[Tungsten Carbide Rasp]

I have a fantastic wood rasp that I inherited from my grandfather some 40 years ago. It is made from a flat piece of steel with abrasive bonded to it. Considering how long it has remained sharp, I'm guessing that the abrasive is tungsten carbide or something similar.

 

Does anyone know where to buy such a rasp?

 

Thanks.

[Aftermarket Makita 18v Batteries?]

Any recommendations for aftermarket Makita 18V batteries? I see lots of different ones on Amazon and reviews are mixed. Do any of these perform similar to original Maklita batteries. Are the ratings (5Ah, 6Ah, etc.) anywhere near accurate?

[Torque control on impact wrench?]

I am considering buying a cordless impact driver, similar to the attached, that can accommodate both 1/2" sockets as well as standard hex shank screwdriver bits. As I have never used one of these tools, I'm wondering how one avoids overtightening when driving screws, since none of them appear to have torque settings.

 

Can someone explain this to me.