Member postings for Robert Atkinson 2

Hi,

J Bull "Bullybeef.com" have long ceased trading. I heard a rumour that the owner was in jail but don't know for sure.

Anchor supplies are still going but are a shadow of their former self. Again I think someone involved was in trouble with the law.
The shop in Lincoln is J Burkett **LINK** Limited opening hours these days.
Government disposal has changed several times over the years with various contracts, auctions and tenders (direct or via agents) being used.
Most stuff ends up being available on ebay but there are a couple of direct dealers:

RAMCO

www.ramco.co.uk

Witham Specialist Vehicles ltd

**LINK**

Most of the "surplus" electronics dealers (M&B Radio, Johns Radio etc) have shut their shops (gone on line), closed down, or greatly reduced their operations.

Unfortunately this means the days of a weekend trip trawling through stockrooms for hidden gems have long gone.

Robert G8RPI.

Plus 1 for LPS-3

It's available in the UK.

Robert G8RPI.

If you know the power and RPM you can calculate the torque. I think a bike motor may run a bit fast and need a bit of reduction gearing. Be aware that their ratings can be optimistic and they may not be capable of the short term acceleration overloads the old ones could take.

A typical ebay "500W 24V DC 26.7A Electric Motor MY1020 + bracket for E-Scooter Electric Bike Is 640W in put power and 500W Max (continuous or 1min?) at 2500 RPM so torque is 1.91Nm or 1.41 lbf.ft

Robert G8RPI.

Well I was fitting new brushes in motors before I was even a teenager so I'm sure you can do it.

I suggest you take the rear motor out and post some more photos of it. We can then give step by step instructions. If you can get that one running on the bench it's a start.

I will be a little blunt here, if you want to get it running to use I'm happy to help, if you just want it running to sell it (you mentioned paint and ebay in another post) then I've better things to do.

Robert G8RPI.

What is your location? Maybe there is someone near who can help. If you are anywere near Cambridge I'd be happy tto a hve a look. Unless they have een cooked or soaked most big DC motors will respond to a clean, commutator skim and new brushes. You can then look at new control system.

Robert G8RPI.

There is third type of electronic angle sensor that uses a liquid bubble. These use capacitive or resistive sensing of a buble of one fluid in another fluid of difffering electrical properties. This could be a bubble of mercury in oil or air in a conductive solution. They use differential / ratiometric sensing so changes in bubble size with temperature do not affect accuracy. Personally I have a long base (200mm) electronic level (Craftsman from Sears in the USA), a vintage "engineers" sprit level and a Hilger & Watts pendulum inclinometer which are used depending on requirements. I could see a place for a Wixey in my collection though

Robert G8RPI.

Hi Neil,

I doubt any cheap meter is an order of magnitude more accurate than an expensive anlogue meter. A classical analogue meter like an AVO 8 has a specificed accuracy of 1% on DC volts. Even a good 31/2 digit DMM e.g. Fluke 110 series is only specified to 0.7 percent. plus 2 counts. Any 31/2 digit meter (1999 count) has only 0.05% resolution so with the best uncertanty of 1 count even if everything else is perfect they can only make 0.1% of full scale. Accuracy for AC, current and resistance is poorer. A single point check is not confirmation of overall accuracy.
Accuracy, precision, resolution and linearity all need to be considered. A great book on the subject is "Calibration Philosophy in practice" by Fluke.
I'm a bit of a ""volt-nut" I have meters up to 81/2 digit resolution, good solid state voltage references, Kelvin-Varley dividers etc.

Robert G8RPI.

Edited By Robert Atkinson 2 on 16/08/2019 11:11:09

Half way is the ideal storage position, no more than 1/2 max turns no matter what you measure next.

My pet peeve is people promoting illegal car modifications like DPF / EGR deletion or LED lights on motoring forums without noting they are illegal

Robert G8RPI.

To be pedantic, it's not the CE mark that is fake, it's that the product is non-compliant. For most things its self certification. As has been said a lack of enforcemet is an issue. Unless there is a complaint or injury there is no enforcement. The Australian system, CTick, haas the useful twist that while self certifiying you have to register the product (on line these days) so they can do random spot checks without ever having to see the product on the market.

The big problem is no one seems to care. There is also an issue with one offs and items built for own use. There is a common misconception that these are exempt, but they are not. There used to be an exemption from actually marking in the old Low Voltage Directive (you still had to do all the compliance work) which was often quoted in this regard. It was dropped in the new revision. It is a potential issue for companies who mke equipment for use in house. In the event of an accident they could be prosecuted or have insurance invalidated.

Robert G8RPI.

