Segmenting failures......

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Janster

Janster

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..... I am relatively new to pen turning and segmenting but I see why the failure rate, (at least for me) is high. The tubes I generally use measure .411 OD, the finish bushing OD is .472. This leaves .061 or .0305 worth of skin on the tube! Turning down that far leaves very little room for error. Factor in the .020 thin edge of your Brass, Copper and or Aluminum segmenting piece, trying to adhere to the tube, although strengthened by the surrounding material, it is just not alot of grab!
I personally do not like the wasp type bodied pens, slim ends and pregnant looking middle ( single tube set up). So, for me, I have but .030 thickness the entire length. But, I got through on today with only ONE (1) blowout that was not too difficult to repair. Hopefully I can post it tomorrow. Any thoughts or input are welcome. If we each share our expeiences and or problems as a community for the growth of pen making, we'll all be better off down the road, JMHO. Thanks and be well.............Jan
 
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I have found that most of my failures occur from lack of heat control. Either I drill too fast, sand too hard, or cut too deep per pass. Even with the very tight tolerances allotted, a good epoxy will hold even the thinnest pieces in place...most of the time. The best lesson I've learned in reference to segmenting is how to repair a failure as that happens as much as a first time success.
 
When teaching someone to turn, lesson one is how to sharpen their tools. If a turner is blowing out blanks, needing to do a lot of sanding, their tools are not sharp. How many posts do we see day in and day out that stress the critical importance of sharp tools. Sharp tools, light touch a turner should be able to start sanding with 220 grit or better. 4-6 seconds per grit is all thats needed.
 
Janster said:
..... I am relatively new to pen turning and segmenting but I see why the failure rate, (at least for me) is high. The tubes I generally use measure .411 OD, the finish bushing OD is .472. This leaves .061 or .0305 worth of skin on the tube! Turning down that far leaves very little room for error. Factor in the .020 thin edge of your Brass, Copper and or Aluminum segmenting piece, trying to adhere to the tube, although strengthened by the surrounding material, it is just not alot of grab!
I personally do not like the wasp type bodied pens, slim ends and pregnant looking middle ( single tube set up). So, for me, I have but .030 thickness the entire length. But, I got through on today with only ONE (1) blowout that was not too difficult to repair. Hopefully I can post it tomorrow. Any thoughts or input are welcome. If we each share our expeiences and or problems as a community for the growth of pen making, we'll all be better off down the road, JMHO. Thanks and be well.............Jan
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Evidently you are new to the site here as well. This is what we do here day in and day out. We all have blow outs. We all make mistakes. But the big key here is you have to learn from them and basically have to learn on your own. Unless there is somene standing over your shoulder and watch exactly what you are doing it is impossible for anyone to tell you why your blank blew up. Now as you read the many many many posts about people's experience of blanks blowing up as we so call them, there is always people stating did you glue them, did you use sharp tools, did you do this and that??? This is all guesses and all we can offer is things we have seen on our own. We have been sharing these things.

What I am trying to say and not being sharp about it is we discuss these problems here every day. Read through the 1000's of posts. And when something goes wrong make note of the reason's YOU think they went wrong. I will tell you this it will happen again.

Heck I just blew a blank up yesterday from a design I made. Right away I knew what went wrong. I learned I could not use a carbide tool to turn the blank down because I could not use a scraping motion. I need to do a shearing cut and the best tool to do this is my skew. I did the next blank and it went flawless. So there is a little nugget you may want to put in your memory banks. Not all blanks can be turned using a scraping motion.

You make reference to thickness of material left when done turning away a blank. Try doing kitless and incorporate your design in those. Some designs are just not meant to be because of the nature of the pen shape. Good luck and keep at it and learn. I say this all with good intent and not to be a wise guy.
 
Butch and John have hit on something that is so key here with sharp tools. John further expounded upon the theory of a scraper and a skew. As John already knows I use my skew for almost all of my turning. I have a carbide tool that sometimes comes into play but with these segmented and extremely thin blanks we need to remember the intense stress that is being imposed on the turned item. In my most recent post I honed my skew at least 4 or 5 times per blank while I was turning the caps. This puts so much less stress on the blank it isn't funny and allows me to do very little sanding to boot. Now honing doesn't need to be a long process it is very fast after you get the technique down. I simply turn around, my diamond hone is sitting on the bench behind me with a squirt bottle of water with dish soap in it take 4 to 7 passes per side and turn right back around and start turning again. I have no excuse for destroying a blank because my tool wasn't sharp. I have way to much time gluing and cutting these blanks to destroy one because I didn't sharpen my tools. Now some may say I should get a better tool so it doesn't need sharpening as often but I have a very good skew and it is as good as you can buy. Sharp Sharp Sharp is where you will find success. I don't want my skew scraping off wood I want it to slice off wood.
 
Thanks guys. This is money in the bank ! Good info and "yes", taken constructively. I read till my eyes hurt but the great teacher is hands on experience, for me at least. It is getting better. I can get out of lo-range compound, still looking for First gear. Be well................Jan
 
I am glad you did not take the comments the wrong way. Mike is so right about the use of the skew on these delicate segments. Honing is basically what I do as the project is being turned. I will sharpen the skew just before turning it. You are slicing not peeling.

I have put together a bit of a new thread that I want to post here probably tomorrow because I am not home right now doing this. I am hoping many will partake in it and it will become very useful. More on that later.

I will also show the blank I blew up if and when I can pull the real deal off sometime next week. I will show you exactly why it happened. After I did it I knew right away.I very and mean very rarely blow up blanks.. Is that luck, I do not think so. I want to think it is because I use a skew to cut my blanks down. Very important tool in the tool box at least to me it is. Far outweighs any carbide tools out there.
 
I just this morning ordered a .75" oval skew for Grizzly Industrial! I take no offense to constructive input from anyone. I am on the IAP site to "learn and share" . Thanks and be well............Jan
 
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