Tips for Working with AcryliwoodTM and Dymondwood®
While AcryliWood (Resin Stabilized Wood) and Dymondwood are entirely different products, they have in common a high polymer content. Therefore working techniques are quite similar. Suggested techniques apply to both unless indicated otherwise.
In general both products are harder than most natural woods. Dymondwood is manufactured in a high tonnage press, and is the hardest and most rigid of the two products.
Dymondwood® Material properties:
Specific Gravity: 1.06 to 1.16 (measured from 2011 stock)
Density: 0.61 to 0.67 oz per cubic inch (measured from 2011 stock)
29 veneers per inch average
AcryliwWood Material properties:
Specific Gravity: .95 to 1.07
Density: 0..55 to 0.62 oz per cubic inch
When sawing AcryliWood and Dymondwood, use fine tooth blades. I have a strong preference for cutting with a bandsaw versus a tablesaw because a bandsaw is inherently safer. A 6 to 10 tpi bandsaw blade will provide the smoothest cut. We use a 4 TPI carbide tipped bandsaw blade equipped with special guides for production. If you do use a tablesaw do not attempt to use a standard ripping blade. In general, blades more coarse than 3 tpi will produce unsatisfactory chipping and splintering.
If you cut these materials only occasionly you can get away with high speed steel. But bimetal is better, and carbide tipped is by far the best. Harder and thicker materials are more likely to cause the blade to wander and cut crooked. With a bandsaw wider blades and proper guide setup are key to producing a straight cut.
When sawing Dymondwood saw with the layers parallel to the table. If you saw with the layers perpendicular to the table, there is a chance the last couple of layers will chip off near the end of the cut. This holds true for many types of wood. If you must cut perpendicular to the grain, use minimal pressure within the last 1/2″ of the cut.
Turners who attempt to drill Dymondwood with the same techniques they use on standard wood will often experience problems with overheated and cracked blanks. A few simple changes in technique will virtually eliminate problems with blowout and cracked blanks. Most of the calls we receive are from turners new to Dymondwood who haven’t yet developed a feel for the material. AcryliWood properties will vary with species.
Brad Point, Pilot Point, or Parabolic drill bits are often recommended for drilling Dymondwood and AcryliWood . Standard jobber bits will work in a pinch, but are not recommended. Every bit has its advantages and disadvantages. Brad Point bits are available in carbide; the big advantage is that you will spend less time sharpening drill bits. Pilot point bits work very well, but to my knowledge aren’t available in carbide. Many crafters prefer parabolic bits, but I haven’t tried them. I use a Carbide Brad Point.
Always use a backup blank underneath the blank when drilling. It will reduce the chance of “blowouts” drilling through a blank. You can also leave the section to be drilled about a 1/4″ too long. Small chips on the exit side of the hole can be trimmed away when the section is cut to the exact length.
For pen blanks use a drilling jig that supports the entire length of the blank. If you don’t have a jig that fully supports the blank trying wrapping the blank in tape before drilling. Electrical tape works well. This technique will provide some support to the blank. If the blank does crack, the tape will hold chips in place, giving you the opportunity to repair with CA glue.
Whatever drill bit you use, run your drill at medium to slow speed, keep your drill bit sharp and use light downward force while drilling. As you develop a feel for the material you may want to try increasing drill speed. With some experience most crafters develop a feel for the physical limits of the material.
Back out the drill bit frequently to clear chips and allow the blank to cool. If excessive heat and force are used, Dymondwood blanks can chip, crack or scorch. If chips are not cleared excessive side pressures may crack the blank.
If you hear or feel a small “pop” during drilling, you’ve probably cracked the blank. This is usually a result of excessive drilling force or compacted chips in the drill flutes. See Gluing below.
If you are experiencing problems with excess heat buildup you can use water as a coolant. I personally do not find this technique necessary. But it will work if excess heat buildup is a problem for you. Drilling speed can be increased if water is used as a coolant/lubricant. Water also works great for reducing airborne sawdust and increases the life of your drill bit. Use a squirt bottle with a fine stream is to squirt water into the hole every few seconds while the drill bit is retracted. Use enough water so that debris come out as slurry. Do not let the drill bit tip run dry. Drilling speed can be increased substantially by using this technique. If you create large amounts of steam (when using water), you know your speed is too high (or your bit is too dull). All the energy being absorbed by the steam (heat of vaporization) would have been baking your blank and annealing your drill bit!
