Best tool for cutting hard plastic component box.

[macabethiel]

I have a large hard plastic component box (11" x 7" x 3" approx) and need to cut out some rectangular holes to house a STC 1000 Thermostat plus holes for a twin mains socket and single mains socket in the lid.
This means some reasonably accurate hole cutting anyone any suggestions as best method ?

In the past I have drilled a series of holes and then filed it reasonably level or have used an old soldering iron to melt the plastic and then cut off the molten waste.

This is a bit long winded and not very accurate. Never used a Dremel is it worth buying one for this sort of application?
Any advice for best method?

[RJL Services]

i use a step drill bit ones that are coned shape on low speed

[Lazy-Ferret]

Personally, I find the Dremel a bit hard to use on plastic, If you use the cutting blades on slow spead, they just keep jamming up, and on higher speeds, it tends to melt the plastic, wrap it around the tool shaft, and then smear it along the edges of the cut, marking it up. Also, often the molten plastic just re-joins again, so you are going round and round.

I use a Weller soldering gun with a plastic cutting attachment, works, like the soldering iron, but a bit easier to work with. I always "Under cut", then use a scalpel to take out to size, shaving a small bit off at a time.

[macabethiel]

Originally Posted by Lazy-Ferret

Personally, I find the Dremel a bit hard to use on plastic, If you use the cutting blades on slow spead, they just keep jamming up, and on higher speeds, it tends to melt the plastic, wrap it around the tool shaft, and then smear it along the edges of the cut, marking it up. Also, often the molten plastic just re-joins again, so you are going round and round.

I use a Weller soldering gun with a plastic cutting attachment, works, like the soldering iron, but a bit easier to work with. I always "Under cut", then use a scalpel to take out to size, shaving a small bit off at a time.

Where did you get the cutting attachent from ?

[rayf3262]

Q Max or Greenlee chassis punches produce an accurate clean cut in metal or plastic.
http://en.m.wikipedia.org/wiki/Knockout_punch

[rustic]

Originally Posted by rambolane

i use a step drill bit ones that are coned shape on low speed

That's ok for round holes, but rectangular ones need this...

I recently cut a sheet of 5mm acrylic, or perspex, I used a multi-saw.
I wanted to fit some digital volt meters and ammeters into a panel.
Basically the blade vibrates at high speed, and the speed is variable.

I used a semi-circular blade, rested it on the surface and the blade did the work.
Take care in the corners. Practice on some scrap, very easy to control.
Mask the area with masking tape, and draw the cut line, and away you go.
You can even cut less than 5mm from an edge without breakout.

The multi-saw is the first tool I choose for any precision job.
I used the semi circular blade to cut clear plastic corrugated roofing sheet, no cracking, no chipping, brilliant. Minimum clean up too, if any, if the right speed is chosen, as not to melt the plastic.

I bought mine from Aldi a few years back.
Sinking in hinges and mortice locks a doddle with the straight blade.
You can trim timbers on a wall, without removing them.

What it is not good at... is cutting metal, but with the right blade, you can cut nails flush, or cut screws deep into timber, eg when dismantling a conservatory.


EDIT:-
The item below gives you an idea what the tool is, for reference, it is not the one I have, mine was much cheaper...


http://www.screwfix.com/p/bosch-gop2...XDKtAode20A3Q#
Best regards,

Rustic

[Lazy-Ferret]

Thanks for that reply Rustic, I have looked at those on several occations, but have never seen anyone using them, or heard anyone talk about them before, so dismissed them as a gimmick. I cut a lot of plastic, so I think I will look out for one now.

Originally Posted by macabethiel

Where did you get the cutting attachent from ?

My Weller one came with them, but they are available on Ebay, at my local motorfactor etc.

They are like this.

http://www.ebay.co.uk/itm/6110-Plast...item4ad82bc147

They also do a plastic welding tip as well, which is almost identical, just horizontal rather than vertical.

[rustic]

Originally Posted by Lazy-Ferret

Thanks for that reply Rustic, I have looked at those on several occations, but have never seen anyone using them, or heard anyone talk about them before, so dismissed them as a gimmick. I cut a lot of plastic, so I think I will look out for one...

I originally bought it for the scraper attachment.
Several of our double glazed units had misted, and they were held into the wooden frames with a wooden beading, which was nailed in place.
I placed the scraper blade between the bead and the glass, and the scraper seemed to melt the mastic, so I slipped it under the bead and then used a screw driver to lift the bead.

I removed the beads without breaking them, so I was able to re-use them, and I removed the double glazed units intact, without chipping or cracks.



I have also ground down one of the straight cutting blades, as I wanted to plunge cut a smaller hole.

If you get one, you will wonder how you managed without it, cutting plasterboard for sockets, less than a minute.

[Lazy-Ferret]

Result, I will keep an eye out of one at a good price.

I have the Bosch power scrapper/chisel, used it to get the cork tiles up off of the landing, and removing tiles in the downstairs bathroom, but it goes back and forward rather than side to side. I have to keep repairing it, as it vibrates so much, it cracks the solder joints where they join onto the motor windings.

[kitchenman]

I got the Aldi recahargable one, paid for itself first job.

To make decent round holes get a starrett type cutter, Aldi did a set recently for around a tenner

On plastic use the cordless drill on minimum speed to avoid the melting mentioned above.

[Terranical]

How about an electric jigsaw or a fretsaw?.