Nearly an hour of lapping, is this what a new DMT 325 should look like?

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07-19-2013, 06:32 PM
Jonah

4 Attachment(s)

Nearly an hour of lapping, is this what a new DMT 325 should look like?

My first DMT 325 arrived the mail the other day, and I have sharpened quite a few kitchen knives off of it to break it in. I started lapping the norton 1000 side of my combo hone that came in, and here are the end results of both -

Attachment 135834 Attachment 135835

The first picture is of the DMT, and as I hope you can see there is a darker area on most of the hone. The lighter areas towards the outside of the hone seem to have more bite to them. My thought is that there is just less grit where it is darker given that I have been doing circles on the Norton 1000. I am kind of surprised though to see that dramatic of a difference. Is that pretty normal?

The second picture is of the Norton 1000, and it shows some feint/shallow but present scratch marks in a circular pattern. It looks pretty similar to the thread posted the other day about a new DMT 325 being used straight out of the box onto a hone. As I mentioned, I ran quite a few kitchen knives over the DMT before I tried using it on the hone. Do the scratches (if you can see them) mean that I need to break out the knives again for the DMT?

About thirty minutes into the initial lapping, I took a picture of the hone with the DMT to show the degree of flatness
Attachment 135836 Attachment 135837

I was expecting to lap the Norton for a little bit of time. I'm over an hour into it and though it isn't that drastic anymore, I have the feeling I have a bit more to do. Should this much lapping be required for the first run?

Cheers
07-19-2013, 06:45 PM
Lazarus

"The first picture is of the DMT, and as I hope you can see there is a darker area on most of the hone. The lighter areas towards the outside of the hone seem to have more bite to them. My thought is that there is just less grit where it is darker given that I have been doing circles on the Norton 1000. I am kind of surprised though to see that dramatic of a difference. Is that pretty normal?"

I noticed the same thing when my DMT was new. The color difference was so pronounced I wondered if I had knocked all the abrasive off of some areas of the DMT. Over time that has pretty much gone away and the appearance of the surface of the DMT is fairly consistent.
07-19-2013, 06:57 PM
jpcwon

My DMT looks just like yours & mine works fine, so don't fret. Believe it or not, I suspect that the differences in color are simply due to the fact that your hand exerts more pressure on the center of the plate than on the edges, so it "breaks in" quicker than the edges do.

As for the Norton 1k, well, it looks like you still got a little ways to go! :shrug:
07-19-2013, 07:30 PM
1holegrouper

Like honing a razor lapping a hone is faster when you do the majority of the work on a lower grit. I use a lower grit DMT (like extra course which is 220 grit) when there is a lot of lapping to do then finish out with the 325. (I only let 'broken in' DMT's touch a hone that touches a razor) Sometimes then on finer hones I even 'polish' the hone a bit more with a DMT 1200. Once you get it right you won't have to do it like this again- providing you do a light lapping before each use.
07-19-2013, 07:55 PM
henryconchile

My DMT 325 looked like yours when I finished lapping a 1K stone and separate 4K/8K Norton stone on it last year. It took a long time to lap each stone grit. I called DMT customer service to see if it was a defect, but they said that everything was OK; the dark spots happen. Although, they also said that the DMT 325 was not designed for lapping, even though they recognize that a lot of people have been using it for lapping. They said that I should try cleaning the DMT with a stiff bristle brush and Ajax. Cleaning it helped remove some of the dark spots, but not all.

Today I finished lapping my new Naniwa 12K stone using the DMT 325. It took me about 15 minutes, but the DMT still works great.
07-19-2013, 08:04 PM
tiddle

Most of the time it just gets clogged w/ stone particles. Mine did the same as all of them will. Some comet, a scotch brite pad and some elbow grease will get it out, and won't hurt the plate, just wipe it dry well, and you'll be good to go.
07-19-2013, 08:13 PM
Jonah

2 Attachment(s)

Thanks for all the words and suggestions, gents. I just did another 20 minutes of lapping and here are the results

Attachment 135838 Attachment 135839

I drew the grid on and left the pencil in the top right of the hone. That is the lowest spot it seems. After lapping, all of the graphite is gone with the exception of that one little spot in the corner. I'm thinking at this point I will just coat that one little spot with graphite and hone my razors on the 1k side, avoiding that little corner. I will still lap the stone and I'm sure it will even out eventually. I can't really see the benefit of grinding off more for the sake of getting that little bit in the corner flat.
07-19-2013, 09:43 PM
CaliforniaCajun

