Okay, it has been a year or more and I am finally back in the knife making mode. One problem has cropped up and for the life of me I cannot remember dealing with this before. I keep scorching/discoloring micarta when shaping it. Basically it seems to be getting too hot and discoloring badly...and somewhat deeply. I tried a new belt (Norton 60 grit zirconia) and it helped slightly, but not much. I have to use waaaay to light of pressure and that makes it take forever.

Bad batch of micarta or is my memory failing and it has always been this much 'fun' to work?

Tricks to prevent the scorch? Cooling with water just makes a muddy mess and didn't stop the problem...

Sounds like you are using a dull or worn down belt. Also, ease up on the pressure to the belt and let the belt do the cutting. A fresh belt should do better. The finer the grit the belt has will also make it burn easier.

quote:

Originally posted by aktoklat:
Sounds like you are using a dull or worn down belt. Also, ease up on the pressure to the belt and let the belt do the cutting. A fresh belt should do better. The finer the grit the belt has will also make it burn easier.

+1

Go slo...

Don

That's what I have done...put on a new (60 grit) belt and lightened the pressure...it just seemed that I didn't have to do that with the last (and first, this is my second batch ever) batch of micarta I used. Since I didn't notice it until I ruined one handle I am a bit frustrated. Finishing a 2.5" peeling knife with 1/8" micarta scales shouldn't take a slow, tedious hour!

Maybe I'm spoiled by working with my mesquite. That stuff will shape with whatever pressure I want to use, nice and quick.

Oh well, back to the grind...

Thanks!

Slow the belt down. Do the next step in shaping with a bastard file. Sand with 180, 320, and 600 wrapped around a half round file. Polish with black compound on a buffer. Rub vigorously with Johnson's Floor Wax several times during the polishing. The finer the sanding the smoother and prettier the final product will be.

As the knife is washed the wax will come out of the handle and the dark color can be restored by a rub down with Johnson's Floor Wax.

Slow is the only way to avoid burning the micarta ... burning will show in the final polish for sure. One of the reasons I really like a belt grinder driven by a variable speed DC motor.

Different brands of micarta vary widely in the finish they will take.

Yep,

I see you're using 1/8" scales. You shouldn't be spending much time on the grinder with scales that thin. Just get the shape about right, maybe 5 minutes with the grinder, then go to hand tools, like the bastard file, then sand paper backed with something that matches the shape of the handle you're making. I have a whole box full of items I use to back sandpaper, so the handle comes out like I want it. I use hockey pucks cut and ground to different configurations, and cork ski wax squares mostly for backing. Wood backing is too hard for me to use and get a good handle configuration.

Don

This one seems to have gone a lot better. Using Al Oxide belts may be part of the solution...I wonder if the zirconia belts were not working well with the light pressure. The file worked right to the point that I hit the tang. I'll venture that I got a good heat treat as a coarse rasp immediately went completely (and visibly) dull everywhere it hit metal!


Linen micarta, nickel silver pins, cryo treated 440C hand rubbed to 1200 grit finish.

Now to finish the next 2 in time for Mother's day...

Yes, if you are not heat treating your own blades, consider Paul Bos!

When I shape micarta with the dremel and sanding drum, the micarta does burn. When I have a rough shape, I then use different shaped rasps to even everything out, then wetsand. Using water eliminates dust, and keeps the paper from loading up. The burn marks disappear from rasp to 220 grit.