Photos Flattening a big hard black Arkansas

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Khromo

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I recently ordered a 12 x 3 x 3/4" hard Arkansas from an Amazon vendor. When the box arrived I ripped it open, and immediately noticed "This hard Ark is black!". Checked the box and sure enough, instead of the hard Ark ($92) they had sent a hard black Ark ($240).

I will confess that I struggled with this for a week or so. Finally I said to myself "If you are having to wrestle with what to do next, your choice should be clear, you ^%#&*&^ $%&*##!!!"

As De Niro said in Ronin, "If there is a doubt, then there is no doubt."

So I e:mailed the vendor and told them what had happened, and suggested that I would be happy to call it even, if that was okay with them.

They immediately mailed back telling me to keep the black Ark, and thanking me for being honest. Nice folks!

Problem is, I've been rubbing this baby on a Grizzly "B" surface plate covered with 80 grit AO paper, and it is a long way from true, and I am getting tired. I ordered up some 80 and 120 grit silicon carbide powder and a tile rubbing block, but I'm thinking there must be a better way.

Does anyone have any suggestions on how to move this process along? I've got a 9 x 12 surface plate and a 4 x 36 belt sander but I don't want to wreck this stone. Should I be looking for a machine shop or a place that makes gravestones?

Please help me. I feel like a cave man over here.
 
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Khromo said:
I recently ordered a 10 x 3 x 3/4" hard Arkansas from an Amazon vendor. When the box arrived I ripped it open, and immediately noticed "This hard Ark is black!". Checked the box and sure enough, instead of the hard Ark ($92) they had sent a hard black Ark ($240).... Problem is, I've been rubbing this baby on a Grizzly "B" surface plate covered with 80 grit AO paper, and it is a long way from true, and I am getting tired.
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Hi,
How could you tell its a "hard black arkansas", by color alone?

As internet tells us, even soft arkansas can be black in color ...

How much out of flat is it (how many mm out of flat)?

P80 grit is only 195 microns (.195 mm)

For hand flattening, you need coarser grit , 24-36 grit or coarser (that is .5-1mm grains or bigger).
Traiditional way to get stuff flat "quick", is sand on concrete and lots and lots of force (50lb) ... or on a cinder block... and maybe an hour? then condition the stone

The fastest option is get a tile cutter to trim it flat, should take all of 1min :) I've seen it with my own eyes
A bandsaw might be a little slower or about same time (some video whose title I dont recall)

Remember to use lube and lung protection, stone dust is bad


17minutes he says Flattening Rogue Arkansas Stones with a Cheap Belt Sander - David W


longer(?) with hand power on concrete block How I flatten/repair Arkansas stones - Rough Rooster Knife Sharpening
 
The black hard Arkansas is better/ finer than the hard Arkansas. I doesn't take 50 lbs. of pressure. One can level it on a coarse area of flat concrete with water. Only the black Arkansas are hard and fine. Not some other designation. The Translucent is close. The grit you are using is enough. Just go to silicon carbide grit. What you have will work as I have done it. Depending on how much out of level it is, I worked mine in a circular motion on concrete and a coarse SiC stone. Then back and forth with water. When the slurry develops rinse it away to fresh grit. I would mark the surface w/ a black felt marker, using diagonal lines and start rubbing it. Check your progress as it may take time, depending. Good luck, DM
 
Arkansas stones are cut after quarried and this cutting may not be level. Once you work it and get it level you'll likely not have to do it again. I would finish it off on the 120 or 220 grit. Don't let it glaze over as then it won't cut. DM
 
Thanks a lot, guys!

The wooden box says "PRO CUT" and "Hard Black Arkansas", and I looked it over with a 30X scope. Seems legit, just a little cockeyed, and spread over 12" it looks like a task to get it flat.

I've ordered some SC and I've got a good piece of glass, but in the meantime I am going to check the rockpile for a Mexican paving stone that looks sort of flat. I've got a brick I trued up for sharpening garden tools, and I will see if I can't get it started that way.

I'll post up the results and post some photos if I can.

Thanks again guys!
 
I am sure you are all anxiously waiting on an update, and since I am new here I figured I should provide some pictures as well. You guys are generously helping out the new guy, so I will try to make it more entertaining!

I wanted to put some of your excellent suggestions to use right away. Here is the workshop.

J3OEOC4.jpg


I hit the trash heap on the north side of the house, and found some sharpening products I didn't know I had!

