Failure rate

[Pjohnson]

I had time the past few days to try some new kits. Enjoyed the hum of the lathe and the challenge assembling new kits.

My problem has been with some frequent blowouts - 2 out of 4.
The blanks that fractured were a mulberry and a self cast with PR. I think the mulberry blow out was caused by the skew catching on the edge of a knot (still learning). The PR was at the nib end and just blew off - no explanation. I think I am seeing more because I am turning more.

what is your blow out rate?

 

[its_virgil]

My opinions and observations only: Most "blow outs" are caused by poor tool techniques. As you mentioned…a catch. Dull tools require more force to cut and catches occur. Also a catch coupled with poor glue coverage compounds the blow out issue. Not bragging but I can't remember the last "blow out" I had. And, I turn a lot of snake skin blanks made with PR. Even turning a pen requires correct spindle turning techniques. I would predict that the more you turn the less the blow outs will occur. Getting in a hurry is also a culprit. Each pen is practice for making the next one better. Pay attention and correct what you are doing incorrectly. Best of luck to you.
Do a good turn daily!
Don

 

[Jerryz]

I find that for me blowouts are almost always related to trying to take material too fast or dull tools. don't rush and keep my tools sharp and it usually goes well.

 

[JohnGreco]

My blowout rate is low, maybe 1%. On wood it is typically because of bad glue coverage, on acrylics because of heat build up. Those are just my own reasons for blowouts, I use a carbide tool to turn so I know it's not from dull tools (though that could do it).

If you're 'hovering' at the nib end trying to really get a good turn, you need to watch heat build up. Focus on the nib, then back off and focus on the opposite end, then back to the nib. Repeat as needed. Best of luck.

 

[Wildman]

I always associated blowouts more with bad drilling technique, than turning. Never had a blowout drilling or turning either wood or plastic.

I do believe you have to vary your approach turning some pen blanks whether wood, plastic, antler, tru-stone or other material. That comes with knowledge and experience.
Early on some of my hole have been off center or out of round. Just backing out and clearing chips faster improved those problems.

I have had glue failures with CA, even with good glue coverage. Blame lack of cap filling ability or age of my CA glue. Never had a glue up problem with epoxy or poly glue. Poly has a short shelf life too, so buy small bottles.

Making pens just about idiot proof if not for Murphy's Law. Have several desk pens laying around to prove that theroy!

 

[mikespenturningz]

The more you turn the better you get at reading your tools too. I can't remember the last time I blew up a wooden blank but I have blown up many segmented blanks. Sharp tool is my answer and also going slowly on the segmented blanks. I will touch up my skew several times during a segmented blank they can never be too sharp.

 

[Jim Burr]

There can be a couple things...JMHO though! Several different techniques can be used, as well as tools. I usually turn from the center out if using a round blank; square blank, side to side until it's round... but that's just me. The reason is the wood is much thinner at the bushings and starting from the end, there is little support. There are times however I will start from the bushing end...depends on the situation and if I feel lucky!
Tool selection is always fun! I'm good with a skew and gouge so I use them frequently. I recently picked up a carbide tool and have really enjoyed working with it. BUT!!!...any good turner will not depend on a single tool. Regardless of whether you turn only pens or turn everything, mastering many tools and their uses is essential. I don't know of a single turner worth a nickel that relies on a single tool.
Maybe get some junk wood, hone (no pun intended) your sharpening skills and practice your technique like crazy!! Youtube can be your friend in the technique area, as can a good turning club in your area.

 

[Pjohnson]

Thank you for the thoughts and comments - all are 100% spot on.

Reflecting on my process with these blanks - heat was my enemy! I hit the blank with sandpaper to remove some chipping and then went to the skew. Not enough time was spent allowing it to cool. Lesson learned and many comments above to incorporate.

Thanks again.

PJ

 

[Jim Burr]

The more you turn the better you get at reading your tools too. I can't remember the last time I blew up a wooden blank but I have blown up many segmented blanks.

Mike makes a good point; the more complex the blank, the higher chance for failure. The buckeye, antler and aluminum blanks I make are crazy hard to turn with the density of 3 dissimilar materials to deal with. Patience plays a factor too!!

 

[sbell111]

When I start to blow out blanks, I find that I'm getting away from the basics somewhere. Did I rush the drilling resulting in a 'fat' hole? Did I fail to glue in the tube properly? Did I allow that glue to properly cure? Did I fail to mill the blank to the tube? Did I over tighten the mandrel? Was my tool dull? Did I turn too aggressively? Any 'yes' answer to those questions could result in a blow out.