How do I cut a plastic box without shattering the plastic?

[OM2]

I need to cut into a plastic box.

I've marked where I need to cut. See this pic:

I started cutting with a jigsaw drill. Not the tool for this job for many reasons!
Really hard to control + dangerous!

The scratches you might be able to see are attempts at me trying to score using an etcher I had. I also tried using a weak stanley knife. Both failed miserably.

It's really important I can keep the bottom lip and the structure of the box if possible.

Hoping someone has a suggestion.

On another box I tried, the plastic shattered and I ended up having to use duct tape to secure. Totally messed up!

Thanks

 

[thomp1983]

Drill a small hole in each corner of your markings then use a small cutting disc in a dremel

 

[big-all]

yes my thought as above dremil type tool or very very fine [junior hacksaw] type tooth set
or even try on wasted bit off plastic with a metal cutting blade in a jigsaw

 

[Koolpc]

Multi tool..

 

[Deleted member 174758]

Drill corner holes then use a fine cut hand saw (e.g. junior hacksaw, fine tooth dovetail or tenon saw, pad saw, etc). Corners can be tidied up with a metal file.

Any reciprocating saw such as a jig saw or a multitool will potentially cause the plastic to vibrate roo much which is not good.

Dremel with a grinding disc will also work well, as will a RotoZip (or similar). Depending on size a hole saw could be used to take out the centre before squaring the corners with a saw or file

 

[Odds]

Is it a hard or a soft plastic?
I ask to see how the box should be supported when the hole is drilled - would a small piece of tape help to make sure the drill bit doesn't slip?

 

[Notch7]

1) stick a bit of small batten either side to stop the 2 single layers of plastic vibrating

2) drill small hole in corners

3) use coping saw or fret was with fine blade across bottom

4) junior hacksaw or coping saw down sides

5) have cup of tea to celebrate

 

[Harry Bloomfield]

A hot wire cutter is absolutely the best way to cut plastics. That type of plastic from which the box is made from, is quite fragile and will easily shatter. Cutting that lip, will really weaken it.

 

[Odds]

A hot wire cutter is absolutely the best way to cut plastics. That type of plastic from which the box is made from, is quite fragile and will easily shatter. Cutting that lip, will really weaken it.

How would the heat affect the plastic?

 

[foxhole]

Heat is best method as the resulting seam of melted plastic is stronger than original , simple soldering iron would work .
Or screwdriver heated over the stove if you don’t have SI.

 

[Harry Bloomfield]

How would the heat affect the plastic?

The melted edge, would help reinforce it, and prevent it shattering.

 

[Odds]

The melted edge, would help reinforce it, and prevent it shattering.

Okay, but would the heat scar the surrounding area if too much pressure is applied?

 

[OM2]

Thanks for the awesome replies.

The starting point for me is to drill holes.
@Odds the plastic is tough on the rim compared to the rest of the box.

Then a saw I guess.
+ sanding.

Heat seems a good option - but would like to keep smooth edges.

After cutting: the structure is compromised yes... but the box will have a lid on when used.
Given that, just wondering if it's worth keeping the lip? Not worrying about the lip makes everything easier.

One problem I found using the (dangerous) jigsaw cutter is that cutting the first line down is OK.
But when cutting the second line, that becomes difficult and the whole plastic is juddering as there is support - was thinking of using duct tape temporarily?

Saw or blade: can someone show me a pic of what I might use?
Don't have a Dremel. I'll consider investing in if I can make using manual sawing and see how that comes out.

 

[scbk]

If you had an angle grinder, that would work

 

[foxhole]

Okay, but would the heat scar the surrounding area if too much pressure is applied?

No , no pressure is required to melt .