- 1Basic Scientific Information About Acrylic
- 2Acrylic In The World
- 3Basic Characteristics of Pen Blank Acrylic
- 4Unique Creations Using Acrylic
- 5My Experience Turning Acrylic
- 6My Experience Cutting and Drilling Acrylic
- 7Special Considerations When Using Acrylic
- 8Turning Speed for Acrylic
- 9Tools For Turning Acrylic
- 10Advice For Turning Acrylic
- 11Finishing Acrylic
- 12Final Thoughts About Acrylic
Basic Scientific Information About Acrylic
An increasingly common material used to make custom pens is a type of plastic called acrylic. Scientifically speaking, the acrylic used to make pens is poly(methyl methacrylate) (PMMA) or poly(methyl 2-methylpropenoate) which is a transparent thermoplastic. Chemically, (C5O2H8)n, it is the synthetic polymer of methyl methacrylate.
Acrylic In The World
You are probably familiar with acrylic since it is widely distributed throughout the modern world. You may have encountered or seen it used as anything from material to make lightweight aquariums, other uses as a replacement for glass (it is stronger and much lighter than glass with a greater optical clarity), visors and safety glasses, shower doors, medical implants as bone replacement material, dentures, fillings, as a component in paint, in molded outdoor furniture, and even as artificial and artistic fingernails. The material is amazingly diverse and in one form or another, most all of us are familiar with it, even if we didn’t know what it was called.
Basic Characteristics of Pen Blank Acrylic
For sake of convenience, pen makers refer to this material, and others like it, in a lump group called acrylics. In its native state, the material is crystal clear so it lends itself to any type of fanciful coloration that one can think of. The use of acrylics allows a pen maker to create items in color possibilities well outside of what would be possible with wood alone. The material is available from a wide variety of sources and each source often has its own color and design palate. Because of this, there are literally hundreds, if not thousands, of color and style possibilities available.
Unique Creations Using Acrylic
An added benefit of acrylic is that pen makers can cast their own blanks in their shops with some simple chemical ingredients. Practically any object with a low enough profile can be cast in the clear resin and turned down to pen size. For example, flower petals, small sea shells, stamps, and even computer circuitry can be glued to a pen tube, cast into acrylic resin, and then turned to shape and size. The only limitation is the size of the starting material and the imagination of the turner.
My Experience Turning Acrylic
Some sources claim that acrylic is as easy to turn as wood. In my experience, nothing could be further from the truth! Acrylic is considerable harder and more brittle that most any wood, meaning that sharp tools and patience are critical to success. Remember that, regardless of what you call it, you are working with a plastic, and turning creates friction, meaning heat, and heat + plastic equals melting. Trust me, I know the heartbreak of turning a beautiful acrylic piece, only to see it melt from too much frictional pressure during final sanding. Use a very light touch.
Also, I find that the shavings from the acrylic tend to come off in long strings that wrap themselves endlessly around mandrels or bits, forcing me to stop repeatedly to clear the work area. And then there is the smell of the hot material which is less than pleasant and highly lingering.
But despite all of that, acrylic still offers design possibilities that are impossible to obtain any other way. After much trial and error, I have learned to make some peace with it.
My Experience Cutting and Drilling Acrylic
Acrylic cuts easily without any special process. When drilling, be patient and use a specialty drill bit like a Colt to make your life easier. The Colt Company claims you can drill 5-6 inches through acrylic with no pull-back and while I have pulled that off, it isn’t 100% assured. Be patient and allow the material to cool a bit in drilling to prevent melting or breakage.
Special Considerations When Using Acrylic
Because acrylic has a higher optical clarity than even glass, acrylics that are light in color do allow the internal brass tube to show though, ruining the beauty of the blank. Some companies sell tubes made of chrome to help with this problem, but usually not in all the sizes you will want and some companies also sell pre-painted white or black brass tubes to use with lighter, or darker, blanks respectively. But again, these painted tubes are usually not available in all sizes you might want. And a premium price is charged.
