Drilling Precision Holes in Acrylic

[jbolt]

I need to drill precision holes in 3mm to 12mm" thick acrylic. The holes range from 0.6mm to 3mm in 0.2 increments. Specialty drill bits for acrylic use 60 or 90 degree points with zero rake cutting angles. Standard point drill bits grab too much and chip the hole edges. They also do not produce clean interior surfaces so they won't work. The holes must have clean crisp edges. I have not been able to find any commercially available drill bits in these sizes. Unless someone has a suggestion for a source my other option is to regrind standard bits. In that case I would be looking for a reasonably priced tool or fixture that could grind those angles.

 

[mmcmdl]

Carbide circuit board drills may do it .

 

[mksj]

Problem will be the sizes, the are specific drills for acrylic called Plexi-Point is one, they come in assorted sizes but not that small and increment. A lettered set may be give close values to metric. Not a big fan of acrylic, cracks if you look at it crooked. The only other suggestion might be a CNC router. If manual you want a controlled feed and put an interface sheet on top of the acrylic sheet so it does not pull up and fracture. I think you may be better trying to make some straight flute cutters from drill rod.

Plastics Drilling: Drill Bits and router bits for plastic | Abbeon

Abbeon, Industrial Plastic Working Equipment & Precision Instruments. Abbeon Cal Inc,

www.abbeon.com

 

[darkzero]

I'm thinking those inexpensive used PCB drills too. Them 60° deg specialty drill bits for acrylic & plexi are stupid expensive. I also need to drill some acrylic but luckily I only need one size but I'm still not going to buy one of those drill bits.

 

[mksj]

Well there cheap so worth a try. They are both suitable for plastic, there are also metric burr sets used for engraving. At that size, I do not think you will have an issue with chipping once you dial in the speed and feed. Might try some liquid soap for lube.

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[pontiac428]

The old school way to drill acrylic is to blunt the cutting edges square with a grinder. Try for .010 or so of square face. Keeps the material from cracking. Not very scientific, but it's worth a shot if you have regular drills on hand already.

 

[royesses]

Maybe this will help?
Toms Techniques
How to Make a Twist Drill Safe for Use on Brass and Plastics:

Roy

 

[jbolt]

I think I will give the PCB drills a try. The holes are drilled on the lathe and the standard point drills chip mostly on the exit edge. If I can get the process down to where the parts can be made efficiently then I have an opportunity to make a lot of them.

 

[pontiac428]

Roy found it! I first learned that trick 30 years ago. Nothing worse than working a sheet of acrylic to shape, then ruining the part with a drill crack!