Shop Made Tools

[Cenedd]

Ok, results
This was my setup. The angle between the 'top' face of the chisel and the back was a little more than 1.75° but not as much as 2°. So I went with slightly shy and jacked up the end to fine adjust. I worked out the sfm's of the Tormek diamond wheel and also Evan's wheel in the 2011 thread I linked to earlier. That gave me 260sfm and 630sfm so I had some guides to work within at least. That equates to 250rpm and 610rpm for my smaller wheel. I settled at 450rpm to start and got really good results with the 12mm wide Stanley. The metal and the wheel were still cold to the touch.



Next up was the first victim. First thing I found was that unlike the Stanley, the sides weren't parallel enough to grip securely in the vise. I put the back of the chisel against the fixed jaw, one edge against the bottom of the vise and clamped the angled face with a dowel in the V of the moving jaw. I trued up each side so that I could grip the chisel and also so that the sides were square to the average of the face I was going to grind - otherwise it was going to tip front to back in that setup.
I found that initially the wheel was probably only making contact at one point around the revolution until it wore true. To be honest, this was quite helpful as it reduced the contact and hence the heat. With a much wider chisel once it was making full contact there was noticeably a lot more drag. I was still doing fine for heat until I was far enough down the chisel that the opposite side of the wheel engaged with the blade too. There wasn't any coolant at that end and the extra contact really made the heat build quickly at that point. I did end up blueing just the tip of the chisel but it should come out when I (hand) grind the primary bevel. Why did I grind the entire back when just an inch or two would have done? Well, to be honest, it just looked really bad. What I did have to do is once I got the deep gouges (from the factory grind) out of the middle was then to grind just the end as far as not making contact with the opposite side of the wheel. You can see a slight difference in colour (about 2/3 along) on this pic where that happens but it's not noticeable by eye. I knew it was cupped but I had to take off 0.5mm before it cleaned up! I did this in 0.04mm DoC steps. Probably took me a couple of hours (I'd have been there weeks by hand!) but this is the result:




As an idea of how it was before I started, this is another that has factory grind on the right hand side and quite a lot of hand lapping on a 140grit diamond plate on the left. You can still see the deep gouges of the factory grind. If you look closely, the top left corner is not planar with the rest so more would have to come off to get that to clean up.



I really struggle to understand how the factory grind can be that poor. Ok, that's not entirely true as it's obviously been outsourced at lowest cost....but it disheartens me that a once dependable brand could fall so far.
Just seven more to go *facepalm* Some of them aren't as bad though and the thinner ones should be less trouble.....I hope!

[rcaffin]

https://www.practicalmachinist.com/vb/general/what-will-happen-if-i-use-diamond-wheel-sharpen-hss-cold-saw-blade-326313/

Cheers
Roger

[Bob Engelhardt]

... If it wasn't needed to preserve the diamond wheel we wouldn't have taken the extra step. ...

Ehhh ... maybe, maybe not. They/you could have experienced diamond wheel destruction in some situation and decided not to ever use it on steel. Not knowing any particulars, of course, I doubt that any controlled study was done (that diverts manpower). Not using it on steel was _sufficient_ to prevent loss, if not _necessary_. People do tend to conclude "necessary" when all they have seen is "sufficient".

[Cenedd]

I did a quick bit of searching earlier and it seems this is all previously-trodden ground and on this very forum too. This is the thread from 2011 covering it.

I definitely plan to cover things to protect from grit - just as I do when using emery paper on the lathe. I did make a vacuum nozzle with pins to fit a knock-off Noga arm on a mag base so I'll see if I can adapt that to my new extractor (one of the reasons I'm keen not to go spending extra money on any more tooling at the moment!).

[bborr01]

Ah, that's an easy one. I'm using a diamond wheel.... because a diamond wheel is what I have.



I'm not aware of any sources saying this would be an issue. With excessive heat diamond theoretically dissolves in steel but not in the range of heat I'm likely to encounter unless I make a right hash of it....which is entirely possible It's a resin-bonded job not an electro-plated nickel solid wheel so it's intended to be friable/consumable to a certain extent....but you have to use it to do that rather than keep it in a drawer gathering dust.



I don't doubt that you're right...but I don't have one of those other than on a bench grinder and I have form at being terrible with one of those. I need something more finely controllable or I'll just make it worse. I'm not saying it isn't possible to do on a bench grinder; just that I'm fully aware of my skill-limitation. Frankly, if it comes to it, the learning curve is more valuable than the cost of the wheel.

If you're willing to sacrifice the diamond wheel then grind away. I worked in a cutter grind department for a time and we had carbide form tools that were silver soldered to mild steel with dovetails on them and we always relieved the carbide by grinding the steel away with a aluminum oxide wheel in a surface grinder using flood coolant. If it wasn't needed to preserve the diamond wheel we wouldn't have taken the extra step.

Also, aluminum oxide wheels are available in most any size and shape that a diamond wheel is available in so you don't need to do it on a bench grinder to use aluminum oxide.

One last thing. The grinding grit is death to things like ways and gears so I'd be covering up the rack and pinion gears that are shown in the picture and use a vacuum to reduce the amount of grit flying around. I think the guy was named Forrest that used to routinely lecture about that on this site.

[Cenedd]

Thanks Roger, I'm only trying to take a relatively small amount off rather than the sort of deep carving it looks like you're doing but I'll try to get as much coolant on it as I can. I'm not in any way set up for flood but I'll get mist on it and break out the hand spray. I'll post back some results when I can - whether successful or a dismal failure.

