NEW GUY EXPLODING ACRYLIC PEN BLANKS

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mcnamar

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I am exasperated and wondering if the seasoned guys and gals can help me out. I am getting comfortable with turning wooden pens (at least a bit). So, I bought some acrylic pen blanks and tried to turn them after looking for hours at You Tube instructional videos and such. I have ruined several blanks (and wasted time and cash), had a variety of problems, but nothing keepable, which also wasted pen kit tubes. One exploded when I tried to ream the tube and slowly drill down to the tubing like I normally do in wood pens. Others didn't shatter, but the turning was so jagged that it left very deep gouges in them. That resulted in them either peeling from the tube at worst and, at best, left a severely gouged up blank that looked like absolute crap when I tried to do the CA and micro mesh. I just tried the micromesh alone first because it was so bad, but was not thick enough to withstand further turning down. Then I added layers of thin CA followed by medium CA and then micro meshed it. There were gouges that really made it good for nothing except trash bags. Any ideas on what I can do to make acrylic a valid option? I'm all ears...or thumbs as it appears right now...Brad
 
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You will get others that will weigh in that probably do more than me... I have done a pen in a couple of years... I concentrate mostly on pepper mills and bowls now, but back when I was doing pens, I used Ed Brown's method of turning... almost exclusively with a skew, a very sharp skew. You want to cut the plastics rather than use a gouge or scraper... they do get chippy. I sanded first with dry sanding to smooth out any rough places, then switched to the micromesh to wet sand to my finish.... then used Hut Plastic polish. I never put CA on a plastic pen.
As said, this was my method and I'm sure you'll get others with a more refined method.
 
TellicoTurning said:
You will get others that will weigh in that probably do more than me... I have done a pen in a couple of years... I concentrate mostly on pepper mills and bowls now, but back when I was doing pens, I used Ed Brown's method of turning... almost exclusively with a skew, a very sharp skew. You want to cut the plastics rather than use a gouge or scraper... they do get chippy. I sanded first with dry sanding to smooth out any rough places, then switched to the micromesh to wet sand to my finish.... then used Hut Plastic polish. I never put CA on a plastic pen.
As said, this was my method and I'm sure you'll get others with a more refined method.
Click to expand...
Thanks. I'll look up the Ed Brown method and give it a look.
 
Chuck has it right. Sharp tools, light cuts,Ed's videos, and keep it cool (the blank, friction heat may cause brittle bubbles). Also, not all "acrylics" are the same, and not everything we refer to as "acrylic" is truly acrylic. Alumilite is a very soft & sweet material to turn, while Inlace Acrylester tends to be very brittle and chippy. So...to get the best help here, it's really helpful to know what it is you're working with for sure--then more accurate answers can follow. Pictures help too.
Best wishes!!
earl
 
First of all lets start at the beginning. You can not treat acrylic blanks the same way you do wood blanks because it is a different makeup which is obvious. Not all acrylics are alike. Boy I wish I could remember who it was that did a whole break down on the terminology of what is called acrylics these days and I believe it was Sylvanite. But have no time to do searches for you.

So will give basics. You need to tell us what you are turning them with and if I may make a suggestion get yourself a carbide round cutter. You need to better control your tools because acrylics are less forgiving than woods. A skew is also a good tool but if you can not control other tools than you need to forget a skew for awhile. Some acrylics will be chippy and some will peel with long strings. Different resins. But the more you turn the easier it is to recognize and adjust. I suggest you do some reading here and do some searching on turning acrylics. Just too much to tell you in one post. Plenty of utube videos out there as well as in the library here.
 
I would bet a quarter (all at one time) that you are turning a blank of either Inlace Acrylester from WoodTurningz or a RhinoPlastic blank.

These are hard poly resin blanks that you cannot turn successfully with dull tools or deep cuts. You can use a gouge but it has to be sharp, used in a shearing position not a scraping position and it doesn't hurt to ride the bevel like you would a skew. Or just use a sharp skew.

A carbide cutter presented at a negative rake angle or a negative rake carbide insert will make a huge difference if using carbide. You must drill slow, Clear often and either not drill all the way through or leave enough to accommodate the blow out of the end.