On the left is a Mexican paving stone. It is pretty soft, and gives up a medium grit slurry pretty fast. It seems to cut pretty well but I couldn't find much flatness in there. I used it right out of the chute, but when I started to get to about 70% I moved along. This stone puts a killer edge on a very hard use axe. It is the very best tool I have found for that kind of work.

The next stone is my "polishing brick." It is light gray, and it seemed fairly coarse at first. After half an hour on the hard black Ark, it almost seems to be glazed, and cutting much more slowly if at all.

The third stone is a paving stone, might be concrete with coarse gravel. It is pretty soft, probably too soft and loose for a hard stone like this.

On the upper right you see various "Nagura bricks" and a cheap 300-grit diamond stone that I used to clean the stone up after a session on the Mexi paver.

QKKNgst.jpg


Here's the stone itself, mostly level at this point, maybe 2-3 square inches at each end not square yet. I'm not sure if it's worth it to get that last 15% or not (considering it is all around the ends, two opposing corners), but the 80 grit silicon carbide powder will be here tomorrow, and I am going to have to try it out for sure!

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At this point, I had to put some steel on there, so after a gentle rub with a 300-grit diamond stone to smooth it out a little, I took a few strokes with an AUS-8 Boker Kwaiken that had been sharpened to 600 grit (on a Wicked Edge diamond stone) at 20 per for rough use in the garden and around the shop.

Using water for lube (the stone has never tasted oil) the bevel glided smoothly over the mostly unpolished stone, and the scratch pattern was finer than the 600. I didn't give it many strokes, but my initial reaction was it is a smooth stone while still providing good feedback. The knife now cuts paper beautifully and pops hairs pretty reliably. I'm looking forward to seeing how the stone performs after it is polished a little.

To my inexperienced hand it felt like something between a hard Ark and a black Ark, but that could easily be confirmation bias.

Because what do I know?!?! Probably less than everybody else on this board! Just ask my wife!!!
 
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It will require the harder grit. Arkansas stones are graded by density/ specific gravity. Only somewhat color. Your black is not jet black. Still, finished off right it
can be a good stone. DM
 
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I would start out with no higher than 60 grit.
36 grit would be best but that is difficult to source at times.

Once flat I would bring it up to 120 grit then sharpen a bunch of knives to smooth it out.
It may seem like a bit of work but these hard Arks are well worth it.
 
annr said:
Can you use a diamond plate?
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Hi,
Yes you can but its very very very slow, as you have to go light since electroplated diamond platess are easy to damage.

You could always get coarse diamond polishing lapidary powder for use (and "infinite" reuse reuse reuse) on tile or sheetmetal, as you can put all your weight into flattening :),
or if you have an angle grinder,
one of those 4" 100mm Diamond Segment Grinding Cup Wheel Disc Grinder Concrete Granite Stone , they're "brazed" or something much more durable,
only ~$4 and up on the ebay :) double and up on the amazon...





See 1412415-Spyderco-Fine-Benchstone-Out-of-Spec-My-paper-thickness-test
thats talking abouts printer paper thickness out of flat, and it takes a long time to flatten with light force and electropalted diamond plates

Flat lapping a Spyderco ceramic bench stone
...I started with .009" hollow (0.2286mm or 228.6micron) and a low end of about .020". It took a bit over an hour to wear down to my stopping point.



Turned my Spyderco bench stone into a combo-stone! (write up / pic's)

Now we start in again, draw a grid to make sure your staying flat and to monitor progress, I spent about 90 minutes with each of the 220, 360 & 600 plates (redraw grid when needed).

After that I moved on to the EF (1200) DMT, this final one took about 2.5 hours of work to get to a point I was happy with it. Same process.





Customer reviews: Spyderco Benchstone Fine 2" x 8" W/Box
Not flat enough
- lapping takes many, many hours
 
Khromo said:
Does anyone have any suggestions on how to move this process along?
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Best answer : Use water stones they are quick and easy to flatten . . . I use a big O' DMT extra coarse to flatten and condition the water stones and yes the DMT is extremely flat.

Next best answer if you are (like I was) all infatuated with hard Arks (you'll get over it when you learn how frekin slow they cut and how limited in WHAT they will cut is) . . . use the out of flat one for a desk decoration or a paper weight and get a real one from Best (that's the brand) Arkansas stones or Dan's. They actually come from the company flat and conditioned.

