Out of round mandrels

[TimD]

I noticed that some of my blank turnings would have 1 side thicker than the other. First I thought that it could be my turning techniques so I paid particular attention not to let the gouge bounce any, still had some that you could just feel a fingernail grab where the wood butts the tip, center ring, etc.
I then checked the MT taper on the lathe with a dial indicator - good there. So I put the mandrel shaft on a arrow straightening jig that I have and checked it, out of round a few 1000's of an inch -18/1000 to be exact. The arrow jig is made to straighen hollow aluminum arrows so I didn't want to stress test it by trying to bend solid steel. I put a nut a steel hex nut on each end of the shaft and laid it on a solid steel bar then tapped the high side down with a hammer. After a few taps and rechecking it's within about 15/10,000 inch now.
The next mandrel that I get will get the dial indicator test before it's ever run the first time. Maybe this will help someone out especially if you're seeing or feeling thick/then sided pens at the juncture of metal to wood.

[Ex19k]

Thanks Tim...now that i am on my third manfrel in a month! My problem is that the tail stok doesnt mathc up..i just sand to the bushings and it all is even when i am done..I have found that if i over tighten the tail stock to the mandre i bend the mandrel..Will be trading my Grizzly lathe for a more precices Jet hopefully in a few months...



Like My old First SGT used to say...old tankers never die..we just smell that way...

[Servcman]

One thing to do to keep the mandrel from going out of round is to set the tailstock to the mandrel before tightening down the nut on the pen blanks. The tube bushings do not fit tight enough to the mandrel to keep it straight. Setting the tailstock first then tightening the blanks ensures that the tailstock is lining up the mandrel to the workhead instead of the blanks.
Dennis

[TimD]

[QUOTE=Ex19k]Thanks Tim...now that i am on my third manfrel in a month! My problem is that the tail stok doesnt mathc up..
If you have the Grizzly variable-speed mini, put your mandrel and taper into the headstock and then where your probelm comes in, if I understand your problem is that the loose end of the mandrel don't quite line up to the live center so you have to push the mandrel a little just to get the little cone on the live center to enter the hole drilled in the end of the mandrel. If this is correct, look underneath your tailstock holder, where it slides up & down the bed rails, you will see two allen head screws holding the block that centers the live center. Loosen those two screws and move your tailstock to where it will go straight into the end of the mandre. Tighten those 2 screws up and that should stop your broken mandrel problem. That will also stop your pens from coming out one sided.
I had already fixed that problem, my mandrel was just bent in shipmment I'm sure. I straightened it and the other day it flew apart at the thread where it screws into the taper. They are made from pretty hard and brittle metal.

[JTTHECLOCKMAN]

Has anyone gotten the free DVD from PennState Industries?? I did the other day and it is very helpful with the making of pens and the use of the mandrels. I have a question for you pen turners I never was one of the basic woodworking people. I always like to be a littleeeeeeeeeee different. Do they make a kit tahat incorporates a pen and a small flashlight together??? One end is a pen and the other a flashlight???

By the way if you want the free CD here is the site http://www.pennstateind.com/store/_free-dvd.html

[Servcman]

Haven't seen any of those yet JT. Penn State and Berea Hardwoods have the largest selection I've seen from the sites, and if the info is correct that the persons at Berea Hardwoods gave me those 2 supply about 98% of the other sites.
Dennis

[Servcman]

One thing I have to add here as an after thought. Even though Penn State and Berea hardwoods have pen kits that look similar the bushings may not match up in the heavier pen kits and larger items. Berea Hardwoods uses an 8mm mandrel for its larger pens and items instead of a 7mm mandrel for everything. This allows it to run truer with less whip. This, along with the fact they are less then 20 miles from me and I can actually get my grubby little paws and pick my blanks makes them a biased favorite for me. although I just finished turning the shop pencil from Penn State and have gotten 7 orders for them just from the one I turned for myself. It has a nice heft to it and very well balanced.
Dennis

[Gunny]

Just a quick note here on mandrels and shafts...
I started out using an adjustable 7mm mandrel turning the upper and lower blanks separately and quickly found it was easier to just turn both at the same time. The adjustable is excellent however, for keychain fobs and other short pieces.
Woodcraft.com charges $9.99 for an excellent MT2 mandrel making it inexpensive to keep a stock of two or three available in the event of breakage. What's more, they have replacement shafts for $2.99 each that fit my adjustable mandrel as well. I've bent a shaft or two myself and while they can be straightened fairly easily, it's handy to be able to screw in a new shaft and keep working, then straighten the bent shafts when I'm done turning for the day.
I also find that if I keep the turned blanks on the mandrel and remove the mandrel from the lathe it's a lot easier to put finishing touches on the blanks at the benchtop buffer.

[Ex19k]

thanks for the tip. now i can spend more money on pen stuff! both fixes solved my problems. now on to the lathe!