Printable View
Ok.... I understand that lapping makes the stone flatter- this part I get.
But..
How can you lap a 10,000 grit stone with a 250/400 grit sandpaper, and not have a bunch of scratches in it?
Oh... And should Nagura stones be lapped at the same time as hones? or does it not matter so much?
Peace Comrades...
I lap stones from 1K through 30K with nary a problem with a DMT 325. If there are scratches, they are not visible and don't affect honing results.
It is not an issue for the function of most stones but if it concerns you you can use another flat stone to further polish.Quote:
Originally Posted by CLaReNCe
Nagura & all stones should have lightly chamfered, smooth edges but the need for uber flatness of Nagura is debatable, after all it is usually softer than the base stone.
I remember seeing a recommendation to use the edge & not the flat for a particular slurry stone so in that case it would also be unnecessary to flatten.
If you mean a small 'truing' stone as supplied by some synthetic makers, it should be flat, as in that case it could be harder than the base stone.
Thanks Chaps...
Ps. Oz. My razor is still sharp as sharp- haven't wrecked it yet. Ta.
Hey guys
I just want to reignite this to throw an idea out there. When you lap a synthetic stone with a DMT 325, what do you think of the following idea. Any scratches don't matter because the bonding agent they use will be both dissolved and reinstated during the lapping process. This could be because you compress the material into the microscopic grooves made my the DMT 325. Also the slurry you make will round the edges of any grooves made on the surface. Just a thought, it doesn't really matter all that much but since gssixgun commented on a barber hone topic I have been thinking about it a lot.
What you think?
Carl.
I think when you are lapping with a DMT 325,after a very short time you are actually lapping with the slurry and not the diamonds.look at the scratch pattern on steel using a 325 under a scope,than look at the scratch pattern on the stone using the 325.
I will take a look this week!
A perfectly lapped stone is not perfectly flat, there is the grit and the microscopic space between them. If it were perfectly flat it would be called glass. What we are attempting to do in lapping is make the tops of the highest layer of grit on the same plane, not really make the stone perfectly flat.
Many naturals and synthetics benefit from lapping with a much coarser stone, refracting the grit and cleaning the area around the grit to keep the swarf from loading up. Think sandpaper sanding drywall compound.
The 325 plate seems a good general lapping/refreshing hone for most stones, but experimentation for your stone is the key. Try different lapping grits and see what works best. And forget about dead flat, even glass is not really dead flat… it doesn’t matter.
this thread was helpfull...thanks for all the input guys :)
Euclid that is a silly thing to say. If you go down to a small enough scale nothing is perfectly flat and there is space between the particles/atoms. For the purposes of the example we are trying to get the stone "perfectly" flat. You are trying to achieve flat on a similar level of "flatness" that you want to be exhibited in your razor. I will agree with you in saying you are trying to remove crap from between the grits though.
The question was “How can you lap a 10,000 grit stone with a 250/400 grit sandpaper, and not have a bunch of scratches in it?” the scratches don’t matter as long as the scratches run parallel to the honing direction. It becomes a matter of aesthetics removing scratches on a hone. Lapping a stone to 8K is a waste of time, effort and 2 stones. Unless it increases performance and you will not know that unless you experiment with that stone.
Flat is a relative term, we are attempting, 1.to get the tops of most of the grit on the same plane, not all the grit. 2. Refract the grit. And 3.Unload/clog the grit, all at the same time.
Attachment 96159
Attached is a stone I pulled from the slow cooker it’s been soaking for a few days, I suspect/hope it may be a coti… maybe an old ark. It was somewhat yellow when it went into the soup.
Now I could flatten the dished side, it would be purely aesthetics, a waste of time, sandpaper and effort. Instead I will lap the bottom side and test for its cutting/finishing abilities. If you could lap the dished side so all the grit is at the same height and you held the spine on the hone you could sharpen on the dish side of the hone. How does a jointer/surface planer flatten a piece of wood? The cutter head is round, and the blades travel in a circular motion, no?
Many times we do thing just because others say to without asking why? I applaud Clarence for asking why? Get as much information, then do what he thinks is best for him, experiment and see what works. To blindly polish rocks to a mirror finish, just because… is not productive or skill building. Now that is silly.
How many threads have we read from novice honers who have done x laps on 1K-12k as instructed and can’t get a razor to shave? Was it sharp at 1K? No one ever checked, but he did the required laps.
We are not baking cakes.
And as for scratches, I do not see how they matter as long as the surface is overall flat to the bevel. Bevels are thin, but microns are even smaller. Dont forget the fact that In the case of the dished hone up there (after its smoothed out), the effect would be similar to a layer or two of tape on the spine. If you pretend the dish is smooth, and take an arc with the same width as a razors bevel from it, for most intents in purposes it will be flat. Now picture the full blade on it. Even for that distance, the stone is relatively flat. But for humor sake, extend the line of the bevels contact out, and it will pass just under the spine of the razor. The dish only really becomes noticable at the 2" mark, and then more so at the 3" mark. give it a try, scroll up and block of the monitor with a couple sheets of notebook paper to only show different sized sections, ignore the ruler in the picture while doin this.
