Bow Outs

[dbarrash]

How much does temperature and humidity affect the occurance of blowing out of blanks?

One day everything I turn goes just beautifully, and the next day every blank blows out at some stage or another.

My lathe / shop is on the balcony of my apartment (no choice at this time). Today I blew out 2 BEAUTIFUL Jeff Powell blanks and an acrylic. The burl was just fine.

Tools are sharp and I did not seem to change anything.

I am in the Baltimore area and it has been very hot and humid. Today was rainy all day.

Your guidance is appreciated. Thanks Dave

 

[toyotaman]

What kind of tool are you using?

 

[watch_art]

ON a balcony? Cool! Wish I had a setup like that. Not in the winter though. Yikes. But COOL! Do bits of wood and plastic chunks fly down and smack passersby on their heads? Sounds like fun.

"Hey!" Guy looks up and shakes his fist.
"Sorry! That was my pen!" Waves down in apology.

 

[dbarrash]

I use Benjamin Best 3 piece set (Gouge) and then Easy Woods Carbide Mini Finisher instead of BB Skew. It is as I get closer to the tube that things seem to blow up.

It's possible I could get impatient as I get closer and rush things but not sure.

Dave

 

[toyotaman]

I use a homemade carbide tip tool. It's about like the Easy Wood tools. Square carbide blade. Once my blank is round I start (from the middle of the blank) and use kindly just the tip and shave once to the right and then form the middle again I shave a little to the left each time it removing about a 32nd. I've done some soft and punky wood with no blowouts yet. (Knock on wood)...... When I get close to where I want I add thin CA and let it set a few minutes. Works for me.

 

[nativewooder]

Could it be something like there was a shortage of glue coverage? Naked blanks do tend to go away.

 

[dbarrash]

I did switch from CA to mount tubes to Epoxy (BarrelBond 5 Minute Pen turning glue).

Blanks sat for 3 days to cure.

Could be anything...........that's why I posed the question.

Dave

 

[76winger]

When your turning are you getting small chunks of ribbons once you've got the blank round? If you're getting chunks,
you're either going too fast of need to modify your technique so as to take of smaller amounts at a time.

ETA: I'm assuming acrylic blanks with the above. If wood, something else isn't right

 

[Dragonlord85]

Where do you do your gluing? Seems like maybe the high humidity is affecting the glue.

 

[dbarrash]

Was just thinking...............
I painted all these tubes..............
1.Roughed up brass tubes with sandpaper
2.Painted tubes with Acrylic Paint
3.Let Dry several hours and then Expoxy glue

Could this be or previous response seems more likely..........
Does get round........pretty close to size and then it grabs a piece imbedded and Kaboom!

Dave

 

[ed4copies]

As you get close to "pen size", you could use a "trick" I learned when turning very intricate glue ups: "Douse" the blank in thin CA--this will soak into the "cracks" and help hold the pieces in. Then, if you are still nervous, coat the blank in medium and thick CA. This will eliminate the "bump" you can feel in the transition between one type of material and the other.

Although I realize lots of turners use the square carbide cutting tool, you realize you are then cutting that whole width with each revolution. If you use a sharp skew, you only touch a mm or so at a time. I BELIEVE the more of the edge (transition between inlay and main material) you hit, the more likely you are to pry out the inlay, at least in part.

Again, some of this is opinion---if you have a successful method, keep it. But, when you find yourself struggling, try the CA coating---it has worked for me.

 

[Culprit]

Building on what Ed said, I do better with an R2 square radiused carbide insert than I do with a true square insert. The edges, not corners, are ever so slightly rounded. It helps prevent me from catching a corner and destroying the blank.

 

[davidpensfan87]

Was just thinking...............
I painted all these tubes..............
1.Roughed up brass tubes with sandpaper
2.Painted tubes with Acrylic Paint
3.Let Dry several hours and then Expoxy glue

Could this be or previous response seems more likely..........
Does get round........pretty close to size and then it grabs a piece imbedded and Kaboom!

Dave

What I do is paint the inside of the blank with spray paint and NOT the tube. I do this because I find that spray paint adheres to plastic better than metal, the paint can be scraped off the tube when you insert the tube and the because you are not able to effectively scratch the tube when it already has paint on it, remember, you are scratching the tube for the glue, not the paint. Another reason to paint the inside of the blank is because sometimes the epoxy will have bubbles and they will be visible. For that reason, think of painting the inside of the blank as tinting your car windows.
Hope this helps,
David

 

[dbarrash]

Thanks all............Turned 3 pens today and all came out great..........

I'll post this weekend...........Have not posted yet.......

Dave..nervous for critique