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Precision ground flat stones

I don't much care for silicon carbide for a precision hone, they are always very friable in my experience. India is far less prone to letting go of grit. But I have not used Tyrolit.

Sorry I can't be more help with grit and hardness, the thing is, once you flatten out several good "precision" hones, you don't really ever need to replace them. They don't really wear much. Sort of a lifetime gig once you have some good ones. Even the ones I use for rougher work can last quite some years.

You don't want to be using these for any kind of work where there's point contact. Keep it to large surface area contact and they last forever.
 
I'm pretty verbose, but I stopped reading the longer replies at some point.
I've made a dozen or two of these with a diamond wheel on a surface grinder, it's not difficult if you have access to that. I also had a nice chat about them with the folks at Professional Instruments.
My experience: The generic Norton 2 grit stones work fine. They're something like $30 or $40 in 6" form, but every now and then show up at $20 on Amazon. Mine have all come in the nice shoebox style boxes which also make for nice storage. I've also used the generic $20 "premium import" ones from MSC. They imports are actually a bit nicer when new because they don't have as thick an oil in them as the Norton ones. Once that oil goes I haven't seen a functional difference.
The coarse side seems to clog ever so slightly slower than the fine side. A more open stone would be better. I've thought about making them from really open old surface grinder wheels, but haven't tried yet.
You can use them wet, and they will clog slower, but the oily paste that forms acts like lapping compound with your swarf and tends to scratch up surfaces slightly, hence the recommendation to use dry.
The best cleaning method I've found is to drop them in a cup or jar of oil (whatever's handy) and then put that entire thing in the ultrasonic cleaner. They quickly come out looking new.
 
I'm lost...I have no clue what the point of this thread is anymore...
As the original poster I feel obliged to reply.

The point is to exchange experiences making and using precision ground flat stones as well as how various abrasive properties affect stone's usability. That's my understanding, anyway.
 
I think it was more a comment on your rather verbose nature... like as though he had gotten lost in there somewhere :D

I find that mineral spirits help to keep the hone clear, and I generally stop and clean if I start to see much discoloration, I never get any scratching that way. Used dry the hones load up pretty quick.
 
I'm pretty verbose, but I stopped reading the longer replies at some point.
I've made a dozen or two of these with a diamond wheel on a surface grinder, it's not difficult if you have access to that. I also had a nice chat about them with the folks at Professional Instruments.
My experience: The generic Norton 2 grit stones work fine. They're something like $30 or $40 in 6" form, but every now and then show up at $20 on Amazon. Mine have all come in the nice shoebox style boxes which also make for nice storage. I've also used the generic $20 "premium import" ones from MSC. They imports are actually a bit nicer when new because they don't have as thick an oil in them as the Norton ones. Once that oil goes I haven't seen a functional difference.
The coarse side seems to clog ever so slightly slower than the fine side. A more open stone would be better. I've thought about making them from really open old surface grinder wheels, but haven't tried yet.
You can use them wet, and they will clog slower, but the oily paste that forms acts like lapping compound with your swarf and tends to scratch up surfaces slightly, hence the recommendation to use dry.
The best cleaning method I've found is to drop them in a cup or jar of oil (whatever's handy) and then put that entire thing in the ultrasonic cleaner. They quickly come out looking new.

Thanks, I'll grind those Norton stones to test too.

The Tyrolit stones BTW can be had for $2, yes $2 bucks when on sale. Normal price is around $15 (including taxes etc). I would have already ordered them if not for the fact they just have 1 in stock and I would like a pair.

So I got two German Muller stones with exact same parameters. Muller makes top notch silicon carbide abrasives including the narrow wedge shape shown on @Richard King photos.
 
I think it was more a comment on your rather verbose nature... like as though he had gotten lost in there somewhere :D

I find that mineral spirits help to keep the hone clear, and I generally stop and clean if I start to see much discoloration, I never get any scratching that way. Used dry the hones load up pretty quick.
It went waayy over my head :)

Yes, I'll try to keep it less verbose.
 
Luke PM'ed me to comment more about my use. I use a https://www.mscdirect.com/product/details/05111265?rItem=05111265
The majority of the time or but have bought https://www.mscdirect.com/product/details/00579425

I use these stones dry the majority of the time when I am scraping ways. Both bands are not flat from the get go. The majority of them are high in the middle and I tell my students to stone their scraping projects, being careful not to hold it in the same direction each time and to rotate the stone as the "DE BURR" the part they scrape. I also tell them to stone dry 4 out of 5 times. The 5th time I tell them to either use Windex glass cleaner or mineral spirits. I also tell them to clean off any bearing blue or highlighter before they stone or the stone gets plugged up or dirty.

I use the stone to remove burrs left over when scraping. These stones are not ground flat. I have no clue how they are made, I suppose they are molded wet and then baked somehow. I use the bent stones up until I am almost done scraping when I have 30 high spots and 20 to 30% contact all over or 100% of the part is covered with high spots, then I use a ground stone by Spencer Webb of Lance Baltzley who grinds and sells them. The ground stones in my opinion are to dull to use when rough scraping and you need to use the bent stones.

I never used ground stones before 10 years ago when they got popular by the hobbyist scraper. Both Lance, Spencer and Adam are my students. The flat ground stones help flatten and spread the high points faster when your finish scraping. I am going to write Spencer and Lance to read and comment on here.
 
