Tips & Hints for Cutting Windscreens &/0r "Cateye" Vent Holes ( ST1100 )

[KoTAOW]

Tips, Hints, And Notes On Cutting OEM Style "Cateye" Vent Holes (And Other Cuts) In Clearview Shields' ST1100 Motorcycle Windshields

NOTE:  Webshots now makes it very difficult to use the copies posted there, so don't bother.  Just open the appropriate attachments at the bottom of this message (left-click) and then download (right-click/Save Picture As) and print.



About making holes (and other cuts) in/on windshields: Here's what I've learned from my own experiences and that of other ST1100 Mailing LiST Members, with special thanks to Craig Stenger of Clearview Shields:

Clearview windshields are made of pretty thick Lucite-L (an ACRYLIC), which is fairly easy to work with. It should be noted that many OEM and aftermarket motorcycle windshields are made of POLYCARBONATE, including the ST1100 OEM shield. "Poly" is softer than acrylic and has a hard coating applied to protect it in windshield applications. Polycarbonate motorcycle windshields are generally thinner, more flexible, easier to break when cutting, and harder to polish when scratched, than acrylic ones. It should also be noted that "Lexan" is a name often applied generically to "plastic" windshields, but is in fact the brand-name for polycarbonate products manufactured by GE.

A note here first about finishing newly cut edges on Clearview's Lucite-L acrylic windshields before proceeding: Craig at Clearview indicates that to make the finished edge less prone to future fractures or cracks, it should be fused/sealed. He recommends the application of a solvent cement to seal and fuse the edge once the cut is completed and it has been sanded to a smooth finish (280-400 grit). He recommends "WELD-ON #3 For Acrylic" and advises reading all the cautions before using. One possible source for this product is Regal Plastics (http://www.regalplastics.com/).

The reason I mention the above is that although many LiSTers have successfully cut their Clearviews with handheld jig/sabre saws, Craig reports long term stress fractures/cracks developing in some of their acrylic windshields after they had made cuts with one. Although not readily visible, the saw's vibrations apparently cause micro-cracks at the cut edges, which remain even after finish sanding.

I think this would be of particular concern for the cateye holes, considering their edges are located "inside" the shield and are subjected to a lot of flexing during normal riding. This would be especially true for the larger, "barn door" size shields which are stressed even more. In comparison, a cut-down "outside" edge would be less susceptible to sabre saw vibration induced micro-cracks developing into visible fractures/cracks.

So if you are going to use the jig/sabre saw method, read the notes below and finish your edges with WELD-ON. Regardless of the method used, or the type of cut made, I recommend sealing all final cut edges on your Clearview with this product.

Before you select a method you might also consider this: You may not have to remove the windshield from the ST to cut the top height down (or to cut the cateye holes, for that matter). In fact, I think it's easier to work on the shield while it's mounted if possible. Just have a vacuum handy to get up all the acrylic dust you'll be making; it goes everywhere and clings to everything! Bracing/securing a shield on the shop workbench while making cuts can be difficult due to its shape.

There are a number of options for cutting the cateye cutouts, or for lowering the look-over height of a windshield by cutting some of the top off. These all use some form of power tool. While I have successfully cut down a shield with a hand coping saw, I don't recommend it. Here are some of the power tool methods:

- Variable speed Dremel or other rotary tool with appropriate bits and attachments. - Variable speed jig or sabre saw with a very fine toothed blade. - Band saw with very fine toothed blade (what Clearview uses). - Variable speed scroll saw with very fine toothed blade. - Variable speed drill/driver with a "cutoff" disc. - Angle grinder with a "cutoff" disc.

CUTTING TIPS - GENERAL/FINISHING

With any of these methods, use the slowest cutting speed possible -- any power cutting tool run too fast will pile up gobs of melted plastic and widen the intended cut. Don't try to cut right up to the marked line initially. Leave a margin of error and finish with a variable speed rotary tool with a carbide bit, followed by a drum sanding bit if you can. Craig reports that heat generated by the rotary action of a sanding drum or cutoff disc helps fuse the final edge on acrylics.

