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Thread: Cutting holes in thick uPVC pipe caps
face BY : Philip Pemberton email (remove spam text)

On 11/02/11 13:49, Carl Denk wrote:
> First I would suggest a hole saw, they are inexpensive,  don't require a
> huge drill to drive it, make a fairly neat hole, and are available in
> 1/16" (1.6 mm) increments.

Well, I picked up two hole-saw kits -- a £10 one from Maplin, and a £15 one from B&Q.

The B&Q one is exactly the same as the "monkey-metal" one I rubbished earlier: a setscrew holding a drill bit in the middle of a metal holder. It sort-of works, but if the saw blade locks up while the drill bit continues spinning, it might (probably will) damage the drill bit.

The Maplin one is a little nicer. The saw blades are solid units -- you pick a blade, attach it to the drill bit via a mounting block, which uses an Allen bolt to hold the drill bit in place. The coupler (which goes into the drill chuck) has a few flat edges, apparently to make it easier for a 3-jaw chuck to grip. Similar idea, but the drill bit is more likely to stick in this case -- but even so, once the drill bit is through, it's not a big deal.

Unfortunately my POS cordless drill decided to play silly devils. The battery won't hold a charge, and because it's a noname POS, you can't get replacements. That'll teach me to buy no-name kit...

Solution: another new toy. A Bosch PSR 18 LI-2. Feels like it was built to hammer nails, fast charge battery, and apparently you can buy everything from case components to the motor, gearbox, switches and the even the speed controller module as a spare part...
Wish I'd bought it from Amazon (about £60 cheaper than B&Q) but I wanted it today, and paid the price... It's still worth £160, IMO.

> No matter which method, drill briefly and allow material and cutter to
> cool, and if possible a coolant. If the material melts, a rougher hole
> happens, and possible to seize tool in hole.

That's pretty much par for the course when cutting/drilling any type of plastic. "Go slowly!"

I still ended up using a set of files to clean up the hole (and the Dremel to cut off a few bits for the lens mount), but it went pretty well. Just need to give the plastic a good clean and apply a bit of black Milliput putty to get rid of a few light leaks.

> 3rd, with dremel, use a 1/8" dia. cutter used to cut wood and drywall
> like Dremel #560, 561, or Rotozip cutters.

I went looking for the Dremel round-cutter while I was at B&Q -- but not a Dremel tool to be seen. Spent a good 15-20 minutes perusing the "electric tools" aisle, to no avail.

> Here again material needs to
> be kept cool. A template that the chuck or smooth part of bit rides on
> will be helpful, these bits like to wander.

In my experience all drill bits like to wander unless you're using a drill press...

Plasterboard bits can usually be persuaded into running straight using a bit of masking tape arranged in an "X" over the desired location, and a small hole (made with a bradawl) in the middle. An automatic centre punch works great on aluminium and other soft metals. It's been a while since I've tried the masking-tape trick on plastic, though IIRC it didn't work too well.

> If drilling multiple holes in a circle, start with smaller pilot holes,
> then using progressively larger bits, say start with 1/8" and stop at
> 1/4". In plastic, if the drill gets near an adjacent hole, it might try
> to walk into the next hole, then it gets messy.

And yet... I didn't think of that. A bunch of 3mm holes joined up with a carbide router bit would have worked pretty well...

(... and it's at this point I start re-reading the "panel building" section of Steve Kasten's book, and all the old EPE "Techniques: Actually Doing It!" columns by R. A. Penfold...)

-- Phil.
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