homemade fly screen ?

[davio]

hey troublemakers ,just wonderin if its possible to cut down and remould a broken fairing screen into a flyscreen usin a heat gun,any replies welcome or ill just give it bash anyway and post the results for your amusement

[latheboy]

Unlikely but do it anyway ... Pic's or it never happened

Welcome

[miniman1]

yeah mate, its do-able

[BANDITROD]

doit doit doit

[sharky]

A thermoplastic is a plastic that melts to a liquid when heated and freezes to a brittle, very glassy state when cooled sufficiently.

Thermoplastic polymers differ from thermosetting polymers (Bakelite; vulcanized rubber) as they can, unlike thermosetting polymers, be remelted and remoulded. Many thermoplastic materials are addition polymers; e.g., vinyl chain-growth polymers such as polyethylene and polypropylene.

The difference between thermoplastics and thermosetting plastics is that thermoplastics become soft, remoldable and weldable when heat is added. Thermosetting plastics however, when heated, will chemically decompose, so they can not be welded or remolded. On the other hand, once a thermosetting is cured it tends to be stronger than a thermoplastic.

[dinorider]

try it if you heat it too much though you will get bubbles in it

[latheboy]

Is that a yes or no sharky;)

[davio]

confused grin here sharky ,, which sort of plastic is a screen made from ?

[Bear]

Go to the hardware store and buy a sheet of tinted or clear perspex and use that.

I had to have two goes at it when I made mine because it takes a while to get heat into it but when you reach the right temp, it goes soft very quickly. Then if you put too much more heat into it, it'll bubble as dinorider mentioned. I used a paint stripper heat gun to create a gentle full curve and a butane torch for sharp bends and kept it moving over the perspex. If you heat one spot too much - bubbling.

I reckon you'll bubble it on the first attempt because there are no visable signs to indicate bend temperature. ;)
You just have to keep applying pressure on the bend and then when it reaches the right temp, it'll bend like putty very quickly. That's when you back the heat off quickly.

Get a mate to help. One of you applies pressure on the bend while the other weaves the torch back and forth evenly.

Here's a link to my bike where you can see what I did with hardware store perspex http://www.streetfighters.com.au/forum/topic.asp?TOPIC_ID=11147

[oldskool]

Ounsin your an idiot!
Iv got heaps of diferant shapes and bends you can cut down and play with;)

[sharky]

Fooked if I know....just googled thermoplastic and found that...

I think you will be ok...as Dino says...heat it gently...My makita heat gun on setting 1 takes a while but it gets it soft....setting 5 just blisters the plastic (tried on fairing plastic a while ago)

[davio]

good man bear thanks did u use a mould or free shape? and yes oldskool get a couple out so i can play. ta fellas sounds like its just a patience game

[Bear]

I just did it free shape.

I cut a template out of cardboard first then marked out the perspex with it. As with sheet-metal - gotta allow some extra millimetres for the bends, depending on the perspex thickness. I think I used 4mm thick perspex and the inside radius of a tight bend was around 2mm.

This is why you'll probably go through a few test pieces first. You need to gain some experience in getting it exactly how you want it without bubbles! Not easy at first. You may have to make changes to your template also. Not hard to do but needs some patience and thought.

I clamped one side of a bend in a vice using timber to directly clamp the perspex and lined one straight edge of the timber along the inside of the bend before heating. Then all you have to do is run the heat up and down where you want to bend and apply constant pressure to the free side of perpex. Use welding gloves to grip the perspex while heating.

The timber also draws heat from the perspex, just something to take into consideration.

Also, remove the protective film from the areas you are heating, otherwise the film will insulate and/or melt and can also hide any bubbles that are developing. The bubbles are basically the perspex boiling.

[loosebruce]

Pre heating in a bucket of boiling water seems to make things a bit easier too.
I've done 10mm acrylic OK with care.
Got some 3mm polycarbonate, tough shit but I have had no success in getting it to form anything useful.
The dreaded bubbles form as soon as it gets soft enough to bend.

[zx12argh]

Put it in the oven - when we worked it at high school thats what we used. You get even temperature distribution - no bubbles etc.

I reckon if you had a timber mould then you could drape the perspex over it then chuck it in the oven.

Just don't use anything painted or giving of organic vapours - you don't want to start a fire!

EDIT - Don't put the perspex straight on steel racks - if you can get is put it on an asbestos sheet - otherwise clean timber and always get you parents permission before trying any of these arts and crafts ;)

[davio]

so thats what ovens are for! always wondered, reckon ill try the mould and oven method first as that seems the easiest and i am a lazy bastard thanks heaps to all who answered i can see why oldskool raves about this site

[zx12argh]

its the dirty fist porn isn't it?

[oldskool]

sure is[:p]