Member postings for SillyOldDuffer

The amount of heat needed depends on room size, how well insulated it is, and how warm the occupant wants it to be. In a typical UK home, between 1500 and 8000 BTU. A heating engineer typically puts the biggest radiator in the living room (a large room we like to be cosy in), and a small one in cool places like hallways and workshops.

If Andrew's room has a 10 foot ceiling, he's looking to heat a space of 1500 cubic feet. With poor insulation, this will take about 8000BTU. 8000 BTU is equivalent to about 2.3kW, so a 300W solar panel or several tea-lights won't touch the sides. Frost protection rather than comfy.

Difficult to beat gas central heating on cost if the goal is to save money. That suggests the answer is to run the central heating system with most radiators switched off. Insulation makes a big difference, as does facing south. Avoid serious leaks like chimneys and patio doors.

Health permitting it may be possible to reduce temperatures in the home significantly. In winter I run my heating for only 6 hours a day at up to 18°C in the hottest room. I dress warmly. Got used to it and now I find buildings warmer that 18°C downright uncomfortable!

An electric radiant heater might be the answer. They throw heat at people rather than warm the whole room up, and then people don't notice it's cold until they move. Arguably a better way to use a small amount of heat. Foot warmers work in the same way - heat where it makes the body happy.

Dave

The forum's proprietary spell-checker is one of it's endearing features, and can't be fixed. Dates to the early Internet before Browsers could do spell-checking, and has more than it's fair share of flaws. Defaulting to US English on a British website is just its first eccentricity.

Everyone in the know leaves the forum spell-checker switched off! Instead, Browser spell-checker plug-ins do a much better job, and they work on all websites. How they are installed depends on the browser. I have Firefox with the 'British English Dictionary (Marco Pinto)' extension installed from 'Settings'.

Pretty sure new forum doesn't have a built-in spell-checker - modern software expects the browser to do it. Firefox will spell-check in New Zealand or Canadian English if that's my wish.

Dave

When everything is right and it still doesn't work, look for something non-obvious.

After I crashed my 280's saddle into the chuck, I thought I'd got away with a bad mistake. All seemed well for quite a long time until I eventually noticed the fine-feed finish was iffy. Reason was that I'd broken the shear pin but it still had enough grip to move the saddle. It was slipping, only obviously on deep cuts.

Set the lathe up to take a deep cut - at least a millimetre - and watch the drive shaft where it's pinned to the gearbox. I could see my drive shaft was rotating slower than than the gearbox output. Needed a new shear pin.

Dave

Can't disagree with that, but one opportunity might be steel welded boilers,. They're potentially much cheaper than copper and silver solder constructions. I think an assured safe design would be popular because lots of people do home welding now.

Dave

I think a stable output is proof of pudding! The Arduino CPUs come with various built-in peripherals including a few counter/timers. Being hardware peripherals makes them mostly independent of the computer.

When set up to do input capture, a hardware counter is clocked by the computer's oscillator, a direct connection unlikely to go wrong.

The Input Capture pin is triggered with the usual logic rules, so provided the rise time and voltages are within spec, that should be reliable too.

An Input Capture event causes the counter value 'now' to be copied. The counter doesn't stop, but the 'now' count is frozen. The event also triggers an interrupt. The interrupt pauses whatever the computer was doing, runs a short user program to process the event, and then restarts the main program. Provided the 'short user program' finishes before the next event, all should be well. With a pendulum period or GPS unit, the events are about a second apart, which is a long time for a computer.

I think the best test is to feed the counter with a known accurate frequency, such as an OCXO. However, Joe put me on to the UBLOX range of GPS Modules, and I bought a MAX M8. These can be programmed to output frequencies other than 1 Hz, not all equally stable, but mostly locked to GPS. I set my M8 to output 10MHz and measured that with an ArdPET fed with GPS seconds from an Adafruit module: it averaged 10MHz over 10 seconds. Then I used the ArdPET to calibrate my OCXO, and watched the OCXO and M8 lissajous on my oscilloscope. This test also showed the frequencies to be identical. The OCXO has to warm up for about 25 minutes before it's stable enough.

Dave

Yeah, I'm the other way round - comfy with CAD and hopeless at maths!

The best book in my library for pressure vessel formula is Machinery's Handbook. Mine is the 20th Edition (1976) which is good for US, UK Imperial, and Metric. Highly recommended - most mechanical engineering facts are covered!

The 6th Edition (1924) is available free online, and might get you started. Pressured cylinders are in the Strength of Materials section, try page 404.

