Cutting down a windscreen advice wanted

[fotoguzzi]

I scored a parabellum used, it's too tall by about 2". Need advice on cutting it down. My Dad has a band saw, is that the best tool?

[nc43bsa]

In a video I saw last week, they used a small electric jigsaw.

[Chuck in Indiana]

Bandsaw, sand, propane torch. I Covered it in the Lario rehab thread.

[Triple Jim]

I cut my National F15 tall down to a short by laying it on a piece of cardboard and tracing the top edge, then cutting the cardboard out and moving it down a couple inches, and then using that to mark the new edge on masking tape that I had applied to it.  I used a bandsaw with a metal cutting blade, running at metal cutting speed (avoid melting the plastic) to make the cut.  Then I smoothed the cut with my 1" vertical belt sander, and finished it by hand with 220 grit wet sandpaper.  If you sand enough to get rid of the previous marks, it will have a matte edge that looks like it was made that way.

[Tom H]

I was a bit too scared to do the same thing. Mt friend that has cut alot of plastic did the cut for me. He did as Triple Jim did. He just did the cut.

I finished it by leaving the masking tape on the shield that he used for the cut and a hand sanding block to take off the rough spots and to finalize the shape. Then took a dremil style tool and a micro buff wheel with plastic cutting compound and polished the edge. The edge came out looking like the stock edge on the rest of the shield.

Good luck and take your time.
Tom

[River Rat]

I use a fine metal cutting blade in a 4" angle grinder (requires a steady hand), file off edge and smooth with fine wet and dry, comes up like new, see link below for an example on my DR650 Suzuki, cheers 
http://advrider.com/index.php?posts/29450203/ 

[charlie b]

I used a cutoff wheel in my dremel tool.  Takes a little time but works.  Sand and finish as above.

I'm not brave enough to use a torch, but, it does work well.  I may try it on a scrap piece next time and see if I can work it.

[Triple Jim]

I guess whether or not you polish the edge depends on how your shield was originally made.  My National shield had a matte edge.

[Lcarlson]

Lacking the equipment (or the skills) to do it myself, I took mine to a local auto body shop that specializes in classic car restorations. I had them take two inches off the highest part of my Touring windshield, while essentially retaining the shield's original shape. They had never done one before, but it came out beautifully, just like stock. It is a huge improvement, as I no longer have the top of the shield right in my line of sight.

[fotoguzzi]

Thanks all, up in the woods right now but I'll do as you say when I get back.

[Rich A]

I use a fine metal cutting blade in a 4" angle grinder (requires a steady hand), file off edge and smooth with fine wet and dry, comes up like new...

I did the same, but taped the area to be cut w masking tape first. That offers some measure of protection if/when the blade slips and contacts some area you don't want damaged.

Rich A

[fotoguzzi]

that's a big screen, no? it would look so much better if I cut off 6 or more inches.. but it's effectiveness would be reduced.. I'll start with about 2"  and see how it goes.. rode 150 miles home against some 40mph gusts and it pretty much cut right thru, I'm a little worn out but sure it woulda been worse w/out the screen.

spent the afternoon fixing my Dad's stair chair lift so didn't get around to cutting it down..

[Triple Jim]

My experience with a windshield is that if the air coming past the top edge falls anywhere in the range of your helmet, or slightly below, the noise will be unbearable.  If it's currently breaking above your helmet, you might want to reconsider cutting it shorter.

Noise is the reason I shortened my National windshield.  Even with earplugs, I couldn't stand the roar, so I cut it down to match their short version, so that the wind breaks at my chest, and now it's not bad, although it also doesn't do much more than keep cold air off my gloves.

[fotoguzzi]

Noise is the reason I shortened my National windshield.  Even with earplugs, I couldn't stand the roar,

that is my main problem too.. the noise enters around my chin and I can block it off with my hand, so if this screen can put the wind above that it should be good..
the MadStad on my Buell did a really good job at it and was not so huge..   .. I never had this noise on the V11 probably because my helmet was tilted down more due to the riding position?

[Jurgen]

When you have a $600 Acrylic raw canopy that needs to be trimmed, you tend to be very careful.  Most of the experimental aircraft builders use an abrasive disk at high speed to cut acrylic which cuts mostly by melting, not ripping.  Saw blades tend to form little jags that often cause cracks.  Using a flame after sanding the edge smooth makes for a nice polished edge.  Jurgen

[rocker59]

Thanks all, up in the woods right now but I'll do as you say when I get back.

Be sure and use masking tape on both sides of the screen.

Draw your line on the masking tape.

I've used a dremel tool, a hack saw, and a coping saw in the past.  Whatever you use, just take your time.

Once cut, I used a foam block with sand paper of various grits to get the cut and the edges smooth.

[Cool Runnings]

 


21 inches tall (above the top of the headlight)


For all you shorty's..... 

How To: Cut Down a Windscreen

[neverquit]

I've used a jig saw on plastic and the up and down motion jerks the plastic around and can crack or outright break it.  I would trust a band saw before I would a jig saw.