I'm glad you got a 325 DMT lapping plate, because I have one and it has done a great job for me for three years. It doesn't have to be perfect. It's durable because it is made of metal. You don't have to work so hard to maintain it.
07-19-2013, 11:19 PM
sharptonn

Just a note, you will not need to use the grid anymore! If you lightly lap it under running water with your worn 325, you will be able to see when the "color" of the Norton is uniform. I usually go (lightly) 20 strokes, change direction and go 20 more. The 1k is soft so it could require more frequent flattening, esp on hard chores! ;)
07-20-2013, 12:15 AM
onimaru55

Quote:

Originally Posted by Jonah

I'm thinking at this point I will just coat that one little spot with graphite and hone my razors on the 1k side, avoiding that little corner. I will still lap the stone and I'm sure it will even out eventually. I can't really see the benefit of grinding off more for the sake of getting that little bit in the corner flat.

I agree the corner is not an issue,in fact I can't imagine how the razor would even contact it during honing.
07-20-2013, 12:20 AM
sharptonn

Quote:

Originally Posted by onimaru55

I agree the corner is not an issue,in fact I can't imagine how the razor would even contact it during honing.

Agreed. In fact, as you flatten it in the future, you shall see that corner come in!
07-20-2013, 12:22 AM
JimmyHAD

I take the shank of a 12" screwdriver to the new DMTs. Break them in with that because I don't have plane blades or chisels. Wet the surface, a couple of drops of dish soap and I give the plate a going over with the screwdriver shank. I make sure I give the corner of the edges a good going over to knock off any divots. When I lap it is always under running water. Been working well for me to avoid stiction and to keep the swarf draining off.

I keep a bristle scrub brush off to the side to clean the plate under the running water between grits. Some guys use scotch brite pads IIRC. :gl:
07-20-2013, 12:31 AM
bill3152

I used to use a screwdriver but lately I use the unlapped side of my phig. Much faster than the screwdriver and eventually I will have a lapped paperweight, I mean c 12k or 8 k or whatever its supposed to be.
07-20-2013, 12:33 AM
sharptonn

Good advise! Truly, I have found that a dedicated stone-maintaining monster is a worn-out DMT325. I am sure the grit rating goes to hell and a handbasket, being worn out. Still, I am trying to kill them. They just get better for the purpose! :D
07-20-2013, 12:39 AM
onimaru55

Spyderco UF is a great way to kill diamond plates ... Literally. ;)
07-20-2013, 12:43 AM
sharptonn

Quote:

Originally Posted by onimaru55

Spyderco UF is a great way to kill diamond plates ... Literally. ;)

Ha! Try some old barber's hones! :p

Seriously, it is seen as blasphemy to get a 325 and ruin the shit out of it, but I must recommend it to have a nice stone plate. Especially if you wear it out on useful purposes!
I also recommend a dab of Comet or Ajax and a scrub brush on the 325.
07-20-2013, 01:05 AM
JimmyHAD

Quote:

Originally Posted by sharptonn

Ha! Try some old barber's hones! :p

The DMT XX (120) eats barber hones for breakfast and is hungry for more.
07-20-2013, 01:09 AM
sharptonn

I am sure! ;) So does the sidewalk! :rofl2: Still, they have to go up grit a bit from there!
07-20-2013, 01:43 AM
Suile

Quote:

Originally Posted by sharptonn

I am sure! ;) So does the sidewalk! :rofl2: Still, they have to go up grit a bit from there!

I gave up on flatting rock pile finds on side walks.
I switch to a nice big piece of 60 grit sand paper blacked on a nice dead flat piece of lumber.
might buy courser sander paper if they go lower.
but it works awesome man your littery sanding and grinding away rock even after the paper part is gone.
07-20-2013, 03:17 AM
mrsell63

Quote:

Originally Posted by onimaru55

Spyderco UF is a great way to kill diamond plates ... Literally. ;)

My Spyderco came with the promise to be perfectly flat from the factory. You can see the grinding marks from a Blanchard type grinding table. This stone was not leveled on a standard surface grinder. Diamond plates don't make a dent in it.
07-20-2013, 05:00 AM
edhewitt

Quote:

Originally Posted by Suile

I gave up on flatting rock pile finds on side walks.
I switch to a nice big piece of 60 grit sand paper blacked on a nice dead flat piece of lumber.
might buy courser sander paper if they go lower.
but it works awesome man your littery sanding and grinding away rock even after the paper part is gone.

The lowest grit usually available is 24 but that is like beach sand glued to paper, my wife used some in a press for ink transfer printing, the sandpaper really didn't do the press roller much good.