testing steel samples in situ

[kaarlotuomiParticipant @kaarlotuomi]

please note that I am not an engineer or modeller of any kind so if you would like to reply please pretend you are talking to a ten-year-old child. thank you.

I am an author, writing a novel set in the 1920s.

the scenario is that a character has to machine a small part, about the size of a fountain pen, to replace a broken part in a steam engine on a small boat so that the party can continue their journey.

there is a much bigger boat nearby, with a lathe and other facilities in the corner of the engine room that he can use to make this new part. there is a bin with some cast offs and scrap parts that he can use and I want to describe him testing these cast offs to see which of them would be most suitable for his purpose. even I can tell just by looking the difference between aluminium, iron and steel, but given two or three different samples of steel, is there a simple test he can perform that would help him decide which piece is most suitable for his purpose?

thank you.

[FulmenParticipant @fulmen]

Sure. If we assume he wants a piece of high carbon steel for strength you can easily test that by watching the sparks on a bench grinder. High carbon steel will throw off more and brighter sparks. It is also possible to judge the quality of the steel by how it machines, either on the lathe or simply by filing it.

[Nigel Graham 2Participant @nigelgraham2]

There is an old, rather crude method that needs the craftsman himself to have sufficient experience.

If the larger ship has a workshop with machine-tools it will have a grinding-wheel for re-sharpening tools. Grinding the specimen will produce a shower of sparks whose appearance gives a very approximate idea of the grade or hardness of the metal. The ship’s engineering-officer will know what steels they had taken on board for repairs, so this method is likely to be close enough for the purpose.

A possibly more credible scene, would be that as he has to seek his host’s permission to use their workshop anyway, is the ship’s artificer identifying suitable material from the scrap-bin.

Here, this is likely by the bar-ends still holding its manufacturer’s own, painted colour-code that identifies the particular alloy. It is not a trade-standard though. In a well-regulated workshop as one would hope on board ship, each job will take its metal from the unpainted end of the stock bar, keeping the stock identifiable right to the point at which it becomes too short to use.

[How do I know? I spent eight years running a factory’s metals store, and was always careful to cut each job’s allocation from the unpainted end!]

 

To be honest, it is not very likely the ship’s artificer would let the visitor use his workshop unless the two men know each other well at a professional level. More credibly, then, the boat owner would come to some private, unofficial arrangement with the ship’s engineer for the latter actually to machine the component; even if the former watches the operation.

Without treading too much on your literary toes, have you considered your intended, primary readership? Workshop minutiae may not mean much to them, so describing the making is fine but the relationship between the two mariners, and the urgency and success of the repair, might be more significant.

[SillyOldDufferModerator @sillyoldduffer]

Welcome to the forum.

The answer is the spark test, whereby steels are identified, approximately, by holding a sample against a grinding wheel and looking at the pretty sparks:

 

The picture is from this website, which explains in more detail.  Grinding wheels are common in metal-bashing workshops, they’re used to sharpen cutters, and to form shapes.

As to giving literary advice, I remember Ray Bradbury being rude about fans critical of his description of Mars.  He sharply said it was a novel: science fiction not science fact!    You might make how the hero gets into the workshop after being told to buzz-off part of the story.  Or, take Neville Shute’s approach in “Trustee From the Toolroom”.  The novel celebrates  model engineers around the world helping out selflessly.  The Trustee has only to ask…

Good luck!

Dave

 

[kaarlotuomiParticipant @kaarlotuomi]

thank you for these very informative replies, much appreciated.

for those who raised concerns, which are appreciated, feedback is always welcome:
the guy performing the test was previously a passenger on the bigger boat. the captain has decided, for political reasons, that it would be unwise for him to continue. some of the passengers see this other boat but it is broken and the guy (an experienced truck mechanic, not a marine engineer) offers to take a look at it to see if he can help and identifies this broken part. he goes back to the bigger boat, where he has previously established a friendship with the chief engineer who gave him a tour round the engine rooms, and he casually performs this spark test which demonstrates to the chief engineer that he knows what he is talking about. does that make sense?

thank you

[Bill PhinnParticipant @billphinn90025]

Has the OP checked whether steel (rather than, say, bronze) would be likely to have been the first choice of metal for the turned steam engine part?

[John HinkleyParticipant @johnhinkley26699]

Or, just ask whoever is in charge of the donor metal for something suitable.

John

 

[duncan webster 1Participant @duncanwebster1]

No disrespect to truck mechanics, but it’s unlikely that the boss of a machine shop, even a little setup on a ship, would let one loose on machine tools. Different skills,  you similarly wouldn’t set a skilled machinist off to rebuild the brakes on a HGV without supervision.

[Howard LewisParticipant @howardlewis46836]

Stating the painfully obvious, assuming that a fairly wide range of material is available, in suitable sizes, the engineer on the larger vessel would help select a suitable material (If a bearing, probably phosphor bronze, or perhaps brass, to carry a steel shaft rather than making the replacement from cast iron and certainly not steel, of any sort. (You’d have to be very desperate to do that on a boat / ship in case it failed again, whilst at sea, and probably ruined the shaft as well).

Whilst boring the, presumed, bearing you could describe the fine twists of metal swarf coming off as the metal is very carefully bored out to finish size, with repeated measurements and spring cuts. (Repeat cuts without altering any settings)

If a lever, say as part of the valve gear on a steam engine, the task would be to concentrate on the dimensions that HAVE to be correct, whilst not spending too much time on making the part look pretty

Howard

[SillyOldDufferModerator @sillyoldduffer]

Anyone else know about the famous Kaarlo Tuomi.  Look him up!

Does it spoil the story to know that:

• Being fired from a giant cannon would kill the crew instantly in Jules Verne’s science fiction classic “From Earth to the Moon”?  Splat.
• Nothing Indiana Jones does in “Raiders of the Lost Ark” makes any difference to the outcome
• There is no Hogwart’s Academy, Quidditch,  or Platform 9¾
• Dr Dolittle cannot talk to the animals
• Based on his age in the first book, Hercule Poirot was 125 in Curtain
• Unlike Hollywood, real guns run out of ammo rather quickly!
• Thomas the Tank engine is imaginary
• Many other examples…

No point in taking novels literally!

On the other hand, Climate Change is real.

Dave

[SillyOldDuffer]

On SillyOldDuffer Said:

Anyone else know about the famous Kaarlo Tuomi.  Look him up!

Does it spoil the story to know that:

• Being fired from a giant cannon would kill the crew instantly in Jules Verne’s science fiction classic “From Earth to the Moon”?  Splat.
• Nothing Indiana Jones does in “Raiders of the Lost Ark” makes any difference to the outcome
• There is no Hogwart’s Academy, Quidditch,  or Platform 9¾
• Dr Dolittle cannot talk to the animals
• Based on his age in the first book, Hercule Poirot was 125 in Curtain
• Unlike Hollywood, real guns run out of ammo rather quickly!
• Thomas the Tank engine is imaginary
• Many other examples…

No point in taking novels literally!

On the other hand, Climate Change is real.

Dave

Well said!

 

Jimb

[SillyOldDuffer]

On SillyOldDuffer Said:

• Thomas the Tank engine is imaginary

 

Whaaaat? Gutted.

[Wade BeattyParticipant @wadebeatty78296]

<p style=”text-align: left;”>I am with Bayzle, I was with you until Thomas the Tank…. you are treading on thin ice here</p>
 

 

s/

[kaarlotuomiParticipant @kaarlotuomi]

I’m not sure about Thomas the Tank Engine because I am ashamed to admit that I am one of the great unwashed who have never read a Thomas the Tank Engine story. but I am reasonably certain the Starship Enterprise cannot in fact travel at warp speed, there are no androids dreaming of electric sheep, there is not in London a tower with thirty-nine steps going up and no map of Surrey includes Cold Comfort Farm. but I have nevertheless taken on board (deliberate pun) the feedback I have received from the very kind members of this forum and have decided to alter the process in the story.

the part being machined has a thread on one end and this has sheared which is why the part needed to be replaced. our truck mechanic will ask the chief engineer if he can machine the main part while our truck mechanic drills out and taps the hole to recieve it. this is not only, if I understand you guys correctly, more realistic, but it is actually better for the plot because the bigger boat is waiting to sail and this team effort is more efficient and quicker. it also allows me to build tension by cutting from one location to the other as the nervous passengers wait to to see if the restless natives arrive before the ship can sail.

thank you

[Howard LewisParticipant @howardlewis46836]

Now that you have said that there is a thread, this implies that tensile loads will be involved, so steel will be better than cast iron as a material to use.

Howard

[Wade Beatty]

On Wade Beatty Said:

<p style=”text-align: left;”>I am with Bayzle, I was with you until Thomas the Tank…. you are treading on thin ice here</p>
s/

Unless Thomas is one of these the fat controller should advise him to stay clear of thin ice

[Author]

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