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Help with a polish


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Hey guys so a couple weeks ago i had made a tanto style knife and tried to give it a mirror polish. It came out ok but not perfect you can still see small faint grind lines. So i did some more reading (actually LOTS of reading) and watching some vids. I did come across alot of good info but i do have 2 questions the best way for me to describe them is to first just tell you what i have to work with so...as far as the grinder goes and the higher grit belts i have 800 grit norton norax, 1200 and 2000 deerfos (the blue ones), 2500 3m trizact (regular not the gators), and 3000 norton norax. Then i have wet/dry sandpaper in 1000,1500, 2000. I also have those 3m pads (i dont know what they are called you can get them in auto part stores they are like sand paper but its a thin foam pad with grit on the front) one is marked 1200-1500 grit, i also have 3000 and 5000 grit. As far as compounds for buffing wheels i have emery, tripoli, yellow stainless, white rouge and red jewlers rouge (Not sure if white rouge or red jewelers comes first any ideas?). "knife makers" green (this is not the green chrome and the only place i found it is a jantz), and pink scratch less. So i was going to go all the way up the grits to 3000 on the grinder then go to the sand paper and the pads....wich is my first question if i go to 3000 on the grinder where should i start on the hand sanding 2000? maybe the 1200-1500 pad? or lower? after that on the buffing wheel i guess it depends where i am at with the scratches at that point to decide where to start...emery if its real bad but probilly tripoli? And the second question i have is i just recently got this "knife makers" green and the pink scratch less so i figure the pink scratch less would go last but i am not sure where the knife makers green fits in the order of compounds. Has anyone used this any ideas? My main questions are about the knife makers green and where to start on hand sanding but any bits of advice if you guys think i am doing something wrong would be appreciated. most of my plan has come from what i have read not on experience as i said i have only tried to mirror polish one blade and its ok but looking to improve on this one. thanks guys.....

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If there are marks left then you rushed the grits. Another common mistake is to not keep the piece moving and NO, not whipping back and forth as fast as you can, a smooth constant motion and change of angle.

You may have also gotten a piece of loose grit trapped between your belt and blade. Brush your hair when changing belts, you'd be amazed what gets caught in your hair. NO do NOT use an air hose! :o Use a soft hair brush and be gentle a sharp grit bit can cut your scalp.

Frosty The Lucky.

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good call thanks frosty....i was wondering if last time i went through the belts to quick and not removing all the scratches from the previous belt. Its hard to tell. When hand sanding you can go in opisite directions on each grit to see when there gone but that is very hard to do on the grinder especially when bevels are involved (for me any way i am still new to knife making i've made a few but definitely still consider myself to be a beginner and have a kmg grinder for a few months now getting better with it tho).........that is a good point about stray grit. i didnt have any hot water in my house a few weeks back so i went a couple days with out a shower and even though i tried to brush stuff out of my hair you wouldn't believe it probilly 5 pounds of grinded metal came out of my hair! never thought about it getting caught on a belt or the blade tho

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Fwiw, here is my suggestion for grinding: Never, ever use 36 grit even for rough grinding a blade. It will leave micro scratches even after going thru the various smaller grits. I know it doesn't sound logical, but believe me the 36 grit belts leave nearly invisible micro scratches that after heat treat are nearly impossible to get out. I like to start at 50-60 grit to rough grind, then move thru the grits to 220 prior to ht. After ht, I go back to 220 to clean up where I left off, then start on higher grits from there. Recently, a maker in Mn. introduced me to 3M film backed belts that go from 60 down to 9 micron film backed belts. They are strictly used for polishing and not stock removal. 9 micron is equal to 1200 grit. After pretty much wearing out the 9, I load it with polishing compound to get a near mirror finish. The 3M belts are purchased thru Trugrit and cost $4-5. ea. Hope this helps.

John

Gearhart Ironwerks

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Don't forget that each stage of grit requires a much longer time to remove the scratches from the last---it's basically exponential and not linear.  It's easy to get rushed or lose track of how much time you have spent removing scratches so you end up shorting the step.  The same thing is also common when people are learning lapidary work:  It seems that you've spent twice as long grinding this finer grit than the last but it's STILL not enough to remove all those previous scratches.  Finer grit takes a long time to remove coarser scratches and if you miss even one scratch, you've got to back up to that grit level and re-start from there.

Cleaning like a zealot between grits is also necessary.  You'd be surprised how much stray (and basically invisible to the eye) grit can ride on the part you are making.  Obviously the grit also gets into everything nearby and can be re-introduced easily.  When you can't wipe things down with a slightly oily clean cloth, you usually can with a cloth soaked with rubbing alcohol--it flashes off so doesn't rust things.

There are some tricks to help--like doing a final pass per grit in a single direction, changing that angle each time you move up a grit.  You can more easily see any previous scratches because they will be at an angle that differs from the current grit.

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Thanks guys 

gear hart....i should have mentioned i never use 36 grit. When i start a blade i cut out with a angle grinder and the put a 50 grit belt on a 4x36 belt grinder. I do what i can there then move to the KMG 2x72 grinder with a 80 grit (usually used but not "dead") for the profiling then move to  fresh 80 grit for bevels and go up from there. I have been using a combinations of VSM ceramic (80), norton blue fire (120-220) also norton ceramic the ones with brown front and orange back also (220), i used to use hermes and klingspor for 400,600, 800. but recently started using the 3m trizact gators for (400-600) and norton norax (800), then i got deerfos (1200-2000) 3m trizact (2500) and norton norax (3000). I haven't tried the 3M micron belts but have seen them and do plan to try them soon. Like i said i am still new yeh i have made a few knives that i am happy with but definitely a beginner and still learning how to best use the KMG. When i started i would clamp the blade to a jig made from angle iron do just a couple passes and then take it off and go freehand. I did just enough with the jig that when i took it off and went freehand i could "feel" that flat part of the bevel to get a consistent angle....i am trying to get away from the jig all together but all of the grits following that initial grind are done freehand.

Kozzy...As you were saying i think one of my problems on the last one was trying to go through the grits too fast i am going to slow it down on this one. I usually wipe the blade with my hand but didn't think of wiping it with a cloth between grits i am going to try that and hope it helps. Now I understand about going different directions with each grit  so you can see when the last ones scratches are gone. Thats easy when hand sanding...one grit tang to tip next side to side and so one. Now going back to what i was saying above about still being a beginner on the KMG grinder. I can see maybe being able to go in different directions on the flat parts but you cant really do that with the bevels right? or am i missing something. And as you said do a final pass in a different direction even if i could do that on the flat parts  wouldn't it take more than one final pass to "erase" lines go one way and make them go the other? Is there any tips on how to "see" or "tell" when the lines from the previous grit are completely gone. especially on the bevels when you cant go opisat directions on the grinder? i think that is the number one problem on the last one the flat parts were good not much scratches but the bevels had those lil faint grind lines.

No one knows where "knife makers green compound" fits in the order with other compounds?

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