Member postings for Robert Atkinson 2

The edge of the casting adjacent to the bush at the 10:00 to 11:00 position looks like it is proud of the surface like the start of a thread being pushed out. This might mean it is threaded. As this is a spare I'd suggest a semi-destructive investigation. If you have a mill start to cut away the end of the bush at it's thickest point. Use an end mill bigger than the thickness of the bush but less than half th diameter. It should be obvious if there is a thread as ou will hit cast iron. A drill or even slitting at an angle with a hacksaw blade (with the height reduced by grinding) would also do.
When removing by whatever method, applicatin of heat will help a lot. A paint stripping type hot air gun is a useful heat source and safer than an open flame.

Robert G8RPI.

The Co-Op and the like will normally at least have a sample tested and act on reported issues. Additionally they will use supplies that meet their requirements for quality control etc and the items will have been tesed before leaving the manufacturer.
The issue in the particular case is that the item with the bad earth had a design / production fault so clearly adequate checks or QA had nott been carried out. Additionally there has been no mention of any recall or other recovery action.
The importer has to ensure the items they sell are safe, how the do that is up to them. If they want to trust the manufacturer that is up to them but they are responsible if it all goes wrong. For whatever reason (greed, ignorance and lazyness are common) some importers do not fulfil their obligations. It is then a game of chance, just hope it's not you or someone you know who looses.

There is a similar issue with other hobby magazines. This Months Radcom had a front cover picture and review of a piece of test equipment and funnily enough a shortform catalogue from one of th UK stockists.

Robert G8RPI.

The thread about a pooryl earthed machine, suppled by UK dealer who advertises on the forum that was deleted also came to my mind. Davd mentioned it and Neil repled " The other thread was pulled as statements were made of dubious legality. For example it was stated as fact that a supplier was negligent because they didn't unbox and inspect every product before sale. "

Without going into the details of that case, it is irrefutably the case that an importer IS responsible for the safety of the items they import. They need to take adequate steps to insure that. Many importers do actually check every item or samples from each batch. In the particular case I was surprised that the suppler has not issued any recall on the product as the problem was clearly a design or manufacturing process issue, not a random failure.

Again in general terms, not specfic to that case, importers should remember that if a non -compliant product (for whatever reason), causes a death, the owners /senior management can face manslaughter charges. It is up to the courts to decide if relying on a foregin companies quality control and testing was reasonable (it obviously wasn't adequate or there would be no case).

What did happen to ARC adverts.

Robert G8RPI.

As suspected that is the main power module. I expect that the capacitior failure is secondary to a failure of the power module.
The unit is probably beyond economic repair. The issue is that other parts have probably been damaged and there is a high probability that if you don't find and replace all of them the new parts you did fit will be destroyed first time you turn it on.

Robert G8RPI.

As Joe says this type of failure of a ceramic capacitor is unusual. The capacitors are connected to the end pin of a 7 pin through hole component on the otherside of the circuit board. I suspect this is the main bridge output device, bot it could be a terminal block.
What is the component on the otherside of the board? Photo nd any part numbers would be useful.

Whay is the history of th fault? e.g bang during normal operation? overload? Bang on switch on?

It could be lighning surge damage, has anyther equipment failed?

Robert G8RPI.

That is still a flywheel, all be it a very out of balance one. It's rotating not reciprocating. Hopper has most of the story with the energy required. the big isse is that a recoprocating mas stops. I horizontal all the inertial energy is wasted stopping it again. If vetical there is only potenial energy which can only be recovered on the way down.

in either case nergy is only stored for hlf the stroke.

Any egnge with a crankshaft has a flywheel - the crank. They only need a extra flywheel if the crank isn't big enough.

Robert G8RPI

There are various versions of "SX2". For starters what motor type, brushed or brushless, does your mill have?

If you don't have athe skills to work it out for yourself, unless you can find someone who has fitted the exact same tacho to the exact same mill you would be better of using the hall and magnet supplied.

Robert G8RPI.

I missed Jed's post as it crossed with mine.
Windscreen wiper motors are reversible electrically but typicall the thrust bearings are only set up for one way running. This is not an issue if you were backing off after capping as ther is no load. However with a wiper motors crank output and a spring you don't have to reverse it, just let it run through a rotation on the parking switch. The spring beween wiper crank and capping lever will let it run pat after the cap is on and capping lever has stopped. The existing spring in the manual capper will lift the lever.
Get an older motor from a scrappy. Ask them which ones they arn't asked for. Those will be cheaper and reliable.

Robert G8RPI.

If the isolator is tripping as you say " The isolator for the mill is a Telemecanique and is the one I used in Oxford. As it is the trip on this isolator that keeps tripping " and is the blue/grey bok on the wall (left side) I suspec that it is mis-wired. Many have a 240V coil and require a connection between one phase and neutral.

There are a few possibilities for mis-wiring. Common ones are:
Connecting coil beween phases insead of phase to neutral.
The phase the coil is connected to is not a true phase. This is less of a problem with the idler motor converter you have, but try connecting the contactor coil supply to a different phase. Note that the mis-wire could be in a number of locations.

