Thread: Homemade Plane Blades from M2 HSS for Wooden Planes

Originally Posted by jmk89

However, my thought was that when the blanks are cut from the strip, they could be cut at an angle. Originally I thought in terms of 45 degrees (probably because I havve been cutting mitres all day!!!), but of course, if you cut at 25 degrees/155 degrees, both blades will be bevelled at 25 deg.

Sorry Jeremy, must be tired. Yes you are right, a 45 degree cut would have been handy and reduced about two thirds of the grinding.

Originally Posted by jmk89

I wonder whether Order 02 should hold off until Order 01 has worked out the best way to get the bevel

The only way to achieve a primary bevel outside of grinding it ourselves is to get a 25º bevel ground by Rippon before heat treatment while the D2 is in its annealed state. This would remove the need for grinding a primary bevel ourselves and would allow members to hone a micro bevel at either 25º or 30º at their choosing after the heat treatment is complete.

I will contact Rippon in the morning to confirm how much this process will add to the price per blade.

Hello, BobL (and all as well)

Originally Posted by BobL

Sorry but I disagree.

If you look at this graph you will see that you need to get it above 350 F (175oC) to get close to starting a small retemper. Even more significant, tempering of D2 requires holding at that temperature for an hour and half per inch of thickness. And even if you manage to get it up to 800F that is only going to drop it to Rc 58 anyway - that in fact might be nice!

By all means, please disagree. I will argue you back, in a most constructive manner of course . I think I see the most interesting special case here for a quick debate.

BobL, I have all the reason to believe that like me, especially You are perfectly aware that those kind of curves considering only temperature/ hardness coordinates are especially data for tempering in oven.

In controlled oven environment there is (should be) no risk for overheating, also heat build in workpieces happens slowly. Therefore factors of heat conductivity and heat diffusion rate can be neglected for small pieces.

I comment this because there is now in many cases just a grinder for bevel making. As it is intensive overheating source, I believe that heat conductivity plays quite a big role now.

Because D2 is so tough even at hard state, it means that it degrades grinder stone relatively rapidly, both smoothening and clogging it up to some degree. Due to these reasons, there may easily happen sudden heat build-up. There is also very much steel to removed, so repeats between grinding heating and cooling will happen many times.

Because it is so that in hardened iron-carbon systems the tempering occurs by controlling the carbon dissolution rate in iron lattice, the more times it is overheated, it may affect deeper than surface region, too. There is just so many repeats. I also think that the temperature registered by fingertip is surprisingly low at the time when you should cool down the piece.

This is why some folks are considering an angle grinder to cut most of the bevel as it cuts so quickly maybe it can be used to grind all, bar the last mm or so away. I have never done this so I can't comment on how effective this would be.

It is generally quite rare to perform a major reshape to a relatively low-tempering hardened carbon steel piece. With HSS it is much more common.

For rough cutting away the major waste before going for bevel grinding, I propose for an angle grinder a very thin (1mm) disc (several discs possibly needed) for cutting stainless steel. Proceeding gradually there could be a bit better change.

Diamond or CBN wet thin disc for steels would be pretty good. The best and least availabe method would be abrasive water jet cutting.

The slow grinding of the bevel people are experiencing is not unexpected - It's not just hard - It's tough stuff - slight difference there. Tough stuff glazes abrasives as some folk are experiencing. I suspect the heat treatment has not changed the hardness of the steel significantly and it is around Rc 62. I won't be able to run an RC test on it until mid Jan when I get my blades back from melb. I will also test the bevel as well as the rest of the blade.

It would be really great to hear the results when you get them. This is most interesting subject all the way.

Derek once presented that excellent belt sander jig for rough shaping of bevels. I have adopted it, at the same time using pump bottle to wet the belt disappearing under the grinded bevel.

One very good device (for everyday use as well) would be supercharged Tormek where revolutions goes beyond 200 rpm. I have an old Tormek and I do not like it to be so slow. I have looked for ways to increase the speed over 200 rpm, but it might be that the original engine does not take the torque increase.

I guess I need to find one of those big oldie wet grinder stones and make a frame for it. I would make a coupling with a 1,5 kW motor, revving slow enough that water does not splash up to the roof . Truing the stone with an angle grinder while stone is running is easy but quite dusty task.

kippis,

sumu

Hello Sumu and all

Originally Posted by sumu

By all means, please disagree. I will argue you back, in a most constructive manner of course . I think I see the most interesting special case here for a quick debate.

No problem.

If the finger holding method of grinding, cooling dips, I use is a problem I would expect to see significant problems of detempering when grinding bevels with O1 steel as it is more temperature sensitive than D2. Like I said even if there is detempering it will only detemper to around Rc 58. Admittedly O1 even at high Rc is not as tough as D2, but D2 can take a higher temperature.

I think using any kind of grinding wheel, even a thin kerf cutting wheel, is going to create much higher temperatures than a hand hold grind and water dip method. I have a water cooled thin kerf cutting wheel which runs in an old small table saw at 2800 rpm which would be much better than using an angle grinder but I will need to make a jig to hold it at the right angle - this should not be too hard.

Groggy, if you want to, you can do a quick scratch test with the corner of a fresh file to determine if there has been any significant tempering while grinding your bevel. Try scratching a regular plane blade for comparison.

Cheers

Originally Posted by BobL

do a quick scratch test with the corner of a fresh file to determine if there has been any significant tempering while grinding your bevel.

I tried this on my M2 HSS blade and i was able to mark a good scratch into the bevel. I did the same to two blades that I have now ruff ground and one that has no bevel. Their is little to no difference between the three D2 blades regardless if i have ground the bevel. The D2 blades are softer then the M2 however it appears marginal.

I called Rippon and it will cost $5 extra per blade, to grind a 25º bevel into the annealed D2 steel in batch 02. John says that he can leave a 1 mm extra on the bevel edge. This will allow us to then to easily remove the last 1 mm of cooked/softer steel at the edge after heat treatment.

Rippon has big machines that will flat ground the bevel so these blades will not be hollow ground however this will be much easier thing to achieve in your average woodshop if you wished to have your bevel hollow ground.

Originally Posted by thumbsucker

I called Rippon and it will cost $5 extra per blade, to grind a 25º bevel into the annealed D2 steel in batch 02. John says that he can leave a 1 mm extra on the bevel edge. This will allow us to then to easily remove the last 1 mm of cooked/softer steel at the edge after heat treatment.

Rippon has big machines that will flat ground the bevel so these blades will not be hollow ground however this will be much easier thing to achieve in your average woodshop if you wished to have your bevel hollow ground.

That looks like the way to go - please put 25 degree bevel on my four blades when confirming my order.

Many thanks for all your efforts.

Hello,

Originally Posted by BobL

I have a water cooled thin kerf cutting wheel which runs in an old small table saw at 2800 rpm which would be much better than using an angle grinder but I will need to make a jig to hold it at the right angle - this should not be too hard.

That kind of method sounds very good, much better than my proposition of thin angle grinder disc. I have found thin discs for stainless steel very usable for thinner and hardened stock cutting, but I admit I have no previous experience on taking something like 15mm wide slice off hardened steel and at the same time trying to maintain temper.

You know, the thing is that I see mr TS as one really cool and enterprising guy when he is pushing this thing through. I want this blade business to become a success, because 1) I can relate, I do similar kind of things frequently and it can sometimes turn into one damn PITA 2) the entire operation is on display all the time, all the business details included (rare stuff and I must say, a bit beyond them usual WIPs) 3) those blades have readily a chance to be some of them beefiest plane irons there has ever been, and because so many guys have ordered them, I can't wait to hear how they do their thing. If I can help there, I will, at least by digging up every related food for thought from my pockets.

It's kinda funny to think that the planes packing those irons will be so fancy that future collectors will be wondering them. Similar kind of irons in very different styles of planes. Here and there.

This WWF thread should have a logo of it's own, to be stamped in those irons.

kippis,

sumu

It takes hours to get the blades ground and honed - $5 is cheap folks.

It looks confirmed batch 02 will have all blades ground to a 25º primary bevel.

Unless you specifically ask otherwise.


Having read the above posts I modified my approach to grinding the primary bevel.

I think it should be a full proof method of avoiding all risk of harming the temper.

1- I clamped my metal working vice to a sleeper
2- Filled a spray and wipe bottle full of water
3- Changed the disk on the angle grinder to Purple (?) Flap Disk
4- Clamped the blade into the vice.
5- Give the blade 3 -5 squirts of water (it will get cold)
6- Take a single pass across the blade edge with the angle grinder - if you feel it will still be cold -
7- Spray 3 - 5 more squirts of water (it will get very cold)
8- Repeat spray three times and grind once again and again.

This may sound slow and it is very conservative, however because the flap disk cuts fast and the steel never gets above cold/cool I am guaranteed (I hope) that I will not de-temper the blade. The blade never got hot and should be at most cool to touch.

Two passes with the grinder one forward once back will make it luke warm, three passes will make it hot cup of tea hot.

It took me about an hour to get 85% of the way I am going to do another blade and time it from start to finish, and time it down to the minute.

The only warning is that I used over 2 liters of water, and my vice, log and pavement was very wet. Make sure the water can drain away and be carfull that you do not zap and yourself.

If you had a mate one could grind and one could pump and you could get done much faster together and with no risk of de-tempering the blade.

*EDIT*
I had a whole bunch of grinding wheels given to me. A few of them were ZEC™ Silicone Carbide Grinding Wheels. These are very coarse disk's however they cut very aggressively and do not build up near as much heat as the Flap disk. I would recommend other look into these disks or something similar. They have a fan like surface that moves air over the grinding surface and removed waste material at the same time.

Originally Posted by jmk89

That looks like the way to go - please put 25 degree bevel on my four blades when confirming my order.

Me too.
Thanks

What does a flip disc look like? I know what a flap disc is, but I don't know about flip discs and I can't find them on the flexovit website.

Sorry Jeremy, I made a doo doo - no such thing as a Flip Disk, it should have read Flap disk.

Originally Posted by thumbsucker

Sorry I made a doo doo - no such thing as a Flip Disk, it should have read Flat disk.

and I think you mean "boo boo"

Originally Posted by sumu

This WWF thread should have a logo of it's own, to be stamped in those irons.

The thought has crossed my mind, but what do call them is the question? U-beaut Blades - but that may conflict with our host. My initials HKB Batch 02 would be obvious stamp.

I would need to do it before heat treatment. No blooody way it will work once it is hard.

If someone comes up with a good name - I would be willing to stamp each blade with it.

Please suggest.

Here is my first suggestion: "The Blade the Forum Built" or BFB - if you had not guessed by now I suck and blow at choosing names.