Member postings for Fowlers Fury

Having experienced difficulties with the "Greenwood" type unless the TC bit was sharpened regularly on a diamond or CBN wheel, I followed a suggestion made by the owner of a small precision eng company. This was to part off with a slitting saw mounted on an arbour. Probably known to you all and It no doubt breaks all the "rules" yet works very well. When the contact tooth gets blunt, just rotate a little & use new one. New slitting saws aren't cheap but seem to appear in abundance at our M.E.Soc's auction nights. (The image shows parting PEEK CA30 piston rings).

(1) "only 11.43% of reports (not 93.75% as you claim) are recording skin irritation."
I am not claiming that, it is reproduced from the literature.
(2) "R(risk) and S(safety) phrases are assigned to chemicals by concensus in an expert committee of the EU. The risk phrases are somewhat of a misnomer because they are hazard phrases but distinguishing between those 2 concepts is linguistically difficult elsewhere in Europe.You are of course free to make your personal assessment of risk with "My own impression about copper citrate is that it is relatively harmless compound".
(3) "From my own long industrial experience as research chemist I have found that most of risks assesments are rather political/legal documents of very limited value in real life".
From my long experience as a toxicologist in the chemical industry I have a different view.
(4) "Their [risk assessments] production is a great time wasting exercise and it is sometimes actually endangering health of workers because they are first forced to produce this nonsense to satisfy legal requirements"
As a past member of the HSE's Advisory Committee on Toxic Substances, I assure you the TUC, CBI and HSE members think otherwise.
(5) I also use dil HCl to remove Cu oxide.

Though requiring some delicate soldering, I got around the button cell depletion problem by wiring each of the 3 heads back to a little "Maplin box" containing a single Mallory battery. Dubious about voltage difference, but everything has worked OK for years. Saved quite some money on the button cells which always seemed to deplete in no time.

Some consolation for my failings in that Dave (aka S.O.D.) fared no better in tracking a source of the erroneous equation. Sufficient grey cells remain to remember that my original search and hence link to CO, was a consequence of using citric acid to remove black Cu oxide after silver-soldering a boiler. Even after washing & drying, the layer of copper citrate had to be removed by a soft wire brush. The particles thus generated proved an eye & nasal irritant, subsequently confirmed by reference to the trusted nih data-base viz:-

H315 (93.75%): Causes skin irritation [Warning Skin corrosion/irritation]
H318 (93.75%): Causes serious eye damage [Danger Serious eye damage/eye irritation]
**LINK**

At some point in that hazard searching, I encountered the dubious “Fe/Citric/CO” equation.

(Yes – I should have worn goggles and a face mask when brushing off that copper citrate residue but as in so many home workshop activities, a risk assessment was ignored).
Renewed apologies for this time deflecting the thread to copper and citric acid.

Posted by Jon Gibbs on 02/12/2017 17:32:26:
This is all interesting stuff but I'm afraid FF that just because an equation that has been reproduced several times doesn't mean it's correct.
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I agree entirely ! My original comment was to the effect that buried in the memory was a link between citric acid+iron+CO. In searching for confirmation, that equation was repeated very frequently, it balanced and so without adequate consideration, I reproduced it. (Energy factors alone should have rung warning bells). Not to justify the error but I've since spent several fruitless hours trying to track down the origin of that equation. It has only been queried once (other than here) in a Norwegian publication.
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It's 39 years since my A-level chemistry but this is pretty basic stuff. A solution of anhydrous citric acid in water is just going to be a dissociated mixture of H+ ions (this is the definition of an acid) and citrate ions (C₆H₅O₇-). All acids will dissolve rust (and iron/steel) and this one is no different. It's a fairly weak acid but will naturally react with the rust reducing it to a mixture of Fe2+ and Fe 3+ ions and citrate ions, liberating water or hydrogen in the process. The iron citrate will then potentially precipitate out, depending upon the solubility of the iron (II or III) citrate (**LINK** and **LINK**), which are both only weakly soluble.
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I thought perhaps your 2nd link to a Wikipedia article might be useful but the reference given to "or by action of citric acid on metallic iron.^[1]" is of no value, like so many refs on there.
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Citrate ions are stable, and so is iron citrate in both forms, and so I agree with Martin that it is highly unlikely that the citrate compounds will decompose and release carbon monoxide.
Jon
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As for Martin Dowing's specific comment "Fe2C3 does not exist...." ~ that error was due to my attempt to use sub and superscript for the equations on this site which has limited text modifiers. I had made the changes in Word and had copied (Ctrl+V) the text directly without checking it appeared correctly. I should have used the "Paste from Word" icon. I'll do that now from this hopefully authoritative source but won't know for sure until after pressing "Add Posting" !
Corrosion of iron to form a hydrated iron (III) oxide Fe₂O₃.xH₂O.
It is an electrochemical process in which different parts of the iron surface act as electrodes.
At the anode, iron atoms dissolve as Fe²⁺ ions:-
Fe(s) → Fe²⁺ (aq) + 2e
At the cathode, hydroxide ions are formed:
O₂ (aq) + 2H₂O (l) + 4e → 4OH^- (aq)
The Fe(OH)₂ in solution is oxidised to Fe₂O₃
(Oxford Univ Press: Dictionary of Chemistry. 2000)
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Apologies to anyone still following this thread.
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P.S. to Martin D. "fosforic acid"? Are you Romanian?

