Spyderco Forums

Hello Spyderco family. Long time lurker first time poster.

Question: I recently had the amazing opportunity to visit with Sal and pick his amazing mind. As we talked (way over my head I’ll add) about metals, sharpness, and a host of other things he dove into REX 121 and that it could cut glass. He told me if I posed the question that you guys could educate me on this and there might be a video? I would love to see it and hear what you have to say about REX 121 and the Sage.

Thank you in advance.

Hi, tymiller:
Welcome to our forum. We hope you enjoy your time with us!

Kristi

Technically regular glass is around 60-61 HRC, glass is not measured in HRC, but if we converted that is what regular glass is. So any steel that is harder than that will scratch (cut) glass. Rex-121 is usually hardened to much harder than 61 HRC in knives ~70 HRC. I don't know what Spyderco hardens it to. The harder the steel is the easier it will cut glass without damage. In addition rex-121 has loads of carbides that are much harder still, so that might help cutting glass as well, not sure about that, but it seems to make sense.

Fastidiotus wrote: ↑

Thu Dec 05, 2024 4:37 pm

that hurt to watch. if the neck shattered that thing would have dug into his thumb.

Just to show that a simple, hard steel can do it too. 26c3 @67 HRC. Of course Shawn is a magician when it comes to steels, heat treats and geometry, but the point still stands. Hard enough steel will cut glass.

Next level party trick...

I got a sprint run Police4 with the PD #1 steel I have no doubt that it's harder than my Sage5 in Rex121, that will score glass after watching that video of the Sage5 scoring the bottleneck.

What is really cool here is that Spyderco has this level of steel in edc knifes we can buy...

Hi Ty,

Welcome to our forum. Say "hi" to Barb.

sal

Thanks Sal. Will do.

All my Maxamet knives and my REX 45 knives can also cut glass.

Spyderfreek wrote: ↑

Mon Dec 16, 2024 6:48 pm

... and my REX 45 knives can also cut glass.

Well, thanks!

REX 45 is my favorite PE steel so far and I tested it on quite some materials yet..

... but NOT glass... will do now though!

Jeb wrote: ↑

Fri Dec 06, 2024 5:23 pm

I got a sprint run Police4 with the PD #1 steel I have no doubt that it's harder than my Sage5 in Rex121, that will score glass after watching that video of the Sage5 scoring the bottleneck.

What is really cool here is that Spyderco has this level of steel in edc knifes we can buy...

It is very unlikely that your PD1 is harder than rex121, not impossible of course, but would be very unusual since rex121 is usually heat treated very hard (68 - 71 HRC) and PD1 not as hard. I agree that it is extremely cool that Spyderco is using all these steels in their knives, giving regular people an opportunity to play with all these exotic steels.

Rex121 dragonfly please!