There are easier materials to turn but few finish as nicely and once you learn to turn it, you should be able to turn most anything.
 
greenacres2 said:
Chuck has it right. Sharp tools, light cuts,Ed's videos, and keep it cool (the blank, friction heat may cause brittle bubbles). Also, not all "acrylics" are the same, and not everything we refer to as "acrylic" is truly acrylic. Alumilite is a very soft & sweet material to turn, while Inlace Acrylester tends to be very brittle and chippy. So...to get the best help here, it's really helpful to know what it is you're working with for sure--then more accurate answers can follow. Pictures help too.
Best wishes!!
earl
Click to expand...
Thanks for the advice! I'm going to look at what kind of acrylic I have been using. I know the first problem is I was using the carbine scrapers (Easy Wood Tools) instead of the skew. I also was doing the turning too slowly. I think I was fearing heating up the acrylic too much. I just need to treat it like regular wood until it comes to sanding/micro meshing.
 
jttheclockman said:
First of all lets start at the beginning. You can not treat acrylic blanks the same way you do wood blanks because it is a different makeup which is obvious. Not all acrylics are alike. Boy I wish I could remember who it was that did a whole break down on the terminology of what is called acrylics these days and I believe it was Sylvanite. But have no time to do searches for you.

So will give basics. You need to tell us what you are turning them with and if I may make a suggestion get yourself a carbide round cutter. You need to better control your tools because acrylics are less forgiving than woods. A skew is also a good tool but if you can not control other tools than you need to forget a skew for awhile. Some acrylics will be chippy and some will peel with long strings. Different resins. But the more you turn the easier it is to recognize and adjust. I suggest you do some reading here and do some searching on turning acrylics. Just too much to tell you in one post. Plenty of utube videos out there as well as in the library here.
Click to expand...
Thanks for the advice.
 
I know when I was starting, turning between centers (e.g. no hard grip on the drive end) helped a lot, because it was so much kinder to a skew "catch"... the blank would just stop spinning instead of blowing up. It was kinda like training wheels for me.
 
I learned that what I was turning was a Poly Resin. Apparently, that is different than what is labeled at Woodcraft as Acrylic. I have 3 blanks for ice cream handles that are labeled Acrylic (not identified as anything other than acrylic). That, combined with not using a skew or turning at a very high speed has been the major errors that I have found out with help and advice here so far (along with researching other things). I am going to go to Woodcraft tomorrow and see if the acrylic I bought actually is decent for turning or if it is one of the many things out there that are sometimes called acrylic, but not the "easy" acrylic I have been reading about. As I said, I am a rookie. Not afraid to look things up, but it is not possible without some sort of rudder. That's why I like this site. I've already learned a lot about the subject and researched a guy JT suggested above. I'm not asking anyone to do research for me, just relay their experiences and advise me on things to look at. Thanks for helping all.
 
Tool and technique. Sharp tool is your best friend. Speed matters. Take your time. Move like a snail with airbrakes. Slow light strikes. Do not rush. We learn by getting started and making adjustments. You'll be fine. Easy does it.
 
Turning any material requires sharp tools. If you think your turning tools need sharpening, you are long overdue! I keep my Rikon grinder and Wolverine jig close by so sharpening isn't a chore as some think. I have recently found that I can sharpen a HSS tool on the Rikon and periodically touch up with a DMT diamond file. Turning is something that we never completely learn but learn each time we turn on the lathe. Old dogs do learn new tricks!
 
All resin can be turned with sharp tools and proper technique. Just because you turn speed up and use a skew will not guarantee success. You have an easy wood tool, get yourself the round cutter. Yes turn the speed up to what is comfortable for you. Present the tool on center to the blank and a light touch. It is so hard to explain with words and that is why I suggest you track down some videos. They will help.
 
Watching my videos will show some of the techniques of using a skew or roughing gouge. Both work great, for me.

However, I am currently helping a young man who has NO experience with tools, but wanted to make a pen for his dad for Christmas.
We are using an Easy Wood tool, with a negative rake insert. As long as he keeps the handle horizontal, turning has been easy.
He selected a kirinite blank, I will turn it to round, then he will make the pen (Jr. George). Lathe speed is about 2200 RPM, but a very important factor, I have the heat on in the shop, it is a little over 60 degrees by the time he arrives AND we are storing the blanks he is working on in the main part of the building, where the ambient temp is 70+. So, our blanks are warm making them easier to cut.