A flat Hard Ark (mostly because I like the way it looks and it comes in a nice box).
IMG_1464.JPG


DMT on the surface plate (it's flat)
Take a bow.jpg

When I want a stone that's easily flattenable (and easily conditioned / deglazed) that actually sharpens something (especially high alloy somethings) I reach for a water stone such as the Shapton Pro stones or the Shapton Glass stones.
The New Team.jpg
 
All right, the Amazon guy dropped off some F 60 SiC powder and a rubbing block.

https://www.amazon.com/gp/product/B06Y3X3FPP/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B00BVDY1HI/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

That combination really bit into the hard black Ark and another recently purchased black Ark. The grit seemed to hold up pretty well, imbedding itself into the rubbing stone until it broke down after about ten or fifteen minutes of hard rubbing.

I also used that F 60 on a piece of glass. The glass seemed to be a more efficient method, cutting very aggressively and evenly. It did seem to break down fairly quickly, maybe within five or ten minutes.

Both stones are now almost completely level, with just a couple of small corners with a 1/2" section that are a little low. These spots are small and out of the way, and while I would like to keep grinding until it's perfect, this doesn't seem to need to be fixed.

When the Amazon guy drops off some F 120 and F 220 later today, I'll start finishing them up, test on some beater blades, and take some pictures.

I learned that the aluminum oxide paper does fine up through the hard Ark, but I'll never try to polish anything harder with AO again. I am new to this!

The SiC powder on glass is very quick compared to other methods I've tried, and it does a fine job of getting to that flat, even surface. Plus I like the sound of the coarse little rocks grinding against the glass.

I originally reached for the AO paper because I figured it would be cheaper, but the SiC powder on glass looks to be much cheaper than any kind of paper. I used a dollar, no more than two dollars worth of F 60 to get a 12x3 and a 10x3 flat on both sides.
 
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Wowbagger said:
...Next best answer if you are (like I was) all infatuated with hard Arks (you'll get over it when you learn how frekin slow they cut and how limited in WHAT they will cut is) . . . use the out of flat one for a desk decoration or a paper weight and get a real one from Best (that's the brand) Arkansas stones or Dan's. They actually come from the company flat and conditioned.

A flat Hard Ark (mostly because I like the way it looks and it comes in a nice box).
View attachment 913511
Click to expand...

Yeah, the natural stones have my attention right now! A new stone like your whitey really looks beautiful to me, and as a beginner the slow cutting action is kind of an advantage as I practice my stroke.

I'm going to rub it to 120 tomorrow and sharpen something with it, then maybe rub it up to 220 and see how it performs. I don't always want a really fine polish so this "hard black" Arkansas may come in handy.​
 
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Thanks, David! I figure it worked out pretty well for the price I paid. I got a large stone that should turn out to be a good finisher, from what I've seen so far (slow and fine!), and just as important I learned some great lapping techniques that will make life easier down the road.

I would not be very happy if I had paid $240 for this stone! It took a lot of hard rubbing to get it reasonably flat, and at that price I think it should have been closer to square out of the box. No biggie, the vendor was very gracious, and the stone should be useful once I get it conditioned. I think I glazed the other one, with F60 SiC and an 80 grit tile rubbing block, no less!

This is turning out to be a great learning experience and I greatly appreciate the help you all have given me.
 
Khromo, you now have greater experience than the guy in post #1. You learned a lot, just keep working at it
and thinking about it. DM
 
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Sorry about the photography!

After about 2 to 3 hours of rubbing, finishing up with the 80 grit tile rubbing block (!), I wanted to see how the stone would work. I sharpened a couple of nicked up old patch knives with 400- and 1,000 grit waterstones, and used them to test the new stone. I used water for lube for starters.

The stone felt very smooth, a lot smoother than the 1,000 grit Waterstone. After about 20 to 25 strokes per side, the edges were looking very neat with a somewhat fine satin finish. It was a long way from polishing out the 1,000 grit pattern, but I could have gotten there with a lot more strokes.

The blades did simple hair popping and paper cutting tricks, which is all I know how to do!

The stone was smooth enough that I could feel the bevel, and it was quiet, with just a little feel for the edge meeting the stone. It kicked up a very faint slurry, very slowly.

Overall, I'm pretty satisfied that this is going to be a nice almost-finishing stone, but I'm a little curious why I am getting this smooth performance from a stone that just came off a 60- to 80-grit lapping session!

I suspect I was rubbing on the SiC powder until it had broken down to a grit much finer than the F 60 it started life as. I rubbed until the crunch of the large particles was completely gone and the stone was sliding on a texture like baby food.

I'm going to run some more blades over the stone as it is. I don't see messing with it while it is working like this!
 
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If it's working I wouldn't tinker with it. Just use it and break it in and see what it will give you from this level. Good luck, DM
 
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