Sunday, January 17, 2010

Flame Polishing Plexiglass

Drilling Plexiglass, How To Drill Plexiglass

 One of the common plastic fabrication questions we get is how to drill plexiglass (acrylic) and not chip it or crack it. Tooling and technique. There are specially made bits for drilling  plexiglass sheet. The most obvious difference is the tip angle, see the attached photo. There are many other differences in the plexiglass drill bit geometry over standard drills. If you want to try to grind your own, check out the fabrication manuals link. There is a manual on drilling that breaks down the geometry. For the rest of us, just buy a plexiglass drill, they're cheap. Onsrud is a top manufacturer of plastic tooling. They make great tooling for plexiglass (acrylic) and most other types of plastics and composites and you can buy online.
 Once you have the proper acrylic drill bit it's pretty simple. When possible try to clamp the sheet firmly and backup the piece being drilled with a piece of scrape plexiglass sheet or mdf. This helps prevent chipping or blowing out the hole when you penetrate the back side. At this point drilling the plexiglass sheet is easy.  Go slow starting your hole and when breaking through the backside. On thicker plexiglass sheets, do peck drilling to remove the chips and cool the drill. If you are having melting problems try blasting compressed air at the point of drilling. You can also use wax, mineral oil or some other lubricant that is plastic safe. Good luck!

Friday, October 23, 2009

Cutting Acrylic, Cutting Plexiglass - Table Routing

Part 3
Using a table router is one of the best methods for cutting acrylic sheet. It’s also a much more versatile method for cutting and generally produces good edge quality. There’s a video on this blog of someone using a table router to trim some acrylic parts. The router bit he’s using has a bearing on it that rides against the part while the excess is trimmed away. This method also works great for cutting when you already have a template of the shape you want to cut. Use double sided tape to secure your template to the acrylic sheet and cut your part. For straight cuts, set up a fence to ensure straight line cutting. Table routers are wonderful for doing edge details such as beveling and bullnosing. Router bits for wood work just fine for plexiglass or acrylic sheet. Cutting is done in the conventional direction, that is, the blade is turning towards the material feed. Just like when cutting acrylic with a saw, use a sharp tool. Don’t use a bit you have been using to cut wood and expect a great edge quality. Larger diameter bits (1/2”) produce better cut quality than smaller diameters. The general rule is to run as high an rpm as possible, however on bits with a diameter over 1” always check what the manufacturer recommends. And never forget to practice good safety.

Thursday, August 20, 2009

Cutting Plexiglass, Cutting Acrylic Sheet - Saw Cutting

Part 2
In Part 1 we gave a light overview of cutting Acrylic or Plexiglass, in this part we are going to take a closer look at cutting Acrylic with a table saw. In general, the better the tooling, equipment and technique... the better the results.
There are a few things we should cover as far as the saw itself. Your saw should be rigid and free of vibrations(vibration = chipping). This also includes the throat plate and fence. The throat plate should have a minimal kerf opening to minimize chipping. The fence, solidly mounted and as parallel as possible to the blade. One of the most common reasons for chipping is the blade and fence not being properly aligned.
Equally as important if not more is your blade. I could write a book on just saw blades, there is so much to them. The most common configuration for cutting Acrylic is a carbide tipped triple chip blade. Acrylic blades are very similar to wood blades. The most obvious difference is the rake angle or hook of the teeth. Wood blades usually have a few degree negative rake angle, while Acrylic blades have a positive rake. The general rule is about a 10 degree hook with a 10 to 15 degree clearance angle. You want to keep your blade kerf to a minimum. If you want really great results, get a blade from a manufacturer that specializes in plastic blades. They use a harder grade of carbide and grind them with a finer grit then a wood or metal blade manufacturer would. The end result is a sharper blade giving better edge quality with less chipping and melting.
Part 3: Table Routing Acrylic/ Plexiglass

Thursday, August 6, 2009

How to Cut Plexiglass, How to Cut Acrylic

Part 1
Let's just get this out of the way first... What's the difference between Plexiglass and Acrylic? Nothing, it's the same thing, Plexiglass is the common name for Acrylic. Paper or film masking? Depends on your application, I prefer film because most plastic sheet manufacturer's film masking is specially made to work as a cutting lubricant.
We are often asked what is the best method to cut Plexiglass(Acrylic). For us, that's easy. We walk over to one of our state of the art computerized saws that is equipped with a high precision top of the line Acrylic blade. Perfect results. For the normal do it yourselfer the best answer is... it depends on what tools you have available to you and what you are trying to do. On the right is a link, Plastic Fabrication Manuals. On that page are a collection of fabrication manuals from different plastic sheet manufacturers. That's a great place to start. They cover cutting, drilling, bending, polishing and much more. Also on the right are a few videos, we'll try to keep adding more. I hear many people say they have had great results using a Dremel, I have never had that much luck. For a Dremel, your project needs to be small and you need to have a great deal of patience.
The most common tools to achieve the best results are either a table saw or table router. Using a table router generally produces better edge quality. Meaning less work if you plan to polish the edges. Don't get me wrong, a table saw can produce a great cut as well. One of the things to keep in mind is to use a very sharp blade or bit and a nice smooth steady feed. Allow the saw or router to freely cut the Plexiglass, don't try to force the material into the blade. You can tell by the sound. If you force it, you are generating heat and now melting the Acrylic instead of cutting it. Remember, sharp blade and smooth feed.
Part 2: Saw Cutting Acrylic/ Plexiglass
Part 3: Table Routing Arcylic/ Plexiglass