Underwater Grinding

[rbscebu]

I am just throwing thoughts around in my mind. If have a SR that I am thinking of modifying the profile. The modification would involve; changing the Dutch (round) point to a Spanish point like the Gold Dollar W59, thinning the spine to take about 1.5° off the bevel angle, and replacing the stabiliser with a thumb notch arrangement.

The blade will be of specially heat treated stainless steel that could easily have its fine gained structure modified if its temperature ever exceeds 200°C. This I don't want to happen.

I was thinking that the best way to do the training of the point and the heel/shoulder would be to grind it underwater. My thinking is this should guarantee that 200°C would never be reached.

I know the normal suggestion is to just grind for a second or two and then let the steel cool, but I would like to try a different approach. My main concern is that, being so thin, any grinding in air near the edge could easily and almost instantly get the steel temperature there to over 200°C.

I could do this grinding using a Dremel with flexible extension. What do you think?

 

[Legion]

I am just throwing thoughts around in my mind. If have a SR that I am thinking of modifying the profile. The modification would involve; changing the Dutch (round) point to a Spanish point like the Gold Dollar W59, thinning the spine to take about 1.5° off the bevel angle, and replacing the stabiliser with a thumb notch arrangement.

The blade will be of specially heat treated stainless steel that could easily have its fine gained structure modified if its temperature ever exceeds 200°C. This I don't want to happen.

I was thinking that the best way to do the training of the point and the heel/shoulder would be to grind it underwater. My thinking is this should guarantee that 200°C would never be reached.

I know the normal suggestion is to just grind for a second or two and then let the steel cool, but I would like to try a different approach. My main concern is that, being so thin, any grinding in air near the edge could easily and almost instantly get the steel temperature there to over 200°C.

I could do this grinding using a Dremel with flexible extension. What do you think?

That is mostly how I reshape knives. Plastic tub with a cm of water in it, knife sits partially submerged, and I grid it with a Dremel. It doesn't need to be completely underwater, as long as it is getting wet by movement, the tool throwing up spray, etc.

Just dry the flex shaft, chuck and bits well, or it will all rust.

For razors I've rested the edge on a big block of ice and ground it that way. Either would work.

 

[Legion]

In my experience, the grind for a second or two and wait method is asking for trouble with a razor. The hollow ground edges are too thin, and heat up in an instant. They need cooling.

 

[rbscebu]

^^^ My thoughts exactly.

 

[bluesman 7]

The vast majority of the grinding is far enough from the edge to not present any problems.

 

[DrStrange]

I was thinking that laying the blade on a wet cloth might be sufficient
and less splashy.

 

[Biltong & Boerewors]

You are right in your assumptions, overheating can happen very quickly, especially along the edge, even with polishing.

If you want to do grinding, a Dremel is a big risk, because of the high speed, even on it's lowest setting. Belt sanders are more suitable because of the lower speeds. I have a small bench belt sander that I fitted with a variable speed controller in an attempt to slow it down ever further, unfortunately the speed control doesn't work well, I think it's overrated for the sander, more or less acts like an on/off switch.

When grinding or polishing I never wear gloves, I am prepared to take the calculated risk for the sake of preserving the heat treatment. If it's cold enough to hold in bare hands, its fine. I also keep a tray of water handy to cool it down.

Like most things, skill comes at a price, be prepared to pay with some ruined razors, so practise on some cheap ones.

I tested a few ideas I had on this Gold Dollar 66:

1) How difficult is it to change the side profile? Tried a thumb notch, I have also changed the point on others- Not difficult at all.
2) How difficult is it to hollow grind? - Easy to do, difficult to do it well.
3) Thinning the spine - Decided to go for a diamond shaped spine, instead of flat. Difficulty? Not too bad, will get easier with practise.