Blade Finishing

watercrawl

watercrawl

Joined
Jun 2, 2006
Messages
422
I've been having fits finishing the sides of my blades and I'm looking for a bit of advice.

Currently I use in order:

50 Grit belt...3M or Blaze
80 Grit belt...3M or Blaze
A160 Gator Belt which is supposed to be 120 grit
A65 Gator belt which is supposed to 240 grit
Fine (Blueish colored) Scotchbrite belt

The Scotchbrite belt I'm kind of guessing on as I don't really remember.

I get a nice finish with this sequence, but it seems more time consuming than I think it should be. What I end up with are scratches from the Blaze belts that are a PITA to take out with the finishing belts.

Am I expecting too much, or will adding a 120 grit Blaze in there before the Gator belts help a bunch?

I reckon it wouldn't cost too much of anything to try that, but I'm asking in case a different method will work better before I go ordering more belts.
 
I start at 80, then you wont get as deep scratches as with 50. How thick is the steel you use? I am no expert so more advice is needed.
David
 
My guess is that the scratches you are having trouble with are actually the deepest scratches left over form your 50 grit blaze. My suggestion would be to spend a bit more time with a fresh 80 grit belt to make sure you've removed all the 50 grit scratches. Then spend a bit more time with the 120 Gator for the same reason. When using powered belts, it can be really hard to see the deeper scratches left behind as all the scratch marks go in the same direction and blend together. A variety of lighting and looking at the blade on an angle with reflecting light can help. Also, I'll sometimes make a pass or two and a slightly different angle just to see where I'm at. Changing the angle of your scratch marks is standard practice when changing grits in hand finishing and can be a useful exercise just to let you know how things are coming when working on a grinder as you can see really well where the deeper scratches are from the courser belt.

Edited to add: As for where to start, I start with Blaze 36 grit belts :D. They cut really fast. As long as you spend your due diligence on the next grit up and leave some metal to remove for the higher grits, they work really well.

--nathan
 
You might try using a 60 grit 3M cubitron belt to hog off steel instead of a 50. Doesn't seem like too much of a difference but I think the 60 grit deep scratches are a whole lot easier to get out in the long run and the 60 grit belt hogs plenty of metal so your bevels should go almost as quick as with the 50.
 
if you want to make sure you have all the deep scratches out from the last coarser grit after moving to the next finer grit, take a few grits finer abrasive and go across (90 degrees) the finish that you already have. it will highlight any deep scratches that are left from the coarser abrasive.
 
I'm with Nathan, I start with 36 or 40 grit belts and get fairly close to where I want to be then switch to a 120 grit and dont stop until I'm SURE all the coarser scratches are gone then I go straight to A65 or A45 then finish up with a scotchbrite.
 
If you get a good, consitent 220 grit machine finish you can rub that out to an inline finish with 220 paper by hand pretty quickly, and then move on to the finer belts knowing that there are no coarse grit marks. If it takes a long time to rub out the machine scratches with 220 paper then you didn't do enough with the 220 belt. I have found that 15-30 minutes of hand sanding is worth the effort even if you are doing a machine finish, to prevent deep scratches from popping out when you thought you were almost done.
 
Thanks guys, I appreciate the input.

To answer the one question, I'm starting with 0.108" material. Heat treated to 62HRC prior to grinding anything.
 
With that thin of stock start with an 80 grit belt do about 50% of your grinding then switch to a 120.Then work your way as high as you wish.
Stan
 
richard j said:
if you want to make sure you have all the deep scratches out from the last coarser grit after moving to the next finer grit, take a few grits finer abrasive and go across (90 degrees) the finish that you already have. it will highlight any deep scratches that are left from the coarser abrasive.
Click to expand...

Exactly what I was thinking, it only takes a moment and will show those deep marks that can be "hidden" by the next belt, only to really make you cuss later.

Those Gators you like are also available in A45 (somewhere between 360-400grit depending who you ask) and I think another step higher still. Going a step or two higher than your final machine-satin or hand-rubbed finish, then coming back to your ScotchBrite or whatever, results in a cleaner, crisper, more consistent finish. Again, if you already have things flat and fairly clean, it only takes a couple minutes.
 
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