Incidence gauge

I made my own when in Cyprus how accurate it was ?

OK chaps, what we are not sure about is the accuracy of these smartphone inclinometers, so I though I would run some tests and share that information with you all.

So what have we got to do the tests with? one old Sony Experia smartphone, no SIM card installed, Clinometer app by Plaincode, a Sine bar, a very flat engineers table and some very accurate slip gauges.

So the engineers table is granite and is flat across its surface to 1/2 thou (0.012mm) although it is not levelled at the moment, so the first thing is to check what angle that the table is sitting at? That is shown in the first photo and we can see that the table is 0.3 of a degree out (low to the right).



So I decided that I would look at a 2 degree angle as that seemed like a number we might see as a wing incidence.

In engineering one of the ways to setup an angle is to use a sine bar, the sine bar is precision ground and has two circular bars that are exactly 150mm apart, so if we put a packer of a known size under one of the circular bars we are creating a right angle triangle with a hypotenuse of 150mm and a vertical edge (what ever the packer size is) I calculated that a 2 degree angle with a hypotenuse of 150mm needs a packer of 5.235mm.

So with my precision slip gauges I selected exactly 5.235mm of packers and placed them under the left hand roller of the sine bar, now we have the top of the sine bar inclined at exactly 2 degrees to the table surface which is sitting at 0.3 degrees, so we would expect to see 2.3 degrees on the inclinometer.

Bingo no tricks or slight of hand, I think it is fair to say that you can measure to 0.1 of a degree with a smartphone.

I would caution though that if the phone is very battered then it might not be so accurate.



Maybe we should come up with a design for an incidence gauge that can house a smartphone? and share it on this forum.

Any questions then just shout out.

Barrie

Superb Barrie, since my last post I found that particular app and 're measured the seat, 2.48 degrees so that's good enough for me!
nice to see some decent engineering practices, I'm ex cnc mainly mazak and Hitachi seiki with Fanuc controls although I did occasionally use Heidemhim.
started with cincinatti and mogg hydrapoint ( blast from the past there!). still got my precious micrometers and vernier, sold my set of slips sadly...

Paul
I thought you were sensible, your previous career reinforces that position.

I am not serious machinist, I leave that to my race partner but I do have some machines.

Those slips are out of a complete Tesa RSD tungsten carbide set that I got on ebay for a song, even has a calibration/deviation sheet for every slip.

I have started buying second hand Swiss micrometers, I did not realise what I was missing, Etalon and Tesa are superb.

B.

I could do with that to make sure the incline on the canyon RR is 2.2 degrees