Top Tips For Using Polyester And Acrylics

Monday 9 July 2018

Sue Harker and Walter Hall discuss their top hints and tips for using polyester and acrylics effectively

Tip 1: be gentle

A very gentle approach is needed to keep chipping to a minimum. Using a bevel supported cut with a spindle gouge, bowl gouge, spindle roughing gouge etc. the material is more likely to chip. If you take very light cuts, when parting off or creating a chucking spigot, chipping can be minimised

Tip 2: Use a negative-rake scraper

A negative-rake scraper produces the cleanest chip-free finish followed closely by a skew chisel used as a scraper. A regular scraper has a tendency to create small chips. (See issue 212 of Woodturning for tips on how to use scrapers effectively)

Tip 3: Use a fingernail profile spindle gouge

A fingernail profile spindle gouge presented with the flute closed – cutting on the lower wing – produces an easily controlled shearing cut. The finish from the tool is very clean – notice here how fine the shavings are

Tip 4: Stop the lathe before removing acrylic shavings

With the lathe running at approximately 1,800rpm, and using a sharp tool the shavings peel off like streamers which accumulate around the turning, chuck and tail drive. Stop the lathe to remove these strands – this will avoid your turning tool from being caught up in them. Don't be tempted to remove them whilst the lathe is rotating

Tip 5: Withdraw the tool regularly

When parting off a section, for example, to make a lid, withdraw the tool regularly to clear away the shavings – this will prevent them from clogging up

Tip 6: Use a fingernail profile spindle gouge for hollowing

When hollowing down the centre of a vessel, using a fingernail profile spindle gouge, it is important to take very light pull cuts and clean out the shavings after each cut. The shavings come out with the tool when it is withdrawn. Doing this will avoid the tool from becoming caught in the shavings and will create a cleaner cut. A straight scraper can also work well

Tip 7: Undercut the piece using an offset tip scraper

Hollowing can be done with any offset scraper that allows you to gain access to the vessel you are working on. However, the shavings begin to clog up inside the vessel so regular stops are required to remove them

Tip 8: Start sanding at 320 grit

If the finish from the tool is smooth and chip-free sanding can start at 320 grit working through 400, 600, 800 and finishing with 1,200 grit. The abrasive clogs quickly so keep moving to a clean piece. You can also use water, oil or wax as a lubricant

Tip 9: Buff with burnishing cream

A very clean, shiny finish can be achieved by sanding to 1,200 grit; however, a buff with burnishing cream, or a power buffing mop loaded with micro abrasive brings out an even deeper shine

Tip 10: Make a jam chuck from timber

When remounting acrylic or polyester resin, for finishing the underneath, jam chucking to another piece of acrylic or polyester resin isn't always very successful. This is because the surfaces are so smooth and rigid, and therefore they have a tendency to slip. Cutting jam chucks out of timber provides a better grip

Tip 11: Keep your tools sharp

Keep all your tools sharp and well honed. Acrylic can chip and shatter if you use tools that have lost their edge

Tip 12: Use your best tool technique

Take care to use your best tool technique: engage the tool on the rest, rub the bevel and slowly lift until cutting starts every time. Acrylics are unforgiving of careless cutting

Take light cuts

Take light cuts and use a moderate lathe speed. Too aggressive with either will give a poor quality finish and can even cause the work to shatter

Tip 14: Drill at a slow speed

Acrylics drill well, but use a slow speed – overheating can cause the acrylic to shatter or even melt

Tip 15: Drill just short of break through the hole

If drilling a hole right through a piece of acrylic, as with a pen blank, for example, leave the blank a little over length, drill just short of breaking through and then cut the blank back to length -this will avoid breakout and leave a clean hole

Tip 16: Use Micromesh abrasive

Acrylic can be brought to a very high polish. As well as burnishing them, I find that one of the best ways to achieve this is to wet sand with Micromesh abrasive and then polish with metal polish or the paste used to polish scratches out of motorcycle helmet visors

Tip 17: Do not sand at too high a lathe speed

When sanding, do not use too high a lathe speed. The abrasive will cut better, and you will not overheat the material