Too hard to hand sand?

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Jun 8, 2018
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I recently sent out a few blades to a professional heat treating company. Assuming the blades were going to come back with forge scale all over them I just left them at a dirty 120 grit. I was thinking I’m going to have to go back with an 80 grit when I got the blades back. Little did I know the blades came back perfectly clean. And hardened to 60hrc. Now no belts will touch the steel. I do two passes on a 120 ceramic and it cuts, then I sharpie the blade and take 6 more passes and no sharpie comes off. I have worked this steel for 3+ hours trying all combinations of belts. Also, when hand sanding (150,320,or 600) the oil isn’t turning black from material removal and no scratch lines are showing up. This is 440c stainless steel. Guys/gals..... I need help.
 
No sharpie at all comes off? I find that hard to believe, even with a dull belt. Are you using new belts? Can you post pics?
 
Yep new 120 ceramics. If you have an Instagram go to my story @austinseibert I have a picture of the lines I’m trying to remove, not the sharpie tho.
 
60Rc is HARD for 440C, which has LOTS of LARGE carbide aggregates. You've got a tough row to hoe ahead of you.
Fresh abrasive matters. I'd try some of the 3M Trizact stuff in the A100-A200 range.
 
I hand sand S110V at 62-63 HRC post HT with no major issues (But I also finish them to a high grit pre-HT). I also grind AEBL post HT at 61-62RC with no issues. What speed are you running your grinder at? Maybe slow it down a bit and see what happens.
 
I recently sent out a few blades to a professional heat treating company. Assuming the blades were going to come back with forge scale all over them I just left them at a dirty 120 grit. I was thinking I’m going to have to go back with an 80 grit when I got the blades back. Little did I know the blades came back perfectly clean. And hardened to 60hrc. Now no belts will touch the steel. I do two passes on a 120 ceramic and it cuts, then I sharpie the blade and take 6 more passes and no sharpie comes off. I have worked this steel for 3+ hours trying all combinations of belts. Also, when hand sanding (150,320,or 600) the oil isn’t turning black from material removal and no scratch lines are showing up. This is 440c stainless steel. Guys/gals..... I need help.
Are you sure that you put belt on grinder with right side out ? I can make dust from 10 inch long piece from 67 hrc steel faster then you turn TV on .............
 
60Rc is HARD for 440C, which has LOTS of LARGE carbide aggregates. You've got a tough row to hoe ahead of you.
Fresh abrasive matters. I'd try some of the 3M Trizact stuff in the A100-A200 range.
I was trying some 120 and 220 ceramic and then went to 40 and 35a trizact. That was probably to high of a grit before even getting the previous scratch lines out. What would make trizact different? I know very little about trizact belts.
 
I hand sand S110V at 62-63 HRC post HT with no major issues (But I also finish them to a high grit pre-HT). I also grind AEBL post HT at 61-62RC with no issues. What speed are you running your grinder at? Maybe slow it down a bit and see what happens.
I’m running it at like 50-70% idk what rpm but it’s a 1.5 horse 2x48
 
Are you sure that you put belt on grinder with right side out ? I can make dust from 10 inch long piece from 67 hrc steel faster then you turn TV on .............
Haha yea I’m sure it’s on the right way. Paper side out right? Lol I’m just kidding
 
2X48, if you can slow that down to say 20% you may do better. A belt that small is going to wear out much faster than 2 x 72. I use a 2 x 42 for years, but did my finish work pre-HT.
 
I made a couple of kitchen knives in S90V. I sanded them to nearly finished before heat treatment. It took me a solid week of sanding to get them where I wanted them after heat treat. I didn't think 440C was as wear resistant as you describe. At least you know now to take the finish much higher before HT.
 
After ceramics I usually go to "gator" belts at a300 then a100 then a65 then a40 before hand sanding.
440C shouldn't be a bear to grind even at as quenched hardness (which you wouldn't do).
 
It is not HRC what make grinding or hand sanding difficult................what ingredients it has inside is what makes the difference :thumbsup:

This is true to an extent. When I hand sand carbon steel at 64hrc, I can easily feel the difference from 59-60hrc.
 
2X48, if you can slow that down to say 20% you may do better. A belt that small is going to wear out much faster than 2 x 72. I use a 2 x 42 for years, but did my finish work pre-HT.
I’ll try slowing it down. How high did you go on the belts before heat treat?
 
I made a couple of kitchen knives in S90V. I sanded them to nearly finished before heat treatment. It took me a solid week of sanding to get them where I wanted them after heat treat. I didn't think 440C was as wear resistant as you describe. At least you know now to take the finish much higher before HT.
Yea now I know. It’s some pretty tuff stuff I’m going to look around at different belts.
 
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