Tightening loose pen tubes

[Oakbear]

Hi all,

I've been turning a few pens of late, and have discovered that not all the brass tubes are made equal!

One in particular has a very nice piece of tulipwood on it, but slips at the slightest touch, however sharp the gouge or fine the cut.
I figure this can't be an isolated case, and must crop up once in a while.

How do you pen types sure up the tube in such a case?

Cheers!

 

[Bodrighy]

I haven't done pens but would have thought that epoxy 2 part resin would do the trick as it can be used for gap filling in small places as well. Maybe not. Let the pen turners advise :lol:

pete

 

[penman]

Hi Ryan
Use Gorilla glue like I do and as it foams up in curing it takes up any slack in the tubes. Since using it I haven't had a tube come loose yet. Although they say let it cure for 24 hours I usually turn my pens after 1 hour and haven't had any problems.

Malcolm.

PS see you tonight??

 

[CHJ]

Oakbear, are you referring to the wood spinning on the tube, ie the adhesive bond not good, or are you referring to the bonded assembly spinning on the mandrel?

With several of the kits I use I drill with drills .2mm smaller than 'quoted' size due to differing thickness of tube material. tubes are abraded with fine abrasive prior to bonding to improve adhesion.

If whole assembly is spinning on mandrel then the clamping/spacing bushes may not be optimum for fit, or is the clamping nut by any chance bottoming on thread.

 

[Dalboy]

Like penman I also use polyurethane glue and have had no trouble.

If it is the whole thing turning on the mandrel then make sure it is tight but be very careful especially if using tapered bushings as this can force the the tube to open slightly (making a loose fit on assembly) and in some cases split the material you have chosen for the pen.

Hope this is clear and you understand

 

[Oakbear]

Thanks for the tips guys, all useful.

It's the tube that's too big for the madrel though, the wood is well stuck with Gorilla glue....

I've tried re fitting it on the mandrel and swapping bushing, but it just seem the tube is too big!

A thin smear of CA at each end and then drying it might sure it up?

 

[kasandrich]

The bushes should be at each end of the pen tubes and they are tapered, so the tube just rises up the taper until it is a tight fit, clamped in place by the nut on the end.

If the tubes are still spinning you are probably putting too much load on, take a finer cut.

 

[Daven]

What mandrel you using? - I have the Axminster one, it is not tapered so I get this occasionally so just tighten the lock nut up a bit more.

I use a bit of aluminimum tube as a spacer as well which helps to grip! Just be careful not to get it near the pen when sanding!

Dave

 

[CHJ]

Oakbear, sounds like you need the appropriate Stepped Bushes to suit the tubes, some can be seen in this picture, pen kit suppliers usually have one matched to the pen kit so that the tube is located concentric with the mandrel and the outer diameter is correct as well, saving any need to measure finished turning diameter.

 

[Oakbear]

Ah thankyou, it is stepped bushings i need!

The ones that came with my Rutland mandrel set aren't stepped, and no matter how tight can't sort this particular tube! I wasn't aware that stepped ones were available for standard 7mm slimlines, as the one stepped ones i have are for bigger kits.

Anyone know a supplier of stepped bushings for 7mm slimlines?

Cheers!

 

[laird]

I must admit I've never used stepped bushes for 7mm tubes. You do have enough spacers in the set up ? i.e the knurled nut isn't coming up to the end of the thread before it grips ?
Another thought would be is your drill set up levelling the ends of the blank (around the tube) correctly ?

 

[CHJ]

....Anyone know a supplier of stepped bushings for 7mm slimlines?....

:shock: never known a 7mm tube to be loose enough on a mandrel to cause problems, what is the exact diameter is your mandrel?

Are you sure you are clamping on the tube ends as laird mentions.

 

[greggy]

ryan, your mandrel should have a grub screwat the left hand side of the mandrel so you can adjust the lenght of it. you can also get stepped bushings for the 7mm kits

 

[Oakbear]

Thanks for the replies folks!

I did question whether i was going mad, but on double checking, indeed the 7mm tube was too big for the mandrel! Either a weird anomaly i guess, or i did something milling it. The others from the same batch were fine!

Anyway, a couple of drops of sanding sealer down the tube, and leaving to dry, prior to remounting worked just the ticket.