What is it? Set 232

[whit3rd]

1305: the diffraction grating and mount from a monochromator or spectrometer. Jeweled movement: that "red ball" is probably a ruby bearing that engages a micrometer-screw driven surface to make fine angle adjustment (because of the linear motion of the micrometer, it will read out the sine of the angle).

[RicodJour]

I'm still a bit dubious about the tool being for cement work. I've done my fair share of cement work and I've never seen a rolling groover. I couldn't find a rolling groover anywhere on the internet. I've seen plenty of rolling joint rakers, but never a groover (two sided) nor edger (on sided). Besides the obvious cleaning issue with the tool you posted, there's the very problematic question of how the tool would function. The typical groovers are like sleds with curved leading and trailing ends, and they have flat bottoms so there's little worry about creating unevenness. Since concrete has aggregate and is not a uniform material a rolling groover would create a divot or hump every time it ran into an obstruction (aggregate) or soft spot. You would have a lot of unhappy customers if you finished off the nice flat work with wavy grooves/edges. Here's a link to Marshalltown's groovers:

designs are all the same, flat bottom and you push it back and forth. I can't imagine any trade is slower to change than concrete finishing - it's been the same material worked with essentially the same tools for thousands of years. I also did a USPTO search and drew a blank for a rolling groover. The tool looks like it has a marking on the wishbone part of the handle. Do you have more information on that? Thanks.

R

[RicodJour]

True, and most dedicated craftsmen don't buy tools that make their job _more_ work.

R

[Esra Sdrawkcab]

Make that 250 years (the art was lost after the roman times see

)

[R.H.]

I've seen a number of other tools that do their intended job but have design flaws of one type or another, and I think that is the case with this particular tool. As I stated before, this exact tool is in one of my books, and though I couldn't find a photo on the web, there was this mention of it:

"Joints in the pervious concrete pavement were cut immediately after rolling using a rolling groover ..."

From this site:

I've seen plenty of rolling joint rakers, but never a groover (two

I haven't worked much with cement but if this tool is as bad as you say it is then it would make sense that you haven't seen one, they probably made them for a year or two and then quit production.

In the photo it does look like a mark of some sort, but it's just pitting; there's not a single number, letter, or symbol on it.

So since I have some evidence that it is a rolling jointer and no evidence pointing in any other direction, I'm going to have to keep my current answer for now. If anyone finds additional information on this tool one way or the other, please let me know, I'd be happy to take a look at it.

Rob

[Gerald Miller]

Ah-ha, a very specialized tool developed to do a common job on a highly specialized and unusual concrete application. This special concrete would only work in frost free areas. Gerry :-)} London, Canada

[RicodJour]

Remember that Japanese fish hook that is pretty much identical to a lumberman's pick? Maybe it's one of those things. Developed for one use, turns out it sucks for that application, then someone fishing around for a tool for another unrelated task picks it up and goes, "Aha!" I'd sharpen it up and use it to cut pizza just to freak people out.

pavement/concrete. That's a relatively new development and the tool looks to be at least 50 years old judging from the patina.

True enough. My eyes automatically shun shoddy tools. ;)

Fair enough. Thanks for the reply.

R