Thread: DMT dilemma

I tried several of the polycrystalline like the Eze-Lap. After testing them, I kept the DMT's and gave all the polys away except for one Eze-Lap that I rarely use.

Here's another link that has mono/poly info from a woodcarving book.

My little 2" x 6" 1200 works nice. Great for those stubborn edges.

Originally Posted by Utopian

I was using a DMT 325 that previously had lapped a Swaty, 2 carborundums, a norton 1000, a norton 4000, and a norton 8000. My 12K was convex--the center faces were highest in the center. That means as I lapped, the center became smooth and the edges were untouched. As lapping proceeded, the smooth center got larger and I was therefore lapping a progressively larger area and the progression out to the edges became slower. That is why I stopped when all but the last 1/2 inch of each corner was polished--the greater the polished area, the slower the lapping was going. Because I like to hone on narrow stones, on both the 12K and all three nortons were honed on a wide side and a narrow side.

Thanks for the clarification. My 12K was convex as well, but not nearly what you describe. I did experience the same thing you did in that the last 1/2" of the edges took about as long if not longer than lapping the entire surface up to that point.

You must have single Norton grits rather than the combo stones. I liked that idea when I had my Norton combo, but buying a single 4000 and a single 8000 were out of my price range at the time. There's a place called toolsforworkingwood.com that sells single grit Nortons rip sawn lengthwise into 8"x1.5"x1" for half the price. I thought about buying those for narrow hones but haven't yet.

Originally Posted by Sticky

I tried several of the polycrystalline like the Eze-Lap. After testing them, I kept the DMT's and gave all the polys away except for one Eze-Lap that I rarely use.

Here's another link that has mono/poly info from a woodcarving book.

My little 2" x 6" 1200 works nice. Great for those stubborn edges.

Great info again, Sticky. Thanks for that. My guess is the Ted Pella poly-diamond abrasive pastes are only more expensive for the reason they mention.......less demand probably equals less supply.

I'm going to email Shapton tonight and confirm if their Diamond on Glass Lapping Plate is mono or poly. For some reason I swear I saw poly somewhere, but now when I look, there's no mention of either. I'll post back here with the answer in case anyone else is interested.

[QUOTE=You must have single Norton grits rather than the combo stones. I liked that idea when I had my Norton combo, but buying a single 4000 and a single 8000 were out of my price range at the time. There's a place called toolsforworkingwood.com that sells single grit Nortons rip sawn lengthwise into 8"x1.5"x1" for half the price. I thought about buying those for narrow hones but haven't yet.[/QUOTE]

You're right. I liked the price of the combo stone but the ability to hone on the narrow side, and the fact that they will last much longer, won me over to the single stones. I absolutely don't regret it.

I don't know squat about these particular hones however I will tell you that any diamond stone or for that matter any diamond cutting implement does it work with very little pressure. Most diamond saws use a gravity feed type mechanism so very little pressure is applied. The achilles heel of any diamond cutter is the ability of the diamonds to be worn away very easily but diamond cutters simple do not require much pressure to do their job anyway.

Seriously, if I had to lap my hones for 70+ hours I would
give up and use a different product. Luckily my Spyderco
hones have been flat enough out of the box -- that is, they
impart a great edge on my razor.

- Scott

I'm kinda' stubborn. I figure with 70 hours plus invested , I might as well finish up at least one side of the UF, otherwise I've wasted a lot of time for nothing. It is now close enough to flat to polish an edge. Pictures available of all three (with visible grid pattern and detailed runout dial indicator measurements) if anyone is interested.

Measurements referenced to my sine-bar/plate, accurate to w/in 0.0001" flatness (the sine-bar, not the runout) The runout indicator is accurate to w/in 0.0005". That's overkill though, the UF is now flat enough to put a decent edge on a flat razor, without seeing too much gap between the two. In practical terms, just looking at the grid pattern that the DMT D8C is not hitting yet is usually sufficient while eyeballing the gap between a straightedge and the hones low spots.

