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Member postings for Robert Atkinson 2

Here is a list of all the postings Robert Atkinson 2 has made in our forums. Click on a thread name to jump to the thread.

Thread: Threads used on electrical brass fittings
19/07/2019 13:01:04

No real standard. As Jason says PG is not uncommon, mostly on industrial fixtures though. Brass holders commonly have 10mm x 1.5, 20mmx 1.5 or 1/2" x 26tpi which does not seem to fit your description. Quite possibly some odd pipe thread.

Robert G8RPI.

Thread: Angle grinders - Dangerous or not
18/07/2019 12:40:17

I would not recommend buying any mains powered item from any far eastern seller on ebay or the like even if they appear to be UK based. For anything critical I will only use reputable established suppliers and brands.
I have recently seen a spate of dodgy kit:

A laptop style power supply supplied with an LED face mask beauty treatment system that I refused to pat test at all. I cut the leads off and broke it open and even the completely not technical owner could see the internal construction was terrible.

A 5V DC plugtop style power supply that had a loose circuit board inside, un insulated mains connections and less than 0.5mm creapage / clearance between the mains live connection and the output 0V

A PC style power lead with a fuse-less imitation of a 13A plug and conductors of 4 thin strands of something copper coloured but very springy. probably steel but I didn't even check before cutting it into short lengths.

All lethal and / or capable of starting a fire.

Robert G8RPI.

Thread: Faulty LED
18/07/2019 12:06:34
Posted by Speedy Builder5 on 18/07/2019 07:48:02:

Side lights, brake lights are all driven by the supply voltage of the car, in your case 12volts. You have a connection problem, not a voltage problem. As others say, check the socket / pins on your bulb and especially, check the earting of the socket to the body of the car. If its an old car, this would be my first thing to investigate. On my 6 volt cars, all electrical equipment has its own earth wire.

BobH (Austin 7 and 2CV)

This is not always true for modern cars. Typically the lights are driven via electronic switches that measure the current and continuity of the filament for failure detection. LEDs mess this up. Some even use PWM (switching on and off very rapidly) to change the brightness. I've only seen this used on DRLs and originally fitted LED light though.

Robert G8RPI.

Edited By Robert Atkinson 2 on 18/07/2019 12:18:43

Thread: Angle grinders - Dangerous or not
18/07/2019 07:29:18

It's the video that's dangerous.

It implies that you can abuse an angle grinder and use it without a guard and nothing bad will happen.
Just about any tool with an exposed cutting edge is potentially lethal, if it's powered then it's worse. They all need to be treated with respect. I have a Dewalt battery powered vibrating multitool which is great for softer materials and you can touch the running blade without injury but even dropping it switched off it could cut an artery if it hit the wrong spot.

Another interesting point about this sort of video is that the makers are potentially opening themselves up to lawsuits, especially in the USA. You are responsible for advice you give people.

Robert G8RPI.

Edited By Robert Atkinson 2 on 18/07/2019 07:31:41

Thread: Faulty LED
18/07/2019 07:15:33

A bit more information would be useful:

1/ Make & model of vehicle

2/ Make & part number of lights and/or link to ebay listing.

3/ Why are you changing them, did the old ones work OK?

Note that unless the lights are from a reputable supplier with "E" markings they are almost certainly illegal for use on the road.

Robert G8RPI.

Thread: Power supply problems for CNC rotary table
16/07/2019 21:47:29

I can confirm that the correct power plug for Sherline / Mumford controller (at least the one Steve has) is a 2.5mm x 5mm coaxial DC power plug. Fairly standard part.

Robert G8RPI.

Thread: Single DRO for 2 machines
15/07/2019 19:39:56

No reason why you can't use two sets of encoders one one readout. Details depend on the type of encoder. An optical one or magnetic with electronicss in the readhead would be simplist. What DRO are you looking a geting? a link to the model would be good.
I've one this sort of switching before with no problem.

Robert G8RPI.

Thread: Myford ML7 tailstock bore, and threading the barrel to fit a chuck
15/07/2019 13:09:36

How about a ER32 collet chuck on the tailstock? They will grip a round or hexagonal bow end quite well. You could even make a split nylon sleeve with a hex centre hole if you needed to grip tight without marking. Possible an adaptor tube to slip over the outside of the tailstock barrel and carry the chuck to maintain the full bore clearance.

Robert G8RPI.

Thread: Lathe improvements?
15/07/2019 12:52:22

Hi Niels,

Nice machining but it must be said that your electrical installation is terrible. This type of connection is just asking for trouble. The power input including the weight of an extension lead is hanging off the conductors. Even worse the earth connection is taking most of the strain. if this come off, even without any other fault the filters in the drive will put your lathe metalwork at 1/2 supply above ground, i.e. 110V AC. Admittedly low current, but even a slight shock around moving machines can cause other injuries as you pull away.

