Cutting curved acrylic sheet.

[burgundyben]

I am making a new curved windscreen section for a motorboat. I used the old one as a template, make a buck using ali sheet and grp, with a hot air gun I mould the new sheet over the buck.

So far so good.

Now I need to cut out the exact shape of the screen from the big sheet I've moulded.

A multi tool with an abrasive cutter makes a gooey mess, as does a toothed cutter.

Jigsaw makes a gooey mess with coarse, medium and fine blades.

A hacksaw blade by hand works, but will take me days.

A grinder with a 1mm slitting disc makes a sort of hot melting plastic candyfloss fly everywhere.

A grinder with a 36 grit flexible disc works on the edge, which might be ok for final trimming. But I have a lot to remove.

Any suggestions?

 

[Cantata]

Surprisingly I have found an electric jigsaw with a coarse blade works well. But run it at low speed to stop the stuff melting.

 

[sarabande]

Rent an ablative water jet ?

Abrasive waterjet cutting systems - Rent, Hire & Purchase - Ashtead Technology

I am surprised that the jigsaw doesn't work. Did you try angling it through the plastic (Lexan ?) so that more teeth are in contact with the material ? Bosch make a specialist Plexiglass blade with a mix of fine teeth pitch plus some bigger ones to clear the kerf. And used slowly to avoid local heating.

 

[PCUK]

Jigsaw with well lubricated blade and running slow works fine. Take your time and don't push too hard.

 

[sarabande]

Oops, there seem to be two types

Amazon.co.uk

and

Amazon.co.uk

Sorry, didn't know about the first one. Clearing the kerf is the important feature as otherwise the plastic melts. Do you have an airline handy to keep the blade cool ??

 

[tillergirl]

Might be a good idea to see the episode of Wheeler Dealers - the Messerschmitt. Ed was cutting the final shape of the new perspex cover using a jigsaw and, despite care, the cover cracked ruining it at a cost of £1k. With a second new cover he ground the cover to shape - at great time.

 

[burgundyben]

Jigsaw with well lubricated blade and running slow works fine. Take your time and don't push too hard.

Lubricated with what? I did think about it, but I didn't try lube.

 

[burgundyben]

Oops, there seem to be two types

Amazon.co.uk

and

Amazon.co.uk

Sorry, didn't know about the first one. Clearing the kerf is the important feature as otherwise the plastic melts. Do you have an airline handy to keep the blade cool ??

Good grief, I'm a motorboater, so by definition not a penny pincher, but £56 for a jigsaw blade! Might order the top one.

I do have an airline, it did cross my mind, I'll give it a go.

 

[[2574]]

Router with a bearing guided cutter. Makes an excellent clean cut and very easy to do any curve.

 

[geem]

I have done 10mm sheet with a jigsaw. Yes it melts and sticks but I cut the sheet over sized then used a belt sander with 60grit abrasive to shape it. It works well. If you can set the beltsander in a vice a move the perspex, it's often easier. Depends on sheet size.

 

[dankilb]

If you need a 'one and done' cut in a show-y/difficult area a multitool does work - just follow the advice above = sharp blade, slow speed, lube (soapy water seems fine for acrylic).

 

[dankilb]

ps a small amount the gooey mess (think plastic swarf) can be removed, within reason, by carefully dragging a knife blade along the edge. This is also the method a pro showed me he uses to break/soften edges.

 

[rogerthebodger]

I used an electric wood plainer to trim the edges of 12 mm perspex for windows on my boat

 

[PCUK]

Lubricated with what? I did think about it, but I didn't try lube.

Any light oil! You can buy specific blades for perspex at the same sort of price as any other blade but they are not much better.

 

[rogerthebodger]

Water as a lubricant and more especially as a coolant to stop the perspex melting

 

[lektran]

I bought these recently to cut 3mm acrylic, worked well: https://www.amazon.co.uk/dp/B00AYNQ2FK/ref=pe_27063361_485629781_TE_item

 

[Neeves]

We found that it is better to make a template in card, or heavy paper, first and then cut to shape when the acrylic is flat. Once you have the acrylic cut, its still flat - then form. Cut slightly over size and grind back (and then, bull nose ? and polish) the edges). We sere working with 10mm acrylic - smaller/thicker might be different.

(You do not mention how the windscreen will be secured.) If the windscreen needs to be adhered you may find you need to abrade the area that accepts the sealant. Similarly if the windscreen attaches to curved white GRP then you will 'see' the sealant, or GRP. through the acrylic - you may need to paint, to make opaque, the abraded surface ....... . You then need a paint that will accept the adhesive.... speak to whoever supplied the adhesive/sealent ... Sika et al.

If only it was simple....

Jonathan

 

[penfold]

Jigsaw for me, it's important to turn the speed right down. If your jigsaw has adjustable pendulum it seems quite sensitive to that, too little and it melts and gums up the blade, too much and it splinters and makes a terrible mess.

 

[hazchem]

I am making a new curved windscreen section for a motorboat. I used the old one as a template, make a buck using ali sheet and grp, with a hot air gun I mould the new sheet over the buck.

So far so good.

Now I need to cut out the exact shape of the screen from the big sheet I've moulded.

A multi tool with an abrasive cutter makes a gooey mess, as does a toothed cutter.

Jigsaw makes a gooey mess with coarse, medium and fine blades.

A hacksaw blade by hand works, but will take me days.

A grinder with a 1mm slitting disc makes a sort of hot melting plastic candyfloss fly everywhere.

A grinder with a 36 grit flexible disc works on the edge, which might be ok for final trimming. But I have a lot to remove.

Any suggestions?

I used small angle grinder slowly following a marked line with several passes used on light aircraft acrylic screens.

 

[Clancy Moped]

A Dremel cutting wheel?