Pen mandrel wobble

[Phil Labowski]

Okay, at some point my novice butt appears to have slightly bent my pen mandrel. I have the WoodCraft one where the bar can come all the way out. It's just like this one: http://www.woodcraft.com/product/2085450/40671/whiteside-pro-pen-mandrel-2-mt.aspx except my bar goes wob wob wob. Now I was hoping I could maybe put it in a vice, or something, to straighten it out. Any ideas before I try this, or tips on how to this better?

[Andrew Kertesz]

You are probably putting to much pressure on it when you tighten it up. Best bet is to just replace the rod, make sure it is not already bent. It doesn't need a lot of pressure. Many people turn between centers and don't use a mandrel. There is also a mandrel on the IAP website that is under tension instead of pressure you may want to look at.

[Phil Labowski]

What is IAP? Also, how do you make a pen without a mandrel?

[Jim Burr]

IAP is the best site on the planet...not just pens and everything is free!! BTC is Between The Center turning. You turn one pen barrel at a time with no mandrel...just bushings that are made custom made for the style of pen. I have a mandrel but haven't used it in years. Go straight to the IAP library, everything you ever want to know about making pens is there. I'm also happy to answer any pen questions...I sell about 250-300 a year and do a lot of custom work.

[Jonathan Clement]

I too would suggest replacing the mandrel as Andrew says. IAP is the International Association of Pen Turners. I'm not sure what the mandrel is that he is referring to but it might be a type of pen center which puts the pressure on the headstock through the bushings rather than on the mandrel. The following is available from Craft Supplies. I have one and it works well. Penn State Industries also has one which is less expensive but I don't think is as well made.

http://www.woodturnerscatalog.com/p/1/-/3/16/-/5492/Precision-Machine-Pen-Center/pen+live+center

[Steve Hudson]

I got a mandrel saver which is a live center that is hollow and the mandrel shaft goes inside the center so the pressure is put on the blank and not the mandrel...works well. It's also nice for turning pens that have just one blank as the mandrel slides all the way in until the center pushes on the bushing

http://www.pennstateind.com/store/PKMSTS2.html

steve

[Jonathan Clement]

Later: I think this is the mandrel saver that Andrew was referring to. I also see it on eBay.

http://www.highlandwoodworking.com/better-pen-mandrel.aspx

[Dan Masshardt]

Woodcraft has replacement shafts for about $3. Get a couple. Mandrel saver is a worthwhile purchase as well. Psi has one reasonably.


I do more and more turning between centers, but I think it's worth having the mandrel around as well.

[Richard Coers]

It's easy to straighten a mandrel. Lightly bring up the tailstock with nothing on the mandrel. Rest a pencil on the tool rest, about halfway down the mandrel. Turn on the lathe, and let the pencil brush against the spinning mandrel. You will see a small mark, and that's the high spot. Rotate the mark to the top center and tap down on the mandrel with a hammer. Repeat, repeat, and repeat until the pencil mark goes almost all around. You can also deflect the mandrel if the blanks are not square on the ends and you tighten it too much. Over tightening is almost always the cause.

[Andrew Kertesz]

I was not talking about a mandrel saver. There is a gentleman on the IAP site that deisgned and sells a mandrel that works through pulliing tension instead of compression. I haven't been to the site in quite sometime since I sold my lathe and related equipment. You may have to look around in the classifieds or just post a question asking about it. Like Jim said it is a great site and ALL information is free.

[Glen Blanchard]

This is taken from their website.




Conventional mandrels are held in compression, squeezed between centers. Squeeze too much and you can ruin the mandrel. But the Better Pen Mandrel is held in tension to keep the mandrel shaft tight and straight. The mandrel shaft threads onto the headstock fitting and the live center. Retracting the tailstock applies the tension--and, because the Morse taper is a locking taper, it won't pop out of the tailstock socket. The Morse taper has been milled to lock securely into its socket, and the mandrel shaft is ground to a precise 0.247 in., for a smooth, tight fit with 7mm tubes and bushings. You get accurate turnings, with no worry that you may damage a mandrel. Exposed steel parts receive a light coat of camellia oil to help prevent corrosion.

http://www.penmandrel.com/

[Jonathan Clement]

I searched the IAP website and found the mandrel Andrew is referring to.

http://www.penmandrel.com/

[Dan Masshardt]

I'm pretty active on IAP. I'm not aware of too many people using that mandrel setup.

If you are going to invest on that level, my advice would be to spend the money on 60 degree live and dead centers and turn between them.

Everybody has they're own preferences though.

[Steve Peterson]

It's easy to straighten a mandrel. Lightly bring up the tailstock with nothing on the mandrel. Rest a pencil on the tool rest, about halfway down the mandrel. Turn on the lathe, and let the pencil brush against the spinning mandrel. You will see a small mark, and that's the high spot. Rotate the mark to the top center and tap down on the mandrel with a hammer. Repeat, repeat, and repeat until the pencil mark goes almost all around. You can also deflect the mandrel if the blanks are not square on the ends and you tighten it too much. Over tightening is almost always the cause.

That is a great way to straighten a rod. Another approach is to remove the tailstock and let about 1" stick out from the holder. Hold a pencil near the end to mark the high spot. Hit it lightly with a hammer until it is straight. Repeat the process by moving the mandrel out in 1/4" or 1/2" increments. When you hit the mid point, it may work best to turn it around and start on the other end. This method allows you to straighten exactly at the spot where the bend is located.

Steve

[James Combs]

Phil, +1 on TBC, if you are serious about making pens of quality, TBC is the way to get there. Here is a recent thread (http://www.sawmillcreek.org/showthread.php?202806-looking-for-info-on-the-mandrel-saver-mandrel&p=2104878&highlight=#post2104878) on the mandrel savers mentioned above but if you scroll down to post #11 you will find a photo and an explanation of TBC.