Trouble Turning "Circuit Board" pens!!!

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TonyBal

TonyBal

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Joined
Dec 12, 2011
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Jacksonville, Florida
Who here has turned the clear "Circuit Board" pen blanks. What is the deal? Talk about a chip-out fest. I thought that I had ruined it after the first few passes. I turned off the lathe to look at my progress and said WTF ("Why The Face", yeah right). It looked like someone went crazy on it with an ice pick. I had "successfully" turned 10 other acrylic pens the day before & thought I had it down. I guess not all acrylics turn the same. I had noticed some minor differences between the other acrylics, but nothing like this. I turned the lathe down to my slowest speed (500 rpm), re-sharpened by pen gouge, & very slowly & meticulously went back to work. I was finally able to get some ribbons flying instead of chips, but there seemed to be a couple of areas that were not going to slice no matter how careful I was. I stopped about 1/16" before getting to the bushing & sanded the rest of the way there out of fear. I had only two of the kits & I needed both pens the next day for my wife's bosses so I wasn't about to risk it. To be honest, I only used sand paper on the second one since I "almost" ruined the first one. 5 minutes & 60 grit sandpaper & it was ready for finishing. How embarrassing. I hated to do it like that but I did not want to risk it. Plus those kits cost over $20 each. Ouch! Anyway, the final product turned out awesome. The clear acrylic was totally transparent when I was finished. I was very happy with both of them. If anybody has any suggestions on how to actually turn these bad boyz I would sure like know. Thanks.:smile-big:
 
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I just finished 2 ten minutes ago. Yes they are very chippy. I use a new carbide cutter at 2600 rpm with light cuts . Like yourself I always sand my way to the bushings.

Good luck with future Kits!

Tim
 
TonyBal said:
Who here has turned the clear "Circuit Board" pen blanks. What is the deal? Talk about a chip-out fest. I thought that I had ruined it after the first few passes. I turned off the lathe to look at my progress and said WTF ("Why The Face", yeah right). It looked like someone went crazy on it with an ice pick. I had "successfully" turned 10 other acrylic pens the day before & thought I had it down. I guess not all acrylics turn the same. I had noticed some minor differences between the other acrylics, but nothing like this. I turned the lathe down to my slowest speed (500 rpm), re-sharpened by pen gouge, & very slowly & meticulously went back to work. I was finally able to get some ribbons flying instead of chips, but there seemed to be a couple of areas that were not going to slice no matter how careful I was. I stopped about 1/16" before getting to the bushing & sanded the rest of the way there out of fear. I had only two of the kits & I needed both pens the next day for my wife's bosses so I wasn't about to risk it. To be honest, I only used sand paper on the second one since I "almost" ruined the first one. 5 minutes & 60 grit sandpaper & it was ready for finishing. How embarrassing. I hated to do it like that but I did not want to risk it. Plus those kits cost over $20 each. Ouch! Anyway, the final product turned out awesome. The clear acrylic was totally transparent when I was finished. I was very happy with both of them. If anybody has any suggestions on how to actually turn these bad boyz I would sure like know. Thanks.:smile-big:
Click to expand...

Welcome to the world of plastics!!!

No, all acrylics do NOT turn the same and the circuit board pens are not acrylics. They are polyresins. And not all polyresins turn the same.

If you'd like to see a similar material turned, look here:
http://www.youtube.com/watch?v=xikciU16Fts

This is a "feather" blank, but they are also made from polyresin and are very similar turning characteristics.
 
You have to use very very sharp tools and a light touch. If you try to remove the material to fast it will chip & can even crack/split. don't be discouraged just another skill set.
 
I had the same problem right when I was almost finished turning a bit chip flew off. I did emergency repair on it with some CA glue and lucky for me it turn out OK.
 
Welcome to IAP... There is a lot of threads on this subject and a bunch of us that can help with advise.

It sounds like you already figured out tip 1 - razor sharp tools. The only thing I would add is to think again about your lathe speed. Light touch on a faster lathe works much better for me that slowing it down. When turning acrylics, I keep my lathe at the top speed (just make sure YOU are comfortable with the speed you use).
 
