Measuring thickness of metal diaphragms

[codefarmer]

Enjoyed the vernier scale diy posted on this site. Reminds me of the "Make a tool attitude" on my Dad's farm growing up. I am setting up to make some metal diaphragms for a stirling engine project, and need to simplify the measuring of thickness on different regions of the diaphragms as I work through the production steps. A typical caliper or micrometer won't reach across radius (4 inches) worse case.

[Jon]

Hi codefarmer - welcome to HomemadeTools.net

Interesting; I'm going to move this to our Tools in Progress subforum so you can get some good ideas.

[Toolmaker51]

Search the toolhouses for a graphic representation, but you'll be able to easily duplicate a dial indicator thickness gauge. Essentially a C-frame; some are aluminum, some are cast iron. It positions a dial indicator in a common centerline over an anvil such as a bearing ball, or polished dowel pin. For your project, I'd compare against feeler gauges to 'calibrate'. The dial body is usually .375 diameter, held lightly with setscrew or Starrett indicator collet. Drill through to the anvil side to hold the anvil. Lastly. band saw out the openings and contours.
https://www.google.com/search?q=indi...utf-8&oe=utf-8

[mklotz]

Mount a DTI (Dial Test Indicator) on a height gage or surface gage and lay the diaphragm on the surface plate or, lacking that, any good flat surface, e.g., mill table, plate glass.

[Frank S]

Mount a DTI (Dial Test Indicator) on a height gage or surface gage and lay the diaphragm on the surface plate or, lacking that, any good flat surface, e.g., mill table, plate glass.

In the case of possible varying thickness and concave for formed shape diaphragms, mounting a ball bearing on a pedestal centered directly under the point of the DTI as mentioned above will allow for measuring any small imperfections which may exist

[mklotz]

[QUOTE=codefarmer;79521 I am setting up to make some metal diaphragms for a stirling engine project, [/QUOTE]


I've built a number of Stirling engines but can't remember any designs that included a diaphragm. Could you elaborate a bit on your design, please?