Euclid,
Honing razors is not easy, but baking a cake isn't exactly a piece of pie either.
Michael
Here, here for bakers, there are bakers and there are… Bakers. True Baking really is much more art than science… even with a recipe. And maybe that makes my point. And you are right Michel, it’s not that easy, anything worth doing well rarely is.
All I’m saying is there is no recipe for much of this, because there are so many other variables. So there only guidelines. X worked for one person it might work for you and your stone. When we tell novices here is the recipe for honing a razor or lapping a stone we may be setting them up for failure because we don’t explain the variables, and we don’t know the largest - the pilot.
Back in the late 50’s Ben Hogan wrote, what at the time people thought was the definitive book on golf. To the dismay of many he wrote down all his secrets. It has sold multiple millions of copies. Why is it, there are only a handful of people in the world that can play golf at Tiger Woods’ level?
All of my finishers have scratches, Thüringen’s, Black & Translucent Arks, c12K and probably Coticlues & Synthetics as well they just don’t show as pronounced. All finish well, no fractured edges that I can see at 100 magnifications or feel shaving on my face. For me, that is what counts.
Lame you are right, if I could figure a way to even out the grit easily and retain the arc, it would make a good experiment, alas I am not that ambitious.
I always seem to have a change of heart when it comes to lapping/soaking/spritzing.
For past few weeks I've been going at 1k Chosera + 5/8/12 SS progression in dry-minimalistic style.
No water on any stones, and occasional lapping only on 1k when setting bevels, and
very light sandpapering with 1200 grit when the SS gets clogged up.
With the minimalist approach, though, I tend to move the razors around to wear the stones down evenly.
My current take is that the razors are as shave worthy as any, I save 10-15 minutes from stone preps, and hands stay dry.
I'm sure in 3 weeks I'll have a change of heart when I get frustrated from dished 8K and go into meticulous lapping/soaking routine for a while.
Speaking of "true flatness" There are items called Gauge blocks. They are used for calibrating measuring equipment, like calipers and such. I came across a set when I was in school for fabrication.
They are steel, and perfectly flat. They are so flat, when you put two together, there's no room for air, so they act as if magnatized. Pretty cool, at least I thought so at the time.
Gauge block - Wikipedia, the free encyclopedia
Recently acquired a hone from JimmyHAD. He had lapped it so well the rubbing stone sticks when you work up a slurry if you push the water out. It sticks well enough to pick the stone up. First class job JimmyHAD.
Lapping does two things.
- Establishes a flat profile
- Removes clogged swarf filled hone stone.
The flat profile is important when switching from hone to hone to hone.
If all hones dished at the same rate this would be almost unnecessary
but they do not wear at the same rate so lapping can help. In my limited
experience hones wear wrong. The coarse hones wear faster and
then the finer hones cannot touch the bevel at the edge. A 10k or
finer hone with a little sway back will produce a nice micro bevel.
Clogged swarf filled hone stone does not cut as fast
as fresh clean stone. A hone that is clogged can glaze over
and get slower and slower. For some barber hones and finishing
hones this is a good thing because it makes the hone cut
less i.e. finer.
I have an extra extra coarse large DMT for lapping flat. I do run a
very very worn old but smaller DMT over my fine hones to smooth
the surface of my finer hones because my big DMT is a bit rough.
I have noted groves on my Norton 8K. As the hone gathers swarf
the deep scratches are visible. As long as I can see these scratches
I consider the hone flat and just rub the swarf off with my hand. The
best Norton 8K edges I get are the third or later razors after lapping. So
yes for me crazy grinding the top of a fine hone is not totally necessary.
Especially because I can see when the hone departs from flat.
Summary:
Lap for flat
Lap to remove swarf when less aggressive tricks fail.
__________________________________________________ _________________Quote:
Originally Posted by Euclid440
Euclid,
You are on the ball. Keep posting.........................
Jerry
This is of course a very good point. The large radius arc, will create a slight convex to the razors edge bevel. When put against a flat stone, it should become noticable under magnification at least. until you wind up re-setting the bevel on the next hone, creating more work & in a staged manner removing more metal than necessary.Quote:
Originally Posted by niftyshaving
When I wrote my post I was more thinking along the lines of slurry to finish, then future touch ups on the same stone. Basically maintaining the same convex edge.