If you store your blanks in a colder climate or your shops cold, place the blanks in your pocket for a little while before turning. IMHO if they are cold they are more prone to chip out. I shape all of my polyresin blanks with sandpaper. Just dont get them too hot or the resin will soften on you and fall off the tube. Dont ask me how I know that....
 
TonyBal said:
Who here has turned the clear "Circuit Board" pen blanks. What is the deal? Talk about a chip-out fest. I thought that I had ruined it after the first few passes. I turned off the lathe to look at my progress and said WTF ("Why The Face", yeah right). It looked like someone went crazy on it with an ice pick. I had "successfully" turned 10 other acrylic pens the day before & thought I had it down. I guess not all acrylics turn the same. I had noticed some minor differences between the other acrylics, but nothing like this. I turned the lathe down to my slowest speed (500 rpm), re-sharpened by pen gouge, & very slowly & meticulously went back to work. I was finally able to get some ribbons flying instead of chips, but there seemed to be a couple of areas that were not going to slice no matter how careful I was. I stopped about 1/16" before getting to the bushing & sanded the rest of the way there out of fear. I had only two of the kits & I needed both pens the next day for my wife's bosses so I wasn't about to risk it. To be honest, I only used sand paper on the second one since I "almost" ruined the first one. 5 minutes & 60 grit sandpaper & it was ready for finishing. How embarrassing. I hated to do it like that but I did not want to risk it. Plus those kits cost over $20 each. Ouch! Anyway, the final product turned out awesome. The clear acrylic was totally transparent when I was finished. I was very happy with both of them. If anybody has any suggestions on how to actually turn these bad boyz I would sure like know. Thanks.:smile-big:
Click to expand...

On ALL of my plastics, medium CA is my best friend. Those chipouts can be totally healed up with applying CA and sanding back level. I still have some degree of chipout on a lot of my resins due to cheap tools and not-ideal sharpening methods. Works GREAT for woods. Resin and acrylic, not so much.
 
It has already been noted, but all plastics, resins, aluminites...etc. turn differently. I turned three of these a couple months ago just to see what the hype was and mine were a little tacky on the outside, but turned fine. You can't just shoot right in there like some acrylics...as stated, the sweet spot on the skew is your best friend with these pen blanks. Best wishes and I hope it works out for you...sanding a blank down takes the fun out of it!!!
 
I just finished a Circuit board pen this afternoon while waiting for glue to dry on other pens. I use a carbide cutter tipped tool meant for acrylics. The tip has an angle between the top and front a bit less than 90 degrees.

You should be getting long ribbons of material. If you are getting hard gritty pieces, your technique needs adjustment. A skew presented in a shearing cut, not a scrap will work best

The Easy Wood Tools are meant for WOOD! They are too grabby for acrylics.
 
I've turned about 50 of the circuit board pens, my technique is razor sharp tools, light passes and lathe at high speed. I think I'm turning ~1500-2000rpm. I have to check the belt to be sure.
 
Yep..good advice, knock corners down prior to turning, sharp tools, high speed. I have turned dozens of these pens, using my carbide tool. The argument that the Easy Wood Tools are for wood only does not hold up under my experience. Properly presented to the blank and light touch will turn these challenging blanks with ease, down to where normal sanding, micro mesh and polishing complete the blank beautifully.
 
So is it the consensus of the esteemed panel that a razor sharp skew utilizing a shear cut at a higher speed is the preferred method for shaping these polyresins? (Rounding corners first is optional, but sounds like a good idea to me.) Also, thank you all of the valuable input. :biggrin:
 
I turn a lot of these also. I sand off the corners on my disk sander all the time - I don't consider this step optional...why take a chance. I use the same shallow angle carbide tools that "randyrls" uses. For sure you can use tools with more aggressive cutting edge, but this requires more skill to stay out of trouble on acrylics. I do these kits in batches, and turn my cutter insert to a fresh edge before I start. High speed is better, I use 2700 rpm. I work the ends first by carefully rounding them over with the flat edged tool. My goal is never to cross a sharp edge on the end of the blank using the tool with the round cutter. After rounding over the edges, I switch to the round tool to reduce the diameter of the blank. If need be I round over the ends again so that I don't cross the end of the blank with a sharp edge. When I'm just shy of the bushings I start the wet sanding, then polishing process. Good luck with whatever method you decide to use.
 
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