Russian/Soviet Straight Edges?

[gard]

I have used something that was called a knife edge straightedge exactly as you described.
I think what I purchased was something else. It was dangerously sharp, it has 4ea holes for flat head bolts. Approximately 2.5*16*0.5". Also it was not particularly flat, off by about 0.01" if I remember correctly.
I have not tried to figure what kind of steel it is but may find a use for it some day.

 

[gard]

Some photos, anyone know what it really is?

 

[Ulma Doctor]

At the risk of being wrong, it appears to be a shear blade

 

[David2011]

Above a certain dollar value there are import duties. I believe the threshold is $800. Under that value there is no duty.

Right. When it comes to import taxes there’s something called “de minimis” which means ’too little to bother with.” The import taxes on small purchases would be too small to justify the cost of collection.

A few times several years ago I bought from a Hong Kong based R/C supplier and paid no import fees. Big importers like Banggood and Temu avoid paying tariffs by not importing in bulk to the US, instead shipping directly to the consumer on the de minimis loophole. That’s part of how they sell similar or identical items for so much less than US based retailers.

 

[gard]

At the risk of being wrong, it appears to be a shear blade

Well that is an interesting idea. Now I just have to make the rest of the shear (after I finish a couple of other projects in the works...).
Or if anyone has a shear that needs a blade we can work something out.

 

[Pevehouse]

I have looked at a few strait edge castings on eBay . Very pricey but I figured it would be a good scraping project

 

[gard]

I learned to scrape starting with a casting from Denis Foster off Ebay, very happy with it. I bought a raw casting and milled it myself, you can also buy it already milled, ready for scraping.
I also made a strait edge from a piece of cast iron that came out of a junk piano, some people buy a chunk of durabar.

 

[G-ManBart]

The Russian straight edge showed up! Shipping took a while, but I knew that going in. It seemed like it sat for most of the time in one location, then once it started to move it was here within a few days...I'd say expect 3-4 weeks if you buy something similar from the region.

It was coated in preservative oil, wrapped in what appears to be corrosion inhibiting paper, and all of that was inside a plastic case along with some kind of inspection results paperwork (I don't read Russian!). It cleaned up easily and there isn't a spec of corrosion anywhere and the machining finish is very nice.

All I've done so far is to put it on my surface plate and use a flashlight on the other side...can't see any light showing on any of the four sides when I do this. I need to do some reading on how to evaluate what I wound up with as far as straightness goes. My surface plate was in calibration when I bought it, and it's been kept covered since I got it, so I think I'm good there.

 

[Rex Walters]

The light test is EXTREMELY accurate for a knife-edge straightedge, but less so for a wider one like yours. Fortunately, indicating whether a surface is parallel to a surface plate is trivial.

The best way to check is to attach a point or sphere onto each of three jackstands, put them on your plate, then rest the straightedge on the balls. You indicate the underside, first adjusting the jack heights until three corners indicate the same with a tenths indicator. Then just sweep the underside surface and measure deviations relative to the plate surface directly.