Test Equipment Anonymous (TEA) group therapy thread

[Cubdriver]

If it has three separate DM8880N drivers, then I suspect one of those, other people have had them fail on the radio forum. Hopefully there is an equivalent that isn't made my National Semiconductor and is easy to find, but I doubt it.

If it's any use I do have a diagram for a Data-tech DPM (not quite the same) if it helps, would need scanning though, I have the DPM somewhere too.
And looking at your pics, the top PCB still has holes for the tubes of the older version, is it also made by Gralex?

David

Interesting - I hadn't noticed the holes for the nixie tube evacuation tips on the top board until you pointed it out. 

The Panaplex meter was made by Gralex Industries of Farmingdale, NY, model 363BXC1A2S15; the HP part number is 1120-0621.

The nixie meter in the 432B was manufactured by Analogic of Wakefield, MA, model 2510-1B-1-RX-CX-A14; the HP part number is 1120-1526.

The Gralex layout board-wise is similar, but the interconnection scheme is much different.  The Wakefield nixie meter makes the connections between the top and bottom boards through the front board, but the Gralex meter uses the ribbon cable on the side to get signals from the upper and lower boards, and the front board is only connected to the bottom board.  Perhaps Gralex also made a nixie version that later evolved into the Panaplex-display units?  There seems to be a dearth of information on them online (at least that I can find).

-Pat

[Cerebus]

We never had any of the later S-VHS machines though, no idea how much better the picture was from those.

"Barely tolerable" was my verdict.  I once did a school project, video art. It was shot on Betacam, editedmassacred in the edit suite, on Betacam and then downmixed to S-VHS for presentation. The quality on S-VHS was horrible compared to what came off the Betacam player, but still way above standard VHS.

Last year I wanted to stop the old VHS machine cluttering the place up and decided to transfer to digital anything that was left on tape that was deemed of historic value - my late brother-in-law appearing on a TV quiz show, visiting Men-An-Tol for the total solar eclipse last century, things like that, and finally get rid of the thing.

I hadn't watched analogue TV for years, let alone off a VHS tape. The difference in quality from digital SD was much more pronounced than I remembered.

A frame grab from one of those to give an idea of the quality:

[Specmaster]

I watched a yt vid a few years back on the process of archiving to digital by the likes of broadcasters who sometimes have to recover lost episodes by using VCR recordings from the public, and how they bake the tapes at a low heat for many hours before playing them maybe once or twice before they are deemed phkt.[/color][/size][/b]

Another trick I've seen for restoring magnetic tape is to hold it in a constant low vacuum* for a period of time to extract moisture and other volatiles without introducing any extra heat into the equation.

*In the strange world of vacuum terminology where 'high vacuum' means a very low reading on a pressure gauge and 'low vacuum' means a relatively high reading on a pressure gauge.

Yeah, I can see this make sense, sort of, but would have thought that it might also tend to help the tape to stick itself or perhaps have a tendency to crumble to lack of pliability?

[mnementh]

Edit: I also remember they had some blinkenlights on almost all the PCBs to aid in fault finding.

I can assure you that by now they are gone.

I'm guessing this was before the Chinesium invasion took over that market too?

mnem
 

[Neomys Sapiens]

Huh... he seemed to not shy away from being critical of Tesla's tech in that vid; or rather, did not shy from saying "VW did this way better here..." Yeah, not the same thing. We know that Tesla's drivetrain is not exactly "good for a million miles"; motor failure in the "S" series is a ongoing gripe among owners.

Still a worthwhile watch.

mnem
 

I always find it amusing to hear people say "OEM X did a better job of the powertrain" or "OEM Y did a better battery". No OEM designed a powertrain or a battery, they decided the specs and wrote the requirements documentation. ZF, Siemens, Bosch or whoever designed and manufactured the motor. LG, Samsung, XeroTech or whoever designed and manufactured the battery. In the funnier cases people are arguing about two devices that were both designed and manufactured by the same company.

McBryce.

Okies... since I am honestly woefully ignorant of this aspect of modern EVs... where exactly is the demarc between the motor design and the gearbox? It seems to me that the 3-bearing input shaft/motor design is def something that would fall in the "OEM" side of things... as well as specifying how the cooling circuit and the inverter are made modular/unitized...? All the stuff about getting rid of the oil bath, etc, would also seem to be a OEM decision?

