Cutting windshield

[dxhall]

I just received a new Cal Sci windshield for the V85tt.  It looks too high.  Rather than sending it back, I’m tempted to give it a try and then, if it really is too high for me, cutting it down a few inches.

Has anyone tried that and, if you have, what kind of cutting tool did you use?  I’m thinking a jig saw would do it, but the reciprocating blade of the jigsaw might crack the windshield material (I think it’s acrylic, but not sure).

[moto-uno]

  There are literally dozens of videos on YouTube that cover this exact subject ! Have fun searching , Peter

[fotoguzzi]

I did it with a power jig saw, fine tooth blade and it worked. You can melt the edge to make it nice and smooth after a little sanding.

[twowheeladdict]

I just received a new Cal Sci windshield for the V85tt.  It looks too high.  Rather than sending it back, I’m tempted to give it a try and then, if it really is too high for me, cutting it down a few inches.

Has anyone tried that and, if you have, what kind of cutting tool did you use?  I’m thinking a jig saw would do it, but the reciprocating blade of the jigsaw might crack the windshield material (I think it’s acrylic, but not sure).

Painters tape on both sides, a fine tooth sharp blade at slow speeds to keep heat down.  Then some different grit sandpaper working down to a fine polish.  You might want to shape it where the dip is in the middle like the triumph trophy se shield. 

[kballowe]

I use blue painters tape and tape both sides to preclude me from scratching it.  Then I draw the cut line and then take a dremel tool with a cut off wheel and keep going over the line, deepening the cut a little bit at a time.

Pad the vise jaws and then mount the cut windshield in the vise.  Then use a bastard file at a right angle to the windshield, drawing it back and forth to remove the cut line and to square it up.  Finally, a sanding block, starting with 100 grit paper and then finer until you get the finish that you desire.

There's probably five more ways to do it.  This is mine.

[stonelover]

Cut mine down with a roto tool using a drywall bit. Made a template of the top curve to transcribe onto the masking tape where I wanted to cut. Tape BOTH sides. If windshield is mounted on the bike, a cover of an old shower curtain will keep the chaff from getting where you don't want it to go.

Bill H in WV

[Ncdan]

Personal opinion and choice only.
Modern polyurethane shields has little to no distortion looking through them.
I had rather have the protection from bugs, bees and flying debris from vehicles in front of me, rain, sleet hail, etc, hit the shield than my face.
Wax the shield and water runs off, therefore little to no viewing issues.

[pehayes]

Start with a vertical strip of painters tape.  Mark in small increments.  Ride the bike to determine exactly where  you want to cut it off.

If you can find a local hobbyist, try to use a band saw instead of a reciprocating saw.  The common 4X6 saws will do the job nicely.  The cutting process with a jig saw also heats and melts the plastic.  I found that a jig saw cut away plastic and then simply redeposited the cut, molten debris back into the kerf slot.  When I finished, the windshield was still intact with a hideous weld along the cut line.  A band saw carries away the debris and gives the blade time to cool so this reweld is avoided.

After you cut, use several grades of abrasive to round the edges and remove any rough spots.  Even after sanding, use a propane torch flame to very gradually melt and round and smooth the exposed edges ever so slightly.  Leaving nicks and bumps can lead to cracks which progress continuously.

I once had someone suggest that the top of the screen should not just be a visual curve.  Rather, it should be a geometric elliptical curve.  Supposed better control of the laminar flow over the top edge.  I've done that several times.  Did it make a difference?  I have no idea, but it wasn't that difficult to add in that feature.  Piece of cardboard, hoop of string, two thumbtacks as focal points, quick draw of an ellipse and then transfer that to the protective tape covering your shield.

Patrick Hayes
Fremont CA

[Chuck in Indiana]

^^^^ What Patrick sez. I detailed the whole operation on the Lario Rehab thread, but photoblockit quit hosting them unless I ponyed up several bucks a month. They can EASD.

[ital4me]

I agree with all here on this topic. I want to add that you can reshape "slightly" with non flame heat. I re-arced the windshield as it came off the fairing on mine in order to lower to lower the height. Of course that meant cutting the lower edges to new angles and drilling new holes. The after effect where the heat and bend happened was frightening to look at but using plastic polish and a little elbow grease it cleared right up. Using a flame to the edges is the way to finish up. Low heat and keep the torch moving at all times.

[usedtobefast]

Before you start cutting, have you called up Cal Sci?  My experiences with them have been great.  Like they would probably ship you out a shorter screen (and charge you for it) and then take back the one you don't like.

But, I guess not if you've used it for like 1000+ miles and have bug splatters all over it. 

They are like 2.5 hrs away from me and they've offered for me to stop by, try out some different screens, and keep the one on there that I like best. 

[dxhall]

Thanks for the suggestions.  For those who recommend applying heat to the cut edge to prevent subsequent cracks, what heat source have you used?  Is a propane torch enough, or would a small welding tip on the O/A rig be necessary?  I assume the O/A rosebud would be too much.

[Sye]

Don't put an open flame anywhere near the screen. Use a hot air gun on the lowest setting. Keep it moving on and off the edge and you will see it smooth over as the top surface melts slightly. Don't touch any heated part until it cools down.

[Chuck in Indiana]

You can use a propane torch just fine, thank you.  I detailed all that in. oh, never mind..
You don't want the point of the flame on it, just a feather on it,  and keep moving. Maybe practice a bit on some scrap first..
(shrug)

[n3303j]

Guy in the plastics shop behind my storefront used an Oxy/Hydrogen torch to "fire polish" cut edges. His finished edges were water clear. Seems Hydrogen burns cleaner than Acetylene and won't add any carbon bits into the soft plastic.
The only caution was in handling the torch as the flame was almost invisible so it took a bit of practice to know where the flame actually was.

[flower_king001]

Question....why not exchange the new/unused shield for a different height?

[dxhall]

The reason I’d prefer not to exchange it is that, while it looks too tall, I can’t tell for sure without trying it.  After I try it, I can’t return it.

If it’s too tall, and I can cut it down, I should be good.  If it’s too short, though, I’m obviously SOL. 

Since the projected high temperature tomorrow is minus 4, I don’t think I’ll be trying it for a while.

[John A]

It was only scary until I did it and it turned out great. I recurved one by laying a towel on a barrel and heating the plastic with a rosebud on an oxy acetylene torch. Getting the volume of heat was the key. If it gets too hot you can get markup which is a cloudy area but I was lucky. I made a shorter windshield for the sidecar out of a classic Guzzi shield, recurved it and hacked it shorter . I guess I’d wait until it wasn’t so close to absolute zero - next month the days will start getting longer!

[Stratodisaster]

I use a die grinder and thin cut off wheel . Keep it wet with water keeps it from getting too hot and melting. Then sand and polish with Dremel. Never had a problem and probably done 10 or12.  I usually buy them tall and cut to size. Haven’t figured out how to add to them yet

[PeteS]

Whats the material? Lexan/polycarbonate or Plexiglass/acrylic? Lexan you can think of like aluminum. Unlikely to crack and you can sand and polish the edge when done using the same materials you would if it was aluminum.
Plexiglass is harder and may crack if the blade is too coarse, you push too hard or tilt the blade. If you haven’t cracked then sand and polish as if it was metal. Band saw or sabre saw will both work.

Pete