Best tool for grinding fiberglass?

[Ross]

I used an angle grinder on a hull repair but found it removed material too fast and was difficult to control. I then switched to a regular variable speed drill with a rubber sanding disc and adhesive backed sandpaper disks. The flexible rubber allows it to form to the surface and it removes material amazingly fast and very controllable with the slower speed. Angle grinders are high RPM for grinding wheels, they work great with a diamond wheel for cutting special shapes on ceramic tile. For the large radius bevel I think the sanding disk would be ideal and less chance of a screw up if it slips.

As with all power tools you get to make mistakes faster. If you are using a 4 1/2 inch right angle grinder with a 25 grit sanding disk you want a light touch and you mustn't dwell in one place. It takes time to master the use of our tools and sometimes we don't have the opportunity to do that because all of the jobs we have are fairly small. I first held an industrial right angle grinder 54 years ago in my Dad's welding shop. In those days they weighed in at about 20 pounds. My Black and Decker is only about 2 or 3 pounds and I don't mind using it overhead for several hours. If you own good power tools take time and play with them on scrap material and develop a familiarity with its performance. For practice with a course disk on a grinder draw circles on a piece of plywood and bevel a dish shape in side the circle. The multiple plies will let you see the uniformity of your cutting.

 

[Roger Long]

After reading al of the above, I didn't think anything sounded enough better than the Universal Super Disk I was using to justify buying something else. It actually works quite well in a hand drill. The geometry was right for the location and the very flexible disk made control and shaping quite easy. I put a Makita rubber sanding back plate, about 2 1/4" diameter on the back of the 7" Super Disk. The job took about 3 hours.

 

[dvideohd]

"You are aware that Interlux Interprotect 2000E is a barrier coating"....

I think 3 gallons is extreme overkill... 4 or 5 layers... is barrier coat... might be a gallon or an additional quart... I think 3 gallons might be a lot of coats....

 

[Ross]

Roger the very course disk would have reduced the time some but wouldn't have done a better job. Only if you have the tools do you get the options. Otherwise it is smart to make do.
For the extensive rework that I did I needed to speed that comes with the purpose made tools.