To me the most obvious problem is that pressure vessel design has long been decided by Codes Of Practice aimed at large boilers. These codes contain 'best practice' derived from a mix of theory and decades of experience, and aren't obviously useful for small amateur boilers: scale matters. The guides put out by the Clubs and Federations are more relevant, but they don't encourage experimental work. And maybe new ideas aren't needed? I suspect it's difficult to get a modern small boiler to outperform older designs because they're already nearly as good as it gets.

Whatever the reason, model loco boiler construction in the UK hasn't changed much for a century. Could be time for a change!

Dave

What else did Task Manager show was running at the same time? If it happens again, look in Task Manager for any process or applications using 100% CPU or 100% disc, or a lot of memory. For example, there's a long unfixed bug in Microsoft's sysmain program that causes it to eat all the computers resources. Everything else grinds to a halt. Other programs can run amok and choke Windows too. If you find a task persistently guzzling resources, kill it.

Running two or more anti-virus programs will delay installations massively if they gridlock. Turn all but one of the AVMs off before starting, and - if needed at all - only turn them back on after the install has finished.

Before starting, make sure the disc is less than 80% full and don't run anything else during the install. Manually update Windows first. This ensures big Microsoft upgrades won't collide with your install, and reduces the chance of the application installer finding Windows is out-of-date and having to stop and wait until a mass of other updates have been applied. Could be a long list! Windows updates are dependency stacked, that is applying one can require many others to be upgraded first, and they all have deeper dependencies. And the computer may have to be rebooted several times to get everything aligned.

Application installs are mostly straightforward, but they can be derailed, sometimes for temporary reasons. Try again.

Dave

Keep it friendly chaps - we don't criticise members spelling or grammar on the forum.

Dave

Means first. The number of counter/timers available depends on the chip.

• The ATmega16U4/ATmega32U4 used in the Uno, Nano and others including your METRO-327 has an 8 bit counter/timer, two 16 bit counter/timers, and a 10bit counter/timer. Of these, the 8 bit counter is mostly don't touch because it's used by the Arduino for micros() and the 10 bit counter isn't useful for this application because it doesn't do input capture. However, both 16 bit counters are available with Input Capture so GPS and the pendulum can both be timed.
• The ATmega 2560 has two 8 bit counter/timers, one available, plus four 16 bit counter/timers with ICP, all available. I use a third counter/timer to simulate the pendulum when testing software changes.

Code: Having bother with dropbox but try this:

• ardPET.ino Like a picPET except can optionally average over 10 cycles. Grounding a pin switches to the external clock input pin, but note this is just a demonstrator because my code expects 16MHz.
• AMegaClock7.ino Latest version of my clock, runs on a 2560. Also requires: clockInterrupts.h hhmmss.h and sus.h

According to Adafruit's documentation, the METRO has a CSTCE 16M0V53-R0 Murata Ceramic Resonator

The METRO looks like a nicer version of the Uno/Nano so ardPET.ino should run on it OK.

Dave

This is what my clock does in measurement mode. The number of pulses output by the Arduino's oscillator per GPS second are counted. Provided the temperature doesn't change much per second, the result is accurate to about 0.25 parts per million. The method automatically compensates for slow temperature changes.

Arduinos fitted with 16MHz quartz crystals are significantly more stable than those clocked with ceramic resonators, so for this purpose better to use a Duemilanove, Uno, Leonardo or Pro-micro rather than a Nano or Mega. Arduino crystals are ordinary - nominally about 100 parts per million, so worth considering alternatives.

I'm using a Mega at the moment for other hardware reasons. A kind friend sent me some temperature compensated 25ppm 20MHz clock oscillator modules, and I hope to replace a Mega's 16Mhz resonator with one. Off the shelf Megas are clocked at 16MHz for compatibility reasons, but they can be reprogrammed to run at 20. Fair bit of work, for a worthwhile improvement in stability, accuracy and resolution.

I measure pendulum beat at high-resolution for three reasons:

1. High variation between beats indicates mechanical problems including external vibration, suspension issues, beam position errors, and electromagnet problems, including over and under impulsing. Also software bugs and shortcomings in the sensors and electronics generally. All stuff that needs to be fixed. High accuracy is helpful.
2. To determine the effect of temperature, pressure and humidity changes on period so they can be compensated. High accuracy is needed because the compensation needs to be good.
3. Impulses can be governed by detecting the small change of period caused by rising or falling amplitude. There are many impulse strategies to explore, such by varying impulse frequency, timing, power, and pulse shape. Impulsing on every beat is common, but many high-precision clocks allow the pendulum to swing free between infrequent impulses. High resolution is more important than high accuracy.

