Warped Mandrels. Grrr!

Signed-In Members Don't See This Ad

sorcerertd

Member
Joined
Sep 30, 2019
Messages
226
Location
North Carolina, USA
OK, so I'm beyond frustrated with my freakin' mandrels. I've noticed wobble in my mandrel, but it just got a lot worst all of a sudden. I really can't even use it. I have a small cheap lathe that isn't good for much but pens and sometimes I use it just for finishing. I have a separate mandrel as it is MT1 and my Jet is MT2. That was just as bad and it wasn't the last time I used it. I don't get it. What kind of cheap steel are these things made of? They are both PSI mandrels with the mandrel saver. I frequently sand by hand to remove the sanding "rings" just turning the handle a little at at time as I go. Searching around here, the only thing I can come up with is that maybe I'm using too much pressure sanding.
Anyway, I need a new mandrel. Damnit. Not sure I want another of the same kind, though. Can I, or is it a good idea to, use the mandrel saver with a regular mandrel with the nuts on it? I was thinking of one with a collet on the headstock end. What do you guys recommend as far as what to buy and how to avoid bending it?
I still don't think I was applying so much pressure that it should bend steel even it it is a little on the soft side, but yet here we are.
 
Signed-In Members Don't See This Ad

leehljp

Member Liaison
Joined
Feb 6, 2005
Messages
7,615
Location
Tunica, MS,
It isn't always the mandrel. Do you have calipers? Measure very carefully your bushings - from the edge of the hole to the outer edge of the bushing at abut 4 spots around the bushing. It is not uncommon to get bushings that are not centered.

Another method: TBC, Turning Between Centers eliminates the mandrel, simplifies the process and has less parts to cause problems.
 

jttheclockman

Member
Joined
Feb 22, 2005
Messages
14,508
Location
NJ, USA.
Yes too much pressure. I am using the same mandrel from 12 years ago and still good as new. Oh yes PSI mandrel. I have no idea about mandrel saver thing. Never used one. I will say this stop doing 2 blanks at the same time and work one blank at a time. Shorten up the mandrel to as short as you can between centers. Make sure the live center in tailstock is a 60 degree center. Again not sure what happens with mandrel saver stuff so will let others chime in on that. Let the sandpaper do the work. Should be no reason to start lower than 250 and I prefer to start with 400 if sanding wood blanks. I can do so because I use my skew to get me almost to the point of no sanding and sometime am there.
 

jttheclockman

Member
Joined
Feb 22, 2005
Messages
14,508
Location
NJ, USA.
Yes too much pressure. I am using the same mandrel from 12 years ago and still good as new. Oh yes PSI mandrel. I have no idea about mandrel saver thing. Never used one. I will say this stop doing 2 blanks at the same time and work one blank at a time. Shorten up the mandrel to as short as you can between centers. Make sure the live center in tailstock is a 60 degree center. Again not sure what happens with mandrel saver stuff so will let others chime in on that. Let the sandpaper do the work. Should be no reason to start lower than 250 and I prefer to start with 400 if sanding wood blanks. I can do so because I use my skew to get me almost to the point of no sanding and sometime am there.
Not sure why double post.
 

MRDucks2

Member
Joined
Jul 17, 2017
Messages
2,192
Location
Washington, IN
I bought a mandrel saver set-up and never regretted it. Not bent a mandrel since. Bought the set for about $60, as I recall.

When I use a mandrel, it is a mandrel saver setup. Doing a lot between centers the days. The problem with cheap lathes (I use the big HF) is making sure you keep things lined up and tightened up. Over tightening enough to bend the mandrel has usually been because I had other issues I was trying to overcome by force.
 
Joined
Dec 22, 2017
Messages
2,133
Location
Wolf Creek Montana
I've been using the mandrel saver since I started this pen business two years ago. I'm still using the same mandrel and bought another set up through PSI for my large lathe. Never had a problem with either one.
 

ebill

Member
Joined
Nov 14, 2017
Messages
38
Location
magnolia tx
I bought a mandrel saver set-up and never regretted it.

+1 for the mandrel saver. I tossed the big gold/brass "nut" in a junk drawer and never looked back.

- my fuzzy mind logic: if I have a small single blank on the mandrel <seam ripper, purse pen etc> then I have to fill up the mandrel with spacers or move the mandrel in the collet chuck every time I use it to the appropriate blank+bushings size. With the mandrel saver, I can simply slide the tail stock up to where I need it to be to eliminate moving the chuck or filling the mandrel with spacers. YMMV.

