Thread: DMTs & does anyone have a micrometer?

I think the pencil grid is just for reference to the flatness of the hone you'e lapping. If the pencil wears away only on the edges with a few laps, then you know the stone was way off from being flat. I heard someone (probably Josh) also say that once they have lapped completely flat the first time, they re-do the grid and give a couple laps. That's all it should take to erase the pencil and you will know it is flat.

Also, I know nothing about micrometers, but isn't it possible that with ANY machined product, even digital, there could be a variance in its measurement? i.e. 0 to a micrometer that may be off could really be 0.0001 or something so that over a large measure, the number will be slightly off, if only by maybe .001"?

On a new hone I would always lap twice. On a hone that I have used for several razors then I would lap twice, maybe.
I always lightly lap my hones on 1000 grit before each honing session so the amount of wear on my hones is never very much.

"Sticky" has a very relevant work backround and consequent insight to the subject of flatness and how it is, and is not, obtained. I will be paying close attention to his comments.

For those of you who believe that 0.001" is too much, I just hopped over to the Shapton site and checked the specs on the two Diamond Reference Plates they offer.

The Diamond Glass reference plate is accurate to 5 micron or 0.0001968498" and sells for a quite reasonable $289.00. But, you say... you want MORE... err LESS.... Ok, enter the big gun in Diamond Reference plates, the two sided, cast iron model which is accurate to an incredible 3.5 microns... that's 0.0001377949" for you non-metric types and it goes for a paltry $489.00. The two sides, one for lapping stones and the other for lapping bevels on plane irons and chisels etc. and would not be suitable for razors based on it's pattern with rather large holes to swallow up swarf etc.

So in a sense, you would have to spend at least $234.00 more to gain approximately 0.0008" in accuracy across an 8" length over a DMT.

Many of us have been quite happy using nothing more than wet/dry paper on a floor tile or a piece of reasonable (we're assuming now) flat glass. I doubt they approch anything near the 0.001" that DMT specs for their diamond plates. Lets not forget that 50 years ago, when straight shaving was more the norm... few if any gents went to these lengths to get their hones flat... I recall my dads hones ( he was a barber and was quite skilled with the straight), they were all clearly hollowed in the center from years and years of use... I suspect they all matched up more or less as he didn't seem to have any problems getting business in his shop for shaves nor haircuts.

I'm all for these kinds of discussions but sometimes we need to do a reality check to keep us in the real world. Well... at least I need to... I'm usually the first one to buy something new and improved only to find out that the old stuff worked just as well.

Regards

Christian

Originally Posted by kaptain_zero

For those of you who believe that 0.001" is too much, I just hopped over to the Shapton site and checked the specs on the two Diamond Reference Plates they offer.

The Diamond Glass reference plate is accurate to 5 micron or 0.0001968498" and sells for a quite reasonable $289.00. But, you say... you want MORE... err LESS.... Ok, enter the big gun in Diamond Reference plates, the two sided, cast iron model which is accurate to an incredible 3.5 microns... that's 0.0001377949" for you non-metric types and it goes for a paltry $489.00. The two sides, one for lapping stones and the other for lapping bevels on plane irons and chisels etc. and would not be suitable for razors based on it's pattern with rather large holes to swallow up swarf etc.

So in a sense, you would have to spend at least $234.00 more to gain approximately 0.0008" in accuracy across an 8" length over a DMT.

Many of us have been quite happy using nothing more than wet/dry paper on a floor tile or a piece of reasonable (we're assuming now) flat glass. I doubt they approch anything near the 0.001" that DMT specs for their diamond plates. Lets not forget that 50 years ago, when straight shaving was more the norm... few if any gents went to these lengths to get their hones flat... I recall my dads hones ( he was a barber and was quite skilled with the straight), they were all clearly hollowed in the center from years and years of use... I suspect they all matched up more or less as he didn't seem to have any problems getting business in his shop for shaves nor haircuts.