The manufacturers of the cheap ones are good at copying. The M&W is CE marked (and probably done properly, I would not be so sure about ones sold on ebay). The difference is in the details.

Robert G8RPI.

Legislation is not retrospective. However all trailer must be road legal and it's worth checking the small print on your insurance policy. Some insurers are limiting cover to commercial or approved trailers. A sigificant change (more wheels, different hitch etc) may trigger the need for a IVA.

Robert G8RPI.

There is a photo of an unacceptable light arrangement (obscured with doors open) in the .Gov "pass the IVA test" page

https://www.gov.uk/government/publications/individual-vehicle-approval-iva-for-light-trailers-help-to-get-a-pass/individual-vehicle-approval-iva-for-light-trailers-help-to-get-a-pass

About half way down, it's obviously a minature railway layout. Trailler looks professionally made, galvanised etc, but still a fail. Possibly modified from a drop down ramp to spit doors.

Robert G8RPI

The 4mm plugs with spring loaded sleeves are pretty useless and no longer common (or acceptable for new mains rated leads).

When teaching use of meters I had a "lesson" on digital accuracy. It involved a PP3 battery, AVO Model 8 analog meter (1%) and AVO DA116 digital meter (0.5% +1 count). Tne lesson was to measure the battery with both meters and discuss the results. The Model 8 read around 8.4V and the DA116 read 9.0V. Most students said the Model 8 was out of calibration and inaccurate (dispite having a in cal sticker) by 0.6V. A small percentage said the DA116 was faulty. - these had noticed that the PP3 was a rechargable with a nominal voltage of 8.4V. The DA116 had been deliberately adjusted to over-read. More digits does not mean more accuracy. The DA116 was only good to +_ 0.055V making the last digit virtually useless.

Robert G8RPI.

You can also scan the PCB, clean up the image, print it onto transfer film in a laser printer, transfer to a clean copperclad board with an iron (don't let SWMBO see you and then etch in ferric chloride solution.

Robert G8RPI.

The old BT leads were only designed for low voltage use. You should really only use leads and probes with sleeved safety plugs. Buy them from a reptutable supplier like RS Farnel, CPC or electrical factor. If you are a business or employer of any sort you must use appropriate safety leads. For domestic mains on the "user" side of the socket they should be "CAT II" at least andfor house wiring work CAT III see http://www.hse.gov.uk/pUbns/priced/gs38.pdf

Robert G8RPI.

Certificates are only as good as the process and people behind them. I've been directly involved in an aircraft case that shows this I'm changing details due to confidentiality. We ordered some one way valves with male and female ports from an approved suppler who sourced them directly from the manufacturer. Normal flow direction is male to female but optionally it can be reversed, this adds a R to the part number. Valves arrived with all correct paper work and were installed on aircraft. They would not fit with the marked flow arrow in the correct direction. Turned out that the reverse flow valves had been supplied. They had the correct part number on valve (no R) but the marked flow arrow and actual operation was for the reverse flow type. Turned out to be marking error but neither the makers or distributors inspection picked it up. This type of thing could cause all sorts of issues as it is often hard to check non return valves when installed in applications like vent lines.
Liability in this case would have gone back to the manufacturer.

A material certificate is also of little value unless there is the quality process in place to support it along with proper stores controls etc. You might have bought the right material and then picked up the wrong bit by mistake.

Conservative design and hydrostatic testing are the best defence. The most useful high tech instrument for a boiler inspector is an ultrasonic thickness meter.

Robert G8RPI.

Since 2012 virtually all trailers need to be approved or inspected see

http://www.armitagetrailers.com/trailerlaw.htm

This ties in with new laws (draft in 2018) that will require registration of al trailers over 750kg.

Note that trailer laws generally don't apply to mobile plant. This can be useful for stationary engines if they are bolted down on a chassis with wheels. Used this clause about 15 years ago when putting a gas tubine airstart unit on a ex MOD Sankey landrover trailer chassis.

Robert G8RPI.

KKKD Indeed the top of the "hump" in a syphon cannot be higher than the local air pressure can push the fluid for a simple fluid. One other issue is vapour pressure. Not a real issue with water but I once looked at control system for a project that was sucking solvent out of a tank to a higher level (pump at higher level) I said it would not work, they would just boil the solvent, but hey I'm just an electronics engineer so they didn't listen to me. Then the pump supplier came over from North America to discuss details, took one look at what they we doing and said "no we don't do pumps that defy the laws of physics".

Robert G8RPI.

The comments are very unfair to RS Components. The devil's in the detail.

The handles linked to in the original post at £12 are made from Stainless Steel. A more common glass filled nylon version is a more reasonable £2.60

**LINK**

Robert G8RPI.

Not common

see

**LINK**

Robert G8RPI.