The drive should be in an enclosed box with ventilation protected from swarf and coolant and the power input and motor connections by either proper power connectors or cable glands with strain relief. The enclosure should also incorporate a fuse and suitable EMI filters unless they are included in the drive. I assume this is just a trial set-up but it can electrocute you just as quickly as a final design. Reaching across the motor, pulley and gearing to reach the drive is not great either.

Robert G8RPI.

Thread: Any other bowmakers on here?
15/07/2019 07:36:52

Couple of comments,

Cost - SWIMBO's bow cost more than my last car (both used, car not as old as the bow)

On carbon fibre , to get the best performance (weight, stiffness / flexibility in different planes for starters) would you not have to layup the correct combination of fabric and direction of lay rather than just cutting out of a pre cured sheet?

Robert G8RPI.

Thread: Aircraft radio scanner
15/07/2019 07:24:54

Any transmitter or in theory even a receiver. The relevant legislation is the Wireless Telegraphy Act 2006. Chapter 4 section 36. **LINK**

"A person who has a wireless telegraphy station or wireless telegraphy

apparatus in his possession or under his control commits an offence if—

(a) he intends to use it in contravention of section 8; or

(b) he knows, or has reasonable cause to believe, that another person

intends to use it in contravention of that section."

Section 8 says" 8 Licences and exemptions

(1) It is unlawful—

(a) to establish or use a wireless telegraphy station, or

(b) to instal or use wireless telegraphy apparatus,

except under and in accordance with a licence (a “wireless telegraphy licence&rdquo

granted under this section by OFCOM."

In practice you are unlikely to be prosecuted for having a receiver.
Software Defined Receivers (SDR) have been mentioned a couple of times. While SDRs can be great, the simple cheap USB Stick ones intended for TV reception do have limitations. For a beginner they can be quite daunting to set up. They need a PC or possibly tablet and this can cause interference issues. There are drivers and various versions of software to install. I have a couple of SDR's including TV stick and a much more expensive ~£200 unit. They are great for what they are but neither offers the "out of the box" operation of a handheld scanner and the TV stick does not offer anything like the performance of a dedicated scanner on AM Airband.

Robert G8RPI

(I have Amateur, aircraft and marine transmitting licences)

14/07/2019 21:17:01

I should have said that the Whistler does not have 8.33kHz channel spacing. It's an American market model and they have not taken up 8.33kHz yet. SOD and Andrew are correct, you technically need a licence to transmit or receive airband but reception as a hobbyist is normally ignored. I have personally seen commercial aviation companies told off for 1/ having a ground radio that could be tuned to other than their licenced company frequency, 2/ playing the tower frequency as their telephone hold "music". It is now illegal to have a transmitter without a licence. This was changed so that they did not have to catch unlicenced operaors with their finger literally on the transmit button. Transmit wilfully and they will come after you. There was a case at Cambridge a couple of yer ago and the offender was cught and proscecuted.

One other thing is that there is less information being transmitted to airliners by voice as digital messaging is being usesd more and more. Google ACARS and CPDLC for more info.

Robert G8RPI

14/07/2019 16:06:44


I'd suggest the Uniden / Bearcat EZI-33 XLT at £60- £80. Lot's of suppliers in UK e.g.

One important feature is the availability of 8.33kHz channels. This is a fairly recent change so mny older receivers only tune to 12.5kHz channels. While not used a lot yet it's good for future proofing.
For home use a outdoor antenna will help a lot, You can make this yourself.

Robert G8RPI.

Edited By Robert Atkinson 2 on 14/07/2019 16:07:14

Thread: Off road bike gates
13/07/2019 13:07:03

It's very difficult to stop a push bike or even a small motorcycle while still allowing access for pushchairs, wheelchairs etc. I can think of no simple mechanical solution.

Robert G8RPI.

Thread: air blast cooling for mill - solenoid control ?
13/07/2019 10:05:32

You should use a separate fuse and control switch in series with the valve solenoid. All wiring should be proper mains rated cable with an outer sheath or inside flexible conduit. Don't forget to earth the body of the valve. If you don't use a separate fuse then the wiring must be rated at more than the rating of the main fuse feeding the machine. Ideally you would use a low voltage (24 or 12V) solenoid for safety,

Robert G8RPI.

Thread: Electric Cars
12/07/2019 07:25:00
Posted by Andrew Johnston on 11/07/2019 17:30:15:
Posted by Russell Eberhardt on 11/07/2019 16:05:27:

Diesel vs petrol: Diesel cars are more efficient and produce less CO2. Older diesel cars produce a lot of particulates and NOx which give rise to poor air quality in cities however current models complying with euro 6.2 standards produce much less.