I agree completely in the case of scraping that using a lubricant may well be counterproductive. Evaporative cooling could cause all sorts of problems during scraping. So too with not using precision ground hones on rough work. I also save them for the final stages of smoothing on items that are already ground or scraped to a finished surface. They really aren't much use for removing much of any material other than micro level stuff.
 
Well, an interesting "discovery". An ultrasonic cleaner used (I assume) for too long messes up the fine grit precision ground stones, but not coarse ones.

As I'm doing my Norton stones, I also reground my Andre ones and the only different thing I did... Was, rather than put it in a degreasing ultrasonic bath for 90 min, then dry in an oven at 100C for 30min,I just put them aside to drain.

And they work :willy_nilly:

Feeling pretty stupid now, but hey, such is life. One lives and learns. Many people use ultrasonic cleaners to clean their stones, but not for 90minutes I guess.

The plan was to get every last bit of coolant out. An alternative theory is that fine grit needs a little oil to work, IDK.

Still I'm pretty happy my chosen stone works.

Here is an updated vid test, the only difference is no ultrasonic cleaning in degreaser after grinding...
 
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I have always laid some emery cloth or sand paper on a flat surface and squirt some glass cleaner and rub the dirty stone on it. It's worked for me for years. In Germany at a rebuild shop I taught at they has a lapping plate, or a cast iron plate with lines cut in it, they used lapping compound and that cleaned them. I also just shoot brake cleaner on the stones holding it above a trash can. I've been told to use a Harbor Freight Diamond hand hone works good at flattening and cleaning stones. I'm going to go buy one and see how it works, Rich

PS: Bourne & Koch scrapers told me they use a sheet of cardboard wet with Windex and rub stones on it to clean their stones. I've tested that and wasn't impressed. But if your testing some ways to do it, give it a try.
 
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I had no issues with repeated 30 minute stints in an ultrasonic, but clearly YMMV. I know they work without oil as I’ve used some that have never seen oil. This is key with some polymer optical plastics as oils damage them. It’s a little harder to find Norton stones that aren’t oiled during manufacturing, but they are sold.
 
Regardless of what grit stone you are using i feel it’s important to have the ability to re flatten the stones your self. The flat stone is a cutting tool and cutting tools need to be refreshed.

I’ve had the best luck using a DMT flat diamond plate to re flatten a stone. Diamond flattening plates are very common with hand tool wood workers. I’ve got a set of water stones that wear so I bought the diamond plate to refresh the water stones and the scraping stones.

I’ve tried a grooved cast iron plate and was not that happy with the resulting stones flatness. The soft cast iron plate dishes fast and the result is a convex stone. The cast plate does clean the stones quick if you use a corse grit abrasive grain.

There are 5 or so stones that I like to use when taking down scrapped high spots. Some for roughing some for finishing, all flattened on a diamond plate.
When rough stoning I use odorless mineral spirits to aid in cutting action and to prevent the stone from loading.

After I’ve generated a flat surface, my cutting stones go away.
The best stone I’ve found for burr checking and surface qualifying is a Norton Crystalon stone that’s the size of a domino and has a very fine grit.
 
If I understood right, the theme of this thread is "precision ground" flat stones with the intention to find standard stones that meet the special requirements of these precision ground stones.
Because the stones do have a very good flatness, they are wanted to be perfect dull (so to say). They work completely different than usual flat stones.
A optimized stone for the use as precision ground flat stone probably would meet these properties:
- particles don't break easily (therefore aluminium oxide (not every type of aluminium oxide!) and not SiC)
- very hard binding of the particles (R or higher would be nice)
- high porosity (e. g. 50 % - that's a lot)

I don't know any standard stone, that meets all these properties at once. Some stones that are made for flatten concrete are quite hard with better porosity, but usual made from SiC.

In an ultrasonic bath just 5 minutes, the coarse side (red, less hard bound than the fine side) of my precision ground flat stones do loose aluminium oxide particles. The fine side (white) also, but less. So the binding of my stones is definitely to soft.

Cheers,
Karl
 
BTW, to the users of Norton stones. Which side do you use more often, coarse or fine?
Whichever happens to be facing upward and clean. I even have a few that I ground the sides (where it is mixed) and it makes no difference that I have noticed. I have some tiny ones (1”x1”x2”) for deburring where I left the coarse and fine sides untouched and only ground the sides. That way I have coarse, fine, and precision ground all in one pocket sized tool. On the surface grinder I like 1”x2”x 6” or x8” with a lip to go under the fence.
 
On a multi grit hone I usually use the finer side for fine (especially hardened) surfaces. Coarser side for surfaces that might have a little more damage or that are more likely to produce any swarf. So whichever side is suitable for what the work is. For me, that's mostly the finer side as I'm usually working with hardened and/or very smooth ground surfaces.
 
OT a bit. I like another stone too - it's not ground, but when I stone off a Bridgeport table I like it. It's round and one side it fine and the other side is coarse. The section between the top and bottom is under cut so your fingers fit in there. On plain stones one can smash your fingers if the slide down the stone and into the T-Slots, ouch.

Norton
Sharpening Stone: 1-1/2'' Thick, Round-Round, Coarse, Fine Grade
MSC# 00580100Mfr# 61463687570
 
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