All three measurements are used to detect errors and set-up the clock before the clock is activated. They aren't used for operational time-keeping : that depends on the pendulum.

Over much longer periods my clock's performance is compared with NTP or GPS time. Bog standard NTP is always within 0.1s of atomic time - good enough for most purposes - and GPS is available when better is needed. Long term measurements detect long term drift, slow instability, and compensation errors.

Dave

I suspect the roof is leaking, or maybe condensation. The ceiling is common to both lights, and should be dry, but isn't. Have a look inside the light fittings for signs of damp.

How long does a shed roof last? Shallow pitch and flat roofs have notoriously short lives. My felt garden shed roof lasts between 10 and 15 years.

Dave

If a freelance boiler is to be steamed at a club, i.e. in public, then the club's inspector has to be persuaded the thing is safe. It's about establishing confidence: design, materials, and construction methods all shown to be in good order. Building a well-known successful boiler from an existing plan helps because there's a proven track record. All the inspector has to do with a trusted design is make sure appropriate materials have been correctly assembled. The list of 'appropriate materials' may be short - in the UK easier to assure a silver soldered copper boiler than welded steel because not many inspectors have the experience or equipment needed to inspect steel boilers. Best ask about materials and methods before building anything!

Formula are helpful, but need to be understood in context, especially if the goal is a light, efficient, high-pressure boiler. Construction methods have to match the formula's assumptions, for which reason heavy inefficient low-pressure over-engineered boilers are easier to make! Design from scratch is quite difficult, typically involving lots of sums, much thought - 'what could possibly go wrong' - and brutally testing several expensive prototypes to flush out bugs.

Another approach is to model the item in 3D-CAD and run a Finite Element Analysis on it. The Finite Element Method doesn't use textbook formula: instead the structure is triangulated and a force applied to the resulting mesh. The effect of the force on all the triangle legs is calculated. As the mechanical properties of the material are known, the effect of the force throughout the physical object is modelled, and can be colour coded:

Blue indicates areas of low stress, rising through green, yellow and orange to high (red). Simply, blue indicates parts of the model that might be reduced because they are over-strong, whilst red highlights sections that might need beefing up.

FEM is a generalised approach that doesn't require particular formula and their application to be understood, Accuracy depends on the density of the triangulated mesh, and substitutes a computer doing millions of calculations for the analytically derived formula found in textbooks.

Stress concentrations are presented visually, and CAD allows the design to be altered quickly. The method makes it possible to fix many structural problems before building anything for real.

No such thing as a free lunch! The engineer still has to understand the numbers behind the colours - red means 'area of high-stress' rather than 'this will break'. And the limitations of his model. For example, FEM is likely to assume perfect construction, resulting in a model with joints considerably stronger than real ones. The designer has to make practical allowances, including adding substantial safety factors. And if the inspector isn't familiar with FEA, it may be asking too much to expect him to approve a FEM model.

Bottom line, however the boiler is designed and built, keep the inspector happy at all stages of the process.

Dave

Sortation isn't quite the same as 'sort', at least in the technical sense. It means a mechanised sort process or processes. I don't know if the word hales from the US or not but appending .ation to verbs is common in British English. Visit and visitation etc.

Engineers can't complain about others abusing the English language. Turning, thread, mill, and lathe, were all jargon in their day. Lay folk often pinch technical terms too: I have a cast-iron case and will blow a gasket if anyone disagrees!

Apparently some Americans are offended by Britishisms catching on in the US. What a bunch of muppets!

Dave

Wood starts to char at about 200°C so that's uncomfortably hot. My main worry at that temperature is the glue - most glues weaken badly when they get hot. Plywood and MDF both contain glue, and performance probably varies by make. I guess the fire-resistant types are better. Ditto heat performance of preservatives - which one?

Does the cladding get as hot as 200°C though? The steam table in Tubal Cain suggests 160°C at 90psi, and probably less than that on a small boiler because a thin layer of wood being a poor insulator tends to keep it cool.

I guess wood and glue are good enough at 160°C, but unreliable at and above 200°C. How long the wood is cooked matters too - big difference between a boiler run for a few hours at weekend, and one steamed all day every day.

