drilling perspex.

[mako]

I read in another thread that when drilling through perspex you should "put negative rake on the drill's cutting edges". Can someone explain what this means. Cheers.

[Dan]

This link probably explains it better than I could (has a pic too), go down to the section on dubbed drills.
http://www.mmsonline.com/articles/068901.html#fig5

[scooter]

Fantastic link, Dan, a really good analysis of the topic. Thanks

[munruben]

Thanks for the link Dan. Have filed that one away.

[Dan]

[arose62]

Having just blown out the bottoms of two acrylic pen blanks, despite having a brand-new sharp bit, and drilling slowly, and clearing the bit frequently, I googled "drilling acrylic".

Seems much like what you're looking for:
http://www.bertram31.com/proj/tips/drill_acrylic.htm
http://www.hawkfish.org/snailman/acrdrill.htm
http://www.sdplastics.com/acrylic.html

http://www.ultimatehandyman.co.uk/AC..._MACHINING.htm

I also wondered about using a masonry bit, as they seem to have zero rake...
Anyone tried that?

Cheers,
Andrew

[scooter]

Enjoyed reading the Drill Point Geometry article linked to above, here is another link to a longer version of the article, for others interested loike moi.


Cheers.................Sean