Meter Scales

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Mick F
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Meter Scales

Post by Mick F »

Our car, the speedo is very poorly designed.
30mph is a dash half-way between 20 and 40.
40 is at about 9 o'clock and 70 is just before 12 o'clock.
The scale goes all the way up to 140mph when the car would struggle to even reach 90mph.
What a useless design! :shock:

We used to have an outside thermometer but the plastic faded out the scale readings, so we disposed of it.
Really miss it, so been looking on eBay for another.
They seem to read from minus 50degC to plus 50degC ................. what an absolute rubbish scale! :shock:

Given the choice of an outside thermometer, I would have one that went down to minus 10degC and up to 40degC ........ by having that, the divisions would be more precise as well as being easier to read.

Same as the car speedo. Spread the relevant range, so you can read it.
Mick F. Cornwall
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Mick F
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Re: Meter Scales

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Mick F. Cornwall
Jdsk
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Re: Meter Scales

Post by Jdsk »

Mick F wrote: 1 Dec 2021, 2:20pm Our car, the speedo is very poorly designed.
30mph is a dash half-way between 20 and 40.
40 is at about 9 o'clock and 70 is just before 12 o'clock.
The scale goes all the way up to 140mph when the car would struggle to even reach 90mph.
What a useless design!
They're compromises, and are often suboptimal for the common UK speed limits.

On many instruments it's easy to add numbers and symbols and marks and lines wherever you want them and of whatever colour you prefer with transfers.

Jonathan

PS: Traditional instruments might evolve as speed limiters become more common...
thirdcrank
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Re: Meter Scales

Post by thirdcrank »

IIRC you have a Yaris. I had one of the early models in 1999, fitted with a digital speedo. The speed reading couldn't have been more legible. The was one of the few things the petrolhead reviewers could find to criticise and it was replaced in later versions with a traditional speedo

(I cannot remember if it had a thermometer but it certainly didn't have a max/min greenhouse type)
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Mick F
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Re: Meter Scales

Post by Mick F »

Yes, a Yaris Hybrid 2014 with many many MANY issues.
Mechanically and drive-ability, it's wonderful and we love it to bits in that regard.
Design as a car?
It's rubbish.
List too long to even say here, when I wish to discuss scales and reading of dials and stuff. :D

I spent a five year apprenticeship and a whole career using instrumentation in the electrical and electronic world.
I know all about precision and accuracy and scale errors and optical and parallax errors etc etc.
Also know that a meter should be designed to read the info that it's supposed to read.

No point having a thermometer outside (in UK) that reads down to minus 50degC and up to plus 50degC. By having that, the scale is compressed and the device is imprecise. Same as having a car speedo from zero to 140mph over perhaps 200degrees of arc or less.

Accuracy is a completely different subject of course .......... and it is with the Yaris too. :wink:
Mick F. Cornwall
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Re: Meter Scales

Post by thirdcrank »

I thought you wanted to discuss the legibility of speedometers. (The thermometer bit was lost on me, which was why I was a bit whimsical about them.)

I was saying that the speedo on the original Yaris was just about as clear as could be: a bright number representing the recorded speed.
philvantwo
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Re: Meter Scales

Post by philvantwo »

Didn't you have a test drive before you bought it Mick F?
You need a thermometer inside with a wireless outdoor sensor!
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Re: Meter Scales

Post by Bonefishblues »

philvantwo wrote: 1 Dec 2021, 4:01pm Didn't you have a test drive before you bought it Mick F?
You need a thermometer inside with a wireless outdoor sensor!
This. Cheap, reliable, accurate.
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Re: Meter Scales

Post by ChrisF »

Mick F wrote: 1 Dec 2021, 3:19pm
Accuracy is a completely different subject of course ..........
I know what you mean (I have also worked in instrumention for almost my entire like) but maybe in this case accuracy is relevant. If the speedo only went up to 90 mph (or you halved the range of the thermometer) the divisions would be larger so then (as you say) you'd be able to read the value more precisely. But then, comparing the value with another (more accurate, calibrated) device, it would be easier to dispute the accuracy of the speedo. Having the divisions close together is maybe a sort of get-out clause for defining how accurate something is.

