On 14/12/2016 12:22 PM, wrote:
On Tue, 13 Dec 2016 17:16:49 -0600, amdx wrote:

On 12/11/2016 10:09 AM, amdx wrote:
On 12/10/2016 6:08 PM, John Harmon wrote:
amdx actually said:

If either of those devices had a laser pointer in them that point
up, you could do a trig problem using the ceiling for camber, and on the
front wall by rotating the device 90* for toe.

I think you're one of the few people who are actually *thinking* about
what
they are saying on this thread, and for that, I very much appreciate your
sugestions.

It seems, from what Andy Burns intimated, that the smart phones use
gravity-based accelerometers (with the compass) and not inclinometers,
so,
while they can be used for camber, the accuracy will be about plus or
minus
six minutes.

However, to use them for toe (as I think it was tlvp who suggested that),
would be folly, I think, simply because toe is in a different plane where
gravity isn't different for various angles of toe.

However, the laser beam is in the right plane for toe measurements!
So is the centerline of the car.

So it should, in theory, be easy to do something like this:
a. Attach a laser to the car centerline and mark where it hits a wall.
b. Attach that laser to the wheel and mark where it intersects.
c. That's the triangle!
https://s18.postimg.org/fq07txfih/11...a_triangle.gif

NOTE: I haven't calculated yet the *distance* it would take for the
centerline and tire to hit the wall, which could be prohibitive.

Hey, just noticed your link,
http://i.cubeupload.com/XocXQ9.jpg
has the sears level shown here,
http://www.sears.com/craftsman-10-in...P?sid=BVReview


That level is "accurate to 1/10th of a degree" (six minutes) so that must
be the standard accuracy of the inclinometers in digital levels.

The Sears level does have a laser in it.
That will do what I suggest, rotate it 90* and point it forward to see
a spot on the wall. Find the centerline of your car and then it's a
simple trig problem.

I think you hit upon a good idea which is to use the laser as the
straight
line for the vehicle centerline and for the tire angle, because where
they
intersect will be the triangle we need to measure.
http://i.cubeupload.com/BzNqBY.gif

The only problem may be the length of the Adjacent (centerline) mark.

The hard part, finding the centerline of your car.
I'm not sure this helps you though, I saw no evidence that you
understood how the trig solves turning the angle into inches.

The trig is easy. soh cah toa.
What's hard is figuring out what the triangles are for "total toe":
https://s23.postimg.org/ajrtf269n/10...toe_angles.gif

Most people here don't even understand the question because they keep
saying it's a math problem. But the math is trivial. My confusion is
how on
earth do they specific total toe in degrees when total toe is simply the
difference in toe from the rear to the front of the tire/wheel but toe
angles are the *same* at the rear and front of the wheel!

I'm sure the answer to that question is simple but everyone says it's a
math trig issue but it's really a conceptual misunderstanding on my part.

I think you have a misunderstanding of total toe. It is simply Right
wheel toe plus Left wheel toe. I don't see why it needs to be measured,
if you have set left and right, total toe is just the addition of the
two angles.
See the explanation on page two, in the verbiage below the top left
figure. http://www.hunter.com/Portals/0/Media/995-T-2.pdf

All your draws use the centerline of your tire, which you can't
physically do. I would use the outside of the wheel, however, when you
get your adapter with laser built, the line will be further out from the
wheel edge.
Here's my vision. Feel from to make your own drawing, Paint wouldn't
modify yours the way I wanted.
https://www.dropbox.com/s/jap3k6l6z3...%20IN.jpg?dl=0

Mikek



Rather disappointed I didn't get a response.
Mikek
I think he's fighting with a cheap harbour freight tire changer now.
If it's not him it's his identical twin brother (perhaps by a
different mother) If not the same guy, their understanding of the
principals is about the same level of non-existance.

Yes, it is an odd discussion and, because of that, one that I have been
loath to become involved in. FWIW, back when I was doing wheel
alignments, and lots of them, Toe was always designated as a 'linear
measurement', usually in fractions of an inch for most of the vehicles
that I worked on, and it was never an issue. The equipment I used, from
the very basic to the most sophisticated computer types, had both linear
and degree scales so the issue in this thread is really a non-runner.
What's more, there always seemed to be some sort of conversion chart on
hand, supplied by the equipment manufacturer, so there was never a need
to deal with trig functions. Failing that, these days there are internet
options of which I supplied the URL to one such in a past post.

--

Xeno

First they ignore you,
Then they ridicule you,
Then they fight you,
Then you win.

Mahatma Ghandi