Member postings for Robert Atkinson 2

As Andy and Andrew have said, the problem is coppers low electrical resistance. In practical terms this means the leads and the connections to the boiler need to huge. If the lead resistance is the same as the boiler resistance , ie same thicknes and length of copper (or thicker and longer) the same amount of het will be produced in them as the boiler. Resistive heating is OK for resistive materials like steel and and titanium, not copper.
Apart from induction heating another approch would be preheating and insulation of the parts not being soldered so a smaller torch can be used. A metal clad element of the type used in domestic ovens formed into a coil around the boiler and some thermal insulation, effectively a bespoke kiln, would work.

Robert G8RPI.

If the welder has an AC output then yes, you could use it as a power source for a demagnetiser. A DC output will make a magnetiser Wind a coil out of heavy gauge insulated wire (4mm2 would be a good start, it has to carry the current for several seconds) with as many turns as you can and the hole in the middle big enough to get the item you want to demagetize into.
Start with the welder on it's lowest AC setting.
Put the item you want to demagetise into the center of the coil (if it's longer than the coil leve the excess sticking out the far side), turn on the current and slowly (over several seconds) pull the item straight out of the coil and about a foot away in a straight line, then turn off the current.

EDIT:

As a guide a inverter welder or one with electronic controls is likely to be DC, a cheap one with a big knob or switches to set current will be AC.

Robert G8RPI

Edited By Robert Atkinson 2 on 24/10/2020 22:07:21

Correct

A Toroid is useless for this application.

Robert G8RPI

As a "collector" of turbine engines and having experience of putting reheated ones in a car, I can tell you this is not worth £565,000 as an engine. Generally the bigger the engine the cheaper it it is. If it can't be flown it's just a display piece or someting to put in a vehicle or run as a stationary engine. Generally it is easier to do this with smaller engines. Even the most valued ones like the Allison / RR C250 turboshafts go for 4 or 5 figures not high 6 figures. They have some scrap value but not much.
Not many people have the money, space and interest for big engines.
I once bought the APU from a Vulcan and was offered the Olympus engines for free If I removed them properly. This was becuse their weight was causing balance and structural issues. I declined to tke them. Last engine I bought was a Honeywell APU that was removed from a scrap aeroplane, complete with all accessories and in runable condition. I was the only bidder on it at £200.

Robert G8RPI.

NDIY and SOD have pretty much covered it.
The Meanwell 24V 14.6A power supply wil run the motor fine with a bit of reserve.
The motor data plate clearly says 200W OUTPUT so 264W input is 76% efficency which is reasonable.

Note that this motor will run at maximum speed (3200 RPM) on this power supply so adequte gearing or belt reduction will be requied. If you want speed control, buy a PWM controller from ebay or amazon. That WILL need overating to get reliability I'd suggest at least 36V 25A "china rating" for a cheap PWM controller.

Speed on a brushed DC motor is directly proportional to the applied VOLTAGE, Current is directly proportional to the output torque (load). Current will rise to maintain speed. For a non ideal mtor the speed will reduce slightly due to the voltage drop across the winding and brush resistance.

With a PWM control the inductance of the windings causes the apparent voltage across the motor to be the supply voltage x PWM percentage so at 50% PWM and 24V supply the motor "sees" 12V and you get half speed.

Robert G8RPI.

The key point is to get the exhaust and DPF hot enough. This requires a load on the engine. The load is the same for the same road speed and incline / load / wind regardless of engine speed. However higher engine speeds mean more combustions per minute and higher exhaust flow so generally higher exhaus temperatures. And of course if you do it for the same time you will have done more miles.
It's bad to generalise though as different engines have different systems.Some have an additive (which may be hidden from the driver). Others don't need this but my hve to regenerate by injecting extra fuel either directly into the exhaust with a valve or by opening the injectors on the exhaust stroke. How often this happens depends on driving condtions and style and alo fuel quality.

Robert G8RPI.