I have a set of 3 lab-standard mercury thermometers each with a range of only 30-40 degrees, so each marked division is only 0.1 C, but they are far more expensive than the cheap ones you linked to.
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Mick F
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Re: Meter Scales

Post by Mick F »

Bonefishblues wrote: 1 Dec 2021, 4:24pm
philvantwo wrote: 1 Dec 2021, 4:01pm Didn't you have a test drive before you bought it Mick F?
You need a thermometer inside with a wireless outdoor sensor!
This. Cheap, reliable, accurate.
Three answers. :D

The car is the car.
Excellent in its own way. Wonderful to drive.
It was only after owning it that we/I found issues with the speedo.
One, the scale was rubbish so it was difficult to see the speed, and two, the accuracy was rubbish.

Speedometers in cars in UK - please correct me if I'm wrong - by law should read within 10% but not lower than the actual speed.
Our Yaris has the speedo reading 8% high or thereabouts. Most inaccurate speedo we have ever had in any car since my first in 1972 and that was a 1968 Mini. Please remember, that I'm a pedantic and pernickety sort of person! :D

Do an indicated 70mph and you are doing 63mph. Real 70mph comes up as 75+mph. This day and age we have GPS and Satnav, so we know the correct speed so we don't need to rely on an analog dial that goes double of the legal speed on the roads which is inherently inaccurate too.


Answer Two.
Found on eBay that a decent device is there for fifteen quid that shows the outside temp as well as the inside temp .......... digitally.
This sounds and looks like something we would buy.
https://www.ebay.co.uk/itm/384097016567 ... SwWqJgeA6E


Answer Three.
Yes, if the scale was bigger on the speedo, the readings could be read more accurately. The speedo cannot be calibrated though eh?
Using a GPS device, you can see the real speed. Yes, I know, it's open to errors, but if the car has a built-in satnav, it's only a small step to link the digital GPS and the analog dial together ......... but they don't.

Three or four quid's worth of thermometer is never going to cut it in the accuracy or precision game, but it would be simple to have one for the same price, that went from -10 to +40 rather than -50 to +50.
Mick F. Cornwall
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Mick F
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Re: Meter Scales

Post by Mick F »

PS:
In my investigations, I found that our Yaris has the odometer spot on, so it's not the tyre diameter or the gearing that gives the speedo a wrong reading. It's a crap dial system.
Mick F. Cornwall
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Re: Meter Scales

Post by Bonefishblues »

Mick F wrote: 1 Dec 2021, 4:48pm
Bonefishblues wrote: 1 Dec 2021, 4:24pm
philvantwo wrote: 1 Dec 2021, 4:01pm Didn't you have a test drive before you bought it Mick F?
You need a thermometer inside with a wireless outdoor sensor!
This. Cheap, reliable, accurate.
Three answers. :D

The car is the car.
Excellent in its own way. Wonderful to drive.
It was only after owning it that we/I found issues with the speedo.
One, the scale was rubbish so it was difficult to see the speed, and two, the accuracy was rubbish.

Speedometers in cars in UK - please correct me if I'm wrong - by law should read within 10% but not lower than the actual speed.
Our Yaris has the speedo reading 8% high or thereabouts. Most inaccurate speedo we have ever had in any car since my first in 1972 and that was a 1968 Mini. Please remember, that I'm a pedantic and pernickety sort of person! :D

Do an indicated 70mph and you are doing 63mph. Real 70mph comes up as 75+mph. This day and age we have GPS and Satnav, so we know the correct speed so we don't need to rely on an analog dial that goes double of the legal speed on the roads which is inherently inaccurate too.


