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Straight edge suggestions

I dont feel . 001 is needed. I make flat with the grid marks and its always been good enough fir me. I know i have more than . 001 flex while honing.
 
That is the I-Gage, pretty good at the price, also look at PEC tools, straight edge.

Yep, dead straight/flat does not matter, the edge of a Diamond plate is good enough for lapping stones. What matters is flattish and smooth, no rough unlapped valleys, not Dead Flat. No harm is lapping obsession, but also no benefit.

If you did get your stones “Dead Flat” they are no longer, after any use. Put your energy into technique and identifying issues not flattening stones, dead flat.

As said if you had a true Precision Straight Edge, the last place you would want to put it, is on an abrasive surface.

The trick to using a pencil or sharpie grid is to remove the grid marks and re-grid and lap to ensure the stone all the grid is removed by the lapping medium and not just washed off by slurry. If it is removed in less than 10 laps multiple times the surface is smooth and flat enough.

Back in the day, not too many guys packed a Precision Straight Edge and Diamond plate with their Arks and slates in their saddle bags, yet they shaved pretty ok for a couple hundred years…
 

David

B&B’s Champion Corn Shucker
As said if you had a true Precision Straight Edge, the last place you would want to put it, is on an abrasive surface.
Nah, no issues here unless you’re careless. I place mine straight down on the stone and then pick it straight up when I’m done checking. I think I got mine in 2014. Next time I’m by the machine shop I’ll have them check it and see if it’s off.
 
I've never fully trusted pencil grids. They can get you in the ballpark but I like to at least do a visual test with a straightedge and a bright light. Rocks don't always abrade evenly, even synths, and the amount of pressure you use can change things too, even if your lapping medium is true. I'm not going for dead flat, just flat enough.
Loose grit on a flat surface doesn't do it for me. I always follow up with a piece of wet dry paper.
I would like to think I'm not that picky but maybe I am.
 
Actually, I seldom use a straightedge. I did starting out, but now I figure its mostly a waste of time. Unless maybe it is a new stone. I just make sure the stone will quickly and repeatedly erase the pencil grid.

After a few honings, you can tell when it needs lapping again by the way the edge undercuts the slurry. Once you get your blade to the undercutting stage, if the blade still undercuts in most spots on the stone, but there is a spot or two where it won't, chances are the stone is getting some slight dips in it. A couple dozen strokes on the Atoma usually fixes it right up if you don't neglect it too long.
 

Legion

Staff member
Loose grit on a flat surface doesn't do it for me. I always follow up with a piece of wet dry paper.
I would like to think I'm not that picky but maybe I am.
Same. Loose grit is the way to go for quick removal of material, but it can have a tendency to convex the edges and corners a little. I'll use grit until it has maxed out its flatness, then switch to paper or an Atoma plate for the final lapping and smoothing of the stone.
 

duke762

Rose to the occasion
I did the geezer toolmaker thing and made my own. I ground it straight and checked it with a .0001" dial indicator on a Starrett, pink granite inspection plate. No indicator movement. It's D-2 about 12" x 1.125" x .190" and 62 Rockwell c.

On a maintenance note....Beware of damaging your straight edge. If it bangs a corner of something hard, it may raise a burr that will throw you flatness observations out the window. Burrs and irregularities can be repaired with either a Trans or Black Ark and stoning the surface irregularities away. Amazing thing about stoning a surface this way is that the stone is only doing it's work on the high spots.

And I'd sure like to know where my beloved straight edge went. I put it somewhere to keep it safe and now can't put my hands on it. That leaves me using an ancient 14" x 7" precision square. Awkward as all get but it makes up for it's awkwardness by saying Studebaker on it.
 
I usually don't care as I would lap my synthetics whenever I use them to avoid building up. However with my jnat I did not lap it often as I usually did just tomo for finish. Been using a fun nagura progression though on the jnat so need to make sure I keep it flat. Might start lapping it after every progression or every other progression.
 
