3M belt question

T

Taximanny

Joined
Jul 27, 2015
Messages
460
About to make an order and had a question on 3M scotchbright belts.

At what point do I use this belt in the process.

Right now before I do A hand rub finish, I take my blade to 220.

So at what point do I use the scotchbright ??
After 220 or when ??

If ordering for a vertical satin finish, do I order the heavy, medium , fine or the extra fine belts???

I do plan on ordering a Trizact belt too.

Any tips ??
 
I can tell you I have a medium scotchbrite and Its is pretty coarse actually. If you are looking for a nice belt finish you probably want to go fine or extra fine.
 
I have a blue (very fine?) that I attempted to use after I hand sanded to 400. It was rougher than the 400 grit so I had to re finish by hand again. Maybe it needs some break in time, but was way rougher of a finish than I was expecting.
I'll be paying close attention to this thread for tips from the pros.
 
I have red, blue, and grey scotchbrite belts. This has come up a few times since I've joined. At first, I couldn't believe people were using them because of how coarse they seemed to be. I use a lot of 3m Scotchbrite products in my day job. Most of them do not have the coating all the 2x72 belts have, and leave much finer finishes.

The red is (in my opinion) useless for knifemaking. It's too coarse to finish, it doesn't remove material fast enough compared to a woven abrasive belt. It's greatest utility might be in breaking and rounding edges.

The blue, once broken in, can give a nice matte finish. My first experiments with it made me think it was also too coarse, but I had 2 other underlying issues. 1- uniform blade hardness. On a differentially treated blade, I would get different finishes between the hard edge and softer spine. 2- I wasn't taking the blade to a good enough finish prior to using. I found going to a true (meaning all other scratches removed) 400 grit and then hitting with a broken in blue belt gave a pretty nice matte finish.

The grey, also needing break in and a 400 grit finish before using, leaves closer to a satin finish.


I wish they made a belt that was a direct duplicate of the red and grey hand pads, with no coating. They would leave a really nice satin finish based on my experience using them to polish things on a lathe.
 
Any tips on breaking them in? Maybe run them against some scrap or mild steel for a bit?
 
Since I have a lot of laser cut blanks I just used them to knock the edges off and make them nicer to handle. Hitting an edge will wear the belt faster than a face.
 
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