Try this, it seems to be a very easy way to learn.
 
ed4copies said:
Watching my videos will show some of the techniques of using a skew or roughing gouge. Both work great, for me.

However, I am currently helping a young man who has NO experience with tools, but wanted to make a pen for his dad for Christmas.
We are using an Easy Wood tool, with a negative rake insert. As long as he keeps the handle horizontal, turning has been easy.
He selected a kirinite blank, I will turn it to round, then he will make the pen (Jr. George). Lathe speed is about 2200 RPM, but a very important factor, I have the heat on in the shop, it is a little over 60 degrees by the time he arrives AND we are storing the blanks he is working on in the main part of the building, where the ambient temp is 70+. So, our blanks are warm making them easier to cut.

Try this, it seems to be a very easy way to learn.
Click to expand...
Thanks for the advice and motivation. I don't have a negative rake insert, but will check into it. I am also going to be reading a lot more over the next couple of days. Cheers
 
One trick that helps me get started with plastics/acrylics is to round off the side edges of the blank on the belt sander as the last step before I mount the blank in the lathe. It makes roughing the blank to a cylinder a lot easier and less "brittle."

The sanding yields a fine plastic powder (like flour!) with extra static cling. I prefer to do this step outside and with some kind of dust collection. Wear eye protection and a mask. Use a ratchet clamp on each end of the blank as a holder. Do each of the four edges in turn. The roundover doesn't have to be perfect, but pay attention to keeping it even. You don't want to tip the blank too much towards one or the other end.

I used to flip a hand belt sander upside-down in a Workmate workbench and clamp the shop vac hose next to it as I worked. Recently, my spouse got a 1 inch belt sander that is perfect for this job. It has a dust collection port.
 
I'll add a couple of things that have been helpful to me. I turn mostly "acrylic", and more technically the Rhino Plastic (polyester) blanks. I use a drill press to drill out the blanks and set the stop so that the bit stops short of the end of the blank. Once I have drilled to almost the bottom, its back over to the miter saw and I cut off the end to expose the hole. I have found (as many others) that sometimes when the bit exits the end of the blank, the flute of the bit can catch the edge of the bottom of the blank and you hear that dreaded crack signifying you are done with that blank. As others have noted, make sure you constantly pull the bit out to clean the flutes of the bit (I use compressed air) as many times the material will gum up on the bit rather than smoothly travel up the flutes and out of the top. When it gums up, it builds up pressure during drilling at the bottom of the blank and then you get the exploding blank.

After glue up with BSI epoxy (use what works for you as there are many good options), I use Rick Herrell's sanding jig for squaring the blanks on my lathe with a disc sander attachment. I used to use the barrell trimmers and had mixed results. I could go many blanks with no problems, and then for seemingly no reason, I would get a catch when squaring the blank and it would tear it up (wood and acrylic). Since I switched to Rick's system, I have done probably a couple hundred pens without a single failure in the blank squaring process.

As others have mentioned, I always sand off the corners on my disc sander and I even sand it down fairly round and get it closer to the final diameter. Make sure you are using good sandpaper as you want to cut off the material quickly, otherwise you will build up too much heat in blank and potentially weaken your tube to blank glue.

I use a round carbide cutter, although I want to try the negative rake sometime as well. I have found that if you put too much pressure with the cutter, you will get a power that comes off the blank and this is bad as you will notice the blank is very pitted vs. smooth. When you are applying the right pressure (light), you will have ribbons of material coming off which is good. I certainly messed up my share of blanks starting off, but with some practice, you can start to get a feel for it and consistently turn good blanks. Hope this helps...
 
Thanks to everyone with advice and words of encouragement. After reading everything several times I have remedied the problems I have been having. I think both me and my wife are allergic to the smell of acrylic and it permeates the house even though I do it in the garage. For that reason, I'll stick o more wood than anything else, but at least I know how to do it now. Once summer hits and the weather outside is good I may change my strategy, but for now (now that all the X-Mas presents are made) I will work with wood. Great learning process though with everyone's help! Cheers
 
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