Small smooth very hard plate material?

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zondar

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Hello Forum Members,

I'm looking for some ideas and leads on some small pieces of hard metal or ceramic material, maybe 1" square or slightly less. The dimensions, and especially the thickness, aren't critically important, as the project is still mostly in the thinking phase. Maybe 1/4" thickness would do, or as thin as 1/16" if it's resting on a separate support. The material has to come, out of the box, quite flat and smooth (i.e. ground flat). I'll need two pieces.

A big problem I face is that I'm not well equipped to cut or shape such hard materials, so it would be best if it comes already sized in suitable shapes and smoothness. I do have a good rotary tool, so I imagine I try to (crudely) cut some hard materials with small abrasive cut-off wheels.

I usually buy materials from McMaster Carr. They have Tungsten Carbide bars, which I could likely make work. A 1" by 6" by 1/16" bar is currently $80 plus delivery and tax, so two of them (if I can't cut one in half) feels pricey. They state that the surface finish is "plain", so not polished. I imagine that these are ground?

Is it practical to cut Tungsten Carbide with a rotary tool and small grinding wheels? Is polishing it by hand practical?

What else is out there that's worth looking at?

The plates are intended act as small anvils on which tool-steel knives will balance and pivot with minimal friction.

Thank you.
 
You could also most likely find off the shelf carbide inserts close to that size .
 
Would glass be flat and smooth enough? If so, dead easy to come by and cut to any size you want. On second thought, maybe not hard enough though.
 
Thanks for the ideas.

I did think about glass. It would likely work for a while, but I think the knives would grind grooves in it fairly quickly, maybe even in minutes. That would ruin the "low friction" goal. Some form of ceramic might be better, like silicon carbide or similar.

Gauge blocks would be about the right size. I thought of that too, but can they be bought individually?

Off-the-shelf carbide inserts are a possibility, but I haven't seen any in sizes that would suit yet.

I did see "solid carbide" paint scraper blades available for quite low cost. The ones I saw were about 2" by 0.5" each, which is in the ballpark. The surface isn't smooth, and I wouldn't imagine that they are particularly flat, but for $20-30, it could be worth a try.

Can carbide be cut via small abrasive cut-off wheels, i.e. Dremel, etc., size?

Probably a particularly hard steel would be OK. Harder than most tool steels. I'm not up on what sorts those might be. Spring steel, maybe?

Thanks again.
 
Hoke style gage blocks would be a winner, they have a countersunk hole in the center, you should be able to buy them individually, as replacements are necessary when sets are calibrated and below tolerance blocks are discarded by the calibration lab, when you see miscellaneous blocks for sane on E Bay, likely they are scrap from a lab. Carbide can only be cut by a diamond tool.
 
Ah, yes, I see Starrett does sell individual gauge blocks. Most are frightfully expensive, though their lowest grade is doable (~$40-70 each). Those have a Rockwell C hardness of 64-65, which may be OK. The size and shape is ideal.

(Ok, I'll scrap any ideas of cutting carbide - thanks.)
 
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As a rule, I don't like to begin a conversation with the word "I". In this case, that might fit. I have seen odd sized gauge blocks on eBay, and some cheap sets. Just how cheap is cheap? But that is a matter of when and where they are available. Then there is carbide. . . It can only be cut with diamond tools. But given the appropriate tooling, it can be scored with a "green wheel" and broken. Actually, carbide is a ceramic itself.

Glass would be a suitable choice. I can't comment on how long it would last, not knowing your concept. But, my father talked of sharpening razor blades on glass when times were hard. I use hair clippers when I shave, Gave up on razors years ago. The point is that glass is harder than a razor blade, so might be suitable.

Along those lines, there is also ceramic tile. There are higher grades of ceramics, but tiles would prove or disprove a concept. The advantage is that they are easily acquired. Not only as 4X4s, but as sheets of small patterned tiles. Ceranic tiles can be polished if greater smoothness is needed. I'm not sure how, but there are cleaners that contain abrasives. They can be had in single lots at big box home stores. And a broken large one is dumpster fodder.

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About glass: It's hard, but the blades would rock back and forth against the glass - quite different than honing - and I think that would result in it being ground in rather quickly.

The link below (credit precisionclocks.com) shows a picture to give you an idea of what I'm trying to do. This configuration is upside-down to my intention, in that what I'm calling the "anvil" is the part that rocks rather than the blade, and there's a pre-cut groove in the anvil, which I would not use (it causes more friction than a flat surface should). I've bought some 1/8" square D2 steel tool blanks for the blades, much as you see below. Those would sit on flat anvils and do the rocking. Without grooves, the blades would have to sit precisely level and the whole mechanism would need to be finely balanced, or the blades will walk (very bad, obviously). It's all really outside my experience level, but stretching is what learning is all about.

knife-edge gymbal
 

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