What sort of RPM for drilling small holes into plastic? (e.g. HIPS & PE)

[pgk pgkParticipant @pgkpgk17461]

Kirschner wires down to 0.9mm sharp pointed. Threaded pins down to 1.6mm from here: **LINK**

For finer threaded pins but unlikely as long as 30mm then a dental catalogue.. I had a quick look here **LINK**

But it seems they've updated the technology on apical posts. Schein have/used to have a vet section and that used to do long barbed broaches (for pulling pulp and nerves out of dog's teeth canals).. inherently they have a coarse thread… hand twist in and tug out with the rotting bits on them… much finer than 1mm at the tip and probably adaptable for an application like this as well as short fine screw studs (drill them in with a slow speed handpiece and once buried they self-snap off the insertion rod.

Back also to syringe needles.. I've used them as intramedullary pins in small bird legs and hamsters when either kirschner wires were too thick or out of stock.

[John Smith 47Participant @johnsmith47]

Posted by Jeff Dayman on 12/11/2015 15:00:49:

Is this a commercial venture, to build a prototype for a work activity?

Good luck on your search for self tap 1 x 30 mm screws (and good luck driving them without twisting them off). JD

It is currently amateur/self-funded/boot-strapped but yes, I am creating a functional prototype (not yet aesthetic) version of a prospective consumer product.

[Chris Evans 6Participant @chrisevans6]

When I worked as a toolmaker making injection moulds for plastic parts many mouldings where drilled after moulding.

The drills used where "Slow Helix" not regular jobber drills and run at around 1500 RPM to suit the ancient machinery in the finishing shop. For production use the drills where flash plated with hard chrome to prolong life, modern coatings will eliminate the plating need. Chris.

[John Smith 47Participant @johnsmith47]

Interesting. Roughly what diameter were the holes?

I guess the important thing is to get the cutting speed of the outside edge of the drill right and so the smaller the diameter of drill the faster in RPMs one needs to rotate the drill…

J

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