Doreen

[hinterglem]

I've had so much help from everyone here, and being such a newbie I feel like there is not much I can give back. But I thought this little 'how to' might be helpful for some people who want to make a roof for a run out of corrugated plastic.

 

As I discovered to my chagrin, if you plonk a piece of corrugated plastic on a workbench, and attack it with a jigsaw, you end up with splinters flying everywhere and your expensive plastic cracked and useless!

 

 

After some research and experimentation, I found a method of cutting this stuff that seems to work reasonably well, albeit a slow process.

 

1) Measure carefully and mark out where you want the cut. You will not be able to guide it by eye, as the plastic will bend and warp a bit while you are cutting. If your jigsaw has a laser guide, you can get away with just marking the top of each 'bump', and using the laser to aim for it as you cut.

 

 

2) Carefully stick masking tape over the line to be cut, making sure you get good contact with the plastic all the way along (if it is pulled taught and not in contact with the plastic, there is a risk of cracking).

 

 

3) Weigh down the work as close to the cut as possible whilst still allowing room for the saw. Make sure the plastic does not hang over the edge of the workbench where you will start the cut, as any vibrations will cause it to crack. If it hangs over the other end, that doesn't matter, you will just have to move it along later so that the part you are cutting is held firmly against the workbench.

 

 

4) Start cutting with a hacksaw or junior hacksaw. If you try launching into it with the jigsaw straight away, you guessed it - it will crack. So start it off by cutting a few centimetres with a hacksaw first.

 

 

5) Place the jigsaw blade a few millimetres in front of the edge you are about to cut, and let the blade get up to speed before engaging with the plastic. Use a thin metal-cutting blade on a fast setting (not a wood-cutting blade). If your jigsaw has a pendulum feature, turn it off as it will generate a lot more vibration. Practise on a waste piece first if at all possible.

 

 

6) Move the jigsaw slowly, especially on the 'uphill' sections. When the blade is going uphill, there is a much greater risk of cracking, and you have to go very very slowly - 1mm per second or less. You can go a bit faster on the downhill and flat sections (this might depend on the direction of the teeth on your jigsaw blade). Every now and then, stop and blow or wipe away the dust, and move the weights further along if necessary - always making sure to keep vibration to a minimum. When stopping mid-cut, wait for the blade to stop moving before withdrawing from the plastic or you risk bashing it and ruining your work.

 

 

7) I found it easiest to cut the final 'bump' with a hacksaw starting from the opposite end rather than trying to guide the jigsaw at arms-length - the risk of cracking seems to be greater at the end. Once you've finished all that remains is to remove the masking tape and admire your handiwork.

 

 

Any fine detail should be cut with a hacksaw, but following the same principles of weighing down the work and using masking tape. When drilling holes for screws, I also recommend using masking tape, and only drill into the flat sections.

 

Hope that helps someone! (I know it would have helped me, and saved me a few quid if I'd known all that a couple of days ago!).

 

Russ.

[Redwing]

Thats brilliant, I knew that after working a lot with plastic at school but it will come in terribly useful to many people and the pics make it even better so thanks for taking the trouble to post that

 

however I have two questions:

 

1) is that BLOOD on your workbench in the second pic? have you counted your fingers since?

 

2) How did you get a cat flap in the wall of your house? thats the coolest thing I have ever seen!

[Ain't Nobody Here]

Wow . I admire your patience . I too learnt to my cost that you can't easily cut corrugated plastic . Unfortunately, I'm a DIY numpty and don't have anything resembling a jigsaw let alone one with a laser .

[Sam]

What a great guide

We tried with a jigsaw but gave up

Good ol' Argos catalogue, always come in use

[hinterglem]

1) is that BLOOD on your workbench in the second pic? have you counted your fingers since?

Lol - I think it is some kind of wood stain, not blood stain!

 

2) How did you get a cat flap in the wall of your house? thats the coolest thing I have ever seen!

We got a builder to knock a hole in the wall, I screwed a small metal splint to the joists to provide support, and you can buy 'tunnel extensions' for cat flaps which glue together (I also plastered silicone all over the joins to keep the rain out). The really cool part is that a microchip sensor is discreetly hidden inside the wall so that only our cat can open the flap (with no need for a collar).

[Plum]

Ah that's how you are supposed to do it.

 

I ruined first sheet then took them inside and laid the sheets in warm and used hairdryer on them to warm them up and cut with scissors. The first ones were in the hot sunshine and they cut easily with scissors.

 

I shall bookmark these instructions in case we have to redo ours and with the trees around it being trimmed soon I very much fear they will be damaged. Thanks

[Dodge]

For those people who do not have access to a jigsaw or are nervous to use one for fear of cracking the panel, when I did my roof I got an old bread knife and heated it up on the gas ring and then I was able to saw through the plastic with out much bother at all. I just put a straight edge accros the panel where I wanted to cut it and drew a line with a black marker pen, I was then able to cut and follow the line with little effort. I could cut about a foot at a time before re-heating the knife. I would say that cut edge was fine but not as good as you would get using a jigsaw but as the cut edges where at the back of the run and not on show then there is no issue. So allways make sure that the machined cut edges of the roof panels are the ones that are on show.

[Redwing]

The mini profile 'blue tinted' type cheap corrugated plastic from Wickes is more pliable and will cut with scissors, its not really as durable or neat though

[Kriscross]

I had problems cutting this material in the past. So I went online and was reading with interest "Hinterglem's" method of cutting corrugated plastic sheet and was preparing to carry out his suggestion when I had one of those light bulb moments, why not try a disc cutter. I have had a Bosch disc cutter which I had bought from B&Q some time ago and fitted a metal cutting disc. I first of all tried it on a s"Ooops, word censored!" piece of sheet and it went through like a knife through butter. Lining my sheet up with a piece of wood below I cut through the whole width of the sheet followed by another in a couple of minutes leaving a nice smooth clean edge and no cracks! This is definitely the way to do it. There are various makes of disc cutter and I have seen both Lidl and Aldi sell them very cheaply with a box of metal and stone cutting discs.

[Guest]

Gosh that looks hard work, full credit to you for your patience.

[Egluntyne]

Really useful. Thanks .

[Plum]

Shall remember the tip but hope I won't need it

[Leicester_H]

OH managed to cut this stuff very successfully - he says he used a padsaw.

He says you need a fairly co"Ooops, word censored!" blade (surprisingly) and saw slowly otherwise the heat slightly melts the plastic and it all binds up.

He has cut straight cuts and curves this way.

 

H