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Hello Fellow pen turners!

I have been turning pens for a year now and have completed about a dozen. One thing I am running in to is an issue with the wood as it comes up to the bushing. For some reason, when I have the mandrel turning, it appears that the wood is flush to the bushing. When I stop it, however, it is flush to the bushing in one spot and the opposite side is proud of the bushing. When I put the pen together, the issue is prominent on some pen kits.

Please help! I thought it was the mandrel being bent so I replaced it and the very first one I turned on the new mandrel did the same thing. I thought it was the lathe - took it back and got a replacement, same issue. I thought it might be the pressure I am putting on the end of the mandrel with the center, I have played around with that but not sure.

Any thoughts?
 

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It may be your brass tube getting slightly flared on the ends when you are using your end mill on it… if it isn't fitting very snugly around your bushings or mandrel it will get slightly out of round…

If you don't think this is the issue, then it could possibly be that your bushing itself isn't exactly round. I've seen some folks who will make their own bushing with acrylic turning them on the mandrel you use will ensure they are truly round. You will have to replace these more often, but they will last for quite a while if you take care when you are turning your blank.
 

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Another issue is when you bring the live center up to the mandrel rod, bring it up until the point just makes contact, lock the tail stock and only turn in the rack and pinion until it has just very very slight pressure. If you turn it in too tight you will bow the mandrel rod and this can cause the problem you mention as well as you will have out of round barrels. This problem will be more pronounced on two barrel kits due to the added length between centers. Also check and make sure your live center is perfectly aligned with the head stock center.
 

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Discussion Starter · #5 ·
Thanks everyone for the quick responses. The tubes are snug on the bushings and the bushings are the metal ones sold by Rockler or Woodcraft for the corresponding pen kits. I will try what RetiredCoastie mentions above and report back.

Thanks again.
 

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could also be you are sanding to much.try to turn as close to bushing and use a skew to finish and then lightly sand.I had same problem ,turner gave me same advise,also my tools not sharp enough and figured I could sand down to bushings,wrong.
 

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What RetiredCoastie said and you can also put a slight bow in the rod with the nut that locks the blanks in place. That nut needs to be just finger tight, just enough that the blanks don't slip. However that usually isn't tight enough at the beginning when you are knocking off corners. So most people bring out the 800 lb gorilla and ask him to tighten that nut.

Here is what I do:
1) SHARP TOOLS
2) Extra tight on the mandrel nut at the start when I'm rounding the blanks, but I'll change this later
3) Just enough tail stock & live center pressure to spin the live center, a smidge less and you would hear the live center squeal.
4) Round the blanks.
5) Stop the lathe, loosen the mandrel nut, rotate the blanks on the mandrel and just snug the nut.
6) Finish turning the pen, mostly using a skew and taking light cuts.
7) Repeat #5
8) Sand (not much needed when using a skew). Also during this step I'm checking with a caliper to confirm the diameters rather than rely solely on the bushings. Bushing wear or there can be slight differences between the bushing and actual kit piece. Using the calipers I bypass that problem. And finally, sand with a light touch, don't push hard against the blank because you will flex the mandrel - been doing all this stuff to avoid that!
9) About 1/2 way through my sanding grits, repeat #5 one more time.
10) Finishing - usually CA + polishing.

Seems like a lot of extra work when you write it out. Takes longer to write or even say than to do.

Good luck!
 

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I have had this problem before. RetiredCostie is correct. If you have the tailstock too tight, it will cause the mandrel to bow and you will get an offset turning. This could also be the result the result of the head and tail stock not aligning properly. I think that either in the pen kit instructions or in the mandrel instructions it cautions against these issues also. This is an easy fix.
 

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If any of the above don't solve the issue try these:

If you have the adjustable rod mandrel, remove the collett and collete nut and insure there isn't any debris trapped in the slots, also place the rod on a cast iron surface and roll it to check for a bent rod. Also inspect rod for any build up of finish, CA glue, or galling.

If you have the pen mandrel that uses a rod that is threaded, unscrew it and check rod on cast iron surface. If you own this type and turn a lot of pens, obtain the professional mandrel, it allows you to adjust the amount of rod sticking out of the Collete, thus reducing the amount of run out that may be there due to the decreased distance of the rod between the head stock and live center.

Inspect head stock and mandrel Morse tapers for debris build up. There are Morse taper cleaners available from lathe manufactures as well as late tool retailers.

After you've chucked up your pen blank, start your lathe and touch the bushings with a round (spindle gouge works good for this) metal rod and if you have everything running true you wont feel any vibration.
 

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I was having the same problems until I went to pennstateind.com and got the mandrel saver. It puts the holding pressure on the bushing thus holding the blank tight without putting pressure on the mandrel and causing it to bow. I don't know why, but the problem of out of round pens went away. It's only about $15.00. Anyone else tried the mandrel saver??
 

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I went to the mandrel saver about 2 years ago, and have not had the problem since. Put the mandrel saver in the tailstock, load up the mandrel with blanks and bushings, and do not use the mandrel nut. The saver is hollow, so slide the mandrel in. Move the tailstock up until the saver presses on the bushing, lock the tailstock, and advance the quill a little. That way the force presses on the bushings and blanks, not the mandrel rod. Get a mandrel saver that matches the Morse taper (MT) of your tailstock. Search Amazon for mandrel saver. They are $16-$20, and Amazon also has a couple of photos showing the m
 

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Maybe only slightly related but I don't trust the bushings for sizing - or rather I don't trust the kits. There is too much variance in the kits to rely on the bushings. I use calipers to measure the kit parts and then match the blank to that part. I notice variations up to 0.2mm in parts. Might not seem like much but your fingers feel it when touching the pen.
 
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