By continuing to use this site, you agree to our use of cookies. Find out more

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: Metrotropolitan Vicker Single phase motor
06/12/2021 21:19:03

OK, A picture is worth a thousand words.
It appears to be a switch (centrifugal) start induction motor. The oddity is that it is "inside-out". The induction part is the stator and the powered winding is the rotor.
The most likely reason for this was to get around a patent. It does simplify the centrifugal switch arrangement thoough.
AC power would just be connected to the brushes as shown in the picture.


26/11/2021 19:16:37

Crossed posts with Martin.

I don't think the 3 phase type slipring system will work with single phase and John says no stator windings.
A inverted permanent magnet stator AC motor won't work on single phase either.

Robert G8RPI.

26/11/2021 19:11:59

Hmm, Any photos? How big is it?

If it is slip-rings rather than a segmented commutator it must be some kind of "Inverted" induction motor. Trouble is I can't see why you would do that or how it is started. Are you sure it is a motor? It could be some kind of permanaent magnet AC generator.

There are 3 phase motors with wound rotors and slip-rings. These have power connected to the stator windings and variable resistors (rheostats) connected to the rotor to control torque and (to a lesser extent) speed.


Thread: EVs and the heater on a cold morning !
22/11/2021 19:58:56

PGK PGK hints at another issue, you can't charge the battery when it's very cold. They have to use mains power to warm up the "coolant" and cells before charging can start. Not too much of an issue in the UK or if charging straight after a run but is an issue in colder climates when using off-peak or sequenced charging.
No I'm not anti EV, I drive a plug-in hybrid. I'd consider a full EV but have nowhere to charge at home. Currently I charge at work which covers my commute.

Robert G8RPI.

Thread: How much is a life worth
19/11/2021 20:07:17

This is typcal lawmaking just to make it easier to get a conviction and look like the politicians are doing something. There are existing laws coving being in control of a vehicle. These have been used long before cellphones to proscecute mobile radio users. The original cellphone law draft covered all types of hand held radio use. Then they realised that this would affect the emergency services so it was made specfic to cellphones. I reserve further comment until the changes are made law.

Thread: Buying a Tachometer - Which type Contact or non contact ?
15/11/2021 19:00:32

You can get the best of both worlds with non-contact tachometer and a contact adaptor. This is just a spindle with target a that fits on the tachometer. The main use is with a wheel for surface speed measurement.


DIY is possible too. You can buy the difficult bits

Robert G8RPI.

Thread: Decent hacksaw blades
14/11/2021 17:12:42

+1 for Starrett

Robert G8RPI.

Thread: Enclosure for Inverter
14/11/2021 14:01:33


Someting from this range or similar is ideal

Sometimes you can pick up a used one (with bonus par inside sometimes) on ebay wth creative search.

Follow the inverter manual for minium space required around the inverter. Don't forget strain releif glands for the cables.
Yo cn of course DIY box. If you use wood or similar I'd increase th sisze a bit and put ventholes (with protection against swarf ingress) in it.


None of the typical inverter drives are suitable for mounting without an enclosure in an accessible or exposed location. They do not have proper environmental protection, touch protection for terminals or strain reilef for the cables.
Just because "everyone does it" and they mostly get away with it is no reason not to do it right.

Robert G8RPI.

Thread: Music on TV Programmes.
13/11/2021 19:09:03

On The licence thing, many years ago I was in a rented aparment and had no TV. TVL came round asking the usual questions saying I didn't have a TV licence.
I said I had a Licence to receive TV, they said I didn't. I said go check the records, I can even transmit TV signals. This confused them so I showed them my amatuer radio licence. They went away muttering....

Robert G8RPI.

Thread: Treadle Lathe- ID Please?
13/11/2021 18:10:21

As it has back gear and the leadscrew in front of the bed it looks like a SuperRelm

Thread: SMR's a conundrum.
10/11/2021 20:31:27

I found it interesting that the BBC used The Nuclear Consulting Group for several interviews, This is an anti-nuclear group but are clever how they do it.
The cost of nuclear is interesting. Hinkley C will cost a lot to build and decomission, About twice the cost of the same avrage capacity off-shore windfarm. However the nuclear plant will last twice as long.......

