Thread: Help with exploding pens

Some questions for you:

• Are you roughing the brass tube with sandpaper first?
• What glue are you using? I found that I eliminated this problem when I changed from CA to a 2 part epoxy.
• Are they timber or acrylic blanks?
• If timber, are the blanks straight grained or figured?
• Are the blanks cut on an angle across the grain?

The speed of your lathe is not an issue.

Yep roughing the blanks,
already using 2 part (araldite)
both wood and acrylic
and the wood blanks are straight grained and not cut on an angle.

What tools are you using and are they sharp.

If it used to work OK for you and it doesn't now, are they either blunt or are you not sharpening them correctly?

Yep tools are sharp and sharpened correctly and even if it was the tools, this also happens if I turn it close to the bushes then sand the rest so I wouldn't imagine it would be the tools.

I do have a theory and that is that I am not getting a perfect hole for the brass tube and therefore there could be some gaps between the blank and the tube but in saying that I am doing it the same way I used to do it when it worked.

That could certainly do it. How do you drill your blanks, any run-out on the drill?

Yeah, exploding blanks are usually caused by air gaps.

You're not using the 5- or 15-min araldite, are you? I've found that stuff to be pretty much useless; it starts to go off before everything is ready and even when all goes well doesn't have anywhere near the strength of the old-style 24hr stuff.

I find that by using the 24hr stuff and coating both the roughed tube and inside the blank before fitting (the old chupa-chup sticks are ideal for poking around inside the blank ) I very, very rarely had a blow-out that exposed the tube.

A second possibility is if you're using oilier blanks than usual. (Cocobolo, Teak, huon Pine, etc.) The oil may prevent good adhesion and it can help to run some thinners, acetone - even nail-polish remover will do - through the blank almost immediately before applying the glue.

Agree with Skew, same used to happen to me early on, but followed that advice-cover both tube and inside of blank with epoxy, then put together, a bit of potato in one end helps to keep much epoxy from the inside of the tube, but you will probably still have to scrape some off. Amos

Another thought is are you sanding all the way up to up to the brass before you start to turn so that the pressure is being transfer to the brass tube and not just the timber. That could be the reason it is blowing out when you get close to the bushes when the timber is at it thinest.

Originally Posted by Rum Pig

Another thought is are you sanding all the way up to up to the brass before you start to turn so that the pressure is being transfer to the brass tube and not just the timber. That could be the reason it is blowing out when you get close to the bushes when the timber is at it thinest.

I don't sand them I use one of those barrel trimmer thingmebobs

I used to get that when I was using CA but since I changed to two part epoxy from Gary Pye I've made about 200 pens and not had one blow out. There is 41/2 oz in each of the epoxy and the hardener bottles. He charges $14.95 for it which is good value compared to Araldite or any of the Selleys stuff. It is a mid cure epoxy and cures in about 20 minutes and Gary has it branded with his name and it comes from the states and I get about 50 pens from it.

I rough up the tubes with 80 grit emery cloth and I clean out the inside of the blanks with a cotton bud and methylated spirits. I mix the epoxy up on a Post It pad and and throw it away straight away to save getting epoxy everywhere and I use the sides of a plastic Ice cream container cut up into 1/4" strips to apply the epoxy to the tubes. I apply a liberal amount to the bottom two thirds of the tube and push the tube up and down in the blank to spread the epoxy inside the blank. I then push the tube right home with a type 17 roofing screw and the excess epoxy that is pushed out on the end of the blank coats the top third of tube as it is pushed in and if the there is too much excess epoxy on the end of the blank I just scrape it off with one of the plastic strips of ice cream container.

Using this method I get no epoxy inside the tube and I don't have to muck around plugging the tube with potato or any other sort of rot. Then I just square the ends with the pen mill down til I see the shiny ends of the brass tube.

And BTW the quill on my drill press has run out so my holes drilled in my blanks are some times not as good as could be desired.

Thanks Jack and all others who have replied, I've just taken the tubes for a barron off the lathe after so many blow outs of beautiful coolabah burls, I don't want to count. I guess I got lucky with my earlier attempts using burl, but at least now I have something to work with.
Thanks heaps................I'd stopped turning for over a week, cos I thought I was useless.
BIG thanks to all.

undies

When turning burls I find it a good idea to stop every now and then epically when getting close to the finish a flooding it with thin CA to hold all the knots and bits together.
I use CA as a finish so it does not effect my finished product.
I also stopped using those barrel trimer's because I found they would tear the blank off the barrel so I now sand them on a disk sander and then finish on one of Big Sheds sanding jigs and I have not had a problem since.

Most of all do not give up you will find out what is going on soon just keep a bottle handy to help with the nerves
Good luck

What tool are you using?

Hey Jack,

I have also had a few blow outs lately, I got caught up in the CA (Superglue) is the bestest stuff, cycle, I had some thick CA and glued up a few tubes and had good results, I ran out of Thick and thought that the thin suuff is as good (It ain't), It really hit home with a couple of Red Mallee Burl Blanks that were really Hollywood, they ended up being really Bagdad. I have gone back to the 24hr Araldite, and waiting till tomorrow night to turn the pen.

Good luck, there has been some good advice from the brains trust, well done guys

HazzaB