Routing and Shaping, Turning, Drilling, Scraping, and Filing Acrylic sheet

Acrylic Sheet can be machined with standard woodworking routers, in much the same way as wood. You’ll find many uses for portable hand routers and small table routers. Use them to cut patterns into edges, or larger holes out of pieces of  acrylic sheet.
For best results, use single-fluted bits for inside circle routing, and double-fluted bits for edge routing.
Routers are designed to operate at high speeds. 10,000 to 20,000 rpm is recommended for acrylic sheet. And because routing speeds are so high, vibration must be scrupulously avoided. Even small vibrations can cause crazing and fractures in acrylic sheet during routing.

Turning

Turning is the only practical way to produce most rounded cross sectioned parts such as knobs, furniture legs, and vases. Acrylic sheet can be turned on almost any type lathe.

Bits designed especially for cutting acrylic are available. But most high-speed tool bits with a zero-degree, or slightly negative rake will work very well. It is essential that rake be maintained at 0° to -4° for satisfactory results. Clearance angles should be from 5° to 10°. Use a turning speed approximately 10 times faster than for wood. You should be bale to get a continuous ship from acrylic sheet.

 

Drilling

Any kind of hand or power drill may be used for drilling acrylic sheet. A stationary drill press is the preferred tool because it gives better control and greater accuracy. But a drill press won’t be applicable in all instances, and with a little care, proper technique, and a correctly-ground drill bit, you can get good results with an ordinary hand drill.

For best results, use drill designed specifically for acrylics.

Regular twist drills can be used, but the cutting edges must be modified to prevent the blade from grabbing and fracturing the plastic. Acrylic sheet is relatively soft. Your drill should have an edge that cuts with a scraping action. To obtain this you can modify your drill bit by grinding small “flats” onto both cutting edges with medium or fine-grit grinding wheel, or a pocket stone. The flats can be parallel to the length of the drill and about 1/32” (1 mm) wide. Tip angle should be between 60° and 90°.

For best possible finish inside the hole, use a drill with smooth, polished, slow spiral flutes which will clear the hole of all shavings without marring or melting the walls.

If the drill is correctly sharpened and operated by proper speed, two continuous spiral chips or ribbons will emerge from the hole.

When drilling a hole three times deeper than the diameter of the drill, a lubricant or coolant should be used. This will help remove chips, dissipate heat, and improve the finish of the hole. Rough, irregular, or fuzzy holes can lead to cracking and breaking months after the pieces has been completed.

 

Scraping
Many of the techniques used to cut acrylic sheet can leave a rough edge that is usually unsuitable either as a finished edge, or to join to another piece of acrylic. It is necessary to smooth and square the edge of the sheet. You can do this by a number of different techniques, depending on the finish desired.

The first step, and perhaps easiest technique, is scraping. A scraper can be most any piece of metal with a sharp, flat edge. The back of a hacksaw blade, the back of a knife blade, or a tool steel blank are ideal. Whatever tool you use must have a sharp, square edge.

 

Filing

It is easy to file acrylic sheet to a surface ready for final polishing. The filing, however, must be done correctly, and carefully.

Almost any commercial file can be used. But the quality of the finish will depend on your choice of file coarseness. A 10" to 12" (250 to 300 mm) smooth-cut file is recommended for filing edges, and removing tool marks. Other files-half round, rat tail, triangular files, and even small jewelers’ files are good for smoothing insides of holes, cutting grooves and notches, or finishing detail.

File in only one direction. Keep the teeth flat on the surface of the acrylic sheet, but let the file slide at an angle to prevent the teeth from cutting unwanted grooves in your work.

Always keep your files clean and sharp. Wire brush them often to prevent the teeth from filling up. And don’t use your acrylic files for working metal or other materials that might dull the teeth.

For small work, try clamping the file in a vise, and rubbing your work across the file.

Article Title:
Routing and Shaping, Turning, Drilling, Scraping, and Filing Acrylic sheet
Article Summary:
Information on Routing and Shaping, Turning, Drilling, Scraping, and Filing Acrylic
Article Date:
4/9/2009
Article ID:
580
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