If you don't have a rotary tool, or can't get a clean final edge using one, finish up with a good half-round wood rasp. I have obtained excellent results finishing edges using rasps. If there was a lot of plastic to remove, I have used a large and fairly coarse rasp which gives excellent control and rapid, precise removal of most kinds of plastic. I then switched to a finer rasp to finish the cut. Always push the rasps parallel to the shield surface/hole edge to avoid any possible chipping.

If you don't have rasps to get to the final edge, coarse sandpaper around an appropriate sanding block can be used. Again, sand parallel to the edge. When all of the marked line is removed, smooth the final edge with fine grit sandpaper (280-400), slightly bevel the sharp surface edges, and seal all acrylic edges with WELD-ON #3.

If you are doing a windshield cut-down, cut off the hanging waste strip at intervals. If it's flapping around it will increase vibration and could possibly crack your shield.

ROTARY TOOLS

I cut the cateyes in my Clearview while it was mounted to my ST. I used a 1" mini circular saw blade mounted on my variable speed Dremel's 'right angle drive' (90�) attachment to rough-cut the openings. I followed that with a carbide side-cutting bit in the Dremel's router attachment, removing almost all of the marked cut line. I then used wood rasps to complete the hole cuts and finished the edges with various grades of sandpaper wrapped around appropriately sized wood blocks/dowels.

As a point of reference, I cut 1�" off the top edge of this same Clearview shield some time ago using these techniques. I have also made many cuts and holes in �" sheet plexi while making soft luggage platforms to mount on my ST and Kawi's small homemade tail racks. I haven't cracked, chipped, or broken anything yet.

JIG/SABRE SAWS

LiST Members have reported using handheld jig/sabre saws to successfully make cuts on their windshields. The key to cutting a clean edge with this type of saw's up/down cutting action is using a good variable speed model with the right blade, minimizing excessive vibration, chipping and melting. Run the saw as slowly as possible using a metal cutting or other fine toothed blade to avoid chipping the edges. Most wood cutting blades have far fewer teeth and cut too aggressively.

Mask both sides of the shield with tape, mark your cut line, drill a starter hole if necessary, and make your cut. Again, allow for a margin of error and finish with the techniques mentioned above. If you are cutting cateyes while the shield is on the bike, you will probably have to shorten (cut) the jig/sabre saw's blade to avoid damaging the body panel under the shield during its down stroke.

A note about masking tape: Craig cautions that the use of almost any masking, packaging, duct, and possibly scotch tape will remove the hard coating found on most OEM windshields. Clearview uses 3M masking tape on their acrylic shields.

Removing the windshield from the bike to make your cuts with a jig/sabre saw will require you to brace it firmly. You will also want to protect it from scratches as best you can. I leave the methods up to you. If you can't adequately keep your saw and shield from vibrating while making the cuts, try another method.

BAND SAWS AND SCROLL SAWS

Bench mounted band saws and scroll saws can also be used to cut-down windshields. While I haven't tried it, I would imagine that even a home size, bench-top band saw would work well, probably better than a jig/sabre saw. A scroll saw with a 360� cutting blade might also be able to cut cateyes if vibrations can be adequately controlled. Use fine toothed blades run slowly in either type saw and mask the shield well if you try this method.

CUTOFF DISCS

Cutoff discs chucked up in many different power tools have also been used successfully to cut down windshields. Again, use a variable speed model if possible and run it at low speed to minimize melting the plastic. A mini cutoff disc in a variable speed tool like the Dremel could also be used to rough out cateye holes. Finish the cuts as described above.

OTHER METHODS

If you've been successful with another method or technique let me know and I'll add it to the list. I suppose just drilling a lot of holes with a variable speed drill/driver and finishing up with a rasp would work too.

CATEYE GROMMETS

The Clearview Cateye Cutout Pattern JPEG file I have made available to ST1100 LiST Members accepts the OEM grommets (edging) used on the ST1100 OEM windshield. I haven't yet decided if I'll order and install them on my Clearview. I suspect they only serve a cosmetic purpose. However, you can get them from your Honda dealer, or they can be ordered from Sport Touring Accessories for about $25 (1-800-889-5550). I didn't see them on the STA website yet: http://www.sporttouringusa.com/

Good luck. Just work slowly -- I think you will be pleased with the results and how easy it was to do.
orignally posted by by John OoSTerhuis, reposted here with assistance from Tom Melnik