Why does it take me so much time?

[Brian Holcombe]

Part of the reasoning is that 15/32's of the 1/2" is doing the registration for that last 1/64.

Agreed it's very tedious work, once the back is flat on a western plane blade I will only work the front and for my jointer I use the ruler trick. For Japanese stuff I run the full series of stones on the back and then on resharpenings I only work the front 1/2"~ on the the finish stone, pretty much never reworking the back again on lower stones unless I cant get the burr to come off, which would imply there is an issue.

[ian maybury]

Think the point Derek makes about getting it flat with a coarse stone first being the step that matters most/is most demanding is an important one to take on board, as is Kees' about bringing up a polish being a quickie job once the first has delivered a truly flat surface. As should be wiping the wire edge off a flat back - if not it suggests it's not quite flat. Marathon honing sessions on waterstones as before are a recipe for losing focus/ending up out of flat. If nothing else rubbing away forever on a fine stone seems likely to greatly increase the wear/volume of stone removed per volume of metal removed, and to exacerbate the possibility of uneven wear of the stone.

Phil for this reason i think is correct about not messing about getting frustrated with too fine grades if there's significant metal to be removed. One problem with this is that if it becomes necessary to bring in the really heavy guns (light grinding - to use a WorkSharp, or a long length of coarse abrasive or a sanding disc or belt) it gets so that a lot of harm can be done in a few moments by heating or removing metal in the wrong places. i.e. the skill/proven technique requirement escalates.

I've for example not had much luck with a 120 grit Shapton which I had hoped might shift metal fairly quickly for minimum risk. It seems just to wear awfully fast, to scratch quite deeply but to actually not remove metal a great deal faster than a 1,000 grit stone. (not so that it's an alternative to light grinding anyway) I'd love to hear from somebody who's done significant work using carborundum on a steel lapping plate - regarding speed, finish/scratching and staying flat over a decent time period. (it also begs the question of what plate to use, as your average bit of steel plate unless it's been ground or more likely lapped isn't actually all that flat in terms of the territory we're talking about.

The honing question i've not yet sorted in my own mind is whether going straight from say 1,000 grit to 12,000 as some do is advisable. For sure it brings up an apparent polish, but not sure it removes the deeper scratched. Not sure either if this matters - but it conceivably could contribute to chipping/shortened edge life.

As the concensus the extent of the area polished is pretty clearly mostly just a consequence of the sharpening technique used - but it's hard to see how good performance requires more than a narrow strip of flatness/high finish right behind the edge. Ruler technique = narrow band, on the flat = necessarily wider band.

[Jim Matthews]

You're right on the beam with this one Mr. P.

Go with your gut, it won't steer you wrong.
Keep up the good work.

[Matthew Hutchinson477]

I'd love to hear from somebody who's done significant work using carborundum on a steel lapping plate - regarding speed, finish/scratching and staying flat over a decent time period. (it also begs the question of what plate to use, as your average bit of steel plate unless it's been ground or more likely lapped isn't actually all that flat in terms of the territory we're talking about.

I just bought some 60/90 and 150 silicon carbide grit (which is what carborundum is from what I understand) to try this. I initially tried lapping with 80 and 220 grit sandpapers on plate glass and had the same problem you had with your Shapton stone--it scratched the metal a lot and seemed to be removing a decent amount but then every time I held an engineer's square up to the blade it looked like the shape hadn't changed much at all and thus the blade wasn't any flatter.

I haven't used the silicon carbide grit enough yet to give any conclusions but I will say be careful with how much pressure you use or you risk embedding grit in whatever you're lapping. The grit needs to roll or tumble underneath whatever you're lapping. I tried lapping a soft arkansas stone with it and embedded some of the grit in it by putting too much pressure on it. I then tried lapping a plane iron back on a piece of sacrificial plate glass (anticipating that it would be ruined but that the grit wouldn't embed in the glass) and the grit still seems to be embedding in the blade a little bit. At least, the scratch pattern looks like it was. From what I've gathered if you use a soft steel plate the grit will embed itself in the plate which would give you a more consistent scratch pattern, which would be nice, but perhaps also not be very quick. If that's the case then it would be the same as using silicon carbide sandpaper. I'd love to hear from someone who's tried this method before because I'm just figuring it out as I go.

[Steve Voigt]

I have never understood the benefit of polishing 15/32" of metal that does no cutting.

David

The benefit is, as the old saying goes, that you can pay me now or you can pay me later. Flattening tools as Kees is doing (and as I do) is tedious, but it's a one-time investment. And once it's done, working the back consists of taking half a dozen strokes to remove the burr. When I see people using the ruler trick, they are taking about the same number of strokes. So, there is no big time savings. But with the ruler trick, you are adding one more step to the sharpening routine. Find the ruler, lay it in position, presumably clean it off when you're done. It is not an onerous step, but it is a complication nonetheless. I'd rather put the time in once and be done with it.