Honestly, this whole design is eerily similar in concept to the integrated motor/ESC pods used by Parrot in the original AR drones, and some other offerings by DJI more than 10 years ago now. They even designed the pods such that downdraft air was drawn through the motors and then to the ESCs for cooling.

mnem
*tzzzzzzt*

I had a gap-filler project at Dt.Accumotive, which makes the batteries for the Daimler EVs and hybrids and I was involved with some professional (not consumer related) EV activities too. The EVs will not get any better as long as the unholy alliance of conventional car designers and roadworthiness bureaucrats is not completely rooted out. Seeing disk brakes on an EV in any but an auxiliary or emergency role makes me sick. Same goes for the concept of recreating the drive train of a ICE car with one motor and a massive gear assembly.

** An electric vehicle must be able to brake with its motors, because there is no better brake **
** An electric vehicle makes much more sense if it is able to recuperate the braking energy **
** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

Then, and only then, a veritable potpourri of additional benefits of the electric drive springs up. By distributing the drives to the wheels, you do not need a differential and a kind of 4WD without the setbacks of conventional 4WD comes for free. Not to start of the benefits more specific to my field of work, like hull integrity, getting rid of the damage prone stearing gear, limp-home capability etc etc....not even starting about applications where another significant use besides propulsion for the electrical energy exists.

But in the commercial market too many manufacturers have foregone the chance to introduce the idea of electrical drive in places where it could bring the whole thing forward. (exceptions exist) Because a municipal authority or a distribution service, where all the vehicles return home at the end of a shift, and can therefore be polled for their data, generates a bigger volume of better proven data about those still to be optimised batteries than any 'we drove from the southern end to the northern end of whereever with 10 electric cars' bullshit showoffs and also, none of those drivers is going to say ''I don't like it and will get a new ICE car'' because the decision isn't his. The way it is going now, it will follow the pattern established by the emission targets for combustion engines, where governments set limits without ensuring that they can be fulfilled or that they even make sense.

[mnementh]

Pretty sure he's right as far as the likelyhood of repair goes: it will never be repaired, the whole module will be repaired. Which means some pennies are to be saved by elimenating a few bolts.

You may not like it, I may not like it but that's how it goes. Last year, I was supposed to fork over 1600€ for a new adblue assembly. Only the pump was shot. No possibility of acquiring a pump. Anywhere.

Yeah, but what happens to the unserviceable unit after the replacement goes in? I'm not saying that it doesn't go straight to scrap or recycling, but with things amenable to component level repair it's not beyond belief that they get fixed and become "service replacement" parts the same way as happens with engines. In the particular case of inverters, there's a high likelihood that the problem with a broken unit is just a blown IGBT module*, and that is surely an easy and economic component level repair, one that could be done as a "stock repair" even if one wasn't going to go in for more detailed and fiddly component level repairs.

There's nothing "in" it for the manufacturer. He's presented with the choice "save a few bucks now" or "please the DIY/grey aftermarke crowd" later.

Accidently, it's obviously a sliding scale. And perhaps VW simply chose "your" route this time.

Perhaps you haven't come across the "service replacement" parts or they go under a different name where you are. These are official manufacturer spares that are refurbished parts, so technically secondhand, but that come with the same warranty etc. that strictly new parts do. Only for major components, and only for things that can be refurbished to factory standard. Service replacement engines are the example that I have come across personally. Cheaper than the wholly new service part, perhaps 70%, but with even lower costs to the manufacturer, so bigger profit overall. So they aren't saving a few bucks, they're making more profit, and possibly getting a sale that they might not at the wholly new part price.

Do you suppose in this case it was a simple matter of availability of component parts, that prompted the decision to make these parts such that they could at least be service on a reman basis?

Even before COVID, the news was full of stories saying the EV market was all up in a heaval over parts shortages; this is a relatively new area for VW to be getting into, and supposedly an all-new design, so perhaps they were ensuring that they don't get screwed by their own popularity with a shortage of warranty repair spares?

At least while this allegedly "all-new drivetrain" is entirely in vehicles that will be under warranty for the foreseeable future with poor availability of new generic spares, and since any which get replaced at the dealership would came back to them anyways, they can ensure a secondary stream of warranty service spares by making them rebuildable?