My solution has been to spray paint my own standard brass tubes either white or black using economy spray paint that cost 99 cents a can. That represents a huge bargain! On lighter colors the white increases reflectivity whereas with darker colors the black intensifies the color effect. Painted tubes certainly are tops over having the shiny brass ruin your effect.
Being somewhat compulsive, I also have the ability to use standard bulk liquid white paint, purchased easily by the pint, quart or even gallon and then tinting a small amount with custom tints made by Mixol. I then use small artist brushes to paint the tube as close as I can get to the exact shade of hot pink or lavender I need for a pen certain to please my niece. The tints from Mixol can be purchased in a set that includes a color mixing and intensity chart that you will likely find useful. This kit is readily available from Woodcraft.
Turning Speed for Acrylic
When turning acrylic, some recommend a slower speed and others say to turn at the same speed as you would wood, but then there is no consensus that I have found about what speed to turn wood pen blanks at! I use 1,800 RPMs for wood and while I have lowered the speed to as little as 800 or 1,200, I don’t find much difference once you are used to the material, and sometimes the lower speeds just add frustration. Try different, preferably lower, speeds to see what works for you. Lower speed can help reduce frictional heat and melting, but so does a light touch and patience at higher, more wood-typical, speeds.
Tools For Turning Acrylic
I use the same primary tool for turning acrylic, a very sharp oval skew chisel, as I do for turning wood, but I do use my belt sander, instead of the roughing gouge I use on wood blanks, to take off the sharp 90 degree angles on the corners of the cubic blank before mounting on the lathe. Acrylic blanks are comparatively pricey and it bites to have one break immediately when your tool hits the corner. Smoothing those edges down has been key to my success.
Advice For Turning Acrylic
You will need to use more pressure when turning acrylic than you do with wood, but be cautious about heat and melting. Feel your tool and your acrylic blank (once it is round enough to do so if moving, otherwise turn off the lathe of course!) and when you start to feel heat, slow down. Once you get it to shape and size, you are still not out of the woods. If you are adept with a skew chisel, you shouldn’t need to start sanding at much below 320 grit, and even that will rough the surface beyond what you have achieved with the skew. But for final shaping or touch up of rough spots, it works well. Don’t despair if there are rough spots or chips, that happens fairly often in my experience, just sand them out, but use a LIGHT TOUCH, don’t put pressure that will generate enough heat, only about 250 degrees F, to melt the acrylic blank. Remember, a moving lathe generates massive amounts of friction on the plastic blank. For particularly rough spots, try sanding just by hand with the lathe off.
To finish the acrylic piece, I sand down all the way through the equivalent of 12,000 grit using sanding kits made for finishing plastics, acrylic, and Corian. This will create an amazingly smooth and reflective surface you won’t believe the first time you try it. Your piece will look pretty sad even at 600 to 800 grit sandpaper, but the micro sanding really polishes it out.
Finally, I finish with HUT Poly Gem, a finish made for plastics. I apply it with only manual lathe rotation using a cotton rag, then I turn up the lathe to its top speed to do the final buff polish and shine. Again, take care to avoid applying pressure (you don’t need it) and don’t let that rag get caught up on the spinning mandrel (yes, I have had it happen). The friction from the caught material will burn and melt your previously flawless blank!
Final Thoughts About Acrylic
From my perspective acrylic is a royal pain and I frequently find myself using some colorful language when working with it. BUT, you simply can’t beat the diversity of effect you can achieve when you make your peace with it. PATIENCE is the ultimate watchword for working with the material, and as you learn to work it, I would recommend finding some blanks on sale somewhere regardless of whether you like the colors or patterns or not. You will break and destroy some blanks until you get used to it and better to find something affordable for that process. Perhaps you will love working with the material and will make it a primary type you keep around. As for me, I always get at least two blanks of any one color or design, just in case disaster strikes in the process of working with it!