In the UK we have actually started burning coal again becaue of the cost of gas

Thread: VFD size
06/11/2021 15:57:12
Posted by Clive Foster on 06/11/2021 15:06:21:


Inverter Drive Supermarket are my go to supplier. Prices are reasonable and they have a well deserved reputation for going that bit further to ensure you get a device suitable for your needs.

When you say reconfigured the motor do you mean that you connected the parallel connected "double Y " windings in delta just as is done with a normal motor with single windings?

I'm told this isn't a good thing to do as it reduces efficiency and raises power consumption. Makes no sense to me as surely a pair of parallel windings is equivalent to a single winding. If it works in Y it ought to work in delta.

However there must be a reason why received wisdom is that you can't do the conversion although all the connections are there.


From the picture of the motor plate in the OP's album the motor is a conventional single speed 3 phase.

06/11/2021 14:54:50

What is the actual current setting on the VFD? This is P12.0 (motor) and P12.5 (drive). The tables you show say 5A set but that a 2.2kW VFD output is 10A max.

Robert G8RPI.

Thread: Restoring the scale on engineering tools
05/11/2021 15:33:23

A Lacquer-Stik Paintstick is the best option for engraved marks.

Random googled supplier

EDIT:  Instructional video (reversed colour)

Robert G8RPI

Edited By Robert Atkinson 2 on 05/11/2021 15:38:40

Thread: Chuck Guard
03/11/2021 20:05:58

Guards that are supplied with or fitted to a new machine must be fitted when used in any commercial environment. Not just schools or training. The guards are part of the machines approval. In theory a company could remove them if a safety assesment was carried out. If there is an accident they may have difficulty justifying that assessment.


Edited By Robert Atkinson 2 on 03/11/2021 20:10:30

Thread: Replacement surgical blades for Swann Morton scalpel handles
03/11/2021 18:59:32
Posted by Greensands on 03/11/2021 15:16:27:

Must confess to only having looked on ebay as I much prefer to pay using Paypal but happy to expand my search

ebay don't allow the sale of knives so you should not find many on there.frown

Robert G8RPI.

Thread: Guided bus lane
26/10/2021 10:22:14

I don't know about St Ives, but there are couple of places in Cambridge where the start of the guided busway is tarmac not concrete, The buses join it there and it would be much easier to mke a mistake than were the tarmac road crosses the busway at 90 degrees or so.
The car traps are visious because the results of a head on collision between a bus and car is serious. You can't swerve out of the way. The hole traps are simple and need minimal maintence. Tyre spikes or one way ramps cost more and need to be maintained.
A has been hinted at, you could als get ticket just to add to the misery.

Robert G8RPI.

Thread: Advice from the photographers.
23/10/2021 20:33:14
Posted by Michael Gilligan on 22/10/2021 21:36:56:
Posted by Robert Atkinson 2 on 22/10/2021 20:55:35:


Another option is a used 35mm SLR one with zoom. The Ohnar ones were OK. […]


But don’t those only zoom in ?

[ which would exacerbate the problem that prompted Nathan’s question ]

… or do you know of a 35mm one which handles larger-format originals ?


The do only zoom in, but they were designed for a full format so 1:1 = 0.6:1


Robert G8RPI.

22/10/2021 20:55:35

You can get new copiers designed for DSLRs with APS-C sized sensors. Quality can vary.
Another option is a used 35mm SLR one with zoom. The Ohnar ones were OK. You might need a new T mount depending what the one you bought came with. Lots on ebay.

Robert G8RPI.

Thread: Aircraft General Discussion
22/10/2021 17:01:59

I missed John Doe's post earlier.
I agree entirely. For engineers a lot of the reduction came with EASA. I did the "old school" CAA mainence engineers licence (avionics). We were expected to know the details of how the systems worked down to component level. Also how the test equipment worked. We were expeced to diagnose faults without detailed guidance. The licenced engineer carried the authority and had the final say on This was one of the best systems. EASA "levelled the field" across europe. This resulted in the company holding the authority and the engineers having less detailed knowlege and being constrained to follow the aircraft fault finding manuals.
As aircraft become more reliable "human factors" are playing a much bigger part in accidents but the engineers role is being "dumbed down".


Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at

Latest Forum Posts
Support Our Partners
Rapid RC
Eccentric Engineering
Eccentric July 5 2018
Subscription Offer

Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest