Good Info Cheap DIY Measuring Dividers

[Geezermag]

At work, I need to make some rough ID measurements of a liquid argon cryostat. To do this, we needed a way to measure the inside wall dimensions of a 39” deep tube with a diameter around 26”, only accesible from the top. This is a rolled, welded, non-machined diameter, so the tolerance is wide open. We just need to take some point measurements for order of magnitude at depth.

After not finding any good options for an affordable“large diameter” gauge we’d only use once, an idea came to me on the way home today that I thought may be useful to some of you.

I made a cheap set of rough measurement dividers using two yard sticks as well as a 1/4-20 1” nylon screw, wingnut, and three washers.

I marked along the already-marked lines on the yardstick, drilled them out with a 1/4” forstner bit over some scrap plywood, then assembled my dividers. I drilled 4 holes in each yard stick at a 10 cm interval for adjustability of the pivot point.

The idea here is that you just drag a tape from the outside corners of the dividers after making a measurement. After some test measurements, as long as you’re careful with them, the ends seem to stay pretty secure, and provide accurate measurement points. Well worth $6 for a one time use.

 

[BWSmith]

Nice. A few weeks ago did something similar in the,"get'r done" approach.

A, 2 .5/12 roof laying over a 7/12 main roof. The rake board top cut can be decifered using a framing square and average layout skills on a scrap of plywood. However,you still sorta have to "sneak up" on this angle because of the "noise" in the system.

So I took a 4' aluminum extrusion piece that was laying around,even had a hole in the end already... quickly bolted a 4' straight edge to it and tightened,just so.

Held it up in this long,drawn out angle on the roof, brought it down and transferred it to the cedar rake board. Cut,and fit perfectly on the first try. Pretty much just a big 4' angle square.

 

[Mike Davis]

When I was in my early 20s I was a sign painter and needed to draw circles almost every day.
So, I made the compass in the lower right corner of the photo.
Over the years I made several other quick and simple tools.

Jon, I like your yardstick dividers, That would be useful for checking the square of a carcass/box or frame by measuring the corner distances.

 

[David Holzinger]

Great Job! One suggestion, if you put your pivot point directly at the halfway point you can measure across the top end without having to remove the calipers to get your measurement.

I do have to admit that I had to Google to see exactly what a liquid argon cryostat was and what it would be used for.

 

[Geezermag]

Great Job! One suggestion, if you put your pivot point directly at the halfway point you can measure across the top end without having to remove the calipers to get your measurement.

I do have to admit that I had to Google to see exactly what a liquid argon cryostat was and what it would be used for.

I only kept them high up so we can reach down to the bottom. The inspection plan is to probe a bunch of points, measuring the top, then replicate these outside the cryostat to see what the bottom reads out.

 

[ashley_phil]

well done! KISS method for the win!

 

[smallboat]

or you could use them as proportional dividers. since you know the relative lengths of the short and long legs, just measure corner to corner at the top end and multiply to get corner to corner at the end thats down in the hole.