- ebill
 

JimB

Member
Joined
Mar 18, 2008
Messages
4,646
Location
West Henrietta, NY, USA.
Too much pressure when you tighten the tail stock or pushing to hard on tools when turning or sanding. Like John I have the same mandrel i started with 12 years ago. I do most of my pens between center but I've used the mandrel to make about 150 pens over the years. Mine is a basic mandrel from Woodcraft. It was the cheapest one they had.
 

magpens

Member
Joined
Feb 2, 2011
Messages
13,319
Location
Coquitlam, BC, Canada
My advice .... turning between centers, or TBC .... learn to do it and you will never look back to your frustrating mandrel days.

You will need: 60-degree dead center for headstock + 60 degree live center for tailstock + calipers

That's about $80 capital outlay to start with but those items will last you for years. . AND ... no more bushings to buy, lose, and wreck.

Be sure to get the all-metal calipers .... with digital read-out (DRO).
 

philipff

Member
Joined
Jun 21, 2009
Messages
489
Location
Williamsburg, VA
OK, so I'm beyond frustrated with my freakin' mandrels. I've noticed wobble in my mandrel, but it just got a lot worst all of a sudden. I really can't even use it. I have a small cheap lathe that isn't good for much but pens and sometimes I use it just for finishing. I have a separate mandrel as it is MT1 and my Jet is MT2. That was just as bad and it wasn't the last time I used it. I don't get it. What kind of cheap steel are these things made of? They are both PSI mandrels with the mandrel saver. I frequently sand by hand to remove the sanding "rings" just turning the handle a little at at time as I go. Searching around here, the only thing I can come up with is that maybe I'm using too much pressure sanding.
Anyway, I need a new mandrel. Damnit. Not sure I want another of the same kind, though. Can I, or is it a good idea to, use the mandrel saver with a regular mandrel with the nuts on it? I was thinking of one with a collet on the headstock end. What do you guys recommend as far as what to buy and how to avoid bending it?
I still don't think I was applying so much pressure that it should bend steel even it it is a little on the soft side, but yet here we are.
So, why bother with all that mandrel and bushing stuff?? Get a caliper and a dead drive and use your tail stock to hold each blank(glued up of course} to hole it in place when you turn. I threw away all my bushings and mandrels years ago. No regrets!!! P.
 

Charlie_W

Member
Joined
Nov 16, 2011
Messages
5,709
Location
Sterling, VA USA
One thing not mentioned yet is checking to make sure your headstock Morse taper is clean. It doesn’t take much debris stuck inside to throw off a mandrel.
You can either purchase a Morse taper cleaning tool or use a shotgun cleaning brush. Also, check for any burr or galling of the mating surfaces...Morse taper and mandrel.
Check and clean the tail stock Morse taper while you are at it.
When clean, check the mandrel again to determine if it is the mandrel itself that is the issue. If so, I would recommend an adjustable mandrel as it is a collet style and maybe better centered than a simple screw in type mandrel.
You can still use a mandrel saver with the adjustable style mandrel.

Let us know what you find.

PS, don’t throw away that mandrel if it is indeed not true. It will make a great 1/4” round skew or an awl.
 

Paul in OKC

Member
Joined
Jul 26, 2004
Messages
2,856
Location
Oklahoma City, OK, USA.
Same mandrel for many years, and I do both halves at the same time, no problem. I am on the thought that you can't bend the mandrel by turning or sanding, unless you get ridiculous with the pressure. The issue is somewhere else. Head stock or tail stock dirty or something.
 

Gersh

Member
Joined
May 22, 2018
Messages
100
Location
Newbury oh
I personally prefer using a collet chuck and mandrel saver but everyone has their own preference as you can see. If you'd like more info on anybody's setup I'm sure they'd welcome any questions. Good luck!
 

Curly

Member
Joined
Nov 20, 2010
Messages
3,963
Location
Saskatoon SK., Canada.
Nobody likes to take the time to read carefully anymore. ;)

Since you said "They are both PSI mandrels with the mandrel saver." and you have now got 2 mandrels giving you grief I think you should try to turn between centres. It does take a little longer to turn a two piece pen but you will have nicer, more consistent results.
 

EricRN

Member
Joined
May 16, 2019
Messages
323
I had the same issue. A couple mandrels must have gotten warped from overtightening. The turned blanks would be off center by a hair. Not enough to notice if you looked at the mandrel but enough to bother me on the finished pen. Now I turn between centers. I shape and rough sand a single piece, up to 240 or so. Then I put both pieces on the mandrel and sand from 320 on and finish.
 

