stephen thomas
Diamond
- Joined
- Jun 3, 2001
since i use and sometimes used to make a lot of carbon steel tools for both hand and machine powered woodworking, i once set up, trued, and used a 2-1/2" wide x 24" sandstone wheel with water flood for a while, adjacent to my regular grinding facilities. It was sort of fun, slow as can be, and tended to burn the steel if you were not careful. (If you got impatient with the interminableness of the process and pressed hard under the water) Emory is not sandtone, i believe it generally refers to corborundum? Silicon carbide. The best way to sharpen carbon steels is with AlO open pore(8 or better) coarse (46g) wheels around J hardness with water mist or coolant and then hone/lap them on hard fine india or Arkansas stone. SiC stones are a good intermediate lap.
I might revisit carbon steel on the shaper or planer sometime as a play project, but as i mentioned, HSS works better.
If you only need to do a small area at a slow speed; a carbon tool might get through. But if you are doing something big, it does not matter how nice the original honed edge cut, it goes away too fast. HSS is almost imperceptible to tell the difference on powered machinery (as opposed to say hand taps).
I would not bother making a carbon form tool for the planer or shaper, for instance. The way they wear takes too much off the shape (need to grind the face back too far to regain the clearance). HSS is just as easy to grind a form tool initially, and it lasts longer and erodes less. I've posted projects with shop made HSS form tools sharpened on the face only, for fairly long run shaper jobs, and a few for the planer. CPM C4 HSS is the best tool steel i've experienced on either machine (Thanks, John Oder) & it is my go-to steel for most work, especially for planing steel. OTOH, Carbide works well for CI, depending on geometry. Most of the "smoothness" of any type cut but especially on recip cutting machines is down to appropriate geometry for the substrate and the shape of the intended cut (flat or form) and then tweaking that geometry and edge detail.
Stellite is a wonderful cutting material, but it is at least as brittle as carbide. The advantage of making brazed on bits and form tools of Stellite or Tantung is that they can be shaped and sharpened by normal AlO wheels, no diamonds needed. I've posted articles about making and using stellite tools, mostly for wood working.
For long running edge tools with the ability to be somewhat productive, you need heat resistance and toughness.
HC tools can be honed very sharp,.some are sort of tough, but they have no heat resistance and the way the edge fails in cutting steel or CI requires that a large amount of edge material be carefully ground back on the tool to regain the edge.
Stellite is easy to shape with normal wheels and can be honed as sharp as HC or maybe even keener. It has excellent heat resistance and durability, but is brittle/no toughness.
Carbide has excellent heat resistance, good abrasion resistance, and can have fair toughness. But it cannot be sharpened to as keen an edge as other materials though gains are being made.
Some grades of HSS have excellent heat resistance, good to excellent toughness, and can be honed as nearly sharp as HC as you can't really tell the difference shaving.
smt
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