+1 for Dewalt 18V Li-Ion. I have a hammer drill, 1/4" driver, vibrating saw and angle grinder. Battery life is good in use and hardly any loss during storage. There are a couple of things to note. They do DY and professional grades of most tools DIY are a lot cheaper and still pretty good. These tools and batteries are marked 20V in the USA but are identical batteries, 18V is nominal, 20V is end of charge. European advertising laws say you have to show nominal.

I was sort of lucky with the drill and driver they fell off the back of a van - literally - in a service station car park. The were left on the rear step and fell off infrot of my car. Van didn't stop despite light flashing and horn blowing and I didn't get the number. Case hit my car and caused some damage but it was a old banger I was running around in so didn't mind. Police said if anyone reported it lost they would let me know for an insurance claim and probably give them a ticket for unsecure load.

Robert G8RPI.

Hmm,
Most of the gauges on that website are luminised with Radium. This makes them a hazard and liability. They re very expensive to dispose of properly. While the amount of radiation won't make you drop dead it is a hazard. The law is complex on these items but if you are a business you can't repair them (or even open them) without a licence. You can't legallly post them either. best left well alone.

Robert G8RPI.

No, we are not.
The restorers are not working under wartime production pressures or doing battle damage repairs.
There is no excuse for not using proper lifting equipment, even worse when you are being filmed.
Even the wing bolt tolerence from the Guy Martin program came from the original drawings. Incorrectlty made or installed wing attachmens can and have caused fatal accidents. More than one Tiger Moth (wrong maerial or improperly made threads in lowwer wing tie) and a Chipmunk (undersize spar bolt) as well as the Reno Mustang (worn out fibre locknut) comme to mind. On the other hand "lapping a bit of canvas on a hole" was and is the accepted way of repairing damage on fabric covered aircraft. Assuming the "canvas" is the correct fabric (linen in WWII) and a bit of are is taken that is.
I have worked on several "warbirds" over the years including Spitfires.

Robert G8RPI.

Just watching this evenings episode and thy are lifting a fuselage with a ratchet type cargo tiedown hooking the end hooks together. While probably strong enough it's certainly not approved and tested lifting gear! Just to top it off they then had two guys worlking under the suspended fuselage. At £2M for a re-build you would think they could afford a proper sling / strop. Then they were fitting the wing with pictures of "fettling" a rear attchment bolt hole with a file and then driving the main spar bolt in with a hammer. Contrast recent Guy Martin Spitfire build TV program where the same bolt was precision ground to original tolerance (0.0005" IIRC) and then having to let it sit on the bench for a while because the heating from Guy holding it in has hand caused enough expansion to stop it going in the fitting.
I'm not impressed by The Spitfire Company.

Robert G8RPI.

#andhow much do you think a modern fuel gauge costs? How about $250 for a non approved one?
https://www.aircraftspruce.com/pages/in/fuelinstrumentation_fuelgauges/belite10-06068.php
You would be lucky to get any approved (TSO'ed or OEM) gauge for £1000.
I've desigined and built fuel gauging systems for three aircraft, one turbo-prop, one jet and an airship. These did not use any "aircraft grade" materials. The turboprop was the NAC Fieldmaster https://en.wikipedia.org/wiki/NAC_Fieldmaster. This was a resistive system with Lucas commercial vehicle float type transmitters, electronics box and a commercial Anders 270 deg meter with custom scale. As a design authority you can use anything that meets the requirements, it does not have to be "aerospace grade". Biggest problem I had with that system was convincing Desmond Norman thatt a diecast aluminium box was OK. The was used to diecast meaning Mazac or pot metal. The electroics boxes a aluminium alloy. I know of another certified aircraft that used a Sodastream CO2 cylinder for the emergency undercarriage power source.
Last custom fuel gauge I specified cost 5 figures. That was just the gauge, not the tank probes or electronics box.

Robert G8RPI.

Indeed,
They did not openly advertise the fact that smart meters have a contactor that can be used to disconnect the supply remotely. Current law stops the supplier disconnecting you but a change in the law could chang all that. The is also the possibility of a software error, operator error or even a cyber attack disconnecting consumers. Unlikely but not impossible.

