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I was making a knife, and using belts to get to the higher grits.
Every time I nearly had it, there was a grit particle, or perhaps a fray, or perhaps just a clumsy movement, and a fresh deep scratch appeared in the polished surface. :rant:
With the last attempt I tried to correct it and made it so bad I had to go back to the lowest grit. Now I am just handsanding the blade before taking it to a buffer.
yeah - know that feeling. i have had this happen many times. Sometimes i think the belt has an odd piece of grit, and sometimes i think an imperfection in the steel. Mostly it may be me. i ususally finish to 600 grit before heat treat. Then hand sand from 400 {yep - backwards} then 600 & 800. Then heat treat. After that it's back down to 360 hand sanding with water, right up to 2000 through all the grits i have available. It is definitely an exercise in patience.
The answer {which i have not yet explored} may be a combination of the best quality belts you can find, plus a variable speed grinder that can be slowed right down on the fine grits.
Whatever the method found, patience is key.
Regards Adam.
I'm curious what type of belt you are using.
My problem with fine belts was that it showed every error from the previous grits. I also used to have problems with errant scratches until I started storing the belts outside of the equipment room. For the record, I'm using Norax abrasives.
My rule is, the finer the belt, the slower the speed. Also, slower that that after heat treating. My grinder is a 10 speed, with a treadmill motor. I like PDobson's idea about storing belts in a clean environment.
Interesting, I think that my solution would be to ask Phil's mother to hand-sand it for me. :D
I like Phil's idea as well.
I've never had errant scratch issue with any of my belts whatever the grit or speed used. The new unused belts do hang on the opposite side of my shop away from my grinders and other power tools. The ones I use hang next to my grinder at hands reach.
look into then3m gator belts they now have them to A30 and notron makes even finer ones slightly different build
the highest std. style belt i have in the shop any more is 120 grit
Hand sanding for me the same as Adam's approach. Everything I do takes time and patience as I use a file and diy jig to set my bevels and a rasp to rough out handle shapes then it's all done with elbow grease and sandpaper.
I've found if I'm doing full flat grinds the quickest way to polish the blade is to wrap various grades of wet/dry round my file and spray with WD-40 and use the same jig I set the bevels with to clean the blade up. Then all I have to do to finish it is a quick hand sand followed by a good rub of Autosol and leather to get the finish where I want it.
Your problem with the random scratch on the higher grades is the only good reason I can think of to not having a belt sander! Basically it's a problem I wish I had if you get me. Hope you find a suitable solution!
I know this isn't a knife forum but what kind of knives do you fellas make for the most part? Just curious...
Apologies for the thread hijack but I really am curious to see what others on here do for knives! Here's my latest, I still need to polish the steel then it's done.
http://i640.photobucket.com/albums/u...p/DSC00722.jpg
http://i640.photobucket.com/albums/u...p/DSC00732.jpg
http://i640.photobucket.com/albums/u...p/DSC00729.jpg
http://i640.photobucket.com/albums/u...p/DSC00725.jpg
As mentioned earlier I do all this by hand with a file and jig and rasps and sandpaper and water stones, go easy on me! Any chance of a pic of what you guys do?