Recommend me a stone for flattening old chisels

[Tom M King]

Jake, Talking about the "feel" of diamond stones: What feel? I can never tell what they're doing without looking.

[Bruce Haugen]

I flattened a 2” Berg on a cast iron plate with 15 micron diamond paste. It worked very well. It still takes time and effort, but i had tried w/d paper, coarse alox and a coarse waterstone. Diamond worked best. Cheap, too.

[Derek Cohen]

For lapping the backs of blades I recommend a 1m long length of float glass (say 10mm thick), to which you will glue wet-and-dry sandpaper (use spray poster glue). Start with 120 grit.



The length enables long runs with the blade, and it is this that speeds up the lapping. Everything else is slow compared to this. Also, the continuous movement will reduce the chance of rocking the blade.

Regards from Perth

Derek

[Robert Hazelwood]

Agree with Derek on length being important in a lap. In particular if you are going to lap plane soles.

Woodcraft sells an inexpensive granite surface plate that is about 4" wide and 18" long, and this is perfect for lapping blade backs and soles of the smaller planes.

[Dean Arthur]

You can also just stop by a place that cuts countertops - they'll have a huge pile of long granite offcuts they'll be happy to give you. Porter cable makes an adhesive sandpaper roll in several grits so you can just roll it onto the granite offcut and get to work. This tool is surprisingly helpful and I use it on basically every project.

As Derek and others have said, sandpaper is a much better way to flatten chisels, plane soles, etc. You had it right initially. The coarse diamond stones wear out shockingly fast on these tasks too. This isn't a task you do that often so save your diamond stone (and return the DMT for an Atoma if you're able).

[Richard Jones]

Buy/cry once. For diamonds, it's hard to beat Atoma. My big 140 has outlasted several DMT plates. I don't know about Norton, but this is anything but soft. https://www.chefknivestogo.com/inpipopro220.html

[Philipp Jaindl]

I'm a bit late but also really like the Atoma plate for flattening both chisels, planeblades and the 1 Waterstone i got. dont have a DMT in the same Grit range so cant quite compare it but the Atoma has a good "feedback" for lack of a better term while sharpening.
As for durability both DMT and Atoma have held up well for now with eh Eze-Lap trailing a bit behind then again those are quite a bit cheaper and not terribly flat.

[Aaron Rappaport]

Another way to hollow the back besides the angle grinder method is to use a bench grinder. Here's a description: http://timmanneychairmaker.blogspot....d-chisels.html

I've done this, and as the poster of the angle grinder method said, it saves 90% of the effort easy.

[Jason Lester]

Add me to the list of people who don't like the DMT plates for flattening. Mine seemed to work well originally, but definitely cut much slower now. I went back to sandpaper.

[Philipp Jaindl]

The Problem with the Diamon plates is that, in my experience, they dont like heavy pressure at all which is what you can tend to use when trying to flatten something quickly. For me they seem to cut better when just using firm but light pressure, let the tool do the work kinda deal.

[Kory Cassel]

I know I'm very late to the thread, and I see you've already bought the 300 grit coarse DMT. I've been working on a set of Stanley 720s for a while and IMO the sharpening level grits are far too slow for the job. Sandpaper will work but I highly recommend PSA backed. If you use loose sheets even when taped down, it will bubble up and dub your corners. I'm using the DMT XXcoarse now and am happy with the speed/flatness I can achieve. The method I've been using is to keep an oiled rag handy and wipe the chisel down in between lapping. You would be surprised how much smoother and faster it cuts with even a super thin coat of oil. I vacuum the swarf off the stone. When you use the oil, the swarf will just tuft up and stick to the edges of the chisel. When you try it dry, the swarf immediately gets between the chisel and stone slowing you down. The steel will also gall up and cut ragged when lapping dry leaving an inferior surface finish. I've found it very quick to lap the XXcoarse scratches out going next to the coarse and fine diamond stones. Then I polish through 1000, 4000, 8000 with waterstones. The entire process moving up through all the grits takes 1/10th the time of the flattening with the XXcoarse, so don't worry about it creating a problem by being too coarse. I also haven't had any problem with using as much pressure as I want, you'll need a very sturdy bench, preferably wall mounted, to really crank on it though. The coarser the grit, the more pressure you have to use to get it to cut. If you're using very light pressure with the XXcoarse, you're just scratching the surface. If you don't use any lubrication, you'll fight a compacted bed of swarf so more pressure will not get you anywhere. I don't recommend water (or water based lapping fluid) for lubrication. It makes a big mess, doesn't control the swarf as well, doesn't cut as freely, the swarf will flash rust and then be ground into the stone, attacking the nickel plating. When you're done flattening, just wash the oil off the stone in the sink with dish soap, no big deal. It's not much anyway, just a very light film. Hope this helps.