We had a Dakin multi-split Air-Air system installed about 18 months ago. Two outdoor units feeding 5 indoor (capacity for one more). It wors really well and heating costs have gone way down. Even using it for cooling in hot weather our bills have not gone up.
Like most modern systems this uses a variable speed compressor and fans so it is very quiet and does not switch on and off with a big change in noise like the old fixed seed systems. I installed a similar Mitsibushi system in my last place about 15 years ago and it was great as well. When I sold it I dad to explain to the energy assessor that it wasn't just air con. He initially put it as electric heaing but after taking advice back at the office our energy rating improved a number of points.

The odd thing was that all the installers on the new system wanted to put single split systems (5 outdoor units) in. No idea why and unlike the system I put in the old place the two multi split outdoor units were slightly dearer than 5 smaller singles.

Robert G8RPI.

Wiring a motor Star or Delta does not affect the rated power output of the motor. It can affect its starting performance under load but that was not the question. The key point is that the current per phase is lower for the star connection than the delta.

With a VFD it i important to note that the mechanical output power is reduced when running the motor at lower speeds. This is because power is proportional to speed an torque and torque in a motor is proportional to current. You can't drive more current than the rating so power drops with speed. Conversly power increases with speed for the same torque / current.
Any motor being run on a VFD should be geared for the highest speed possible.
The limiting factor for this is the insulation of the windings. This is because the voltage must be boosted to mainntain the same current and torque at higher speeds.
Some motors desigined for VFDs have improved insulation to allow for this or are designed for maximum output at 400Hz and line voltage this gives higher output speed and a much smaller motor for the same output. Aircraft use 400Hz or higher to take advantage of the significant weight savings (transformers for 400Hz are much smaller too).

Robert G8RPI.

The majority of opto-solators are analog. Only those with comparators on the output are truly digital. The problem is that the transfer function varies between devices and with temperature. To counter this they are often used with on/off input signals and hard on output devices. The are bein used with digital signals but are analogue devices. For a simple 3 level system I don't see any problem using opto isolators.

A "soft-Start" circuit can have a downside depending on the power on reset circuit being used. If a simple power on reset is used with a slowly rising power supply the reset may finsh before the supply is stable enough for correct operation. This can lead to unpredictable operation.

Robert G8RPI.

You can buy a "USB Endoscope Camera" on ebay, Amazon etc for around £10 these connect to a android 'phone, tablet or a PC. They have built in lights and arv around 8 or 10mm in diameter. They can be had with 2 or 3 metres of cable.

I use one for all sorts includng looking inside engines

Robert G8RPI.

Edited By Robert Atkinson 2 on 01/10/2020 21:33:26

These gauges are NOT suitable as they are not direct pressure gauges.They are contents gauges.

If you look closely at one with the pionter axis in the center of the dial you will see the pointer is attached to a coil of flat material. This is a bi-metallic temperature compensator. Thus the gauge indication stays the same as the pressure in the extinguisher rises and falls with changes in ambient temperature. This is obviously not a good thing for a boiler!

Robert G8RPI.

The last F104 I saw (and sat in) had lost it's wings and was once flown by Chuck Yeager. North American Eagle. Unfortunatly even without wings it still crashed in August lst year killing it's driver, Jessie Combes.
https://en.wikipedia.org/wiki/North_American_Eagle_Project

On a happier note Burt Rutan designed and built an asymmetric aircraft
https://en.wikipedia.org/wiki/Rutan_Boomerang

Robert G8RPI.

I crossed with Rodgers post. His description is correct for the wet vacuum pumps like the speedi-vac and EV range. As the EB3A will also act as a compressor I'd expect it to have valve on inlet and outlet but I've never had one apart.

Robert G8RPI.

The EB3A is classed as a high vacuum but i't's relative. Specification seems to be 26" Hg / 133mB. So pretty good. Certainly good enough for a pendulum enclosure. It's not an oil free pump but is not wet/oil sealled. The wet ones have a "sump" cover over the pump block with a level glass. The Black plastic "cheese head" screw is normally the oil filler on Edwards pumps. Was the wadding wet with oil? If so it likely that is the oil filler.

Most likely issue is leacking or stuck valves. These will be poppet or reed (possibly combination) type.

Robert G8RPI.