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

"Leaving it in" raises interesting possibilities. I mean one could potentially forget the glue completely and just melt one's way in - you'd barely need a point at all, just a lot of speed. If I work fast the heat should stay localized.

But wait... a tiny screw ended pin that you leave in... Isn't that called a self tapping screw?

In which case I'd just need to find a very long (20 or 30mm) but thin (1mm) one! Any suggestions as to where to get such a thing? Might be useful in a variety of other places for me...

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

Thanks JohnW1 - that Titan is amazing value for money at just £80. As you say particularly useful is the depth stop and ability to tilt the axis of the table. Plus the rotational speed would make more sense for styrene cutting (280-2350rpm). I hate to think what a Proxxon / Micromot equivalent would cost!

Right now I don't really have the space for such bulky kit, plus having just bought a Proxxon mini drill (Micromot 50/EF) I am starting to run short of £ !

But definitely something for thinking about in the future...

Comes back to turning the drill by hand

You may also want to look at slow helix drills which are better suited to plastics and soft materials if you are going to be doing a lot of this.

What about heating your needle to red hot and just plunging into the two pieces of material, as it cools the molten plastic will bond the needle into the two and as heat welding is the usual way to joint PP you should get a good bond

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.

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.

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.

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