If you dont want to play with that dished stone, I might be interested in experimenting on it. On second thought, probably not. I have learned though here that doing a coti-only sounds like a long involved process. Let alone learning and starting a coti progression on a dished stone, sounds like heck to troubleshoot when I dont have the stone experience, or means to check how the bevel is going for a razor level edge. Means I could only confirm it works, not that it dont work. Only way I could confirm it dont work is over a course of years. And I havent even touched on the battle to consistently lap out a dish. :/ too much for me.
Reading this topic I started to think about a Glass DE razor hone that I received by surprise when I bought the DE razor off eBay. The glass hone is Dished! While I haven't tried it. The idea is to move the blade up and down the dish to hone it! Based on everything that's been said about Flat, how would this glass hone work?? Then if it works, then Why wouldn't the dished hone,above, not work if you 'back' honed the razor?
Johnus, there are threads on the internet on sharpening double edge razors on the inside of a glass. And I recall seeing concave glass or porcelain Double edge blade hones. I suspect the goal was to hone both ends of the blade at the same angle and an easy, safe way to hold the blade. The hone does not have to be flat, just at a consistent angle and an even grit cutting height.
I believe the scratches don’t matter because if the surface of the hone or tops of the grit is even, the razor edge will bridge the scratch. If you were to keep the razor exactly in the same track with the scratch it could cause a land/protrusion in the edge, but doing so on a random scratch would be impossible, one of the benefits of the x stroke pattern.
To answer the original question (or attempt to):
Yes, 250/400 grit sandpaper will leave scratches on your hone. Don't panic though, the finish off of 400 grit paper is fine. I used 400 grit paper to finish my hones for a while.
So you get the flat part, that's good. But what else does lapping do? For one it cleans the hone. IME, plenty of swarf builds up, esp on the finer hones.
IMO lapping controls the texture of the surface, and thus its level of aggression. Heres what I think:
After lapping, the hone's surface is covered with ridges and valleys left by the grit of your lapping plate. The razor edge contacts only the peaks on a freshly lapped hone, and exerts more pressure on each contact point than if it were making contact all over the edge. The ridges wear quickly and make fast cutting slurry. New cutting material is constantly exposed. Swarf collects in the valleys. After a while the peaks and valleys left by your lapping plate, will wear down. The hone smooths and begins to act finer and slower. The razor is exposing less material and swarf begins to clog the stone. Re lapping the surface, preps your hone with new peaks and valleys and the hone gets more aggressive again.
When I lap with the Norton plate I see the above in action. My stones are definately more "ready to work" right after lapping. After a while they do slow down, and polish finer. On the 8k, I even see a yellow slurry form after the first, no pressure strokes and the stone seems very quick cutting. I don't think the stone works as well after lot's of use without lapping.
With luck, some of this made sense.
Michael
____________________________________Quote:
Originally Posted by Euclid440
My grandfather extended the life of his razor blades with a drinking glass back in the early 1900's. My father did also.
Jerry
When you press down on the DE blade inside the glass it flexes flat so the edge is not actually meeting a curved surface as you might think.Quote:
Originally Posted by Johnus
Of interest I honed with a coti for years and never lapped it flat.Quote:
Originally Posted by LameBMX
No slurry... just used it like a barber hone wet with tap water.
The hone and my three razors abraded together and shaved just fine.
Then one fine day I discovered this place. I lapped my coti flat
and to my distress learned that the razor and hone no longer
shared a common profile.
It took months and a Norton 4k/8k combo lapping on a tile etc...
to get things back to normal shave ready.
Thus began HAD, RAD, SAD and serious latherin.
You can always not push it all the way down. if you have a clear glass, experiment to find the pressure where the bevel contacts the glass.Quote:
Originally Posted by onimaru55
Some of those curved glass DE hones also had a flat side for straight razors IIRC.
I have often thought that the dished out hones from the late19th & early 20th century and the designed curved glass hones were used for the troublesome old wedges. Like if you have a lovely old dished hone and the wedge blade just rides on the spine and the edge and therefore taking out all the grinding on the sides of the wedge blade. AlxQuote:
Originally Posted by onimaru55
This is a very well thought out observation.Quote:
Originally Posted by alx
Ya, sort of like the razor bridges the gap of the curve of the hone, and this takes out of play all the effort of working on the middle meat of the wedge. Alx
As already discussed, lapping will flatten and expose the true heart of the next level into the hone and remove all the unnecessary particles.
There are so many diamonds in a random spatter on a lapping plate (e.g. DMT 325), that you are effectively not making linear scratches in your hone. Where one diamond misses, another one cuts. And where 1 diamond cuts a line, another 100 cuts across, parallel and opposite to it....and so on...you get the idea.
True, there will be random scratches in your hone, but it really does NOT make the hone "act" like a coarser grit hone because of the scratches. Logic often makes guys think this, and that is why a lot of guys want to get it as smooth as humanly possible, but it does not really matter.
Remember; it is the particle size of your hone that abrades the metal of your razor, not the scratch marks in it.