1. 2Fe + 2H₂O + O₂ = 2Fe²⁺ + 4OH^-
2. Fe²⁺ + 2OH^- = Fe(OH)₂
3. Fe(OH)₂ in O₂ → Fe(OH)₃
4. Fe(OH)₃ → [dehydrates] → Fe₂O₃.nH₂O or rust

Apologies, despite those equations appearing to display as intended, returning to the site they show with weird characters. This time I'll try cut'n'paste from Word and hope they don't become mangled.

"I'm quite surprised to see the equation quoted above for citric acid action on rust. What's it's provenance?"

My fast-declining memory resurrected the CO/citric acid link from way back so I had to check b4 posting.
Its "provenance" is that several reputable websites confirmed the basic equation. But rust is actually a mixture of Fe(III)₂O₃ “iron oxide”, and Fe(III)(OH)₃ “iron hydroxide” so the quoted equation is only partially correct in that it relates to Fe₂O₃ and not Fe(OH)_3.
It appears that the equation for trivalent iron hydroxide is:-
C₆H₈O₇ + Fe₂O₃ = Fe₂C₃ + 4H₂O + 3CO₂
However, several sources list the sequential equations for rust formation:-

1. 2Fe(s) + 2H₂O(l) + O₂(g) 2Fe²⁺(aq) + 4OH^-(aq)
2. Fe²⁺(aq) + 2OH^-(aq) Fe(OH)₂(s)
3. Fe(OH)₂(s) =O₂=> Fe(OH)₃(s)
4. Fe(OH)₃(s) =dehydrates=> Fe₂O₃.nH₂O(s) or rust

So from this, Fe₂O₃ is the final product and the original equation would seem to be applicable.

"I don't think (and haven't checked) that Citric Acid and Rust produce Carbon Monoxide."

C₆H₈O₇ + Fe₂O₃ = 2FeO + 6CO + 2H₂O + 2H₂

The "fizz of bubbles" consists of carbon monoxide and hydrogen.
"..........Every form of treatment has its eco downsides, it's up to us to ameliorate their impact on the environment, the alternative is to sit in a chair and do bugger all, personally I'll just get on with using my citric treatments, at least you can stick your hand in the stuff without them vanishing in front of your eyes."
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Wasn't my original intention to add anything about either hazard or risk of CO and H release from citric acid use.
The hazards of both gasses are evident but the risks are for an informed user to assess according to their particular circumstances and beliefs.
CO represents the greater hazard because of its explosive and health effects in a confined & unventilated space.
For simplicity: Risk = Hazard x Exposure.

Citric acid and rust
"Very satisfying to see a steady fizz of bubbles gassing off the bits when the crud is being eaten,"

The "fizz of bubbles" consists of carbon monoxide and hydrogen.

LBSC (Curly) wrote that during WW1 when in charge of girls operating lathes for munitions, he was amazed how quickly they could set up work in a 4-jaw to be "right first time" just by eye.
Perhaps I should request SWMBO comes into the workshop next time I'm going to spend 30 mins faffing around chasing the last thou on the 4-jaw ?

à propos les voitures Français; their soft suspension may be explained by a comment attributed to a PSA executive:-
"When driving, if the French suffer a bad ride they will blame the car but the British will blame the road".

Not that there aren't hundreds of weblinks to electrolytic derusting but here's the one I followed - now with an update about hazard of stainless steel electrodes and hexavalent chromium (which IMO is a very low risk).

**LINK**

Follow Gordon A's advice for anything where you do not want to affect the non-corroded metal surfaces e.g. reamers.

Electrolysis only converts the rust to elemental iron which collects at the bottom of the plastic tub. You do need to degrease first though and ensure you connect the rusty bit to the cathode of the battery charger !

Martin,
Certainly "it" originated in North America and during the severe post-war austerity, British manufacturing industry was instructed by govt. to export only. For some period, steel was only made available for making exported products. North America was then the affluent export market so Brit car makers had to make cars which conformed to US tastes.
Your point 4 must be contentious though. They were generally swtiched on to design trends but mostly failed to produce vehicles which were reliable enough for typical driving in North America e.g. sustained long distance cruising. Of course they were also guilty of that same failing for the home market or the Germans & Japanese would not have caused such devastation of our car (& m/cycle) industries from the early 60s.

