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View Full Version : Initial Coarse Belt Scratches - How to Remove Question



Marko Tsourkan
04-12-2011, 07:51 PM
I thinned one of my white steel honyaki gyuto. I used Norton Blaze Ceramic 50 grit, Blaze Ceramic 120 grit, Ceramic Norax X65, Norax Piramid x45, and finally Norax Pirmaid X30.

I then moved onto a hand-sanding, starting with 180 grit 3M automotive paper. I discovered that under all these grits above, the initial scratches done by Blaze Ceramic 50 are still here and there on the blade.

After some more sanding, some scratches were still difficult to remove. I wrapped a sand paper around a wooden block and applied a good amount of pressure. but I felt that I need to drop way below 180grit to make a difference. Didn't have a a lower grit paper on hand, so had to just keep sanding with 180. Very lengthy and inefficient process, as it turned out.

Norton Blaze is quite popular line of belts, so how do you guys deal with this issue (deep scratches) before moving onto a hand rubbed finish? Is there a better way to remove the deep scratches? I heard people use a disc sander for that, but I haven't tried it myself.

Marko

Delbert Ealy
04-13-2011, 12:31 AM
Marko,
Every time you change grits, you need to make sure you remove all the scratches from the previous grit, before you move on to the next one. In your progression when you moved on to the norax x65 you should have had no 50 grit scratches left. You may have jumped ahead in your grit progression a bit fast, and that may have complicated your problem. When you change grits try tilting your blade so that it will change the direction of the scratches, it will allow you to see the deeper scratches better.
I go all the way to an 800 grit belt and then move back to 400 grit for hand sanding. I don't have any scratches below 800 grit when I go to hand sanding. Take your time and slow down and get it right and then worry about picking up the speed when you are confident that your process works every time. You will save yourself time this way, 50 grit scratches take hours to remove by hand sanding.
I would add a norton(or trizact cf) x160 after the blaze 120, I think you will find it easier.

Marko Tsourkan
04-13-2011, 12:41 AM
Thanks for the advise. I will give it a try.

M

StephanFowler
04-13-2011, 09:32 AM
Delbert hit it right on.

patience patience patience.
also spend some effort getting used to your belts and what speed they want to run at. I find that my best belt finish is from a 600g belt running wet (I spray it down with a bottle every couple passes) at about 1200spfm but I think it would finish a lot better if I could go a little slower.

anyone wanna loan me 300$ for a variable speed controller???

Lefty
04-13-2011, 09:39 AM
anyone wanna loan me 300$ for a variable speed controller???

I'm sure quite a few would love to, in exchange for one of your knives :p

l r harner
04-13-2011, 09:52 AM
VS is great
and i love the finishe the gator belts give but the bigest tip is the angle change to see the big scratches as you work up the grits and make sure you ahve good lighting
also i only use 5 grit belts for hogging and most the time use 80 then 120 to get things closer to finish before anything higher

Marko Tsourkan
04-13-2011, 10:05 AM
Thanks again. I am fairly new to grinding steel, so there is much to learn.

Time to buy more belts (sigh).

I am a big fan of VFD. Have three from KB Electronics, but two are for up to 1HP, so I use them for disc sanders, horizontal and vertical (in works). I got both them new on Ebay for about $100 and both have a knob dial.

Stephan, I see digital VFD for higher HP motor quite frequently for about half what you need, but I take you would like it with a dial.

Is there a difference in Gator belts from 3M and Norton or is it just a preference thing?

M

Delbert Ealy
04-13-2011, 11:45 AM
I know a lot of makers love the blaze belts, but my favorites for roughing are the 3m 967, for finishing I love the trizact cf(gators).
I have variable speed on my grinder, but I mostly run it full bore(its how I learned to grind).

StephanFowler
04-13-2011, 11:49 AM
I know a lot of makers love the blaze belts, but my favorites for roughing are the 3m 967, for finishing I love the trizact cf(gators).
I have variable speed on my grinder, but I mostly run it full bore(its how I learned to grind).

the 967's just seem to lose there bite a lot faster than the blaze when I use them, could be technique though

I run full tilt too until I get to 400 and up

Michael Rader
04-16-2011, 02:16 AM
Great advice there. The key is one Delbert hit earlier, and that is to tilt the blade 20-30 degrees with every grit change. This way, if you look carefully, you will always be able to see the deeper scratches until they are gone. And regarding Gator belts, I love them for "belt-finishes." However, if you plan on hand-sanding out the finish, for some strange reason, Gator belts always leave deep scratches here and there. It's like using a 400 grit belt that has three pieces of 120 grit stuck in it. I don't know, but some of the other custom makers have found the same problem.

One more tip. I use 36 grit Blaze belts and then go straight to 220. Give it a try sometime. Got to use a new 220 (I like Blue Zirc, still waiting for a good ceramic in that grit.)

p.s. I've just remembered that the 36 to 220 grit trick doesn't work so well on super wear-resistant steels like M4 and A11. But, still try it with what you are using.
-M

Marko Tsourkan
04-16-2011, 08:28 AM
Thanks. I will try some of the methods you mentioned. I have heard from another maker that the old school guys would grind with 50 grit and then go to 400 and eventually mirror finish.

M

RRLOVER
04-16-2011, 10:17 AM
As a newbie to grinding I keep the grit progression tight.I used a blaze 50-80-120 then norax 100-65-45 then hand sand 400 & 600 before i etched.Del gave me the advice of tilting the blade so i had no issues with my last knife.

Diamond G
08-21-2011, 12:10 PM
Marco
Other than getting the scratches out on the grinder, one thing I was turned onto a couple of years ago is Mobile 1 engine oil for sanding. I dont have a clue why it works, but it does. Put a few drops on the blade while sanding, and the material seems to float off the blade. It cut my hand sanding time to almost half. Again I cant explaine why it works, only that it works very well for me.

God Bless
Mike

PierreRodrigue
08-21-2011, 12:50 PM
+1 on the Mobil 1

jmforge
08-21-2011, 02:34 PM
The little EDM stones are good for chasing scratches. The suggestion of grinding at a slightly different angle to see if you have gotten rid of the bigger scratches is a good one. Usually, the only place that you can
t do that is up by the plunge cuts and that is where the EDM stones come in really handy. They are also good for getting the scratches right out on the tip where you might be afraid to grind to aggressively.

SpikeC
08-21-2011, 05:07 PM
I use WD40 for oil stones and wet/dry paper. A small spray can is convenient and tidy.