I will be selling the Spyderco medium and fine as soon as I replace them with a D8EE (I will guarantee at least one side of each to be flat enough to work an edge). I'll keep the UF so I can compare it to a Chinese 12k later. The UF just put a wicked edge on a wedge and a full-hollow last night, as is. I've spent so much time with the UF that I see it as an old friend now, instead of an enemy...

The hardness is kinda' cool, I bet it'll be a very long time before the fine or UF need to be lapped again. These Spydercos have also been an excellent test of the D8C's lapping abilities and durability; for me. It's been informative.

DMT update: I used HEAVY pressure (over 40 pounds) on the D8C last night, for the first time, using the Spyderco UF. Yes, it did start to pop diamonds off one edge. Moral: Use light pressure as DMT recommends and let the diamonds do the work. I normally use either the weight of the hone itself, or about one pound for the items weighing less than 2 pounds.

Originally Posted by Chrisl

I have a post into the Shapton Japanese Woodworking forum asking the guys why they think the Shapton DGLP as they call it (Diamond on Glass Lapping Plate) is the cornerstone of the entire Shapton CERAMIC on glass stone system but the Spyderco UF Ceramic seems to eat DMTs, another diamond lapping plate for lunch. We'll see what kind of responses I get. Some of those guys also mention having/using DMTs so they may have a dual frame of reference.

Although the woodworking forum I referred to is a very tight knit group, they've been listening to my diamond lapping plate and ceramic stone questions with interest. I'm asking for more specific info on the Shapton Diamond on Glass Lapping Plate and its performance.

Interestingly, one person DID mention that the Shapton higher grit stones, when lapped extremely flat are prone to strong stiction if an edge is honed perpendicular to the length of a stone. It's recommended that a plane iron (or razor in our case) be drawn at a 45 degree angle on the stone instead.

Any polished and perfectly flat surface would exhibit the same sort of stiction. Gage blocks made from hardened steel and which are truly flat and polished need to be wrung apart after use as two surfaces which are flat will not permit air to enter, thus the stiction. The very high grit Shaptons are simply displaying the same tendency when a largish bevel is honed and polished to the same flatness as the hone. This of course does verify the claims for the accuracy of the Diamond Glass reference plate and it's ablility to flatten the 15k and 30k hones.

I just finished flattening my blue and yellow coticule on a DMT 325. After both were dry I placed them together and got a fairly good stiction between them. Nothing like a pair of gage blocks mind you but good enough to indicate that my DMT is quite flat. The scratches left from the DMT are enough to allow air to migrate in between the two stones. Had I carried on, using a finer grit but equally flat DMT, the stiction between the two hones would increase. After all is said and done though, considering the narrow bevel we use for shaving, this issue of extreme flatness quickly becomes a case of diminishing returns, measurable to be sure but insignificant in actual use/performance for our purpose.

As for lapping ceramic hones.... it's the surface scratches on the hones that determine the the way a ceramic hone cuts, not the size of the grit it was made from. I realize that the coarser grit in the medium brown Spyderco IS coarser and can be seen with the naked eye as it is almost porous due to it's different binder/grit combination but the Fine and Ultra Fine would seem to be the same ceramic substance with a differing pattern ground into their surface as they do not shed their grit as it gets worn but rather remains as manufactured. By lapping one of these hones, you are essentially changing their cutting behavior to whatever pattern your particular diamond hone displays and the method in which you use it. This of course does not mean it won't work because it does, but much of it's cutting action will be determined on how the user flattens the ceramic hone (circular or crisscross movments on the diamond hone) and to an extent the diamond grit size as well as how worn it is... A fresh diamond hone will have sharper tips on the grit and will presumably create sharper edged scratches than a worn hone with more rounded tips on the diamond grit. Lots of variables and the reason why I won't flatten my Spyderco hone... I just cannot predict the outcome, so if it works as is, I'm not going to fix it.



Regards

Christian

Lots of variables and the reason why I won't flatten my Spyderco hone... I just cannot predict the outcome, so if it works as is, I'm not going to fix it.

I agree with you here Christian. I sure would like to get
my hands on a D8EE though...

- Scott