It was recently suggested that a stone was not enough to flatten the back, that in addition to stones you should keep a piece of lapping film on a lapping plate to remove the burrs. OK, that's another step added to the routine. If you use a honing guide, that's a third step. All these little steps add up, and suddenly sharpening is a pain in the butt. I prefer to keep it simple, two stones and nothing else. That way sharpening doesn't interrupt my work routine.

I have no objection to the ruler trick. I do not deny that it works. I just prefer not to use it, for the above reasons.

[Jim Koepke]

I have no objection to the ruler trick. I do not deny that it works. I just prefer not to use it, for the above reasons.

+1 on that. If something is working for you, fine. If something else is working for me, fine.

It is amazing how evangelical folks get about creating a cutting edge on a piece of steel.

jtk

[ian maybury]

My instincts are much the same. It's less about absolute right and wrong than understanding what's going on between the iron and stone - and if necessary changing tack to respond to a new reality.

If for example a person works from a flat back on e.g. plane irons - but through a slip up (e.g. forgetting to flatten a waterstone frequently enough) manges to dub the edge then it's very possible that the next rational option is the ruler technique - or stropping - or something else that doesn't require a perfectly flat back.

This because it's not very realistic for example to cut back the maybe 5mm or more of the edge/bevel to get rid of it, or to thin the entire polished area of the back of the iron enough working on the flat over what is a big area to restore flatness.

[Pat Barry]

+1 on that. If something is working for you, fine. If something else is working for me, fine.

It is amazing how evangelical folks get about creating a cutting edge on a piece of steel.

jtk

I think you are forgetting Jim, that in the internet world we are part of, that there is a right way to do things, a best way, my way for example (LOL). You can choose to go your own way (and have by the sound of it). More power to you and I'm happy you get satisfactory results. This whole thread started because someone was frustrated and wondering why it was taking so long, more or less asking for help. Lots of responses and some degree of controversy ensued because not everyone does it the same. I bet you could put all the woodworkers in this forum together and walk through their respective sharpening processes and tools for sharpening and not find two that are the same. Sure their are similarities and maybe a handful of general methods shared by subgroups but not everyone does it the same way (nor do they have to in order to achieve acceptable results). On the other hand, if we don't have discussions like this, whether they are evangelical or not, that means everyone is in agreement and things are very boring.

[Jim Koepke]

(Clipped for brevity)

This whole thread started because someone was frustrated and wondering why it was taking so long, more or less asking for help. Lots of responses and some degree of controversy ensued because not everyone does it the same.

I bet you could put all the woodworkers in this forum together and walk through their respective sharpening processes...

Maybe it would have been better if I had done a +1 on the posts that may have actually addressed a possible cause of the OP's problem, unintended rocking of the blade while attempting to flatten the back. On a stone the swarf can lift the edges of the blade to cause this effect or prevent it from changing.

It is my tendency to bail out early on sharpening threads. My approach is to keep it simple. One plane meets another, no need for all the other tricks. For me, sharpening is a necessary part of woodworking, not a practice of rituals with secret handshakes and sacred incantations.

jtk

[Brian Holcombe]

Well, I feel I picked up a pretty worthwhile tip from this thread.

I've been using diamond plates to set bevels and flatten backs, more or less to my satisfaction with exception to the time commitment, and so I took to trying the Granite plate and sandpaper method and put it to use on some back flattening.

Working my way up from 120 grit through 600 on the plate, then going to stones. So far so good. I feel like I get a better finish at each level of grit by comparison to diamonds. I'm finishing up at 600 and the finish is very fine by comparison to diamonds. It doesnt take long at all to remove the minor dubbing on the 1k cho stone.

[ian maybury]

I'd tend to agree Brian - there's something 'scratchy' about the diamond plates I've used. When new anyway. As though they tend to have stray grits standing high or something.

The other issue for me is that they are definitely not all as flat as is desirable for back flattening and the like.

[Kees Heiden]

The tip that was the most usefull for me in this thread was KEEP THOSE STONES FLAT.

[Brian Holcombe]

Ian, I've noticed that, I think it is something to the effect of some standing high. It's interesting how much a different medium can affect the result of something that should be very similar.

As far as flatness goes my diamond plate seems to leave a lot to be desired, and I dont know if it is the plate itself or the result of it's use. Meaning I dont know if some fillings are causing it act out of flat, where the water on sandpaper does not.

Kee's, it's so very accurate. I literally work from one side of the stone to the other when lapping the back, then return, and by that point it needs to be flattened.