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Parting Tool Razor

I hope he does! It would be interesting to push the boundaries of what is possible. Put a thin steel frame on it and then use tape to fatten up the bevel angle. Then start reducing tape to see how low you could go.
I'm swamped with cleaning out the house I've lived in for 30+ years so I can escape to a State that is friendlier toward responsible Americans.

A parting tool razor will have to get added to the list of other "G-Jobs" (personal jobs) that need doing once I've set up my shop in hopefully a bigger space.
A quick look didn't turn up much on "what" the steels make up is

I glanced around too - found very little, some Mo-Max tools were M33, some M42. I'd assume many alloys have been used, not sure if there is a way to figure out which is which.
I have a pile of these. I'll do some testing and try honing up a few different angles and see how they do. As far as the spine width, it would be easy to build up the thickness by TIG welding (just do it before doing any grinding and with short beads letting it cool in between). I've done it plenty of times repairing old cutting tools in the machine shop I used to work at. You can just use another piece of HSS for the filler. It's pretty tough to lose the temper on HSS unintentionally.

Slash McCoy

I freehand dog rockets
Wow... I don't know what to say about that except it would be really cool if you are successful. Myself, rather than trying to TIG some thickness on, I think I would look for a purely mechanical means of attaching a frameback spine sort of thing to the blade, and not even risk pulling the temper. A separate spine could be formed and heat treated and custom tempered to a desired hardness, then final fit and polish and bobs yer uncle. A shallow groove ground into the blade on both sides near the spine would be all the modification needed to secure a split tubular spine. The spine would not be needed for support, only for angle maintainence, so it only needs to be about as long as the shaving edge. The steel of the original tool can be the tang. For extra thickness, if desired, you could add a thin slab of acrylic or even MOP (mother of pearl) or maybe vintage ivory.

I can actually see this being a thing, but I have doubts about the welding. Fingers crossed, though. Lets see what you can do with it!
It's virtually impossible to unintentionally lose the temper on HSS actually. You can weld it and let it air cool and it will be just about as hard as when you started. To soften it the rate of cooling must be controlled - it has to be heated to something like 1600°F and then the temperature must be ramped down slowly over a period of many hours. It will hold its temper even at red heat - it's really tough stuff.

This is all academic though until I see if it can hold an angle in the neighborhood of 16° - 20° without chipping out. If it can't it won't be of much use going further.
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OK, selected a candidate from my stash. Tests to commence soon. If it will hold the edge at 20° or under, I'll make a razor from this blank.


Slash McCoy

I freehand dog rockets
It would be interesting to try that steel for a small work knife. A chippy edge would not be a terrible thing.
Actually, there are quite a few knives made from HSS these days. Anyways, I finished a test hone and it holds 18 degrees with no chipping issues. I expected it would - M2 is alloyed with tungsten, vanadium, and molybdenum - all carbide formers. Anyone who tries this is definitely going to want to use a diamond plate progression to hone until finish level though - this stuff is hard as hell. My 1k Chosera got hardly anywhere with it. Was mostly polishing. Switched to DMT 325, Atoma 1200, DMT 8k progression and finished with a JNat. Shaves nice, but might be even better finished on something else. The JNat left a little rougher finish than I'm used to seeing, possibly carbides pulling out? Not sure. Edge still looks pretty good though. Frames are about 1mm left to right - measure the frame on your screen and divide to get true magnification.

Here's a ring light shot:


Edge Lit:


Raking Light, emphasizes scratch depth:

Almost definitely. Anytime you see the "cobalt" designation it's obviously a cobalt alloyed steel - usually M42. They are even tougher than M2 at red heat and even harder to chip. If it doesn't say cobalt it's usually M2. There are a few other grades also though. Cobalt alloys are good for a few more points of hardness - about 64 to 65HRc for M2 and up to 67 HRc for M42.
LOL, it's not done yet Doc! This was just a test edge to make sure that chipping of the edge wouldn't be an issue at razor angles. I'll post pics when I get it finished.
Sure, it's fun! Ha-ha, anyways Vic, I've been meaning to try it for years. I tried a Suehiro 20k finish just for giggles, the scope shot makes it pretty clear that the carbides in this stuff are viciously hard - I'll post it later tonight. Not sure if they are the tungsten carbides or the vanadium carbides but they stick out like a sore thumb from the mean bevel surface.
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Slash McCoy

I freehand dog rockets
Because the carbides are so hard, and not homogenous in the matrix, I think dislodging them will always be the 600 lb gorilla in the room. Maybe what is needed is fine diamond and light light pressure on the right substrate, to cut the carbides instead of cutting around them or knocking them loose. Needs to be harder than pine. Maybe .1u diamond on lapped and polished aluminum? I guess it would need to be lapped again after every use. I do believe the reason I get great results from diamond on balsa is the diamond particles are embedded and not rolling around on the surface. Shallower scratches, I think.

Lots and lots, like several hundred, maybe a couple thousand very light laps? Extreme light pressure? The material is pushing the envelope I think, and extreme measures are called for. Just my feeling on it...
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