Help With Blanks Sticking On Mandrel

[Ken Massingale]

I now have a real problem getting the blanks on/off the mandrel. This started last week, I was then using a machinists vice on the drill press to hold the blanks. The holes, not always exactly in the center were always straight. I did not then have a barrel trimmer, I used a jig on the BT to cut the blanks square and flush to the tube. I was using a Jet MT2 mandrel, to make slimline, 7mm, pens. Not every blank pair was tight, but several.

Christmas came, I was apparently a good boy. I got a Woodcraft centering jig, barrel trimmer, new Woodcraft MT2 mandrel, etc. The blanks are now drilled much more consistantly centered holes, and still straight through the blank.
I use the barrel trimmer (I cut the blanks 2 1/4" long to have plenty to trim) running it in/out of the tube to clean it good.

I still have the problem. I know when it's tight going on, I will have real trouble getting the slick finished blank off, ruining the nice finish.

What can I be overlooking, doing wrong?

Thanks for any ideas,
ken

 

[Gary Max]

The first thing that I can think of is are you getting finish on the mandrel?

 

[KKingery]

I had that same problem awhile back. Was'nt sure if it was finish on the mandrel or what, but to fix it, I took the mandrel and lightly ran some fine sandpaper up and down the length, cleaned it, and lightly lubed it with some wd40....no problems since. Another possibility could be that your mandrel is slightly bent....check it by rolling it on a flat surface....

 

[smoky10]

What type of glue are you using to glue the tube in? If you're using CA glue and get some in the tube, the barrell trimmer will sometimes leave a little in the tube and you need to run a round file, or something simular, in lightly to remove the glue.

 

[DCBluesman]

Woodcraft recently changed from using Berea mandrels to a machinist making them exclusively. They appear to be about .001 or .002 larger than Berea. Either lightly sand or apply a very light coat or Renaissance Wax and your bushings should slide much easier.

 

[Fred in NC]

Thanks Lou! This raises a couple questions for me:

1. Do you know how 'recently' Woodcraft changed their mandrels?

2. How can I tell if they are the new mandrels?

I have several mandrels from Woodcraft, bought over the last 18 months or so. They all look exactly alike, so my guess is that they are the old ones.

Thanks again!

 

[DCBluesman]

It was very, very recently. My source on this is Bill B. I actually like them, once I put a thin coat of TSW on mine.

 

[Guest]

Before you start sanding the mandrel,Check the ends of the tubes after you milled them.
First for glue second for a burr.
With some barrel trimmers ,if you knick the tube it rounds the tube over to the inside.
THere is a "reaming" tool that can be bought so I'm told,but I use the end of a pair of needle nose pliers and VERY gently revolve one side of it in the ends of the offending tube to knock off the burr.
If that doesn't do the trick then you might take a look at the mandrel.
Do the bushings bind also?
If the bushings don't I would look long and hard at the ends of the tubes.

 

[jkirkb94]

I agree with Eagle. You might try a reaming tool on the ends to make sure that you are not flattening the tube when you use the barrel trimmer. You might try installing a tube straight from the package to see if it fits first. Kirk[8D]

 

[woodpens]

Ken,
Where did you buy your pen kits? If you are using Penn State kits, it is likely you will find them to be too small for the Woodcraft (and others) mandrel. PSI's 7mm seems to be a bit smaller than most. I am using the Pro Mandrel from Woodcraft, but had to replace the shaft with a PSI to get the tubes on it.

 

[dougle40]

I think that you'll probably find that your pen mill is raising a burr inside the tube. Just take a rat tail file and run it inside the tubes to get rid of the burrs .

 

[Randy_]

After trimming my blanks, I use a 1/2" twist drill to chamfer the inside rim of the brass tube. This will remove any burrs or deformation at the ends and makes it easier to insert the hardware at the assembly stage!!

There was a recent thread on the Yahoo forum about exactly this problem. It turned out there was a burr on the reamer portion of the barrel trimmer and it was messing up the inside of the tubes. Eagle's suggestion of checking the tubes on the mandrel before doing anything else will tell you if the tubes are the problem or whether you are introducing the problem at a later date. It really should be pretty simple to figure out where the problem lies. Just check the tube against the mandrel after every operation that might affect the tube. The tube is going to fit just fine for a while and at some point in time it will not.....at that point, you will have discovered the problem. []

 

[Randy_]

I posted this info once before; but it may have been on another board.

