Currently I'm either making a template for the dashboard, or the dashboard itself, out of 5mm Perspex.

Drilling it isn't a problem, and I managed to circle cut a nice clean hole for the steering column too, but a jigsaw clearly isn't the right tool for cutting it.

The jigsaw with a rough blade is great for finish, but in terms of speed, it takes ages just to do a few inches. Probably about 5" per minute.

I think the problem is that the jigsaw has a fixed lowest speed, which is too fast so the blade is basically polishing the cut rather than cutting it

I've got some carbon grit (or whatever type of grit they are) blades somewhere but before I hunt them out (which will be a hunt) should I be using a totally different tool/blade anyway?

Clearly a hot wire cutter may be good, but I do need a nice long straight and a couple of large curves, so surely that'll be difficult with such a small "cutting" width, ie. a sneeze and you've suddenly got a nasty zigzag where with a jigsaw you're guided by the blade depth (front-to-back).

Advice appreciated

ta
Chris

What you really need is a small router with a slot cutting bit!

You can cut perfect circles with it if you setup some kind of centre point to revolve around.....Freehand isnt to hard either if you take it easy.....

If you get a slot cuting bit with a rounded shank you can cut and radius at the same time

What you really need is a small router with a slot cutting bit!

You can cut perfect circles with it if you setup some kind of centre point to revolve around.....Freehand isnt to hard either if you take it easy.....

If you get a slot cuting bit with a rounded shank you can cut and radius at the same time

Stunning idea chap.

Although given that a router is about as easy to cut straight lines with as a hot wire, I'll just use it to rough cut the shape then use the bench sander to go to the line.

Bet a router is going to scream a bit though cutting it.

It depends what blade you fit to the router...

Go for the thinnest one you can without it being so thin it snaps!

I would recomend sticking the perspex to some plywood with doublesided tape to stop it cracking when you machine it....the router blade doesnt have to actualy cut into the wood though!

If you use a long batton of wood G-clamped to the material you can get super straight clean lines....

i do a lot with a router at work. Best bet is to make a jig to guide it, mine cuts 8mm bigger than the jig. Clamping to ply is also a good idea. Make sure you use a new or sharpened blade.

Are you using the right blade for perspex with the jigsaw? I would also recommend taping or clamping it to a thin piece of ply for extra support... also, some wide masking tape or gaffer tape either side of the cutting line, to avoid the jigsaw plate scratching the surface of the perspex

quote:

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Originally posted by Humbug
Are you using the right blade for perspex with the jigsaw?

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Jigsaw and patience in the end.

Still need to finish the edge on the bench sander and sort out the "leg" holes.



[Edited on 17/6/06 by the_fbi]

Umm.. have you tried sitting in front of that dash and working the pedals? I only ask 'cos I first made my dash to be straight across like that - then found that I couldn't swing my legs enough to work the clutch, change pedals, etc.

Now I have a big cut-out on each side...

David

quote:

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Originally posted by David Jenkins
Umm.. have you tried sitting in front of that dash and working the pedals?

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I cut a perspex fly screen with a variable speed jigsaw.

Its quite a slow speed that you need as you melt the perspex. To prevent cracking cut it on a sacrificial piece of styrofoam or sponge.

Place the object to cut on top of the foam (make sure that the material is thick enough for the blade not to bottom out !). To finish the edge run a metal ruler along it a couple of times.

I seem to remember from school (yes they did have perspex that far back ) that the teeth on a blade to cut perspex had to be the reverse of normal, ie the teeth pointing back from the work, rather than forward. Same went for drills.

There is a special design of blade to cut Perspex and Polycarbonate sheet. You are almost right with it being 'push' rather than 'pull' action but the design on the teeth is incredible and looks nothing like a regular wood blade. One thing for sure it does not crack or split the material you are cutting. Available from B&Q and made by Sandvik IIRC, well worth the money.

Steve

quote:

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Originally posted by Hellfire
There is a special design of blade to cut Perspex and Polycarbonate sheet. You are almost right with it being 'push' rather than 'pull' action but the design on the teeth is incredible and looks nothing like a regular wood blade. One thing for sure it does not crack or split the material you are cutting. Available from B&Q and made by Sandvik IIRC, well worth the money.

Steve

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You can get a fitting for a Dremel that will do the same thing as a router. Probably a lot easier to control too.

I have always used a good old stanley knife....

a good deep score line ensures it breaks cleanly for a rough cut and then sand down to final shape

A rasp takes the edges down quickly too if you need to remove a lot of material....