Oddly we had a meeting today at a gas sensor company for whom we're designing an updated PCB and signal processing for their NDIR CO2 sensor. They also sell optical particulate sensors, often used for air quality monitoring. At lunch one of the scientists was saying just that, modern diesel engines are less polluting than petrol for some gases and especially for particulates.

Whatever we do there'll be some "expert" or government "adviser" thinking up a new pollution source or new target to hit. Even if we all walked people will be worrying about particulates from shoe soles. The only permanent solution to pollution is to get rid of everybody. Then at least there'll be nobody to worry about cows farting. smile


Correct, according to published figures my DPF equipped 150hp 1.9 turbo diesel Fait produces less particulates than the wifes 2.0 140 HP petrol (and 3 years younger) Ford. The new direct injection petrol's are worse for fine particulates than the old ones.
One thing has not been mentioned is that most people seem to think that the proposed ban on new petrol and diesel car sales means we will have to buy plug-in electrics. This is not try, Hybrids will still be sold and I'd guess initially a lot of those will be "light" ones with most power from the IC engine.

Robert G8RPI


Edited By Robert Atkinson 2 on 12/07/2019 07:25:41

Thread: Power supply problems for CNC rotary table
10/07/2019 19:21:47

The DIN connector is for the controller to stepper motor connection. The power seems to be a standard cylindrical power plug. These come in several size especally the centre hole. If @Steve Crow can tell me the OD and ID (gaugig with a pin or drill shank is best) of the plug and if it is positive or negative centre (should be marked on label) I can sen you a suitable NOS quality supply (Laptop "soap on a rope" style) for the cost of postage.

The controller does have to be CE marked for sale (or use unless personally inported) in the UK / EU. As it has a microprocessor it needs to meet EMC directive and even if it does not need to meet machinery, LVD or LVD it still needs the mark to confirm this. Unfortunatly most small importer in niche markes either don't know or don't bother.
The controller without PSU is $50 cheaper so that would buy a proper supply like
even without the cost of the 120V adaptor.
I don't recommend buying mains powersupplies on ebay/amazon/banggood/aliexpress as you have no idea of the quality.

Robert G8RPI

(This stuff is part of my day job I'm a Chartered Engineer and have done CE/UL/CSA compliance)

Edited By Robert Atkinson 2 on 10/07/2019 19:32:29

10/07/2019 19:03:46
Posted by Emgee on 10/07/2019 13:50:45:

This or similar rating would be my choice of unit,



That, on it's own is not suitable. It is a component, not a consumer power supply. To be safe it needs a housing, power inlet connector (or properly strain relief on the cable), fuse and output connector as a minimum. IT probably needs n EMI filter as well. Just sticking a mains lead on this is down right dangerous.

Robert G8RPI.

10/07/2019 13:00:48

First thing first,

It is ILLEGAL for a UK company to supply a US only specification power supply for use in the UK.

The best option is to get a proper UK approved power supply. The 120V converter is rated at 45 VA (Volt Amps) this means only resistive (or PF=1) loads can be at the full 45 watts. The 120-24V supply is only 24VA output an input is likely to be 1.1 times this. BUT its an electronic supply and these have very poor power factor so VA at the input is likely to be well above 45VA. Add in the fact that we are 50Hz and the mains voltage is likely to be nearer 240V than 230 The little converter is over stressed. It is also probably an autotransformer and the 24V supply is only rated at 120V there is a shock hazard if the neutral of the transformer or it's connection fails.
I'd be less worried about a 24V 1A supply on a notionally 2A stepper motor because the controller is likely to limit the current and may even have a switch mode regulator that will increase the current available. What plug is on the controller end of the 24V supply? I almost certainly have a supply that will fit this and is properly designed and approved.

Additionally, is the controller CE marked? No disrespect to Bryan Mumford but I'll bet it's not. Again it's illegal to sell this in the UK unless it meets the required regulations and is CE marked. In this case at least the EMI regs apply to the controller and LVD to the power supply.

Robert G8RPI.

Robert G8RPI.

Thread: Aircraft General Discussion
07/07/2019 12:58:57
Posted by Andrew Johnston on 06/07/2019 17:07:09:

Dunno, could have been a Sea Fury. The aeroplane was definitely silver and my impression was it was too dumpy to be a Sea Fury. Didn't sound quite right either. The jury is out, but on balance I might stick with a Thunderbolt? I can't say for sure if there were invasion strips.


Presumably the same aircraft is over Bar Hill right now I. I concur with your P-47 Thunderbolt identification. eep front fuselage and harvard-esque tail are key. I then googled P47 UK and found this

which pretty much confirms it.


Robert G8RPI.

Edited By Robert Atkinson 2 on 07/07/2019 19:04:56

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