After struggling to cut a G10 disk today, I came up with a good technique. There might be better ways to do this, like with a router, but I don't have one.
First I cut the rough shape of the disk from a sheet of .093 G10 (Garolite on McMaster.com) using my jigsaw. I cut it a little big since I am not good at making accurate cuts with the jigsaw, and I figured I could just sand it down. I use a carbide abrasive bit which I think was originally intended for cutting hardwood floors. Then I drilled a hole in the center and tightly bolted a machine screw in it. Next, I mounted the whole thing in my drill press.
Here's where I ran into trouble. First, I tried sanding it down with sandpaper on a sanding block. It kept bouncing off, and it didn't really do anything. Next I tried a sanding sponge. It worked to get it mostly smooth and round, but it wasn't taking off much material (I think most of the grit wore off the sponge). I went back to sandpaper on the sanding block. I went through 2 strips of 100 grit sandpaper, and it only removed a little bit of material. The sandpaper was worn out within seconds of touching the spinning disk. I kept it moving, but after a minute, it didn't seem like I was making any progress. I knew fiberglass would wear out the sandpaper quickly, but it would have taken hours to get the disk to the size I wanted, changing sandpaper every minute or two.
A little later, I remembered the diamond cutting wheels I have for my Dremel, which I got from Harborfreight for a few dollars. They don't work particularly well for cutting things since most of the grit is on the flat surfaces not the edges. But as I found out they work very well for grinding down material using the flat face (like the Dremel paper sanding disks). With the centering ring still mounted in the drill press and the drill press set to the lowest speed, I held the Dremel so the diamond bit spun in the opposite direction of the rotating G10 disk. The Dremel disk was perpendicular to the G10 disk. With that setup, it only took a minute to grind almost 1/8" of G10 off the disk, and there were no diamonds missing from the cutting wheel when I was done.
Fiberglass dust is really nasty stuff. I had the shop vac running with the hose clamped to the drill press table, but since it didn't get all the dust, I also wore disposable gloves and a respirator (and of course safety glasses in case the Dremel wheel explodes).
I hope this helps anyone looking to make their own G10 disks. Unfortunately there isn't really a good way to make centering rings with this technique.
First I cut the rough shape of the disk from a sheet of .093 G10 (Garolite on McMaster.com) using my jigsaw. I cut it a little big since I am not good at making accurate cuts with the jigsaw, and I figured I could just sand it down. I use a carbide abrasive bit which I think was originally intended for cutting hardwood floors. Then I drilled a hole in the center and tightly bolted a machine screw in it. Next, I mounted the whole thing in my drill press.
Here's where I ran into trouble. First, I tried sanding it down with sandpaper on a sanding block. It kept bouncing off, and it didn't really do anything. Next I tried a sanding sponge. It worked to get it mostly smooth and round, but it wasn't taking off much material (I think most of the grit wore off the sponge). I went back to sandpaper on the sanding block. I went through 2 strips of 100 grit sandpaper, and it only removed a little bit of material. The sandpaper was worn out within seconds of touching the spinning disk. I kept it moving, but after a minute, it didn't seem like I was making any progress. I knew fiberglass would wear out the sandpaper quickly, but it would have taken hours to get the disk to the size I wanted, changing sandpaper every minute or two.
A little later, I remembered the diamond cutting wheels I have for my Dremel, which I got from Harborfreight for a few dollars. They don't work particularly well for cutting things since most of the grit is on the flat surfaces not the edges. But as I found out they work very well for grinding down material using the flat face (like the Dremel paper sanding disks). With the centering ring still mounted in the drill press and the drill press set to the lowest speed, I held the Dremel so the diamond bit spun in the opposite direction of the rotating G10 disk. The Dremel disk was perpendicular to the G10 disk. With that setup, it only took a minute to grind almost 1/8" of G10 off the disk, and there were no diamonds missing from the cutting wheel when I was done.
Fiberglass dust is really nasty stuff. I had the shop vac running with the hose clamped to the drill press table, but since it didn't get all the dust, I also wore disposable gloves and a respirator (and of course safety glasses in case the Dremel wheel explodes).
I hope this helps anyone looking to make their own G10 disks. Unfortunately there isn't really a good way to make centering rings with this technique.