Curly

Member
Joined
Nov 20, 2010
Messages
3,963
Location
Saskatoon SK., Canada.
A though just came to me. If you don't get the ends of the blank perfectly square it can cause a bend in the mandrel when you tighten things up (I think). It does if you use regular bushings when turning between centres.
 

sorcerertd

Member
Joined
Sep 30, 2019
Messages
226
Location
North Carolina, USA
Thanks for sharing all your experience. It sounds like my setup should be fine based on the various things that work for you guys without issues, but I'll consider that TBC option. The weird part is that I never removed the mandrel from the lathe between turning and finishing. I usually loosen the tailstock if I'm going to leave the pen on the lathe even though the pressure isn't directly on the mandrel shaft. It would seem that it's got to be the pressure I used to sand. If I work on CA application and get a smoother finish, maybe I can do less sanding to start with. I've been using a barrel trimming system that fits on the drill to square the ends of the blanks. It seems accurate, but maybe that contributes. Also, the same set of bushings worked fine before, but I'll definitely check them.

Since some of you guys haven't used the mandrel saver, it basically slides up the mandrel to apply the pressure on the bushings instead of the mandrel shaft. The only pressure on the mandrel itself is inside the headstock quill/taper. I did clean both the mandrel and quill sides of the taper.

philipff, are you just placing your centers directly into the pen tube ends? I would guess you are using typical 60°centers? I've seen the TBC bushings/caps, but assume they would still need the normal pen bushings to accommodate the different tube diameters.

One thing about turning pens, and maybe it's just because I'm a newbie still, but I like having both pieces on the mandrel so I can see the entire pen, picturing what it will look like when completed. If it will save me that frustration, I'll certainly try them one at at time. It makes perfect sense that there would be less wobble with a shorter distance between centers.
 

Woodchipper

Member
Joined
Mar 15, 2017
Messages
3,292
Location
Cleveland, TN
I used to turn both pieces at once. I now just do them one at a time. Got all the stuff for TBC and need to learn that technique. A fellow in our AAW chapter uses a mandrel where the shaft is adjustable to keep from bending under pressure. I guess the longer the mandrel shaft, the more prone to bending with too much pressure from the tailstock and/or too much pressure on the blank.
 

byany2525

Member
Joined
Oct 16, 2019
Messages
3
Location
usa
My advice .... turning between centers, or TBC .... learn to do it and you will never look back to your frustrating mandrel days.

You will need: 60-degree dead center for headstock + 60 degree live center for tailstock + calipers

That's about $80 capital outlay to start with but those items will last you for years. . AND ... no more bushings to buy, lose, and wreck.

Be sure to get the all-metal calipers .... with digital read-out (DRO).

why is the "60 degree" so important?
 

magpens

Member
Joined
Feb 2, 2011
Messages
13,319
Location
Coquitlam, BC, Canada
why is the "60 degree" so important?

The 60 degree is not important, except that is the most commonly available angle ... perhaps the only angle unless you make your own centers.
A smaller angle is actually better and I have made my own centers with about a 45 degree angle or less.
The actual angle is not critical at all.
I like the smaller angle because it allows the cutter to get in closer without "fouling" on the cone surfaces of the dead center and the live center.
I use a round carbide cutter which is 11 mm diameter and it comes VERY close to hitting the 60 degree centers when turning a Sierra pen blank down to its smallest diameter of 0.474" (matching the hardware size at the blank ends). . Getting to a smaller diameter without your cutter hitting the cone of the 60 degree center is extremely difficult or impossible, unless you make your own centers. . Of course, you could use a smaller size cutter. . I hope you get what I mean. . Using the usual wood-turning gouge, the right grind could easily get you smaller.

I sometimes use a metal working lathe to turn blanks. . In that case you can put clamps on the lathe bed to limit the horizontal travel of the cutter.
It is good if you can do that. . If you do that, then you can use a perfectly square carbide cutter and the setup is not so critical at the finished blank end diameter of 0.474". . However, you must set up the cutter edge to be "exactly" parallel to the cylindrical surface of the blank you are turning (and then no shape other than perfectly cylindrical is easily possible).
 

penicillin

Member
Joined
Feb 27, 2019
Messages
336
I buy supplies mostly at Rockler. When I got started in pen turning, I bought the MT2 adjustable pen mandrel at the recommendation of an experienced friend. I had consistency issues, so I got a mandrel saver at Woodcraft.

At some point I noticed that the end of the pen mandrel had a lot of runout. The tip made a 1/2 inch circle rather than spinning in place. I assumed that I had bent the mandrel from aggressive pressure while sanding. Since I had a mandrel saver, I bought a non-adjustable MT2 pen mandrel at Rockler. (I have a mandrel saver, and it costs less than their adjustable mandrel.) It made a much smaller circle than the old mandrel, so I took it back to Rockler and they told me that it was as good as they get. I have been using it with the mandrel saver, and it is working out better, or maybe my skills have improved.