I usually don't care as I would lap my synthetics whenever I use them to avoid building up. However with my jnat I did not lap it often as I usually did just tomo for finish. Been using a fun nagura progression though on the jnat so need to make sure I keep it flat. Might start lapping it after every progression or every other progression.
Just for kicks I checked each stone in a 4-stone synthetic progression for flatness after a single honing and I was a little taken back by how out-of-true each one had become after such a limited amount of use.
 
I use a sacrificial (cheap) straight edge that I check against a good straight edge. Moving a measuring tool around on an abrasive surface is not very good shop practice.

I liked this because it strikes me as being true. Not much is needed in my opinion since the stone or hone doesn't necessarily need to be flat to do its job, the stroke being used having the potential to overcome vagaries. Here locally in the States, I use six-inch and twelve-inch Empire rules that I picked up in a local Home Depot to determine flatness (and its discontents). And if one wants to get anal, the light-passing eyeball test isn't enough. One needs to place the rule across the diagonals of the (rectangular) stone, and perhaps the x and y axes as well, each time attempting to pass a .001 thickness feeler gauge under the rule to see if the gauge passes underneath or not. If the gauge doesn't pass, the stone is considered flat; if it passes then the stone isn't flat. Or maybe it's the rule that isn't truly straight? The search for perfection never ends. In the end, it doesn't really matter as long as it's "close enough" (a relative term) if one is seeking flatness. Some folks aren't even after flatness, intentionally seeking convexity, and so forth.

Perhaps it's better to have flat hones at the lower stages with synths. But with harder, more durable natural stones at the finishing stages, my sense is that it isn't as critical so long as the application (stroke) being applied is consistent.
 

duke762

Rose to the occasion
I set up one of my Ark finishers on a granite inspection plate and checked it with a .0001 dial indicator. It was flatter than Kansas with no movement of the dial. I bet if you check it with a straight edge and a flashlight, it may not look so flat. I like to trust repeatable numbers and not my withered eyesight. I'll bet it's flat enough, it sure works some voodoo on my razors. And that's the goal....
 
Still undecided on if I am getting s straight edge for the couple years I'm over seas. Have been flattening the jnat more often though, about every other use and results have definitely improved. Don't think it is really something I will worry about with my ark or even 5x2 coti. However making sure the jnat is flat before nagura progression and final finishing has been a nice improvement edge wise.
 
If flatness is the ultimate goal, these machined plates are accurate to 1um and not too expensive

 

duke762

Rose to the occasion
I lapped about 9 hard Black and Trans Ark's on a iron surface plate that I had freshly resurfaced, with loose grit and when I resurfaced it again, I had only caused .0015" wear. Some materials are surprisingly resistant to wear. Somethings, than you wouldn't believe could be abrasive really are and some materials that you wouldn't believe can be abraded, actually can be.
 
0.0015" translates to 38um. Maybe not practically a lot the first time, but it adds up.
If it were my reference plate, I'd protect it with a sheet of wd sandpaper.
 
Still undecided on if I am getting s straight edge for the couple years I'm over seas. Have been flattening the jnat more often though, about every other use and results have definitely improved. Don't think it is really something I will worry about with my ark or even 5x2 coti. However making sure the jnat is flat before nagura progression and final finishing has been a nice improvement edge wise.
When you use naguras, the areas you generate slurry can develop low spots if you are not working it evenly over the stone.
Just try to rub a nagura in one spot in the middle. Then apply a pencil grid and just do a couple of strokes under running water with your lapping plate.
You will see that this can have a significant effect, especially on softer stones.
None of my razors are within the tolerances of my atoma plate. So to me it makes more sense to shift the pressure on the razor to make good consistent contact.
When you are honing a twisted blade like this, the atomic level flattening does not matter that much.

20211118_201210.jpg
 

Legion

Staff member
0.0015" translates to 38um. Maybe not practically a lot the first time, but it adds up.
If it were my reference plate, I'd protect it with a sheet of wd sandpaper.
Why pay for a surface plate that is accurate to 1um if you are just going to throw a sheet of WD on top? What sort of thickness tolerances do you fancy they manufacture sandpaper to?
 
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