Obviously the customer is not going to see any benefit from this; usually when a manufacturer really wants that core they make the core charge ridiculously high on top of the part price. They do not make the part cheaper under any circumstances.

mnem
 

[Neomys Sapiens]

Made an offer on a digital meter earlier and it got accepted.
www.ebay.co.uk/itm/384656190755
I don't need to measure the PH of meat. I didn't even know it was a "thing".  For £10 shipped I'll at least get a 16x2 VFD display module and a Mean Well 12V 1.5A wall wart.
But it is much more likely I'll re-purpose it into a geiger counter if a 2" pancake tube will fit in the front.

You are right to dismantle it. From the symbology one must assume that it is only capable of beef and pork measurements.

[Specmaster]

Service exchange alterntors and starter motors used to be very common.

Doh! Don't know how I managed to forget about those when I was scrabbling to think of examples.

Many years ago I actually worked at a place that sold these service replacement parts, taking the old unit in part exchange. We would then strip down the alternators, starters etc, dip casings into acid to strip the years of crustiness away, skim the commutators, and slip rings etc on a lathe, fit new diodes, brushes and bearings etc and then paint the cases (dynamos and starters) to make them look new again, test them and put back into stock. If any windings were damaged, they would get send away to motor rewinders for stripping and rewinding and then put back together again.

It makes perfect sense to do this as we will one day if we are not careful eventually run out of the natural resources if things are not made to be repairable.

[mnementh]

I had a gap-filler project at Dt.Accumotive, which makes the batteries for the Daimler EVs and hybrids and I was involved with some professional (not consumer related) EV activities too. The EVs will not get any better as long as the unholy alliance of conventional car designers and roadworthiness bureaucrats is not completely rooted out. Seeing disk brakes on an EV in any but an auxiliary or emergency role makes me sick. Same goes for the concept of recreating the drive train of a ICE car with one motor and a massive gear assembly.

** An electric vehicle must be able to brake with its motors, because there is no better brake **
** An electric vehicle makes much more sense if it is able to recuperate the braking energy **
** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

Then, and only then, a veritable potpourri of additional benefits of the electric drive springs up. By distributing the drives to the wheels, you do not need a differential and a kind of 4WD without the setbacks of conventional 4WD comes for free. Not to start of the benefits more specific to my field of work, like hull integrity, getting rid of the damage prone stearing gear, limp-home capability etc etc....not even starting about applications where another significant use besides propulsion for the electrical energy exists.

But in the commercial market too many manufacturers have foregone the chance to introduce the idea of electrical drive in places where it could bring the whole thing forward. (exceptions exist) Because a municipal authority or a distribution service, where all the vehicles return home at the end of a shift, and can therefore be polled for their data, generates a bigger volume of better proven data about those still to be optimised batteries than any 'we drove from the southern end to the northern end of whereever with 10 electric cars' bullshit showoffs and also, none of those drivers is going to say ''I don't like it and will get a new ICE car'' because the decision isn't his. The way it is going now, it will follow the pattern established by the emission targets for combustion engines, where governments set limits without ensuring that they can be fulfilled or that they even make sense.

Most modern EVs do employ regenerative braking to a certain point; but I'm not sure I believe it is reasonable to wholly eliminate friction-braking altogether, as the driver is still the best judge of what is the best at low speeds, especially the last 10% of coming to a full stop and parking maneuvers.

As for one-wheel-per-motor designs... there you're talking about something that will require even more complex "flight controller" type real-time mixing of the ESC signals to not grossly affect steering at highway speeds.

I personally think the current compromise of a diff with a motor for each axle is probably going to be as reliable or more so due to the fact that hub motors still have a gearbox in them, so now we're looking at 4 motors/4 gearboxes, etc. vs a diff which incorporates necessary gear reduction for two wheels, plus it inherently does all the torque mixing for each axle in the hardware, not firmware, and I really do believe that two complete drivetrains is more than adequate "limp-mode" redundancy.

And a parting shot... hub motors are effing heavy. As soon as you make the motor part of your "unsprung weight", your handling and road manners goes straight to hell. The solution is, of course, hubs with CV axles to inboard motors... and if you're going to do that, you might as well consolidate the two motors into a motor/diff unit.