There is also a posibility that the mill has failed electrically in storage. Possible causes are damp and rodent or insect activity. Do you have a multimeter and a insulation tester ("megger"? If so check the phase to pase resistance of the motor windings and phase to ground for motor and wiring.

Robert G8RPI.

p.s. I looked at Transwave's information on converters and was surprised how biased it was.

American "screw-top" beer bottlles are really "twist-off". They are still crown caps like traditional bottles and put on the same way. The difference is in the neck of the bottle.

Robert G8RPI.

I'd go for off the shelf bottle cappping machine, windscreen wiper motor and a spring. Have a number of spring attachment points on the lever to change applied force.
You can even use the park switch on the motor to run a single cycle everytime you press a foot switch. Most will give a choice of speed too.

Robert G8RPI

Edited By Robert Atkinson 2 on 13/06/2020 10:42:31

The 250 Bar/liter limit is not to do with how long it takes to empty, it's an energy limit. Less energy means less damage if it fails. Steam has no lower limit becaue of the additional heat energy and the possibility of superheated water being present which releases even more energy as it boils when the pressure is released. Google BLEVE (boling liquid expanding vapour explosion)

Robert G8RPI.

The regulations on pressure equipment at work apply when the product of pressure and volume exceeds 250 Bar Litres. So a 250litre receiver has to be inspected if it operates at more than 1 bar at 10 Bar (~150PSI) 25 litres an above have to be inspected.
There are a couple of notable exceptions, no test mandated below 1 Bar (gauge i.e differential to local ambient) regardless of volume and all steam equipment has to be inspected regardless of volume.

Robert G8RPI

There is no point guessing what the plastic is you need to have a better idea. Looking at the photo I think Polyethylene is unlikely to be the material, it is too soft to make a ridid wheel lik the one shown. A couple of quick checks could be carried out on a sample (one of the remaining teeth would do). First is to try disolving it in an aggresive solvent like acetone (nail varnish remover if you don't have the pure kind). If it softens or dissolves it's unlikey to be PE, PVC or polypropylene and can for your application be glued with epoxy, just abrade the surfcae well.

If it does not dissolve try the tests here:

https://www.twi-global.com/technical-knowledge/faqs/faq-how-using-simple-manual-tests-can-i-identify-an-unknown-plastic-material

If the wheel runs on a shaft, whatever plastic it is, if you cut LH and RH grooves in the surface an epoxy would probably make a adequate mechanical joint regardless of surface adhesion. There is big surface area and the joint is in shear both of which are good for a bonded joint.

Robert G8RPI.

A picture and dimensions of the shaft it goes on would be useful. As Rod said, 1/4" is easy but a lot of industrial switches use odd shafts.

Robert G8RPI.

Hi,

That capacitor is maginally rated on Voltage, 3 minutes on 220 V or 1 minute at 300V. UK mains is nearer 240V than 220V depending were you are. As Clive says they have very short life. Ideally the capacitor should be non polarised but these are larger and more expensive. The one you linked is effectiviely two 200uF polarised (electrolytic) capacitors conneted in series positive to negative.

A better choice wold be a film capacitor 4.16.51.64 100uF 450 V at £25
https://uk.farnell.com/ducati/4-16-10-51-64/cap-100-f/dp/2829375

Better again would be two 4.10.61.64 60 uF 450 V at £17.50 each wired in parallel (more capacitiance, less current through each capacitior.
https://uk.farnell.com/ducati/4-16-10-61-64/cap-60-f-450vac-5-pp-can/dp/2132090

Best of allis wire for Delta, fit a VRD and weigh the transformer from the old converter in for scrap.

Robert G8RPI.

Edited By Robert Atkinson 2 on 04/06/2020 08:22:31

Well that circuit applies 180 degrees to two phases (should be 120) and about 90 to the other. not an ideal situation.
The capacitor that reads in nF range is faulty. The 8uF are about right, tolerace is tpically +- 10% and normally under. Note that it's not just capacitance and basic voltage rating that matter when replacing. It must be rated for motor starting applications.

Robert G8RPI.

Work threw one in the skip last year - literally The Rennishaw touch probe was still attached but smashed up aginst the edge of the skip.

Part of the UI problem is related to the "Maker" approach to electronics where things are built from ready made modules like Arduinos, stepper drivers and serial LCD and switch modules. This makes it easy but limits variation and customisation. Unfortunatly it does not build understanding of the basic principals or skills. I've seen electronics magazine projects using breakout boards and screw terminals so you don't even have to solder.

The ME version would be making a loco from ready made bogies, boiler. cylinder and valve assemblies from different manufacturers. Better than nothing, but not good.

Robert G8RPI.

What sort of "small jobs"?

If electical / electronic I'd recommend a temeperature controlled iron in the 30-50W power range.
My personal choice has been Weller for over 30 years. Always liked the TCP series where the temperature is set by a alloy pellet with the correct curie point at the end of the bit. I don't like the new two part tips though.

Problem is decent ones are expensive and a lot of the cheaper ones are cheap nd nasty.

Robert G8RPI.