PM-V11 steel grinding

[Haitham]

Hello,

With my Tormek T8 I received the standard SG-250 super-grind.
I've already ground three VERITAS PM-V11 chisels by veritas up to 1 inch with success.
Yesterday I've put a new 25 degrees primary bevel on a pm-v11 jack plane
2 1/4 wide and it took me ages. The stone had just been trued up with coarse serrations
but it kept glazing. (Maybe the pm-v11 being a powder metal is the issue). As I was approaching to the very edge it seemed to take forever. I think that for these wide hard blades and full edge restoration I have to true up again the stone halfway

Do you think that the black stone would be quicker? SB-250
I wouldn't try diamonds as my diamond benchstones struggle with pm-v11

Thank you

[RickKrung]

Couple options, one cheap, the other spendy. 

1) traditional grinding wheel, such as 64 grit Norton 3X, mounted on the Tormek.  Takes some custom fitting to mate the 1" arbor hole to the 12mm Tormek shaft.  Can be a simple as drilling out some PVC pipe to go with the plastic bushings that come with the wheel and some 12mm fender washers to fill the space.  Or, if you have the ability to machine your own, make the bushing and flange washers (or have them made at a machine shop).  Do a search on the forum for "Norton" and you'll turn up a number or threads on this.  I machined my own bushing and flange washers.  AFAIK, Norton only come in 8" dia., which work, but I came into a 10" dia., no-name wheel that works much like the 250mm wheels. 

2) Coarse CBN wheels, run in water on the T8.  Third party vendors supply them, some can be run in water, at least one states the warranty will be voided if run in water.  I've been running a 180 grit CBN, from the "no water" vendor for years without any problems.  I use the Tormek ACC solution and am careful to dry the wheel after use. 

Another option is to get a variable speed belt grinder and run it as slow as it will go for roughing and then take them to the Tormek. 

Way back, before doing all of the above, I tried the SB grinding wheel.  Does work better but tends to glaze up quickly. 

It also may help to get some coarse diamond plates to remove the glazing, short of retruing the wheels, for both the standard and SB wheels.  Search "diamond plate" and you should find discussion of this. Knife Grinders may have been the originator of the diamond plate technique. 

[Haitham]

Hi,

Thank you for your reply. I came out with this wheel sold by dictum in germany:

https://www.dictum.com/it/mezzi-di-affilatura-per-affilatrici-efc/disco-a-smeriglio-dictum-carbon-cut-grana-80-716030

they have some dictum custom made wheels compliant with the tormek

Did you know about these?

Thank you

[RickKrung]

I don't know anything about the Dictum wheels, but if it is 80 grit, might be just the thing you need. 

[John Hancock Sr]

Your problem is that PM-V11 is harder than you Aluminium Oxide or corundum wheels. I have some PM-V11 and I sharpen them with Diamond wheels. Not sure why you have issues with diamond bench stones with PM-V11 - they should be fine. They will obviously take longer than lower hardness carbon steels but that is to be expected.

Your options are Silicon Carbide or the black stone, Diamond and CBN all of which are harder than PM-V11 and thus suitable for sharpening them.

The wheels you linked to is corundum, or Aluminium Oxide and thus too soft for PM-V11 - pretty much the same as the Tormek SG wheels.

[Haitham]

Very interesting John Hancock.

What kind of diamond wheel do you use? Coarse, fine or extrafine?

Thank you very much

[John Hancock Sr]

What kind of diamond wheel do you use? Coarse, fine or extrafine?

Depends really. If you re re-establishing your primary bevel Start with Coarse and go up to whatever grit you prefer. I move through DC to DF add DE then hand hone on a 5000 Shapton before stropping. It only takes a few strokes on the 5000.

[Haitham]

Thank you very much.

What do you think if, for now, I try to stick with the stone that I have and try and touch up the bevels every now and then just not to make them build a too big secondary bevel?
It seems that if the amount of steel to remove is little I can still use the super-grind stone.

When you touch the bevel with the 5000 (I use an Ohishi 6000 - actually I have to use the 1000 first because if I arrive to the edge and look at it with a jewellers loupe I can see a ragged edge left from the stone - i don't dress it with the stone dresser, I should) do you use the hollow to find the bevel on the stone and just hone the heel and the bevel together?

There are two schools. Frank Klausz clicks the bevel on the stone to find the angle and just hones in that position so he actually hones the bevel and the heel of the hollow.
Rob Cosman after finding the angle raises the blade a bit and doesn't touch the heel.

Regards,
Haitham

[John Hancock Sr]

There are two schools. Frank Klausz clicks the bevel on the stone to find the angle and just hones in that position so he actually hones the bevel and the heel of the hollow.
Rob Cosman after finding the angle raises the blade a bit and doesn't touch the heel.

Both are experienced and skilled woodworkers and both are good options. Rob is a big proponent of these shortcuts such as the ruler trick and secondary bevel.

The traditional method is to not create a secondary bevel which was what I was taught. Older steels were softer carbon steel and you would take them back to the stone often, no stropping.  You would go back and forth between the bevel and back to remove the burr. It is only in recent years that the plethora of different and more sophisticated techniques has begun to arise. If you look at the older generation they tend to pretty much keep it simple. People such as Frank and Paul Sellars use the more straight forward and simpler methods.

I think that one of the reasons that secondary bevels has become so popular is the modern use of harder steels in chisels and planes where if you work on the primary bevel only it takes much longer.

I don't tend to use secondary bevels that much on the older tools but with the PMV-11, O2 and A2 steels it makes more sense to create a secondary bevel, remembering that it will take that much longer to create the primary bevel when needed. The other advantage of a secondary bevel is that it takes less skill to get a better edge, but of course that is moot when solely using the Tormek.

Having said all of that I do raise the tool rest up a turn or so when finishing on the DE, partly that the DE seems slightly larger than the DC and the DF and partly just to reduce the time to bring the edge to 1000G.

In the end it really is up to you as to which technique you feel most comfortable with. What you are trying to achieve is an intersection of co-planer surfaces and on your chisel with as flat a back as possible. There is a lot to be said for experimenting with different techniques until you find one or more that you are happy with. Also using different techniques for different tools and steels is also an option.

As a final note look up Paul Sellars videos on sharpening. What he does is pretty much how I was taught.