Dave

Rule of thumb, operated properly, one Horse Power will cut one cubic inch of mild-steel per minute. The Warco Major has an 1100W motor, so it has the potential to cut about 1½ cubic inches of steel per minute. Don't!

'Operated properly' means cutter in good condition, at optimum depth of cut and feed-rate, with cooling and lubrication. The rule of thumb also assumes the machine is rigid enough to make the cut without bending, the drive train is man enough to take the strain without breaking, and that the motor is rated for continuous operation.

Industrial equipment is heavily built to meet these requirements - one reason it costs 6 to 25 times more than hobby gear. Hobby equipment is relatively lightly built down to a price, designed for intermittent cutting at moderate rates. (A 300kg Warco Major is lightly built!)

Most hobby mills can cut steel. The very light small machines used for model railway and similar work are the exception. Intended for quietly machining Brass, Aluminium, Wood and Plastics on a small scale they're not very rigid, the motors are small, and they run at high speed. They're good within their limitations, and can be operated inside the house. Although they can attempt steel, it's out of their comfort zone. A Warco Major will happily cut steel but is too loud, heavy and messy to run inside a home - separate workshop needed. It's not a production machine - don't expect it to cope with Piece rate work in a Victorian Sweat Shop.

All milling machines have limitations. Sadly I don't have room for my heart's desire, a Bridgeport. Much more capable of hard sustained accurate work than a Warco Major, yet Bridgeports are considered flimsy by big mill standards...

Dave

I advise against starting with high accuracy measuring. Trouble is it's skilled work that's easy to get wrong. Dozens of booby traps. One is not making sure the instruments are OK before starting, check that dial and learn how to use it!

As unpractised measuring applied randomly with dodgy kit is dangerously misleading, I suggest better to start simply by cutting metal with the machine. If it cuts OK, stop worrying. Measure the work it produces, not the machine. Distinctly ratty tools can still produce good results. Takes longer because the operator has to compensate and double-check, but quite severe backlash and bearing wear can be tolerated.

Only take measurements if the machine doesn't perform adequately, and remember measurement is only one of several ways of pinning down problems.

Best engineering advice ever: if it ain't bust don't fix it.

Dave

The 'little valve' may be a safety value - above a certain pressure it lifts and blows off steam to avoid damaging the boiler. They can be tested by lifting them - use a rod because the valve will be hot and it might blow steam over your fingers.

Not much steam pressure will be needed to drive that model workshop. My guess is 10psi or less. The few engines I've built were about that size and I ran them on compressed air. Best made one ran at about 3psi, my rougher engines needed 5 to 8psi.

Volume of steam or air matters more than pressure.

For a first run, I'd disconnect all the belts, raise steam gently to about 5 to 10 psi, and then open the throttle. If it doesn't run at 30psi, something is wrong - stop and ask again.

Looks OK but assume at first that the boiler is a widow maker! It's a pressure vessel full of superheated water. If it fails, perhaps due to internal corrosion, might go bang and fling metal fragments about. More likely to fail by splitting and spraying a brief fountain of steam and boiling water - don't get too close. Safety glasses and a simple shield.

Worst case by far is injuring someone else - the legal and insurance complications are potentially horrible.

Dave

The forum doesn't help much with searching.

The 'Search This Site' box top-right looks for basic word matches in Post Titles. Not wonderful.

Much better is the Google Search hidden away half-way down the home page.

Also possible to to search the forum directly with advanced search syntax in your browser. For example:

SillyOldDuffer site:model-engineer.co.uk causes your internet search engine to only return hits from model-engineer.co.uk The syntax is standard, works for me with DuckDuckGo, should also be good with Google, Bing and the other usual suspects. By default albums are created 'Public', and there's no need to login to explore them.

Be quick! The forum is about to be replaced, maybe next month. Images in an album that aren't referenced by a post will be lost.

Dave

Let me put a spoke in the wheel!

As Archimedes was Greek, and didn't speak Latin, it's obvious the right word must be Ακτίνες. Pity I can't pronounce it.

Dave

+1

A photo would help.

I'm wondering what the word 'play' means. My first thought was run-out, that is the arbour axis is misaligned with the mill's spindle axis. If so 1.5mm is huge! Second thought is 'play' means the socket goes part way in, and there's an all round gap in which it rocks. If so that suggests the tapers are mismatched - the arbour's male taper doesn't match the taper in the mill's socket. Several different tapers are available, and identifying them often causes bother.

Dave

Edited By SillyOldDuffer on 16/09/2023 19:54:46