What is the best way to cut down a wind screen???

[1000lbs]

I'm playing around with some ideas to dress up the DR and add a little more wind deflection...  I have a double bubble screen sitting around and I'm looking to cut it down some and fasten it to the headlight cover...  So, what is best, dremmel, jig saw with fine tooth blade, or something I don't know about yet???

[M.Brane]

 I've never cut a windshield, but I have cut hard plastic before with a router. If you use a fresh bit, and take it slow it works good. Just don't slip.

 Chips ahoy!

[RBEmerson]

+1 and... use wide painter's tape to mark the cut and protect the area near the cut.  A fine-toothed blade at a slow feed rate works, too.  I drilled a pair of holes to install snap vents (using a common hole blade) and the biggest problem was keeping the speed down to avoid melting the plastic.  Use increasingly finer grades of rubbing compound to buff out scratches (never, never, never mix grades of compound in the same bonnet!).  

[bomber]

if you have access to a band saw with a fine-tooth blade, that may be easier to ouse than a jig saw or router . . . . . . windshields are full of compound curves, and are tough to secure (though clearly not impossible) .. . . .

[RBEmerson]

It kinda works both ways.  Using a bandsaw is going to call for some sort of jig and so is using a hand tool of some sort.  At least with the latter, it's the tool that moves and the shield stays clamped down.  Sliding around a clamped shield for a bandsaw is...   put it this way, I wouldn't do it.  YMMV  

[bomber]

zactly what makes a horse race, innit?

;-}

[black hills]

Masking tape both sides, draw your line and use a fine blade in a jigsaw. Go slowly as the plastic will melt if you go to fast. When you have made the cut start with 80grit sand paper to remove the blade marks and straighten out any waves in your cut (I used a belt sander but you have to be very careful). then work your way up to finer paper until the edge is clear. It's actually a lot easier than it sounds, but if you had an old screen to practice on it's not a bad idea.  Good luck.

[1000lbs]

 I've never cut a windshield, but I have cut hard plastic before with a router. If you use a fresh bit, and take it slow it works good. Just don't slip.

 Chips ahoy!

I don't have access to a router and have not worked with one, but I'll see if I can get my hands on one to try it out...  I do have a jig saw and blades so if the router doesn't work out this will likely be the way I go...  What ever manner of cutting I will definitely go slow to keep the heat down and use tape to protect the plastic...  

Thanks for the suggestions so far, and keep'm coming...

[Fudge]

Masking tape both sides, draw your line and use a fine blade in a jigsaw. Go slowly as the plastic will melt if you go to fast. When you have made the cut start with 80grit sand paper to remove the blade marks and straighten out any waves in your cut (I used a belt sander but you have to be very careful). then work your way up to finer paper until the edge is clear. It's actually a lot easier than it sounds, but if you had an old screen to practice on it's not a bad idea.  Good luck.

What he said, worked well for me.  I recommended leaving the shield on the bike when you do it, easier to cut when held in place.  

[bomber]

I'll admit the router tip has got me confused (and intruiged)  -- since most windscreens are compound curved, and tough to secure to a bench or the like, I have this vision of one hand holding the windscreen steady, and one holding the router (which would be a very bad idea, I'm thinkin!)

can you splain how a router might work in this application? I'm sure I'm not "seeing" it right

[M.Brane]

I'll admit the router tip has got me confused (and intruiged)  -- since most windscreens are compound curved, and tough to secure to a bench or the like, I have this vision of one hand holding the windscreen steady, and one holding the router (which would be a very bad idea, I'm thinkin!)

can you splain how a router might work in this application? I'm sure I'm not "seeing" it right

 You'd definitely need to have one or the other secured. Leaving it on the bike is an option if the mounts are strong enough to keep it from flexing too much. You could alternately chuck the router in a vise, and move the screen over it. This would make it easier to watch your cut.

 You'll want to make sure you relieve your cut too i.e. make it wider than the bit so it won't get pinched in the cut causing it to jump or crack the plastic. You'll also want to use a face shield, and work in an area where the plastic chips won't get into places you don't want them. There will be many.

 The problem with using a jig/band saw is if you need to make a curved cut the blade can bind in the cut which can crack the plastic. It also leaves a rougher edge which means more cleanup after the cut.

[county]

Google it, there's some good directions with pic out there. I have seen them.

[Fourstring]

Walk into the glass shop and hand them $10.  Works every time.

[Walker]

Tape it, draw your line, then use your Dremel.  Cut it off long, then grind and polish it down to your final desired line and a nice, rounded finish.  

I've had bad luck using a jig saw to cut plexiglass.

[1000lbs]

Tape it, draw your line, then use your Dremel.  Cut it off long, then grind and polish it down to your final desired line and a nice, rounded finish.  

I've had bad luck using a jig saw to cut plexiglass.

I do like working with the dremmel, but I was hoping to avoid the added time/work of cutting big and finishing down to final desired shape... I'll do some test runs on the outer portions next week and see what method I like best...

[ruddy]

Another alternative is a belt sander. I've taken quite a bit off to lower the height of a sport shield using an 80 grit belt. Worked like a champ. I used a felt tip marker to draw a line across the shield and sanded down to it. Once I got it to where I wanted it, I beveled the edge with the sander and then smoothed it with a file. Finer sandpaper would work, too.  

[RBEmerson]

You didn't have problems with the plastic overheating?  How fast was the belt running (slow, fast, or...)?

[bomber]

Walk into the glass shop and hand them $10.  Works every time.

OK, this here's the best response yet -- heck, even if you only pay yourself minimum wage, this is a no-brainer!

[dnlwthrn]

To deal with the heat issue (when drilling or cutting) try using windex... That's what we use for coolant here at work when cutting lexan or plexi.  Works wonders

[ruddy]

You didn't have problems with the plastic overheating?  How fast was the belt running (slow, fast, or...)?

I had no overheating issues with the belt sander. It did leave a lip of plastic along the edge, which is easily removed when you use the sander to bevel the edges.

[shil]

I cut back the windshield on my wife's Piaggio.

Before


After


I taped it up, drew a line, freehanded it on a bandsaw, and smoothed it out with a random-orbit sander.  Plexiglas is easy.

It does help to have a bandsaw.  

[1000lbs]

Very nice...  

I thought a band saw may make the quickest job of it, but I will need to find access to one...  I've been busy with other things so I haven't even looked at the windscreen yet...  Keep the ideas coming, I'll post up some pics when I get around to it...