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Straight edge materials and stiffness

Rich, you've got to dial it back. You've been totally out of line in this thread. I'm sending you a PM to speak further about this, and I'm going to lock this thread until I clean up some of the out of line comments here.
 
Oops...I did get a bit off the topic. I screwed up and apologize to the forum and Dennis and eg. I've been told I'm going to be suspended for a few days. I'm bad. If anyone needs help, my phone number and email are around. I'm like the old part in the neighborhood who is a crab. I'll put people on ignore again. Rich
 
A quick answer to the original question asked by Avivz:
Alumina and silicon carbide are used in metrology applications when material performance is more important than cost. The criteria includes modulus of elasticity/material density , thermal expansion, thermal conductivity, and hardness.

The Saint Gobain, Coorstek, and Schunk websites can provide some insight into the advantages of ceramics.



 
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does your credibility no good at all.
Mmm. Every time I see one of those ego-laden posts I have to smile, hearing Homer Abner's description of Mr King's rebuilding talents in my mind. If you ever knew Homer, you'd be smiling too :D

@Robert R, if Schunk is so great, why aren't they making straightedges out of beryllium, eh ? cheap german crap :D
 
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Beryllium was chosen as the substrate for the Webb Space Telescope mirrors. Silicon carbide was the second choice. For large earth based structures ceramics are a better choice.



 
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Nobody 'owns' threads here. It's not grade school. [1]

I seem to recall the moore book suggested that box-type straight edges were best - and that camel-back types had some inherent problems.

[1] well maybe the site owner 'owns' them.
 
Nobody 'owns' threads here. It's not grade school. [1]

I seem to recall the moore book suggested that box-type straight edges were best - and that camel-back types had some inherent problems.

[1] well maybe the site owner 'owns' them.

Right. But it's good to give an OP a little leeway as far as steering a thread back on topic somewhat, that's just good Internet etiquette.

Just for everyone's info who saw this thread degenerate a bit, Rich got a 3 day temp ban for the unprovoked attacks on and attempts to discredit Denis. Thank you to Denis for not responding in a provocative manner.
 
The difficulties of scraping steel have been discussed in this thread and certainly are significant using standard scraping techniques. However, today, a friend, unaware of this thread and not participating in PM sent me a video that he thought was interesting concerning scraping steel. And, indeed,I did find this video to have some information that I think might be useful to anyone considering scraping steel and I think the guy did a very nice job of explaining what he was doing and carefully investigating scraper geometry for steel versus cast-iron. The cut geometry that he uses seems to really scrape the steel smoothly and efficiently.

So, have a look:
Steel scraping cutter geometry.

Denis
 
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That video has circulated here previously and has some good information for sure. I like that guy, he has several good videos. He also is responsible for my owning a couple Wild Heerbrugg theodolites... 😂
 








 
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