My two cents' worth, having worked on some EV conversions and oodles of multi-motor RC vehicles for land and air. 

mnem
*juicy*

[Cerebus]

Can you clarify on this point:

** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

I'm guessing you meant "separate from any of those" and that's just a slip of the pen/keyboard? And which "those" do you mean?

Are you saying that there are some fundamental reasons for keeping the motor and wheel separate?

My reason for asking is that I always imagined that the most satisfactory EV wheel/motor would be a PMSM with a tyre wrapped around the rotor, and the stator at the wheel hub with one at each corner. It might need some clever-ish bearings if you wanted avoid spokes (to keep metal and eddy currents away from the coils), some magic to minimise or overcome issues with unsprung mass and lots of poles and/or a lot of vector current drive capability to be usable at parking speed but it just seems so quintessentially neat and simple.

[mnementh]

Many years ago I actually worked at a place that sold these service replacement parts, taking the old unit in part exchange. We would then strip down the alternators, starters etc, dip casings into acid to strip the years of crustiness away, skim the commutators, and slip rings etc on a lathe, fit new diodes, brushes and bearings etc and then paint the cases (dynamos and starters) to make them look new again, test them and put back into stock. If any windings were damaged, they would get send away to motor rewinders for stripping and rewinding and then put back together again.

It makes perfect sense to do this as we will one day if we are not careful eventually run out of the natural resources if things are not made to be repairable.

Yes, but doing that means in some way paying for the disposal cost of your product, not just burning up all resources you can buy, bribe or steal and kicking those costs down the road for future generations to pay.

In short, the antithesis of the corporate business model. 

I worked at a local motor/alternator rebuilder shop in Central New York for a summer job. Even then, the wear component parts (brush holders, bearings, rectifier trios, etc) were mostly made in Asia and Mexico; the truck that delivered them had Coahuila plates.

I find it highly unlikely they survived another decade after I was there.

mnem
 

[Specmaster]

I had a gap-filler project at Dt.Accumotive, which makes the batteries for the Daimler EVs and hybrids and I was involved with some professional (not consumer related) EV activities too. The EVs will not get any better as long as the unholy alliance of conventional car designers and roadworthiness bureaucrats is not completely rooted out. Seeing disk brakes on an EV in any but an auxiliary or emergency role makes me sick. Same goes for the concept of recreating the drive train of a ICE car with one motor and a massive gear assembly.

** An electric vehicle must be able to brake with its motors, because there is no better brake **
** An electric vehicle makes much more sense if it is able to recuperate the braking energy **
** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

Then, and only then, a veritable potpourri of additional benefits of the electric drive springs up. By distributing the drives to the wheels, you do not need a differential and a kind of 4WD without the setbacks of conventional 4WD comes for free. Not to start of the benefits more specific to my field of work, like hull integrity, getting rid of the damage prone stearing gear, limp-home capability etc etc....not even starting about applications where another significant use besides propulsion for the electrical energy exists.

But in the commercial market too many manufacturers have foregone the chance to introduce the idea of electrical drive in places where it could bring the whole thing forward. (exceptions exist) Because a municipal authority or a distribution service, where all the vehicles return home at the end of a shift, and can therefore be polled for their data, generates a bigger volume of better proven data about those still to be optimised batteries than any 'we drove from the southern end to the northern end of whereever with 10 electric cars' bullshit showoffs and also, none of those drivers is going to say ''I don't like it and will get a new ICE car'' because the decision isn't his. The way it is going now, it will follow the pattern established by the emission targets for combustion engines, where governments set limits without ensuring that they can be fulfilled or that they even make sense.

Most modern EVs do employ regenerative braking to a certain point; but I'm not sure I believe it is reasonable to wholly eliminate friction-braking altogether, as the driver is still the best judge of what is the best at low speeds, especially the last 10% of coming to a full stop and parking maneuvers.

As for one-wheel-per-motor designs... there you're talking about something that will require even more complex "flight controller" type real-time mixing of the ESC signals to not grossly affect steering at highway speeds.

I personally think the current compromise of a diff with a motor for each axle is probably going to be as reliable or more so due to the fact that hub motors still have a gearbox in them, so now we're looking at 4 motors/4 gearboxes, etc. vs a diff which incorporates necessary gear reduction for two wheels, plus it inherently does all the torque mixing for each axle in the hardware, not firmware, and I really do believe that two complete drivetrains is more than adequate "limp-mode" redundancy.

