Recommend me a stone for flattening old chisels

[Lasse Hilbrandt]

Im trying to restore a full set of socket bergs from 1/8" og 2" They all need som work and at the moment im working on flattening the back of the 2" Berg.

Im using adhesive sandpaper on a marple slab which is flat enough, but even though I use 80 grit paper the flattening is really really really slow and I wear down the paper too fast IMO.

I was thinking of trying ceramic stone that won´t dish too easy but it need to be really coarse.

Is it really possible to have a stone that wont dish and being really coarse at the same time ?

I have a Norton 220 waterstone, but it is soft as a piece of soap and useless.

[Doug Hepler]

Lasse

I gave up flattening with sandpaper, although I like it in finer grits for honing.

Consider diamond plates. I use a DMT extra coarse, followed by a DMT coarse. That's approximately 220 grit (60 micron) followed by P320 (45 micron). The extra coarse stone is really aggressive at first and makes some deep scratches but it wears in after a while and then is very durable. You probably know this already but (a) you need to flatten only the area directly behind the edge, say 1/2" to an inch. (b) be very careful not to allow a back bevel on your chisels.

Doug

[lowell holmes]

I use a diamond hone,
https://www.sharpeningsupplies.com/DMT-10-Dia-Sharp-Diamond-Stone-P318.aspx?gclid=CjwKCAiArK_fBRABEiwA0gOOc-_3ordNmm7OI8IBzdp8ToKHaNVznG4QrjJz0rddA4PIxZFLVzRT HRoCoNIQAvD_BwE

It will make short work of it.

[Malcolm Schweizer]

+1 for Diamond plates. I use DMT diasharp. Beware that coarse is REALLY coarse. Get the medium to fine. It works fast and leaves less finish work to do.

[Mark Hennebury]

I use a 1/4" die grinder with a 2" cut-off disk to lightly hollow out the middle, check by occasional lapping on a fine stone. Just stay away from the edges and tip of the chisel. You don't need to remove all of the grinding marks, there is no reason to have the entire back flat and polished, just as long as the outside edges are flat, the Japanese seem to manage quite well with hollow back chisels. I will touch them up on occasion with the die grinder. It's a 100 times faster and easier then lapping all of the back for absolutely no practical benefit at all.

[Lasse Hilbrandt]

Thank you guys. I just ordered the DMT 10" diasharp. I opted for the coarse and hope it smoothes out.

[lowell holmes]

You won't regret it and it will last forever.

[Tom Bender]

In any case you will need the diamond plate to flatten your water stones, once you give up on sandpaper

[Brandon Speaks]

I have a bunch of diamond stones and love them, but if I need to really remove some metal its 80 girt on granite. It is so much faster than the roughest DMT stone. You might go through some paper but it is cheap compared to time. Some windex will revive paper that is pretty caked up, you still go through it fast, but it takes 1/10 of the time of the roughest DMT. I do still love the diamond stones, just dont see them helping with your specific issue.

[Eric Rathhaus]

Another option is foregoing the paper and buying the abrasives loose and grinding directly on granite or your surface. Here's one provider - you can buy 40 grit silicon carbide material: https://www.willbell.com/ATMSupplies/ATM_Supplies.htm

[Tom M King]

If you use loose grit, you might as well use diamonds. I flattened a steel plate on a surface grinder, and use that. I think the steel plate is something like 1/2" x 6" x 18", but don't remember exactly. There are many listings on the auction site for loose diamonds. I forget what grit I bought, but think it was either 60 or 80. It does a really fast job, and hasn't come close to slowing down. I just spray 3.36, or WD40 on it, and leave it sitting until next time.

They go from that to a 300 King, which is a lot different than all the other King stones, but I mostly only use 01. I don't think that stone is much good for fancier metals.

edited to add: I used to use silicon carbide grit, on glass, but found out that I owned a surface grinder, and have a bunch of scrap steel. That sort of mess doesn't go in the woodworking shop though.

[steven c newman]

396660
Do you see that 6" disc on the side? That is what I use to flatten the backs of both chisels and plane iron,,,
396661
Does not take very long, either. That shiny "bar" across this iron? Is from the shop light overhead.

Grit on the disc? Have no idea,,,,disc is pretty well worn down....

[Robert Hazelwood]

Your comment on sandpaper is odd to me. If you use 80 grit paper you need to change it often, like every few minutes, so a roll of PSA paper is the most convenient. I have bought all kinds of coarse stones and such trying to do these jobs quickly, and was disappointed with the speed of X-coarse DMT plates. Actually my conclusion was that all coarse stones suck in some way for flattening, either they are too slow or do not stay flat. Fresh out of the box, a new DMT stone might be ok, but it quickly becomes too worn to be efficient for a heavy job.

They are worth having for maintaining other stones, though, and for oddball sharpening jobs that might damage something like a waterstone.

[Jake Rothermel]

I might be one of the few who doesn't care for diamond stones, like, at all. I love the IDEA of them, to be sure; but in practice I've never had one that worked as fast or as well as I felt it should have. Diamond stones, in general, just have never felt right to me. The feedback is entirely different and it's never jived with me. I'm sure they work and the issue is with me & my technique and/or expectations; certainly plenty of craftspersons use and swear by them (and THEY seem to do wonderful work *and* get good results from diamond stones...).

When I left behind abrasive paper, the only grits I kept for sharpening purposes were the lower ones (i.e. 100, etc.) for serious lapping. Yes, I go through a lot of sheets on a really intense lapping job (which, thankfully, is not very often these days), but that's preferable knowing the my substrate is not dishing, uneven, or otherwise not flat. The feeback feels better to me, too; which I never would have thought to be as important as it apparently really is to me.

You might try a coarse Norton Crystolon stone for flattening and/or lapping. They're supposed to be roughly 120 "grit". I've got a medium (180-ish) and it eats metal in a way that's efficient and feels right to me - more like my other arkansas stones. It also stays flatter longer than the few low-grit waterstones I've tried (which I confess, hasn't been many...).

Your mileage, of course, may vary.

-Jake

[Lasse Hilbrandt]

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

[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.

http://www.inthewoodshop.com/WoodworkTechniques/Lapping%20the%20Backs%20of%20Blades_html_m43b9470d .jpg

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.com/2014/01/tuning-up-and-re-handling-old-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!:D

[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...