think the runout might be another topic to discuss. That, to me,
indicates a problem with the morse taper in the headstock, or perhaps the
headstock shaft itself might be bent. It's like the taper on the mandrel isn't
seating into the headstock taper straight. The mandrel does, however, fit
tightly even with just a small amount of pressure when installing it, and it
takes a good whack with the removal tool when the time comes. I've cleaned and
examined all of the mandrel tapers and the headstock taper, and they are clean
and appear undamaged. No galling, no burrs, no caked on finish, no stuck dust,
filings, or chips, no nuttin.
I mentioned that the headstock shaft might be bent, but I have also put my dial
indicator on the headstock and there is very negligible runout there. Putting
the indicator point on the inside of the taper and had turning the shaft slowly,
there is less than .001" runout. Maybe something on the order of .0003" or
..0004" (3 or 4 TEN-thousandths). The indicator needle just barely moves. If
the shaft were bent it seems like it would be more than that. And measuring a
point outside the taper and behind the threads matched that reading.
Anyway, after all that I do appreciate your input.
Thanks,
Wayne