Even accordionists have to eat............

[boxplayer4000]

We try our best with a small garden to harvest and store a range of vegetables and fruit as well as making use of many berries etc. growing wild nearby. Apart from the satisfaction of producing, the taste of the home produce often exceeds that available in the supermarkets. We make good use of a steel/alloy stock pot (about 10 litres capacity) to prepare much of the food and the main cook in the house (also doubling as my fashion and financial adviser) expressed the view that she thought the bottom of the stock pot might be getting thinner, allowing the contents to burn more easily and sticking to the bottom.
The ‘engineer’ in me immediately made me think of measuring the thickness of the metal and though I have the usual range of calipers, vernier and micrometer tools to hand none of these are any use in this situation. I suspect the answer is a costly electronic device which probably can’t be justified so I thought I’d call on the wide range of expertise and ingenuity on this site to offer their views.

 

[Pipemajor]

I would have thought if you lay a straight edge across the top, then measure the inside height at different points inside the pot, it would show any variations, checking with the sidewall thickness.
Assuming the base was the same thickness as the sides

 

[knobby]

You could use the "depth gauge" part ot your Vernier Caliper.
Measure from the top of your stock pot down the outside to a work surface to give overall depth. Now measure from the top of the pot to the bottom on the inside of the pot.
Subtract one from the other and you'll have the thickness of the bottom of your pot

 

[JeffJetton]

First, I suspect that the pot is fine, and the sticking food issue is more likely the range needing adjustment and/or the pot being in need of a good scrubbing (do they sell Barkeeper's Friend in Scotland?) After all, if the bottom is getting thinner, what would cause that? And where would the missing material go? In your food? Ugh.

But that's no fun, because then we don't get to try to solve the problem you pose. I'm assuming that the reason you can't use your current tools to measure the bottom is because it's too deep?

Well, note that you don't actually need to know the thickness of the bottom, only whether that thickness, whatever it is, is decreasing over time.

So how about the old Archimedes method of sticking it in a container of water and measuring the displacement? Accuracy might be an issue, so you could do this every day for a few days and take the mean. Then repeat at intervals of a couple of months. If it's displacing slightly less water over time, it's losing material. Use your calipers to ensure the sides are remaining the same, which leaves the bottom as the culprit.

Or maybe you could use a multimeter and measure the resistance across the dead center of the bottom of the pot. One probe inside the pot in the middle, and another opposite it, underneath the pot. See if resistance drops over the months/years, suggesting a thinning of material.

 

[boxplayer4000]

Thanks for coming back to me.
As best I can measure over the top edge rim the thickness of the side of the pot is 0.8mm. (approx 0.031")
Pipemajor and knobby: Reaching into the pot to measure the bottom will only work if the bottom is perfectly flat. Unfortunately this is not the case as it is easy to see the bottom is in fact decidedly concave on checking with a straight edge against a light.
JeffJetton: Rest assured everything here gets a good scrubbing. Visitors are advised not to remain stationery for too long as they too will be in danger of a scrubbing (or a coat of paint). Inside and out the pot is shining clean and the exterior's condition, at least, I attribute to changing from a gas range to an electric one ie. no combustion with all that goes with that.
I'm not aware of 'Barkeeper's Friend' here. Our 'Ajax' cleaning powder sounds like it might be a rough equivalent; just add elbow-grease!!
You mention about the removal of metal in the heating process. I don't know how the metal removal comes about but it certainly does. We're from a generation who were quite used to making jam from local produce and jam making pots were common, only they tended to be made with copper.
They definitely had a working life which was defined by the bottoms becoming increasing thin. The pots were quite decorative, capable of taking on a shine and often finished their life as plant pots in the garden.
Your suggestion of a multimeter (measuring resistance) might have some merit though I doubt if the meter I have, which is a fairly basic hobbyists model, would measure to that level accuracy or sensitivity. Perhaps looking again at the invention of Charles Wheatstone (the 'wheatstone bridge' in measuring unknown electrical resistance) might help. (The same Charles Wheatstone of concertina fame).
Thanks again to all for bothering to respond.

 

[JeffJetton]

(The same Charles Wheatstone of concertina fame)

Wow! I'd heard of a Wheatstone bridge *and* the Wheatstone concertina, but never put together that they were same guy.

