A radius gauge

These radius gauges are sold for use in metal shaping by various people. I think the original gauge may have been done by Fay Butler.

I wanted one and since I have a CNC mill I decided I'd draw up and make my own. I ended up making a small batch (7 ea) since I had to buy a length of aluminum bar, and they made nice holiday/birthday gifts for some gearhead friends of mine.

I called them "Arrr!" gauges because who doesn't like to talk like a pirate?

Attachment 26685

I don't have any photos of them on the mill. The two 1/2" holes were for hold-down studs during machining, but they could also let the gauge be hung on a nail on the wall.

cheers,
Michael

I used to have a set of radius and fillet gauges which had both concave and convex surfaces for checking weld sizes very handy to settle a dispute over weld size

Something like this?

Attachment 26686

I've got those in both metric and inch versions and they are very handy, but they only cover smaller sizes of radii. I took a length of scrap AL round bar, about 1.75" or so diameter, and made as many different OD discs out of it as I could, with a hole in the middle of them to string them on a piece of soft wire. Those let me do some checking for radii a bit larger than the machinist sets cover.

The gauges like I made are commonly used for checking a radius on a body panel. If you are extremely serious (or a designer at an auto manufacturer) you might have a set of sweeps like this 85 part set for $3000 from Fay Butler

Fay Butler Metal Fabrication: Sweeps

That's a bit beyond my needs! If I have to, I can print off some different radii onto paper and cut them out to try and narrow down the dimension on the part I'm checking.

I also got a set of these inside/outside radius gauges

https://www.baileigh.com/rg-750-radius-gauge-set

That measure from 2.5-30" radii. There are larger ones to cover larger radii. I have to admit there was a definite "that's a cool mechanical device" thought at work nudging to make the purchase. :)

As with angle grinders and clamps, measuring instruments are another of those tools where "no one ever said they have too many".

cheers,
Michael

Mine were Starret but similar the weld gauges looked like this
Attachment 26687

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Thanks MichaelMoore! We've added your Radius Gauges to our Measuring and Marking category,
as well as to your builder page: MichaelMoore's Homemade Tools. Your receipt:

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On this theme of radius gauges I have just posted details of a digital gauge based radius gauge at
http://www.homemadetools.net/forum/r...673#post123621

Hello Michael,
can you make these even in metric sizes? I think in Europe there are a lot off machinist ho will order a set.

I suppose the radii could be multiplied by 25.4 to make them metric. :)

Anyone who has even a small amount of knowledge of CAD could make the outline with standard metric sizes for standard metric stock, and any CNC shop could knock them out as they are a simple 2.5 D operation, no fancy surfacing involved.

Here's a PDF of the basic gauge. It is 16" long by 3.8" tall and I think the PDF should be to scale. All I did to create it was to make a number of circles and fit them to three sides of a rectangle, and then trimmed everything and put a radius on the sharp corners. That should give you an example to help you to lay out a metric version.

I hope that is of some assistance to you.

cheers,
Michael