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Splitting when turning

2.6K views 8 replies 5 participants last post by  BarryJM  
#1 ·
I have been making Slim Line and Sierra pens and having trouble with blanjks splitting on the lathe, is the speed too fast at 2,500 rpm, toolsnot sharp enough or?
 
#3 ·
Speed shouldn’t matter, sharp tools and good tool control. You need to take very light cuts with pen blanks, not much material there to start with. Tool presentation is critical. If you’re using traditional tools, riding on the bevel of the tool supports the wood as you’re cutting it.
Mike Hawkins
 
#4 · (Edited)
For great penturning advice and knowledge, check out this website:
https://www.penturners.org

I have turned a few pens. Speed is not the issue. I adjust the speed knob as I'm turning, but for most pen turning I bring up the lathe to the highest speed to get the smoothest results.

If you're asking about tool sharpness, then they probably need sharpening.

What does "blanks splitting on the lathe" mean? What types of pen blanks are you using? Which turning tools are you using?
-> How are you gluing the pen blanks to the brass tubes?

A few of my early pens split off from the tubes. I had other early issues to overcome, too. Some fixes for me were:
  • Sharp tools. If you aren't sure, try sharpening your turning tool and see if there is a change. The hardest woodturning discipline to learn is to stop turning and sharpen the tool.
  • Light touch. Learn good turning technique. What turning tools are you using? Are you presenting the tool correctly? What do the shavings look like? Dust? Ribbons?
  • Don't use CA glue for the brass pen tubes. Most skilled penturners use epoxy to glue the brass pen tubes, but I prefer polyurethane (original Gorilla glue), which foams. I use Clear Gorilla glue (silane-based) or epoxy on a few special pens and pen blanks.
  • Try easier woods. It took me three tries to make a marblewood pen early on. Marblewood split along the grain and flew off the brass pen tube on my first two attempts. Marblewood is a brittle wood that likes to split along the grain. I had to learn a lighter touch for marblewood, too.
  • Try easier materials like switching to wood at first instead of going for the plastic blanks. If you are using plastic like inlace acrylester, it likes to chip out or simply crack apart. It took me three tries to make an inlace acrylester pen from Rockler's "holographic black" pen blank. For those blanks, I use a clamp to hold the pen blank, and use belt sander to round off the four long "corner edges" rather than rounding them on the lathe using a roughing gouge. I had to learn a very light touch for some of those brittle plastic blanks, too.
 
#6 ·
For great penturning advice and knowledge, check out this website:
https://www.penturners.org

I have turned a few pens. Speed is not the issue. I adjust the speed knob as I'm turning, but for most pen turning I bring up the lathe to the highest speed to get the smoothest results.

If you're asking about tool sharpness, then they probably need sharpening.
using 2,500rpm

What does "blanks splitting on the lathe" mean? What types of pen blanks are you using? Which turning tools are you using? i am using the tool with the curved noce, they are aas sharp as i can get them on my Scheppach grinder

if you mean wood, its various woods doing it, cyprus, Huon Pine, Sassafras blackheart, english oak
-> How are you gluing the pen blanks to the brass tubes?

A few of my early pens split off from the tubes. I had other early issues to overcome, too. Some fixes for me were:
  • Sharp tools. If you aren't sure, try sharpening your turning tool and see if there is a change. The hardest woodturning discipline to learn is to stop turning and sharpen the tool.
  • Light touch. Learn good turning technique. What turning tools are you using? Are you presenting the tool correctly? What do the shavings look like? Dust? Ribbons?
  • Don't use CA glue for the brass pen tubes. Most skilled penturners use epoxy to glue the brass pen tubes, but I prefer polyurethane (original Gorilla glue), which foams. I use Clear Gorilla glue (silane-based) or epoxy on a few special pens and pen blanks. Ihave used CA before and not had this problem

  • Try easier woods. It took me three tries to make a marblewood pen early on. Marblewood split along the grain and flew off the brass pen tube on my first two attempts. Marblewood is a brittle wood that likes to split along the grain. I had to learn a lighter touch for marblewood, too.
  • The harder woods seem to stay together

  • Try easier materials like switching to wood at first instead of going for the plastic blanks. If you are using plastic like inlace acrylester, it likes to chip out or simply crack apart. It took me three tries to make an inlace acrylester pen from Rockler's "holographic black" pen blank. For those blanks, I use a clamp to hold the pen blank, and use belt sander to round off the four long "corner edges" rather than rounding them on the lathe using a roughing gouge. I had to learn a very light touch for some of those brittle plastic blanks, too.

  • using only woods
 
#5 ·
If you are stuck with using CA glue know that when you stick a tube covered with thick or medium CA into the blank hole its not going to coat the surfaces inside completely. My remedy that seems to work is after gluing in the tube to wick some thin CA in from the ends between the brass and the wood until any gaps are filled and no more goes in. It takes a bit of care to avoid making a mess doing this and you will definitely need to scrape the excess glue from the inside of the brass.
This lack of coverage is one of the most common reasons a blank splits off as theres nothing under the wood eventually to keep it in place once close to the final dimensions.
 
#7 ·
Well some success today, only one split and the wood felt dodgey on the drill.

I sanded the ends of the blanks back to the tubes and put some CA in the blank before inserting the tube, turning it the whole way in. I hope this solves the problems,

Thanks for everyones input it has helped, I will post back how tomorrow go as I am using softwoods Cyprus and Spalted Sassafras