And a parting shot... hub motors are effing heavy. As soon as you make the motor part of your "unsprung weight", your handling and road manners goes straight to hell. The solution is, of course, hubs with CV axles to inboard motors... and if you're going to do that, you might as well consolidate the two motors into a motor/diff unit.

My two cents' worth, having worked on some EV conversions and oodles of multi-motor RC vehicles for land and air. 

mnem
*juicy*

I also have serious doubts abut relying on regenerative braking will be sufficient because it relies on having a load connected to the motor to generate that braking effect, now what would happen if by any chance that load were to be disconnected, due to a number of possibilities, loose connection, fractured connection etc, all braking would be lost.  For that reason, I think that disc brakes would still be required, but they would in effect be used in the main for emergency braking and also for the final coming to a rest where you require being rather than where the car and other external forces such as a nudge from another vehicle, gravity, wind etc decide where you're going to actually stop.

My current ICE car has regenerative braking on it, and while it's not aggressive, it is noticeable, and I can in many instances rely on it to drop my speed, if I'm given plenty of time to react correctly, it cannot bring me to a complete standstill, I still require brakes for that last bit. But in reality that does not happen very often as you simply are not given that luxury of having the road to yourself. There is always going to be interplay with others, be it in the form of pedestrians, animals, other road users etc to prevent the effective use of regenerative braking alone.

[Specmaster]

Many years ago I actually worked at a place that sold these service replacement parts, taking the old unit in part exchange. We would then strip down the alternators, starters etc, dip casings into acid to strip the years of crustiness away, skim the commutators, and slip rings etc on a lathe, fit new diodes, brushes and bearings etc and then paint the cases (dynamos and starters) to make them look new again, test them and put back into stock. If any windings were damaged, they would get send away to motor rewinders for stripping and rewinding and then put back together again.

It makes perfect sense to do this as we will one day if we are not careful eventually run out of the natural resources if things are not made to be repairable.

Yes, but doing that means in some way paying for the disposal cost of your product, not just burning up all resources you can buy, bribe or steal and kicking those costs down the road for future generations to pay.

In short, the antithesis of the corporate business model. 

I worked at a local motor/alternator rebuilder shop in Central New York for a summer job. Even then, the wear component parts (brush holders, bearings, rectifier trios, etc) were mostly made in Asia and Mexico; the truck that delivered them had Coahuila plates.

I find it highly unlikely they survived another decade after I was there.

mnem
 

Sorry, but I'm not understanding your logic here, are you that items should not be made to be repairable  I'm confused because you seem to be saying both yes and no?

[xrunner]

Playing with paint

I did a quick test of the Tamiya X-1 glossy paint on a "raw" 3D printed button. Meaning NO sanding, NO priming.

In the pic the original plastic button is left and the test is on right. I painted the "raw" button two coats letting it dry in-between. The paint looks pretty good and the finish is already a lot better. But ... the other button I've been working on has been sanded and primed three times prior to being painted. I will put this paint on it tomorrow.

I'm feeling pretty good about this ...

[Specmaster]

Playing with paint

I did a quick test of the Tamiya X-1 glossy paint on a "raw" 3D printed button. Meaning NO sanding, NO priming.

In the pic the original plastic button is left and the test is on right. I painted the "raw" button two coats letting it dry in-between. The paint looks pretty good and the finish is already a lot better. But ... the other button I've been working on has been sanded and primed three times prior to being painted. I will put this paint on it tomorrow.

I'm feeling pretty good about this ...

You know, I think that if the spot was filled in with suitable paint and left with a clear divide between the colours (no bleed through) I think it would only be someone like Vince with his/their anal attention to detail, that would most people would not notice that the button was different from the rest. 

[Neomys Sapiens]

Can you clarify on this point:

** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

I'm guessing you meant "separate from any of those" and that's just a slip of the pen/keyboard? And which "those" do you mean?

Are you saying that there are some fundamental reasons for keeping the motor and wheel separate?