 

[Giovanni]

Wow! I'd heard of a Wheatstone bridge *and* the Wheatstone concertina, but never put together that they were same guy.

Wheatstone Bridge takes me back to the early 60's at technical college for electrical engineering

 

[Alan Sharkis]

See, we’re a multi-faceted bunch, after all, with a wide range of knowledge, ability and talent beyond accordions. I’m surprised that nobody here has mentioned an alternate meaning for the word “pot” … like potentiometer, or a vessel filled with soil in which to plant something or the act of doing so, or the act of totally encasing something in epoxy, or …

 

[Giovanni]

See, we’re a multi-faceted bunch, after all, with a wide range of knowledge, ability and talent beyond accordions. I’m surprised that nobody here has mentioned an alternate meaning for the word “pot” … like potentiometer, or a vessel filled with soil in which to plant something or the act of doing so, or the act of totally encasing something in epoxy, or …

You are taking me back to technical college again ........we always used the term Potentiometer .I thought Pot was what small children sat on pre toilet training !!
The other Pot ......I think was smoked .....but I've led a very sheltered Life ...ha ha ha

 

[boxplayer4000]

The Wheatstone Bridge is (sadly?) from a bygone age. I learned about the 'bridge' in the late 50s/60s when receiving marine engineering training. It was used in the ship's steering system then where the steering wheel/helm on ship's bridge was one element of the wheatstone bridge and the motor powering the rudder was another. When the helm was moved the rudder motor would move to 'balance' the bridge. This system was made by a firm called McTaggart and Scott who also developed bow and stern cross thrusters. They virtually done away with the need for tenders and tugs. The firm is still in existence today a few miles from here (Nr. Edinburgh/Scotland).

 

[Rosie C]

The Wheatstone Bridge is (sadly?) from a bygone age. I learned about the 'bridge' in the late 50s/60s when receiving marine engineering training. It was used in the ship's steering system then where the steering wheel/helm on ship's bridge was one element of the wheatstone bridge and the motor powering the rudder was another. When the helm was moved the rudder motor would move to 'balance' the bridge.

That sounds like the same sort of system in the 'servos' used in model aircraft?

 

[Dingo40]

I seem to remember the Wheatstone Bridge from Intermediate High School physics classes.

 

[JKJ]

The ‘engineer’ in me immediately made me think of measuring the thickness of the metal

I can think of several ways to measure the thickness of the bottom of an arbitrary vessel. For example, woodturners often make simple calipers from things like small diameter rods held in a shop-built frame. However, the precision needed for that application is not high.

But an easier and more precise way - know anyone with a machine shop? I might use my milling machine. For example, securely fasten something with a curved top on the mill bed, perhaps a piece of rod. Mount a dial indicator or a dial test indicator on the end of the z-axis column, lower to touch the top of the curved rod and zero the indicator. Note or zero the z-axis position. Then raise the column, position the bottom of the pot on the rod and lower the column to the precise previous z-axis position. The reading on the dial indicator will give the thickness at that spot. The measurement could be repeated at various points if desired.
This should be a easy for a good machinist with precision equipment.

I could also do the same thing on my lathe (with a DRO) with a little rigging, but with my tools, alrhough the z-axis range is large I would be limited (due to the lathe swing) to measuring near the outer part of the pot bottom but I couldn’t measure at the center.

A good machinist might have other ideas and equipment.

 

[boxplayer4000]

JKJ: Thanks for the response. I must admit I don't fully understand your approach; maybe somethings 'got lost in the translation' crossing the Atlantic.
My stock-pot is quite modest by some standards; approx 10" dia. and 7" high. About 10 litres capacity and metal thickness at the side estimated 0.8 mm, about 31 thou.inch.
Calipers I have access to cannot reach the bottom of the pot.
You refer to a z-axis. I wonder if we are talking the same language here. I think I remember the x-axis as being the width, the y-axis as vertical and the z-axis as being the depth. Does this make sense?
I've used flat-beds and dial indicators in the past but don't have access to those at present.
There are model makers clubs in the neighbourhood and I suppose they could help.

 

[JKJ]

With those dimensions you could use a straight edge, a simple long digital caliper, and possibly a small block (if the bottom in not flat. I have a caliper that will measure 12” - I see plenty on Amazon, some for not too much money. (you can’t have too many tools!) Or maybe you can find someone local that has one.