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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: Which oil and oil gun
28/08/2019 12:39:39
Posted by Kevin Murrell on 28/08/2019 11:17:32:

Cleverer people than me will know the whole answer, but I believe modern engine oil is not suitable for your lathe. Those oils are designed to work at a much higher temperature. I suspect that the various additives in them wont help either!

Actually a modern 5 or 0 weight engine oil is probably OK and better than a engine oil comtempary to the lathe. Modern oils have fewer additives that might harm yellow metal bearings.

That said I'd still go for a good SAE32 hydraulic oil.

I just bought a 5l tin (lifetime supply for me) of OM33 (UK military spec oil similar to Nuto 32. Hyspin 32ZZ meets the OM33 spec) on ebay for £10

Robert G8RPI.

Thread: Battery longevity
25/08/2019 14:28:01

The battery has lasted because A: it was made before the total ban on mercury inn akaline cells and B: the battery is actually disconnected when the shaver is off.
Allaline cell made afetr about 2005 had no mercury added and as a result tend to leak due to hydrogen build-up. The mercury stopped the pressure build up IIRC it acted as a catalyst for a re-dsorbsion reaction. Any alkaline battery made between 2005 and about 2016 is likely to leak. Both Duracell and Energiser dropped their leakage warranties agound this time. They seem to have cured the issue though as recent batteries seem to be better and the warranties are oming back.
Modern electrnic kit discharges batteries when "off" because there is not real switch, the elecronics is active, just waiting until you push the on button.

Robert G8RPI.

Thread: Current leakage om CNC
25/08/2019 11:21:04

+ one for Joes comments. and as Dave says fault can develop, you arn't using an extension lead by any chance?

All metallic parts of the machine that might come into contact with a voltage ove 50V in the event of a fault MUST have a path to ground (unless the machine is double insulated which is unlikely and not the case ith yours as you have an earth). This path must be designed in and able to carry the full fault current. Just continuity becuase conductive parts hppen to touch .s not good enough. Unfortunatly many machines do not meet this requirement.
The use of a 110V spindle motor may indicate a more serious fault/ design issue if the main supply is 230V.

Sponges and saltwater have no place in any safety earth.

Robert G8RPI

24/08/2019 18:15:12

Commercial CNC machine or homemade?
5uA is enough for a shock. Assumuing you are in the UK or EU with 240V mains the 120V you are measuring is caused by the inut filter capacitors acting as voltage divider, The common of the filter appears to be connected to the machine metalwork but not the mains earth. This could be a fault in the machine or the workshop wiring.

Robert G8RPI.

Thread: Are there any left?
22/08/2019 18:23:46

Well if you want a gasturbine engine try Everett

I like small turbines and had several some years ago but a change in curcumstances and job move means I don't have any at the moment.

Robert G8RPI.

21/08/2019 20:50:51

Anchor are still in business but a tiny store in Nottingham compared the old one. They had a "museum" collection which was lost in the fire. Their Ripley depot is still there.

Robert G8RPI

Thread: Need a lot of help from you good people
21/08/2019 19:31:40

Allowing for losses and being conservative, three 18H 12V batteries would do assuming full load all the time. If you are optimistic then three 12AH would do.

However as noted above running a battery at it's 1H rate or faster is not good for it, Ii'd go for a bigger battery if you have space.

Three of these would be OK (I've never used this seller or brand)

Robert G8RPI.

Thread: Are there any left?
21/08/2019 12:56:36


J Bull "" 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:


Witham Specialist Vehicles ltd


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.

Thread: What coating/grease for long term tool storage
21/08/2019 07:21:10

Plus 1 for LPS-3

It's available in the UK.

Robert G8RPI.

Thread: Need a lot of help from you good people
20/08/2019 13:41:39

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.

20/08/2019 07:39:15
Posted by terry callaghan on 19/08/2019 20:59:50:

Thanks Robert, I am in Somerset. Commutator skims, new brushes are way out of my knowledge. I have always been a hit it with a hammer type of guy and if that does not work, use a bigger hammer. Much the same goes for resistance checks. What I can’t get my head around is why into days world there is not a replacement 12v motor I can fit in. I would think that a lot of power would be lost with the locos old control system. Taking out and fitting in new motors I can do. Understanding what looks like 50 year old units I have not a hope.

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.

19/08/2019 20:27:15
Posted by terry callaghan on 19/08/2019 19:26:01:

Ron, I think you are right the Sinclair motor is not man enough. I think that this is going to be too much for me to sort out as I am a complete donut when it comes to electronics. Sad to say that there is nothing useful in my location in the way of motor servicing. So I think I will get on with the repaint and eBay it. Thanks for your input.

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.

Thread: Digital inclinometers
18/08/2019 15:04:05

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.

Thread: Meter Probe
16/08/2019 11:09:45
Posted by Neil Wyatt on 14/08/2019 16:13:24:
Posted by John Haine on 14/08/2019 08:55:26:
Posted by Neil Wyatt on 13/08/2019 20:57:53:

Even my cheapest £5 'disposable' multimeter has shrouded plugs. Sobering that it is an order of magnitude + more accurate than my expensive old moving coil meters.

My better meter has shrouded plugs and only the very tips are bare - I find this style much easier to use TBH.


Or at least precise? wink

No, very much more accurate, at least if the agreement of multiple meters on a reading and the occasional test against an accurate reference voltage is sufficient test. Essentially, it isn't any more expensive to make them accurate to within a few tenths of a percent, so there's no incentive to make them less accurate.


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

Thread: Pet peeves!
16/08/2019 09:40:12

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.

Thread: Digital calipers made in same factory?
15/08/2019 21:31:38

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.

14/08/2019 21:05:13

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.

Thread: Home built trailer
14/08/2019 20:29:58

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.

14/08/2019 14:37:48

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

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

Thread: Meter Probe
14/08/2019 12:23:15

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.

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