My reason for asking is that I always imagined that the most satisfactory EV wheel/motor would be a PMSM with a tyre wrapped around the rotor, and the stator at the wheel hub with one at each corner. It might need some clever-ish bearings if you wanted avoid spokes (to keep metal and eddy currents away from the coils), some magic to minimise or overcome issues with unsprung mass and lots of poles and/or a lot of vector current drive capability to be usable at parking speed but it just seems so quintessentially neat and simple.

No, I meant separate drive for any driven element, i.e. one motor for each wheel or track.

[mnementh]

Many years ago I actually worked at a place that sold these service replacement parts, taking the old unit in part exchange. We would then strip down the alternators, starters etc, dip casings into acid to strip the years of crustiness away, skim the commutators, and slip rings etc on a lathe, fit new diodes, brushes and bearings etc and then paint the cases (dynamos and starters) to make them look new again, test them and put back into stock. If any windings were damaged, they would get send away to motor rewinders for stripping and rewinding and then put back together again.

It makes perfect sense to do this as we will one day if we are not careful eventually run out of the natural resources if things are not made to be repairable.

Yes, but doing that means in some way paying for the disposal cost of your product, not just burning up all resources you can buy, bribe or steal and kicking those costs down the road for future generations to pay.

In short, the antithesis of the corporate business model. 

I worked at a local motor/alternator rebuilder shop in Central New York for a summer job. Even then, the wear component parts (brush holders, bearings, rectifier trios, etc) were mostly made in Asia and Mexico; the truck that delivered them had Coahuila plates.

I find it highly unlikely they survived another decade after I was there.

mnem
 

Sorry, but I'm not understanding your logic here, are you that items should not be made to be repairable  I'm confused because you seem to be saying both yes and no?

Of course things should be made to be repairable; everything you said is the absolute truth, except that it is the exact opposite of "business as usual" in the modern age, so it isn't going to happen until the entire global economy bubble collapses and "big business" ceases to be treated as gods.

Even as a teen working in that rebuilding shop, which provided good, honest work for decent people to feed their families, I could see that it was a dying way of life; nothing we needed to do the job was made in America anymore. How could it possibly be sustainable?

mnem
"Use it up, wear it out; make it do or do without." Better get used to it again... there is a Depression coming that will make the aftermath of Black Tuesday look like a summer picnic.

[Neomys Sapiens]

I had a gap-filler project at Dt.Accumotive, which makes the batteries for the Daimler EVs and hybrids and I was involved with some professional (not consumer related) EV activities too. The EVs will not get any better as long as the unholy alliance of conventional car designers and roadworthiness bureaucrats is not completely rooted out. Seeing disk brakes on an EV in any but an auxiliary or emergency role makes me sick. Same goes for the concept of recreating the drive train of a ICE car with one motor and a massive gear assembly.

** An electric vehicle must be able to brake with its motors, because there is no better brake **
** An electric vehicle makes much more sense if it is able to recuperate the braking energy **
** The drives of an electric vehicle should be as close to the driven elements (wheels, tracks) as possible, and separate for any of those**

Then, and only then, a veritable potpourri of additional benefits of the electric drive springs up. By distributing the drives to the wheels, you do not need a differential and a kind of 4WD without the setbacks of conventional 4WD comes for free. Not to start of the benefits more specific to my field of work, like hull integrity, getting rid of the damage prone stearing gear, limp-home capability etc etc....not even starting about applications where another significant use besides propulsion for the electrical energy exists.

But in the commercial market too many manufacturers have foregone the chance to introduce the idea of electrical drive in places where it could bring the whole thing forward. (exceptions exist) Because a municipal authority or a distribution service, where all the vehicles return home at the end of a shift, and can therefore be polled for their data, generates a bigger volume of better proven data about those still to be optimised batteries than any 'we drove from the southern end to the northern end of whereever with 10 electric cars' bullshit showoffs and also, none of those drivers is going to say ''I don't like it and will get a new ICE car'' because the decision isn't his. The way it is going now, it will follow the pattern established by the emission targets for combustion engines, where governments set limits without ensuring that they can be fulfilled or that they even make sense.

Most modern EVs do employ regenerative braking to a certain point; but I'm not sure I believe it is reasonable to wholly eliminate friction-braking altogether, as the driver is still the best judge of what is the best at low speeds, especially the last 10% of coming to a full stop and parking maneuvers.