[Lasse Hilbrandt]

I know I'm very late to the thread, and I see you've already bought the 300 grit coarse DMT. I've been working on a set of Stanley 720s for a while and IMO the sharpening level grits are far too slow for the job. Sandpaper will work but I highly recommend PSA backed. If you use loose sheets even when taped down, it will bubble up and dub your corners. I'm using the DMT XXcoarse now and am happy with the speed/flatness I can achieve. The method I've been using is to keep an oiled rag handy and wipe the chisel down in between lapping. You would be surprised how much smoother and faster it cuts with even a super thin coat of oil. I vacuum the swarf off the stone. When you use the oil, the swarf will just tuft up and stick to the edges of the chisel. When you try it dry, the swarf immediately gets between the chisel and stone slowing you down. The steel will also gall up and cut ragged when lapping dry leaving an inferior surface finish. I've found it very quick to lap the XXcoarse scratches out going next to the coarse and fine diamond stones. Then I polish through 1000, 4000, 8000 with waterstones. The entire process moving up through all the grits takes 1/10th the time of the flattening with the XXcoarse, so don't worry about it creating a problem by being too coarse. I also haven't had any problem with using as much pressure as I want, you'll need a very sturdy bench, preferably wall mounted, to really crank on it though. The coarser the grit, the more pressure you have to use to get it to cut. If you're using very light pressure with the XXcoarse, you're just scratching the surface. If you don't use any lubrication, you'll fight a compacted bed of swarf so more pressure will not get you anywhere. I don't recommend water (or water based lapping fluid) for lubrication. It makes a big mess, doesn't control the swarf as well, doesn't cut as freely, the swarf will flash rust and then be ground into the stone, attacking the nickel plating. When you're done flattening, just wash the oil off the stone in the sink with dish soap, no big deal. It's not much anyway, just a very light film. Hope this helps.

Thanks, I already found out that the coarse is not coarse enough.... I think somebody has tried to flatten some of the chisels before, because some of them has a corner thats very low, suggesting the build up of loose grits.

I can´t afford a XX coarse DMT now, since my money just went on the coarse....

Another thing.. I noticed that going from an already lapped back which was done with sandpaper, to the DMT reveals that its not as flat as I thougth. I suspect my granite slab isnt as flat as I hoped.....Sighhhhh

[Kory Cassel]

Yeah, once the vintage chisels are dubbed or out of flat, it's a lot of labor to work that hardened tool steel down by hand. I'm still working on my 2" 720. I've gotten to within 1/16" of the dubbed edge and I'm going to be regrinding the primary bevel past it. A lot of surface area on those 2" chisels. All the other sizes were pretty reasonable, less that an hour on the XX coarse. Those youtube videos demonstrating chisel flattening seem to have been done with chisels that were pretty close to start with. Definitely not super quick or easy. I saw one where the guy annealed his chisels and reworked them with files, but I'm not doing that with my vintage Stanleys. The best way is probably some skilled use of power tools as mentioned earlier in the thread, but I've also seen some disastrous over grinding on one of my ebay chisels. It's way too thin to use with a mallet now; ruined. I'm just going to carry on by hand. I've found that the flatness on the backs can't really be assessed until they are polished up a bit. The coarser scratches will reach through some of the subtle low spots making the chisel look flatter than it really is. Progressing through the grits is important to get the best final result. If you have low corners, there has probably been more than one facet established on the back of the chisel over it's life. The best method of attack will be referencing one of the back corners on the stone and working back and forth diagonally keeping the whole chisel on the stone. Which front corner is low will determine which back corner you use to reference against the stone (you have to work the high diagonal down) if that makes any sense. Always work only ONE diagonal and then straight in to finish. If you do any kind of alternating X pattern, you will end up with multiple crossing facets with a ridge in the center which will result in one corner being low when you finish with the straight in strokes. Now we know why it takes a Japanese sword polisher over a week to do one sword!

[John Turner Indiana]

jeeee now im wondering if I pulled the tricker on that DMT to fast..... well time will tell

No. DMT plates are great and will get the job done, you bought a tool that'll last you a very long time. I personally use water stones, but I have diamond stones at hand when I don't feel like soaking my stone (necessary for the ones I have, but not all water stones) for 30 minutes pre-sharpening.

Just make sure to dry the water off your diamond stones after use! Nobody likes rust

[Jake Rothermel]

Tom, that might be another way of saying my point exactly. Abrasive paper, arkansases, and water stones all have a ...feel to them (I don't know I can explain that better....); they give feedback to the user as they sharpen. Diamonds have never had that for me...