[rcaffin]

Yes, water cooling helps with diamond tooling. I have tried using diamond on HSS without cooling, and it died - although that might have been general destruction rather than diamond dissolving. Early days.

I even water-cool AlOx when grinding cryo-steel, not to mention diamond grinding on basalt (Mohr 9).

[Cenedd]

Why are you using a diamond wheel on steel.

Ah, that's an easy one. I'm using a diamond wheel.... because a diamond wheel is what I have.

With coolant you may not ruin the diamond wheel

I'm not aware of any sources saying this would be an issue. With excessive heat diamond theoretically dissolves in steel but not in the range of heat I'm likely to encounter unless I make a right hash of it....which is entirely possible It's a resin-bonded job not an electro-plated nickel solid wheel so it's intended to be friable/consumable to a certain extent....but you have to use it to do that rather than keep it in a drawer gathering dust.

but an aluminum oxide wheel will do just as good of a job.

I don't doubt that you're right...but I don't have one of those other than on a bench grinder and I have form at being terrible with one of those. I need something more finely controllable or I'll just make it worse. I'm not saying it isn't possible to do on a bench grinder; just that I'm fully aware of my skill-limitation. Frankly, if it comes to it, the learning curve is more valuable than the cost of the wheel.

[bborr01]

Finally something that fits the category! I saw a Joe Pieczynski video a while back on diamond grinding HSS on a mill. Obviously that went in my shopping basket and obviously I've done nothing with it for the last 18 months. Now, I've bought myself a nice set of 8 chisels for a project and standards aren't what they were in the 70's (when the other two 'identical' chisels I've got were made) and the backs need a LOT of flattening. It's still taking too long even on a 120 micron diamond plate (that's approx 140 grit). I know there are shortcuts involving a tiny back bevel but partly I want these as perfect as I can get them - they have sort of inherited sentimental value as they replace the missing ones out of my dad's set - and partly the back is so bad that one entire corner is unusable as is. Clearly the overkill solution would be a surface grinder....and I did look! There was even one of the mythical bench size variety available...but collection only from three hours drive away....and it's been very difficult to get fuel here in the UK for the last week of so. It would have needed work anyway as it looked like it was someone's self-build project. So I suddenly remembered I had this resin-bonded diamond wheel that just needed an arbor. One chunk of EN8 (roughly 1040 equivalent) later and here we go. Turned the shank first and then held that in the 20mm collet that it'll be running in to do the other side.



Runout was....far from what I'd hoped it'd be. I'm not sure how much was my failure and how much was in the wheel but it clocked in at 0.3mm on the outside of the cone and the edge of the flat at the bottom. So I just chucked the whole lot back up in the lathe and trued it inside and out - the arbor's dedicated to this tool anyway so it won't be coming back off.




There shall be some unimportant test piece tried first, of course....and much covering of things shall be done first
What grit is it? Well, I guess we're going to find out as it's unspecified. Could be about 200-ish as other "D12A2" wheels seem to be. Gotta give these things a try.....even if it's just to find out that they don't work!

Why are you using a diamond wheel on steel. I spent the last 10 years of my career grinding all sorts of stuff but diamond wheels only got used for carbide and occasionally M4 tool steel. With coolant you may not ruin the diamond wheel but an aluminum oxide wheel will do just as good of a job.

[J Tiers]

Yes, actual water, probably with a tiny bit of detergent in it to break the water tension and allow it to "wet" the surfaces.

I have a Glendo accufinish, with a slow speed wheel on a horizontal axis, that grinds on the side. I give it a spray of water before I start, and it lasts until I am done. That is essentially a honing machine, so I do not need continuous drip

[Cenedd]

When you say "wet" do you specifically mean water? I have got an MQL mister now but so far have only been using it for air to clear the chips - works nicely for flycutting. I could load it with some (diluted) Tufcut Aqua that I have from when it was possible to buy the tiny bottles of the stuff. Or I could put water in it...or use a spray bottle as I was using when hand lapping. It's just a bit difficult to hand crank smoothly and spray with the other hand.

[TGTool]

John Stevenson commented on grinding steel with diamond. He did it without any visible issues and he was engaged with a Chinese company developing a benchtop endmill sharpener that finally came to market. It's a theoretical problem but more difficult to find in real life.

[J Tiers]

Grind them wet, and the heat issue goes away even more. Yes, somewhat of a problem with the wheel upside down like a Blanchard, and the work just a tiny edge, but at a slow speed won't likely be an issue anyway.

Also, grinding steel with diamond has been done for a long time. If there was was that much of a problem, it would not have been done.

[Cenedd]

My understanding - from Tormek's video is that, like Elf said, it's only a problem at much higher heat levels. I've got to avoid that sort of heat for fear of wrecking the steel anyway so I think it should be ok. I'll be testing it first on a cheap modern Stanley chisel that's been horribly abused already so hopefully I should notice when I then sharpen it whether it seems softer.
I've got a CCGT insert in CBN; it makes a very nice fly-cutter insert for hot-rolled steel with the mill scale still on.

[elf]

Caution: using a diamond wheel on steel is not a good idea. The steel (iron) absorbs the carbon from the diamonds and degrades the wheel.
Yeah, seriously. Save the diamond for carbide tooling.
If you want to work on steel, you will need CBN: cubic boron nitride, instead. You can get almost identical wheels in CBN from ebay. It does HSS steel very nicely. Go softly.
I made my own T&C grinder, and use both diamond and CBN.

Cheers
Roger

That would depend on the speed and heat generated.