Drilling through acrylic hatch

[justapheonix]

I need to drill through the hard (acrylic?) washboard on my yacht. Having never drilled acrylic before, I'm concerned that it may shatter or crack on drilling.

I'd be grateful for advice about bits, drill speed, lubricant, pressure, etc...

 

[squidge]

sharp HSS drill , pilot hole first ,not much pressure take your time, Not fast as you will melt it. Beware that it might grap the drill if not carefull.
Regards

 

[chippysmith]

Ideally you want to grind back the cutting edges to introduce a negative rake. Easiest way is on bench grinder but can be done with a metal cutting wheel or an angle grinder. Touch the cutting edge onto the wheel to basically blunten the drill. Difficult to explain, will try and find a picture for you. This will prevent the drill bit grabbing

 

[chippysmith]

Cannot find a picture but this C&P better explains the procedure..

Regular twist drills can be used, but the cutting edges must be modified to prevent the blade from grabbing and fracturing the plastic. Polycast 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 a 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" wide. Tip angle should be between 60 and 90°.

 

[30boat]

This is what you need.
Use a wooden pad underneath.

 

[Norman_E]

IMHO those are not suitable for acrylic. As others have said, an ordinary twist drill is correct, but needs the edges correcting. I would not even attempt to put the negative rake on the edges with a grinder as it is far too difficult unless you have something like a Quorn Tool and Cutter Grinder. Instead use a fine oil-stone to produce a very small flat on each cutting edge.

 

[Spuddy]

I agree about modding the cutting angle at the tip - a few strokes with an oilstone should do it. This then makes the drill even more prone to skidding about but fear not - stick some masking tape on the acrylic and mark then drill through it

 

[RIMCOas01]

Use a bit suitable for ceramic tiles, it worked for me ... but maybe I was just lucky ?