Thread: Exploding Pens

I like epoxy myself just be sure to make sure there is none inside the tube. sometimes a bit of playdough is good to block the end. forgot to mention I rough up the tube with a bit of scothbrite to remove the shiny stuff.

I had a similar problem when using superglue. As was said above, switch to a different glue than CA to insert your tubes and make sure you rough them up. I use polyurethane glue for timber blanks and epoxy for acrylics. Let them set overnight.

When turning the blanks, if you notice any weak points or cracks in the blank as you turn, fill it with thin CA, leave it to dry (no accelerator) and keep turning. Can't say these are my own ideas (just gleaned them from this site) but they seem to work and my pile of 'practice pens' isn't growing at quite the rate it used to.

Cheers

Gab

I'm not a large scale pen maker so I'm not overly concerned about how long a pen takes to make or how long it takes for glue to dry. I go for quality and longevity and only use a good quality "24hr epoxy." I purchase the epoxy in bulk 500 g tins which in the tropics seems to last many years. I generally make up 20 or 30 pen blanks at a time.

My process is pretty basic -

• drill the pen tube holes at least 0.5 mm oversize
• lightly sand the brass tube using 240 or 320 g
• thoroughly mix the epoxy in correct quantities - I use a cheap set of digital scales to weigh mixes.
• lightly coat the entry hole to about 1/3 to 1/2 depth in the pen blank with epoxy
• lightly coat the tube about the same length
• push the tube into the blank with a rotating motion using a tapered mandrel inside the tube
• clean off & recover any excess glue using a modified paddle pop stick
• clean off remaining excess glue with a cotton bud & metho.

Occasionally I will get a failure, but the failure rate is very low.

I cant add too much to what has already been said. But yes, ditch that CA for gluing in tubes, I use mid cure epoxy, the 15 or 30 minute stuff from GPW or Timberbits.

I think you are turning too slowly also, I turn my pens flat out , 3500rpm. Give it a try, I'm sure you will like it.

I go through a similar process as used by Mobyturns but use polyurethane on my timber and epoxy on my acrylics

Only two splits I've had recently are from getting the fittings crooked and splitting the resulting pen that way - first time it's ever happened actually
and the other instance was with a piece of timber that was not fully seasoned - cracked as it dried damn

Luke, is there a chance your chisels/tools are too far away from the blanks - tool rest too far away?

How about going to a faster speed - max.

l had a lovely blank of birdseye huon explode at the end, whilst just starting to remove the corners/edges - lathe was too slow and l reckon the timber was too dry, also chisels were not that sharp.

l get my polyurethane glue from the green shed, the CA just soaks into the timber too quickly and goes off too quick for that reason.

l reckon using the abranet abrasive sheets towards the end saves any small blow outs, just takes a bit longer, you can small sheets in boxes up to 500grit

buy from here - http://www.bccoatings.com.au/compone...d=766&Itemid=1

Disclaimer - l'm only learning myself but the above are worth a shot.

Originally Posted by Luke Maddux

...using sharp, well presented tools...

What sort and what approach? CA is problematic but you shouldn't be getting that many failures, so sounds like something else is also wrong

Ok, it sounds like moving to epoxy is going to save me some grief. I have two part techniglue in the shop already, so maybe I'll just go to that and always allow an extra day for the glue to dry.

When I say sharp, well presented tools, I mean a roughing gouge to start and a spindle gouge to finish. I leave the burr on m y gouges if that is relevant. I used to use the skew for finishing, but I found that I was having less chipping at the ends of the blanks by using a spindle gouge. I'm not sure why. Possibly the lower angle or the ability to present the tool to the end of the blank as opposed to the skew which works better when you start in the middle and move off of the end.

As far as RPM, i was going flat out before and I slowed it. I had always had a "faster is better" approach with mandrel-mounted pens because safety is less of a concern (Please don't jump on that statement. Let's just stick with topic at hand). I was thinking that the excess centrifugal force may have been playing a role in the blanks flying apart.

I drill between centers and have been using a pen-specific bit. Depending on the timber I tend to push about 15mm into the blank at a time before removing the bit and cleaning the flutes. If I see smoke or if the dust in the flutes does that expanding thing when it comes out then I go slower. I have the lathe spinning at ~700rpm. I also adjust according to wood type.

Maybe that will help shine some light on the subject, but it seems to be a consensus that epoxy is fundamentally better.

Thanks for all of the feedback.

Luke

When your blanks let go, is the glue attached to both surfaces or only one? Giving the tube a good scuff up with 120 sandpaper in a spiraling pattern and ensuring that there is no oil from skin contact or the coating they put on the tubes during manufacture should ensure good adhesion. If I think there might be some contamination on the surface I will clean the tube with Acetone or Metho. I rarely use epoxy except where the tube is a fairly sloppy fit. I normally use the medium CA as it fills voids better and gives a bit more time to wiggle the tube around when inserting it. Failures are very rare and are usually the result of me doing something wrong during turning. I only leave the blanks for about 1 hour after gluing before I start turning them if I'm strapped for time and they don't let go.

Just wondering what kind of wood you are working with
Luke?

If you are trying to turn burl wood it can be tricky particularly
if you are using a roughing gouge.

The angle of presentation of the chisel is crucial in avoiding
any blow-outs.

Get used to using a very sharp skew and don't be too
aggressive.

Your rate of failures is obviously a cause for concern but there
will be an answer.

Allan

Originally Posted by Treecycle

and ensuring that there is no oil from skin contact or the coating they put on the tubes during manufacture should ensure good adhesion. If I think there might be some contamination on the surface I will clean the tube with Acetone or Metho.

Good points and one I probably overlooked as I wear disposable gloves when I sand the tubes and a different pair when I do the glue up.

Over the past 10 years I have used only CA to anchor the tubes and have never had a tube come loose. Very rarely have I had a blank split or shatter while turning wood or acrylic.
I Knock the corners of with the BS, 3800 RPM, TBC and razor sharp tool with a light touch.

Les

Originally Posted by Les in Red Deer

Over the past 10 years I have used only CA to anchor the tubes and have never had a tube come loose. Very rarely have I had a blank split or shatter while turning wood or acrylic.
I Knock the corners of with the BS, 3800 RPM, TBC and razor sharp tool with a light touch.

Les

You've literally quoted the exact steps I take, so there is obviously a subtlety which is causing the drama.

I use 5min 2 part Epoxy and only mix up enough for three or four tubes at a time, I never have any issues with tube & Blank glue ups )

Cheers
Tony