As for one-wheel-per-motor designs... there you're talking about something that will require even more complex "flight controller" type real-time mixing of the ESC signals to not grossly affect steering at highway speeds.

I personally think the current compromise of a diff with a motor for each axle is probably going to be as reliable or more so due to the fact that hub motors still have a gearbox in them, so now we're looking at 4 motors/4 gearboxes, etc. vs a diff which incorporates necessary gear reduction for two wheels, plus it inherently does all the torque mixing for each axle in the hardware, not firmware, and I really do believe that two complete drivetrains is more than adequate "limp-mode" redundancy.

And a parting shot... hub motors are effing heavy. As soon as you make the motor part of your "unsprung weight", your handling and road manners goes straight to hell. The solution is, of course, hubs with CV axles to inboard motors... and if you're going to do that, you might as well consolidate the two motors into a motor/diff unit.

My two cents' worth, having worked on some EV conversions and oodles of multi-motor RC vehicles for land and air. 

mnem
*juicy*

I was expecting some well funded critical response to that post. As you might have noted, I was not proposing to eliminate mechanical brakes for exactly the reasons described by you. But when you see that major automobile companies turn out cars which do no regenerative braking because this has been deemed 'unsafe' by the KBA, then you might understand that somewhat polemic post. Long before EVs were a topic, system architectures to make that perfectly safe have been thought out. Of course, you would need a high-rate storage element in addition to the battery. AND you would preferably have a redundant resistive element too.
My post was largely influenced by what I've seen in terms of efficiency and usability when engineers can go to work on the EV topic unfettered by the type of rulings applicable to 'normal cars' and the common perception of how a vehicle should be build. I can even see the merit of an ICE, especially if it is running at it's optimum point of operation.
And given my occupation, you can imagine that those examples were related to (mostly thick-skinned) vehicles painted in mottled shades of green. 

[SilverSolder]

Modern industry targets a specific design life for most consumer products - when that time is out, you are not expected to repair, but replace!  Similarly, most parts have become modularized to the point where a "repair" consists of swapping relatively large modules.

The basic philosophy seems to be that labour is a "bad thing" and must be prevented at all costs...   freeing it up, to do...  what? 

[xrunner]

You know, I think that if the spot was filled in with suitable paint and left with a clear divide between the colours (no bleed through) I think it would only be someone like Vince with his/their anal attention to detail, that would most people would not notice that the button was different from the rest. 

Thanks.

Regarding the dot - additional tooling is being brought to bear on that issue. 

[Cerebus]

I also have serious doubts abut relying on regenerative braking will be sufficient because it relies on having a load connected to the motor to generate that braking effect, now what would happen if by any chance that load were to be disconnected, due to a number of possibilities, loose connection, fractured connection etc, all braking would be lost.  For that reason, I think that disc brakes would still be required, but they would in effect be used in the main for emergency braking and also for the final coming to a rest where you require being rather than where the car and other external forces such as a nudge from another vehicle, gravity, wind etc decide where you're going to actually stop.

Similar failure modes exist for hydraulic disk brakes as you list for regenerative braking. The thing is that a motor that you were relying on to push a few seconds before will 'pull' a few seconds later, relying on exactly the same connections etc. as it was to push. The likelihood of those failing in the intervening second or two is pretty small. So with regenerative braking you've much more chance of detecting a problem (engine won't 'push') before it becomes an issue; also electrical components that are already relying on quite advanced measurement systems to make them work at all, the same systems will detect faults sooner than in a hydraulic system that usually have nothing more sophisticated than an "low brake fluid level" warning in the way of monitoring. Backup, emergency disk brakes would still be a good idea, and then you have real redundancy rather than the one system (with cable backup) that you have in an ICE vehicle.

As far as the amount of force produced, try shorting the windings of a smallish PMSM, say 500W, then take your biggest adjustable spanner and try to turn the shaft - you won't. Now try the same with a multiple kW motor that you'd find in an EV, the torque while shorted is hugely impressive. The torque while under control is also massive, you won't get moved by a nudge when the motor controller is trying to actively hold the motor shaft at X degrees of rotation. That's the thing about PMSM that bypasses our intuition about motors in general, they produce as much torque at 0 rpm as they do anywhere from there to their rated speed.