I'm all for these kinds of discussions but sometimes we need to do a reality check to keep us in the real world. Well... at least I need to... I'm usually the first one to buy something new and improved only to find out that the old stuff worked just as well.

Regards

Christian

Excellent comments. I have long suspected that back in the day, hones were seldom or never flattened and yet they worked just fine. Barber hones are hard enough that I can't imagine anyone would be able to flatten them without the benefit of 21st century equipment. Out of the box they aren't really flat, and unless you have an extra extra coarse diamond hone, those hones are a real beast to lap.

Glad to get some confirmation on my theory.

And I agree that we can go waaaaaaay overboard here. I think the unavoidable variations in the operator's stroke--human error--play a much bigger role than the hone's flatness to within a few thousandths of an inch.

Josh

Originally Posted by heavydutysg135

My DMT plates are all perfectly flat as indicated by my machinist straight edge.

Nothing is perfectly flat. I am reasonably sure that your DMTs have more than 0.00000000001 " error to them.

Originally Posted by JoshEarl

Excellent comments. I have long suspected that back in the day, hones were seldom or never flattened and yet they worked just fine.

Josh

Here's the "rub" so to speak on both of these posts...
I unfortunatly totatly agree with them, "back in the day" I do believe that people got perfefctly accapetable shaves from barbers hones and concaved Eshers and such, heck we see the proof....
Here is the one point I would bring up, How many razors have you passed up buying because the hone wear was way out of line, huge smiles, huge frowns, or worse a 3/8 toe with a 6/8 heel. I am of the belief that all these things are related.....FWIW

The great joy of having flat hones is that you can go from one hone to another without being forced to re-establish a new bevel on each hone. Flat hones will also give you a much faster sharpening job, assuming your workpiece/razor is also relatively flat.

A hone that is moderately flat in the spine direction can be heavily dished in the long stroke direction, and give nice edges (using an X-stroke). As long as that particular razor stays with that particular dished hone. As soon as that razor sees a flat hone, you'll be working a while on the "new" bevel. Hence the popularity of a flat hone. Maximum portability.

Glen,

I don't think those hone wear patterns are from the shape of the hone as much as from improper pressure during the honing stroke. You can create similar patterns on a flat hone by applying too much pressure during the middle or end of the stroke.

It's hard to say, though, because we all have so many razors that we don't hone them very often.

Josh

Originally Posted by Sticky

The great joy of having flat hones is that you can go from one hone to another without being forced to re-establish a new bevel on each hone. Flat hones will also give you a much faster sharpening job, assuming your workpiece/razor is also relatively flat.

A hone that is moderately flat in the spine direction can be heavily dished in the long stroke direction, and give nice edges (using an X-stroke). As long as that particular razor stays with that particular dished hone. As soon as that razor sees a flat hone, you'll be working a while on the "new" bevel. Hence the popularity of a flat hone. Maximum portability.

Good point!


Thats what I like about these forums. A significant amount of civilized discussion that increases our knowledge and allows us to make our own decisions. This has been a very good thread.

Originally Posted by Sticky

The great joy of having flat hones is that you can go from one hone to another without being forced to re-establish a new bevel on each hone. Flat hones will also give you a much faster sharpening job, assuming your workpiece/razor is also relatively flat.

A hone that is moderately flat in the spine direction can be heavily dished in the long stroke direction, and give nice edges (using an X-stroke). As long as that particular razor stays with that particular dished hone. As soon as that razor sees a flat hone, you'll be working a while on the "new" bevel. Hence the popularity of a flat hone. Maximum portability.

Steven,

I'm not sure this is true. I have a significantly dished hone (Belgian blue) sandwiched between my DMT 1200 and flat coticule. I don't have any problems with this or I'd just lap the blue more often.

If you think about it, the slight arch of a dished hone is probably like a 24' radius. Since the spine is only 5/8" from the edge, the difference in angle during the stroke is minimal enough to not screw things up.

Josh