From grinder to buffer

Good Saturday Morning guys,

I’ve got a question about finishing stainless steel. I just got back my first group of 440c stainless steel knives from heat treat. They are all marked “59” in hardness. Unfortunately, I use a 1 X 30 HF grinder. It works pretty good with the coarser grit belts and I generally get very uniform flat grinds up to about 220 grit. When I go above 220 I tend to get ripples or waves in the surface. So, for instance when I go from 220 to 400 I will get a non-uniform finish. Most of the blade surface will be good at 400 but there will be one or more “channels” or” troughs” running from point to recasso that will still show 220 scratches (maybe 1/8” wide). If I take it back to 220 I can get the fully uniform finish but go to 400 and I get the “rippled” finish with some 220 scratches. Can anybody explain to wm why that happens? I have thought it was because the higher grit belts are less rigid that the coarser belts they might tend to buckle against the platen and skip some areas of the blade.

Anyway, I sent these knives to heat treat having grinded them to 400 and leaving whatever 220 scratches that happened to be there. My thought was I would hand sand them from there to 1200 as I always did. Well, being a bit lazy and having these orders due by Christmas I’m looking for something a bit less labor intensive and a bit quicker.

Previously, on my high carbon blades I have hand sanded from to 220 to 1200 grit and then gone to the buffer to finish (I do mostly mirror finishes.). With the first stainless steel knife I tried to find a system whereby I can take a 400 grit flat grind with the 220 scratches in it directly to the buffer to finish, thereby eliminating the hand sanding. Let me interject that in a former life I was a silversmith and I am pretty familiar with the high speed buffer - both its dangers and it capabilities. I am not having good results with buffing out those 220 scratches. Short of purchasing a 2 X 72 (which I plan to do as soon as I can) can anyone provide for me a protocol, focusing on buffs and compounds, to go from the grinder at 400 with some 220 scratches and use the buffer to finish the knife from there without any hand sanding. I would be eternally grateful. Thanks,

Wallace

Regardless of the steels, you should probably round out your belt selection to work to your advantage. I've never used or owned a 1x30 but I do have a 1x42 that has belt selections from 36 grit to 600 readily available. I'm willing to bet that if you filled in the gap between 220 and 400 with a 280 grit AND a 320 grit, you'd get better results. Your 400 grit is just rounding off the tops of the canyons that the 220 made. Even a medium Scotchbrite belt inbetween the 220 and 400 would probably help, which I do know is available in 1x30. You can't beat a good belt progression for good results. I can't imagine doing an entire knife on a 1x30 but IF I did....I'd use every trick available .

Rudy

I find that I get better results in polishing ferris metals by using a medium hard felt buff instead of a stitched buff. I will sand until I think I have all the scratches removed with one grit. A quick buff on the blade will reveal any scratches. I will then sand those scratches to remove them with the same grit. I will then go to the next grit size...after cleaning the blade in between grit changes. I use a 3 step process using a titanium polish (TP100, TP200 and TP300). I use both the front and the sides of the felt buffs. Each stage is kept in it's own plastic zip lock plastic bag to prevent contamination. I also use various shaped cloth buffs to hit those problem areas that are unreachable with the felt buff.

Remember that in polishing, like soldering, cleanliness is next to Godliness. If you buffs are cross contaminated with polishing compounds, the contaminated buffs will actually scratch your blade when going to a higher grit.