Trimming the Fiberglass Cowl

[twcroy]

Hello all,

I'm considering trimming a larger opening from the lower cowl to open more clearance for the exhaust pipes. Is there a recommended tool for this? I'm considering a dremel tool and putting masking tape over the painted surface to avoid any chipping. Will this work or am I making it too easy? I also need to figure out a way to smooth and seal the exposed, cut edge.

Thanks for any thoughts, and your time,
Tim

[bret]

I used a thin cut off wheel.

[lr172]

Be sure to go slow. The cut off wheels can produce a lot of heat on F/G parts and could bubble the paint if you let the heat build up.

[woodmanrog]

The best tool I have found to cut straight lines in fiberglass is a cutting disc on a detail sander. Feinstein makes the best.

[rv7charlie]

If all you want is to enlarge the cutouts, have you considered a carbide burr in a die grinder? I've used one to do that.

edit: What I did was to cut semicircles into the trailing edge of the cowl at the points where the two pipes exited the cowl.

Charlie

[BillL]

Originally Posted by twcroy

Hello all,

I'm considering trimming a larger opening from the lower cowl to open more clearance for the exhaust pipes. Is there a recommended tool for this? I'm considering a dremel tool and putting masking tape over the painted surface to avoid any chipping. Will this work or am I making it too easy? I also need to figure out a way to smooth and seal the exposed, cut edge.

Thanks for any thoughts, and your time,
Tim

A HF small diamond grit disc will work well. Dremel is a little hard to make a precisely straight cut, but taking care not to cross the line and then sanding up to it will work just fine. Cut in 3-4 passes as it will heat, as mentioned. 80 grit sandpaper on a wood backer works good to sand and finish. Progress to finer grit for desired finish.

On green epoxy (less than fully cured) a more aggressive tooth is needed.

How much are you cutting off?

[twcroy]

Hey all,

Thank you. I think I might try the carbide circular saw bit on a drill. Hopefully if I use a water pool around the cut it won't heat up too much. I used a 3/4" I think for cutting holes in porcelain tiles this summer for pipes. It may just work here too, or maybe a bigger one, and then sand it down a bit as Bill mentioned. I'm not sure what I'll do for sealing the edge, maybe put a little bit of paint on it.

Bill, I think I'll only need to cut less than a 1/2 inch off in a close to semi-circle. It probably won't look perfect (cowl opening isn't symmetric to the pipes), but it shouldn't bad either.

Thanks as always for the help, God bless,
Tim

[DanH]

You might think I'm crazy, but try a fine tooth hacksaw blade, handheld. Clamp a guide to the fiberglass and saw along it with light pressure.

[jrs14855]

Originally Posted by DanH

You might think I'm crazy, but try a fine tooth hacksaw blade, handheld. Clamp a guide to the fiberglass and saw along it with light pressure.

Plus one. Any hardware store will have a lightweight hacksaw blade handle for one handed operation. The blade slips into a slot in the handle and is held by a single screw.

[N941WR]

Use some electrical tape to determine where to cut, then be very careful.

I used a dremel, cut wide, and then used a straight four by four with a belt sander belt glued to it to sand it to the final line.