Answer Two.
Found on eBay that a decent device is there for fifteen quid that shows the outside temp as well as the inside temp .......... digitally.
This sounds and looks like something we would buy.
https://www.ebay.co.uk/itm/384097016567 ... SwWqJgeA6E


Answer Three.
Yes, if the scale was bigger on the speedo, the readings could be read more accurately. The speedo cannot be calibrated though eh?
Using a GPS device, you can see the real speed. Yes, I know, it's open to errors, but if the car has a built-in satnav, it's only a small step to link the digital GPS and the analog dial together ......... but they don't.

Three or four quid's worth of thermometer is never going to cut it in the accuracy or precision game, but it would be simple to have one for the same price, that went from -10 to +40 rather than -50 to +50.
Chuck some different profile tyres on Mick :wink:

Half-joking, but you could self-calibrate your car if it's 8% overreading, and stay legal, and be more to your satisfaction :D
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Re: Meter Scales

Post by thirdcrank »

Remote temperature range: -4.4℃ to 65℃
Indoor temperature range: 0℃ to 60℃
From your own criteria, those ranges seem inappropriate. 65/60 degs C are much higher than we experience in the UK while -4.4 wouldn't go low enough for what's been reported in Storm Arwen.

It's description includes "weather station" and for that level of accuracy, the siting has to be meticulous. If you just want to know how cold it is - as in big coat or cardi - then that looks great for somebody easy-going but not for somebody who prizes accuracy. One common use of an outdoor thermometer is to know how cold it got during the night and I don't think this one does that
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Re: Meter Scales

Post by 661-Pete »

Mick F wrote: 1 Dec 2021, 2:20pm The scale goes all the way up to 140mph when the car would struggle to even reach 90mph.
What a useless design! :shock:
Yes, I've long been puzzled at the absurdity of all this. My car's speedo (also a needle-and-dial type) goes up to 160mph. Half of that range totally wasted! Is it to dupe prospective buyers of the said motor into thinking they might attain such a speed?

I can still remember, as a kid, being in my father's car (an Austin A40) as we swept down a long straight hill, when suddenly he pointed to the speedo and exclaimed "Look, it's at the end point!". The end stop was at 75mph and sure enough, the needle was pointing at that speed (this was long before the days of the NSL of course).

Of course, that car would never have come anywhere near 75mph on the level. Those were the days... :(
Suppose that this room is a lift. The support breaks and down we go with ever-increasing velocity.
Let us pass the time by performing physical experiments...
--- Arthur Eddington (creator of the Eddington Number).
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Mick F
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Re: Meter Scales

Post by Mick F »

thirdcrank wrote: 1 Dec 2021, 5:21pm
Remote temperature range: -4.4℃ to 65℃
Indoor temperature range: 0℃ to 60℃
From your own criteria, those ranges seem inappropriate. 65/60 degs C are much higher than we experience in the UK while -4.4 wouldn't go low enough for what's been reported in Storm Arwen.
It may be out of range at the low end for people Up North, but down here it rarely (if ever) gets below minus 4degC. Even if it did, so what? It's damned cold!
661-Pete wrote: 1 Dec 2021, 5:38pmOf course, that car would never have come anywhere near 75mph on the level. Those were the days... :(
Some yonks back - decades - I fitted a different diff to my Mini. One that would give it "longer legs" but the speedo drives available weren't available. The diff was a modified competition one ................ long story!

The speedo drives went up a Bowden Cable to the back of the speedometer/odometer on the dash. You could get a few different ones with fewer or more worm-drive teeth on them that were inserted into the rear of the gearbox to give more rotation or less rotation to the mile.

It was a simple - to me at least - to go along the dual carriageways and count off the 200mtr marker posts using a stopwatch. Simple arithmetic could tell you the actual speed and I found 30mph and 60mph quite easily. I used Tipex (remember that stuff?) to mark off the dial. Extrapolation and experimentation got the other speeds correct.
Mick F. Cornwall
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