Cutting fiberglass - what's the best way

[88 Club Sport]

I installed a glass valance in prepartion for a front mounted cooler. As you can see from the pic, I need to cut out the opening in the valance for the cooler.

I'm assuming the glass will want to splinter when I attempt to cut it so I'm looking for advice and how best to do this.

Thanks

[widebody911]

I use an air-powered body saw with 18tpi blades I use a die grinder to cut a starting slot, and awaaayyy we go.

Small bites is the key, ie small pitched blades.

[88 Club Sport]

Thom,
Is there any reason I could not use the air powered die grinder for the entire cut? I do not have a "body saw".

Thanks

[geof33]

I used a fine tipped diamond cutter for my dremel. It takes a steady hand, but works for plunge cuts like you have. Use masking tape on the finished side of the glass to minimize chipping. With a fine cut bit, it really shouldn't be a problem though. Err, on the inside to allow for some sanding to get the edges perfect.

[5speed]

You can use a die grinder to make the entire cut, just make sure you have a dust mask. With a body saw there is alot less dust flying around.

[Jeff Alton]

A jig saw works very well indeed. Use a fine tooth blade and put masking tape on your cut line to reduce chipping.

Jeff

[fhernand]

Both ways sound good to me. Whichever way you decide, make sure that your blades are sharp this will avoid splitting your fiberglass. Best wishes.

[Pat S]

thin metal cut off blades for a 4" or 4.5" angle grinder work well and make it easier to cust straight lines.

[Zeke]

I think you'd need a long blade if you use a jig saw to keep it from popping out of the cut. You don't want that as is messes up the surrounding areas. A Sawzall would be a good tool in place of the air powered body saw. Any rotary cutting tool is going to make a ton of dust and you're going to itch like crazy unless you have something like a disposable hazmat suit on. I'd be willling to cut mine with a hack saw blade held at an angle so I didn't make much dust.

If you go for the dusty method, get a house fan blowing the stuff away from you and do it outside.

[Jeff Alton]

Any standard length blade in a jigsaw will work. You need to keep firm pressure on the saw so that it does not jump around on you. If you use a fine tooth blade it won't want to jump anyways, it will cut like a hot knife through butter. Drill holes in the four corners of your cut to mark the ends of the cut lines. Drill a hole in the center of the cut out large enough to fit the saw blade in, then slowly move out to the edge. You have lots of control with the jig saw and you can control the speed of the blade easy to help get the feel.

I have done this sort of thing too many times to count with a bunch of different tools and found this to be the most accurate way.

Jeff

[3.2 CAB]

Be sure to tape the bottom of the jig saw foot before you start, and the entire area you are going to cut, that way it won't scratch the surface from the vibration of the saw.

[Install425]

The best way is to use a jigsaw with a masonry blade (Home Depot) The blade looks like a bunch of metal bits gluded to it. I have cut tons of fiber glass and this blade is by far the best for the job. A regular blade will go dull very quickly and get harder to cut. It is probably best to cut from the back side with holes in each corner, makes for easy turning.

[Zeke]

Originally posted by catca
Any standard length blade in a jigsaw will work. You need to keep firm pressure on the saw so that it does not jump around on you. If you use a fine tooth blade it won't want to jump anyways, it will cut like a hot knife through butter. Drill holes in the four corners of your cut to mark the ends of the cut lines. Drill a hole in the center of the cut out large enough to fit the saw blade in, then slowly move out to the edge. You have lots of control with the jig saw and you can control the speed of the blade easy to help get the feel.

I have done this sort of thing too many times to count with a bunch of different tools and found this to be the most accurate way.

Jeff

OK, this is all true if you cut from the back. Trouble is, I like to see the finish side while cutting. You can always cut from the back, which is a good idea anyway, cut short of the edge ot the opening and finsish/smooth the cut with a sander, hand or disc.

I'm a carpenter and have owned one or another jig saws since 1968. I just had to get the last word in on this. It's a pride thing.......

[dsfnctn]

The Fein Multitasker tool is the best thing I have ever used. If you have ever had a cast cut off your arm you will rember the blade that vibrates but wont cut your skin. The tool is also a detail sander as well. This tool makes me tons of Money.

[dsfnctn]

By the way, the blades are only 16 thousands thick.

[JMPRO]

These holes are cut with a hole saw on the round ends and a jig saw to clean out the part in between. You might try a 1" hole saw in the corners and cut between.
Jerry

[Jeff Alton]

Milt, what can I say? You have owned a jigsaw for one more year than I have been alive!! Lets hope 88 Club Sport gets this thing cut and doesn't bugger it up by using our suggestions!

Jeff

[88 Club Sport]

Thanks to all for the input.

It was all put into perspective today at the track when my instructor, who saw my post last night, said .... "The first time you go off the track, you'll rip the thing apart anyway"

Thanks for putting it into perspective Jess !!

[Jeff Alton]

LOL!!!! Good point, oh well hopefully it works out for you and post some pics when you are done.

Jeff