- Camber smartphone electronic measurement accuracy & precision - 4 Updates
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| Elder Jones <Elder@spambottrap.net>: May 24 09:00PM -0500 As a simple quick check at home, sort of like checking the oil dipstick, is the accuracy & repeatability of a smartphone yet sufficient to check automotive camber? |
| Allodoxaphobia <trepidation@example.net>: May 25 11:17AM On Fri, 24 May 2019 21:00:25 -0500, Elder Jones wrote: > As a simple quick check at home, sort of like checking the oil dipstick, > is the accuracy & repeatability of a smartphone yet sufficient to check > automotive camber? I'm sure it depends on how accurately you park the vehicle on the phone. :-) Jon esy-- Marvin L Jones | Marvin | W3DHJ.net | linux 38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD * Killfiling google & XXXXbanter.com: jonz.net/ng.htm |
| Elder Jones <Elder@spambottrap.net>: May 25 10:13AM -0500 It seems that recently said: > I'm sure it depends on how accurately you park the vehicle on the phone. :-) The three measurements that we need to accuracy & precision of about a tenth of a degree are caster, camber, and toe. o Caster is a function of camber at ±20 degree angles o Camber has a range of from 0 to about ~±6° ~±10' o Toe has a far smaller range of about 0.05° to about 0.1° per wheel [https://blog.bavauto.com/11758/bmw-and-mini-camber-and-caster-adjustment-how-to-street-track-best-tire-wear-diy-kit/] Since toe can be more easily measured linearly, only tenths of a degree accuracy & precision would be required for measuring Caster & for calculating Camber. [https://forums.bimmerforums.com/forum/showthread.php?1666987-1998-528i-REAR-Wheel-Alignment] For toe, we can obtain linear equivalents simply by converting a factory given front total toe spec of 0°5'±10' and a factory given rear total toe of 0°22'±4' to a non-angular linear distance given just the tire diameter a. P235/45R17 = (235)(2)(0.45)(1/25.4) + 17 or about 25.3" b. Factory total front toe = 0°5'±10' & factory total rear toe = 0°22'±4' c. Toe from tread centerline to vehicle centerline is half that d. Individual toe to centerline is 1/2 of 0°5' = 0°2.5' (halving may not be needed though) e. 0°2.5' divided by 60' is ~0.0417 decimal degrees f. 17" diameter rims * tangent ~0.0417° = 0.0124" g. 0.0124" is roughly about 3/256ths" (or about 0.3mm) [https://www.bmwcca.org/forum/index.php?threads/1998-bmw-528i-front-end-alignment-specs.979/] The rears, calculated similarly, would be ~0.33" for total toe in. [https://robrobinette.com/ConvertToeDegreesToInches.htm>] We could also use the sine instead of the tangent if we consider the radius of the tire to be the hypotenuse (the linear measurements are likely to be taken at right angles to the centerline of the car, or an imaginary line through the steering axis parallel to same) not at right angles to the tire centerline; but at these tiny angles sine and tangent are basically the same anyway so that makes no significant difference where the major linear measurement error is likely in the gravitational bowing of the typical tape measure. Hence the toe measurement accuracy & repeatability is due more to the fact that the tire isn't very large, and the factory-specified angle is very small, causing even a miniscule difference in distance with the tape measure to translate to a fairly large portion of the angle. [https://forums.pelicanparts.com/porsche-911-technical-forum/213336-alignment-conversion-inches-degrees-help.html] Given that both toe and caster can be derived from other measurements, the only question at hand is for Camber degrees to be measured by a smartphone. For Camber, tenths of a degree in repeatability & accuracy would be nice. Does anyone here know if a typical smartphone can achieve that feat yet? If not... When do you think phones will be able to achieve that accuracy & precision? |
| Fox's Mercantile <jdangus@att.net>: May 25 10:23AM -0500 On 5/25/19 10:13 AM, Elder Jones wrote: > If not... > When do you think phones will be able to achieve that accuracy & precision? Nice try, but most of us have enough sense to have this done by someone with the correct equipment. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| tabbypurr@gmail.com: May 24 12:07PM -0700 On Friday, 24 May 2019 01:14:38 UTC+1, Tim R wrote: > The basement ceiling fixture is the simple one socket ceramic plate, no globe or shield, so it will mount base up. > > that won't help it last. > So it should really be used base down? yup. Not sure about sideways. > It occurs to me that the majority of the light may be emitted sideways, but if I mount it sideways then half the light goes up. (I teach handbell ringing, and the sound comes off the sides of the bell, with very little coming from the end, so I coach my ringers in holding the bell so the sound reaches the audience.) Yes, more sideways than end on. In practice it doesn't seem to create problems though. LEDs are more directional. NT |
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