I agree with Mike Poole's conclusion (except perhaps the value of cruise control on our congested roads). Having spent years "driving" on the M25: stop > edge forward > stop >... repeat for n miles, an automatic was, and is, considered essential. Likewise, I now forget my 8 speed transmission and have also tried the manual overide a few times but traffic density demands so much concentration these days, it's safer to let the ECM and drive train get on with it without my intervention.

[Note to self: must not get onto subject of m/way middle-lane drivers ]

Clive wrote "Maxi Mk1 version upsets the journalists and by osmosis all informed opinion agrees its hopeless."

I had one too and the gearchange was summed perfectly for me by one motoring journalist who likened it to "stirring a bucketfull of nuts and bolts with a bamboo cane".

Maxi Mk 1 - another sad example of innovative & clever British design let down by a poorly engineered feature. It had 5 doors, 5 gears, 1500 ohc engine and great roadholding for the mid 70s. Before that purchase I had a Standard Vanguard Vignale 6 with bench seat & 3 speed column change. So much torque you could move off in 3rd.
Those were the days.....Between 1950 and 1960, the number of vehicles on the roads of Britain more than doubled, from 4.0 million to 8.5 million. At the end of June 2017, there were 37.8 million vehicles registered for use on the road in Great Britain.(DVLA statistics).
Anyway, looks like manual boxes are on the way out "Last year, almost 650,000 new cars with an automatic gearbox were registered in Britain, representing a 55 per cent increase compared to 2013. It’s estimated that demand for automatic gearboxes is growing 300 per cent faster than the total market growth.It’s worth pointing out as well that alternative-fuel vehicles, including virtually all hybrids and fully-electric cars, tend to use an automatic gearbox. Alternative-fuel vehicles are becoming much more popular, with the year-to-date sale figures in the first third of 2017 already up by 23.8 per cent compared to the same time period last year."
(Source: https://www.carkeys.co.uk/news/more-uk-drivers-are-picking-automatic-gearboxes-over-manual)

John ~ apologies, you'd clearly covered everything; it's well past time to withdraw back into my shell.

John, I wonder how much additional information you provided in your "bearing grade" PEEK request to Davis Plastics.
For example did you specifiy for it was for reciprocal motion, not rotary - in the presence of hot saturated steam - running over stainless steel with cut-outs? If not, then you might need to be cautious about their recommendation. After all. Davis Plastics are primarily stockists.

As I wrote before, it does require quite some online research comparing the properties of different HPPs for our 'peculiar' model engineering uses. The PEEK grade "CA30" did seem to me to be preferable for steam valves in our applications. The "carbon loaded PTFE" (graphite or carbon fibre?) Duncan refers to exhibits many attractive properties but it's linear expansion is a negative factor at twice that of PEEK CA30, although it may be prefectly servicable for slide valves with lower temperature steam. (My use was in piston valves in the presence of superheated steam at 180psi).

By the way ~ did you see from Davis' website section "Hobbyists" that they have a special Ebay area of small pieces at reduced prices?
**LINK**

John,
As I wrote (& mistyped) in my first post Davis Industrial Plastics were extremely helpful considering I was a small-time buyer. Despite PEEK CA30 (C-fibre PEEK) not being listed on their website, they were prepared to sell an off-cut from 20mm thick sheet at a very reasonable price. Since you're making slide valves I assume sheet is more use than it was to me when making rings.

The material can be hell to machine in that it will blunt HSS tools quickly, whereas sharp TC-tipped tools have no problem with it. Nevertheless it is easy to shave with a sharp blade and a file will produce a smooth flat surface.

"Having had a look at the fixings for the dial & hands, I see that they’re tapered pins"
If the hands are secured by tapered pins you should have no fear of damaging the face.
It's where hands are friction fits on the shafts and have been twisted off by 2 screwdrivers that damage is done
To play safe cut a disc of paper and then a radial cut to the centre and insert that between hands and face.
Ensure the taper pins go back in their original holes.

As for clock oil ~ I've not looked at the difference in price recently but suspect Moebius is the more expensive. It's not as though you're going to use much and when I purchased Moebius from M&P it came packed in several small vials so you don't contaminate the whole lot when keep dipping your oil pin into the stock. I'd think with a clock of that size and vintage you'd be fine using the cheaper (?) M&P oil.
To repeat what others have posted, you only need the tiniest quatity of oil on each end of each arbour. Using a pin, as Russell suggests, will give you an idea of how little is needed.

I hope this quick solution (solvent + oil) works for you because old & oxidised oil can be difficult to shift without dismantling. If it doesn't, at least you'll have maybe overcome your hesitancy about tackling a rebuild.