[mnementh]

Modern industry targets a specific design life for most consumer products - when that time is out, you are not expected to repair, but replace!  Similarly, most parts have become modularized to the point where a "repair" consists of swapping relatively large modules.

The basic philosophy seems to be that labour is a "bad thing" and must be prevented at all costs...   freeing it up, to do...  what? 

Freed up to not cut into corporate profits, and no other reason.

This current social paradigm is the classic double-bind; they tie your worth entirely to whom you work for, while at the same time actively doing everything they can not to pay people for working.

IME, corporations should be taxed based on the disparity between their profits and how few people they pay a living wage. The more people they employ per dollar, the less they pay in taxes.

mnem
*toddles off to ded*

[Robert763]

Playing with paint

I did a quick test of the Tamiya X-1 glossy paint on a "raw" 3D printed button. Meaning NO sanding, NO priming.

In the pic the original plastic button is left and the test is on right. I painted the "raw" button two coats letting it dry in-between. The paint looks pretty good and the finish is already a lot better. But ... the other button I've been working on has been sanded and primed three times prior to being painted. I will put this paint on it tomorrow.

I'm feeling pretty good about this ...

You know, I think that if the spot was filled in with suitable paint and left with a clear divide between the colours (no bleed through) I think it would only be someone like Vince with his/their anal attention to detail, that would most people would not notice that the button was different from the rest. 

Paint the existing black buttons as well and even Vince won't be able to tell.....

[m k]

A frame grab from one of those to give an idea of the quality:

But motion plur was better and you can't live without it.

BTW,
I never liked retension.

[Robert763]

<SNIP>

I was expecting some well funded critical response to that post. As you might have noted, I was not proposing to eliminate mechanical brakes for exactly the reasons described by you. But when you see that major automobile companies turn out cars which do no regenerative braking because this has been deemed 'unsafe' by the KBA, then you might understand that somewhat polemic post. Long before EVs were a topic, system architectures to make that perfectly safe have been thought out. Of course, you would need a high-rate storage element in addition to the battery. AND you would preferably have a redundant resistive element too.
My post was largely influenced by what I've seen in terms of efficiency and usability when engineers can go to work on the EV topic unfettered by the type of rulings applicable to 'normal cars' and the common perception of how a vehicle should be build. I can even see the merit of an ICE, especially if it is running at it's optimum point of operation.
And given my occupation, you can imagine that those examples were related to (mostly thick-skinned) vehicles painted in mottled shades of green. 
[/quote]

I don't know why the KBA think regeneratve braking is unsafe. Do you have a reference preferably in english? Is it completely banned or do they say you must have friction as well?
All cars I know of that have Stop-Start and most if not all with "Smart" alternators use at least a low level of regenerative braking.
You can not of course have just regenerative braking. This is becuase it only applys a retarding force when the rotor is moving. A frictionless system with regenerative braking will take forever to come to a complete stop and will slowly creep if external force (gravity on a slope, wind) is applied. You can of course DC injection brake to a stop. Injection braking consumes power which sort of defies the purpose. There will always be some kiind of friction brake or transmission lock on a car.
All hybrids and EV's use regenerative braking. If they did not they would have no advantage due to the mass of the batteries and motors. My plug in hybrid allows you to dynamically control the amount of regeneration using paddles on wheel. On a highway off ramp with a upslope I can come to a controlled stop without using the brake pedal (regenerative and friction) at all. At high speeds the retardation available from the paddles is so high the system puts the brake lights on.
Currently I can't see any advantage in one motor per wheel for road cars. Unsprung weight is too high for integral wheel motors. Motor speeds are not well matched to wheel speeds so some gearing is needed. Overall with current technology a single motor (per axle maybe) driving a differential gear and two drive shafts is still optimal for road cars. Separate motors and gearboxes add weight and friction losses. For 4WD and heavy vehicles one motor per wheel, possibly with geared hubs / portal axles, becomes a viable option. Controlling motor speed and torque for handling and traction control is trivial wih modern motor drive systems. You could actually dispense with conventional steering and control direction by differential drive with a one wheel per motor set-up. Might need some castoring to prevent tyre scrub. The safety case might be a bit of a challenge and keeping steering may be cheaper than meeting the relability and integrity requiment of a differential system.