Gluing and Repairing
AcryliWood and Dymondwood can be bonded to itself and other materials with Cyanoacrylate (CA) adhesives and most epoxies. Polyeurethane adhesives also work. I generally would not recommend wood glues.
Small nicks or chips can be repaired by filling with a fine matching sanding dust and wetting with thin CA glue.
Tight hairline cracks repair easily with super thin CA. Allow the CA to wick into the crack for a few seconds and lightly clamp (if necess ary) until dry.
Epoxies work well for bonding AcryliWood and Dymondwood sanded surfaces to itself and other materials (metals, glass, other glueable plastics.
Turning and Carving
Always use very sharp lathe turning tools. Don’t try to get too deep with your cuts. Due to its hardness and brittleness, Dymondwood can chip or crack. Dymondwood is similar in machining properties to Ebony. AcryliWood is generally easier to cut than Dymondwood because it has not been compressed.
CNC operators often run into trouble if they attempt to run a program previously used for softer natural woods. Chipping and cracking issues are generally eliminated by reducing the depth of cut and/or feed rate.
Both products can be carved with Dremel type rotary cutting tools. Carbide and diamond points work well.
Sanding and Polishing
I find Dymondwood and Acryliwood much easier to sand than most regular woods. Since it has very low water absorption, it wet sands wonderfully.
I sand with wet or dry sandpaper beginning with 120 and progressing to 220, 320, 600, and at least 1200 grit. I sometimes continue with 1500 and 2000 grit. For a finish that will pass the “Magnifying Glass Test” some crafters also wet sand with 4000, 8000, 12,000, and 20,000 grit Micro-Mesh™ Cushioned Abrasives.
At this point I should mention a technique to remove small material defects. Acryliwood and to a lesser degree Dymondwoodmay have tiny surface voids that become visible to a sharp eye after sanding to about 220 grit. I routinely wet sand with CA at this point to remove these defects. This is not a CA finish, but rather a means of producing a uniform base to continue sanding throught finer grits. I wear eye protection and disposable nitrile gloves when performing this step. It is a good idea to have CA release agent within arms reach. Gluing yourself to your lathe is a very real possibility if you aren’t careful!
The technique I use is to stop the lathe and apply 2 or 3 drops of CA to the piece. Don’t use so much that you glue the work to the mandrel or the bushings. I place 220 grit sandpaper over the work and turn on the lathe. Quickly sand with a back and forth motion until the CA is dry. Repeat as necessary until blemishes are gone. Don’t try to do over an inch or so at a time. Be prepared to go through quite a bit of sandpaper as it loads up quickly. Then continue normal sanding through progressively finer grits.
For most work I switch to plastic polish after sanding with 1200 grit. The plastic polish is issentially buffing compound in a liquid form. There are several good plastic polishes on the market. We use Novus #2 and #1 cleaner. Don’t ask me why, but you use #2 first, then #1. Automotive polishing compounds will also work in a pinch. When the polish is applied a high gloss finish will begin to appear within seconds.
While not completely necessary I like to finish with a couple of coats of lacquer based friction polish. I prefer a high gloss lacquer based product over shellac based or wax because it is more durable. The friction polish will even out the gloss and achieve a higher gloss than possible without. Note that friction polish is a misnomer, it is actually a finish leaving a very thin material film, not just a polish or buffing agent.
Notes just for Pen makers
A gap filling adhesive is highly recommended for gluing pen tubes. A foaming polyurethane glue is a good choice. Many turners like to use thin CA, but we have heard more reports of cracks and splintering during turning. A gap filling adhesive doesn’t leave un-bonded high spots inside the blank drill hole like thin CA will often do.
When using a blank end mill, use a cutter slightly smaller in diameter than the width of the blank. An oversized cutter is much more likely to chip or break the end of the blank.
Many turners save time by plugging the tube ends before gluing. Some of the materials I have seen used are Play-Doh and raw potato. A non-greasy material is important.
Standard pen blanks are intended for 7mm and 8mm (if you drill straight) holes. You’ll need jumbo blanks for 10mm holes.
Northern Lights Pen Blanks: These blanks are unusual in that they do not harden when stabilized like most other woods. The trick to these blanks is turning them without developing cracks. The method that has worked best is to stop occasionally during turning and wet the blanks with CA glue. It will harden the surface and penetrate any small cracks before they get out of hand. Use the CA again before sanding to provide a harder uniform density surface.