Per their catalogs:

Berea 7mm mandrel.....0.247" +0-0.002"
Craft-USA.............0.246" "..accurate to 0.003".." Don't know if that means ±0.003" or ±0.0015".
PSI...................0.243"

I just got my new Berea mandrel and it actually measures 0.2465".

The mandrel on my lightly used JET pen lathe measures 0.2475" and the PSI 7mm tubes fit on it just fine.....not tight at all.

0.003" is about the thickness of a sheet of newspaper.

Bottom line here is that most likely the problem lies elsewhere than with the size of the mandrel.

 

[Efletche]

I have had this problem too. Part of the cause was when I used CA on the blank while it was still on the mandrel. Apparently the a small amount of the CA seeped down to the mandrel and bonded the blank to it. I now have a nice collection of useless mandrels.

 

[wayneis]

Edward, by useless do you mean that the tubes are still glued to the mandrel or that you bent the shaft getting the tubes off? If the shafts are not bent to badly I would first soak them in acetone or debonder and then go to Russ' page and find out how you can true up the shaft.

Wayne

 

[Efletche]

The blanks are still stuck to the mandrels. I'ce tried acetone, clamps, pliers and they are there for life. Since the blanks that are stuck are so pretty, I was thinking of making them look like flower stems and sticking them in a vase.

 

[Guest]

THis will probably jix me but I use ca on blanks on the mandrel All the time.
I purposely put CA on the bushings so I don't get the "grey" on the blank when I sand.
Here's where I will jinx myself.
I have never glued a blank to the mandrel.
THere are times when I am going to turn a separate piece along with the blanksd and don't want to glue it to the bushing.
It is then I will put a piece of wax paper on either side of the piece to separate it form the bushings.
If the ends are milled properly I don't see how you can glue a blank to the mandrel.
Now gluing a blank to a pen mill...
That's easy!

 

[Ken Massingale]

Thanks to everyone for the helpful responses.
The problem is resolved. I was doing a combination of getting CA into the tubes, and occassionally being too aggresive with the barrel trimmer, causing a burr. I now clean the wooden insertion tool between inserting tubes and use the .22 cal. brass brush before using the blanks. No more sticky blanks.
Thanks again to all.
Ken

 

[jkirkb94]

Now you see why a lot of us joined the IAP. Help is just a few short sentences away! Glad to see your problem is solved. Kirk[8D]

 

[woodspinner]

Don't forget that CA becomes soft at 185 deg.f. Put them in boiling water and then try to pull them off.

Good turning and be safe
Bill in Casa Grande, AZ.

 

[Guest]

Originally posted by kmassing
<br />Thanks to everyone for the helpful responses.
The problem is resolved. I was doing a combination of getting CA into the tubes, and occassionally being too aggresive with the barrel trimmer, causing a burr. I now clean the wooden insertion tool between inserting tubes] and use the .22 cal. brass brush before using the blanks. No more sticky blanks.
Thanks again to all.
Ken

Try a wrap of wax paper around the insertion tool.
makes clean up a snap.

 

[Randy_]

Originally posted by woodspinner
<br />Don't forget that CA becomes soft at 185 deg.f. Put them in boiling water and then try to pull them off......

If that doesn't work, just turn them off. It will require a delicate touch when you get down to the brass tube; but not something that is impossible. And if you screw up a mandrel or 2, so what??? They are no good the way they are!!!

 

[woodspinner]

Boil them to get them hot. CA softens at 185 deg f. Then try to pull them off. Use your hands as the brass may crush and get tight against the mandrel. You can also use a screwdriver and push them off.

Good turning and be safe
Bill in Casa Grande, AZ.

 

[Bmerkle]

Dear Edward,

I love your attitude! I had the same problem, however I "surgically removed" it by sanding the darn thing from the mandrel. Call me "cheap". It worked.

Best of luck,

Barbie