To save on mandrels, my newest plan is to buy some "D" size drill rod, cut it to the desired length, and insert it in the adjustable mandrel with the mandrel saver. Someday I may try turn-between-centers, but I guess I am not ready for that yet.

Mandrels:
https://www.rockler.com/adjustable-pen-mandrel-2-taper
https://www.rockler.com/pro-pen-turning-mandrel-2-morse-taper
Mandrel Saver - I can't find the mandrel saver on Woodcraft's site. Rockler has a Nova-brand version, but half the reviews are very negative, and the one I got at Woodcraft looks like it. Here is a different-looking one from Penn State:
https://www.pennstateind.com/store/PKMSTS2.html
Drill rod example. I plan to order one of these, cut off a piece, and give it a try in the adjustable mandrel:
https://www.mcmaster.com/8893k202
 

sbwertz

Member
Joined
May 11, 2010
Messages
3,217
Location
Phoenix, AZ
I have to replace mandrels fairly often at the blind center because they tighten the tailstock too tight and bow the mandrel.
 

Alchemist

Member
Joined
Aug 13, 2020
Messages
307
Location
Central Valley, California
One thing not mentioned yet is checking to make sure your headstock Morse taper is clean. It doesn’t take much debris stuck inside to throw off a mandrel.
You can either purchase a Morse taper cleaning tool or use a shotgun cleaning brush. Also, check for any burr or galling of the mating surfaces...Morse taper and mandrel.
Check and clean the tail stock Morse taper while you are at it.
When clean, check the mandrel again to determine if it is the mandrel itself that is the issue. If so, I would recommend an adjustable mandrel as it is a collet style and maybe better centered than a simple screw in type mandrel.
You can still use a mandrel saver with the adjustable style mandrel.

Let us know what you find.

PS, don’t throw away that mandrel if it is indeed not true. It will make a great 1/4” round skew or an awl.
Good idea on the skew!
 

leehljp

Member Liaison
Joined
Feb 6, 2005
Messages
7,615
Location
Tunica, MS,
A blind person using a lathe sounds a little dangerous! (Bad joke?)
You should follow the threads that Sharon has posted over the last several years. Sharon has long been instructing a number of people on this, and they (the blind) make support money through pen making. Several people on this forum have donated items to help in this project. Excellent work and for an excellent community service.
 

egnald

Member
Joined
Jun 9, 2017
Messages
441
Location
Columbus, Nebraska, USA
Greetings from Nebraska,

The actual mandrel shaft I use is a length of "D" Drill Rod that I buy from Granger. It is 3-feet long and 0.246 inches in diameter. (Sometimes my 7mm slimline tubes feel a little tight on it so I also have a piece of "C" Drill Rod that is 0.242 inches in diameter). Since a 3-foot piece only costs about $6 bucks my cost is only $2 per mandrel shaft so I repurpose them whenever they start running a little out of true or if they get galled up from bushings, etc.

There is a thread that covers various mandrels called "Do Mandrels Wear Out" that was posted not that long ago. It contains some good information about TBC and various mandrels and mandrel savers. Here is a link to the thread: Do Mandrels Wear Out

Regards,
Dave
 

sbwertz

Member
Joined
May 11, 2010
Messages
3,217
Location
Phoenix, AZ
A blind person using a lathe sounds a little dangerous! (Bad joke?)
You would be amazed at what they can do. I have three turners who are totally blind and can come in, set up the lathe themselves, mount their blanks, turn and finish the pen without help except that I have to make sure their sandpaper is in the correct order. They make pens, peppermills, salt and pepper shakers, wine bottle stoppers, ice cream scoops, pizza wheels, etc. Turning is very tactile, and their fingers are extremely sensitive. Often I've said "That looks great," only to be told, "no, it's still a little rough right HERE."

One of my totally blind turners (that's her guide dog lying in the background.)

 
Last edited:

Alchemist

Member
Joined
Aug 13, 2020
Messages
307
Location
Central Valley, California
You should follow the threads that Sharon has posted over the last several years. Sharon has long been instructing a number of people on this, and they (the blind) make support money through pen making. Several people on this forum have donated items to help in this project. Excellent work and for an excellent community service.

I’ll do that! Thanks!


Sent from my iPhone using Penturners.org mobile app
 

Paul in OKC

Member
Joined
Jul 26, 2004
Messages
2,856
Location
Oklahoma City, OK, USA.
why is the "60 degree" so important?
the center that comes as standard on most wood lathes is 'more pointed' than 60 degrees. This can let the point go into the bottom of the 'dimple' on the end of a mandrel, which will not center well, if at all. You can file the point off a bit so it at least sits in dimple without bottoming out. I did this for a couple of years when I first started. But a 60 degree center is a must long term.
 
Top Bottom