iSpindel Calibration

[StrontiumDog]

Thought I would start a thread here as I don't want to clog up Rob's on the marketplace any more than I have already.

I'm having real problems working out how to calibrate this thing. These were my steps;

1. I made a 1.080 solution measuring with my hydrometer then diluted it approx 1.010 at a time. At each step I took my measurements of the tilt and the SG reading on the iSpindel as instructed and put them on the excel spreadsheet

2. After I had reached 1.000 I then pressed the 'Formel update' button and copied down the 'Plato Formel' value

3. I reset the device and under configuration I put the 'Plato Formel' value in the Polynominal box.

4. Once done I saved and then went back to Ubidots. When I went to have a look however I was shown a gravity reading in plain water of 94,244.88!?!?!?!?

I have no idea what's going on. Everyone else sharing their data seemed to have the SG values reporting in 1.xxx format where as mine were double digits to 2 decimal places.

I have no idea what I'm doing so hoping someone can help......

[StrontiumDog]

Updated the firmware and rolled back to before calibration but it's still giving me the same values I had before and not showing SG in the normal format. Re-input the polynominal and it's straight back to showing insane values. I put it in a sugar solution of 1.019 and I'm on negative figures - -2,335,078!!!!

Really starting to loose faith with this

[ben034]

Can you post the formula on here that you are using?

[ben034]

I had better luck using the online calibration tool instead of the excel spreadsheet

[spook100]

Where did you get your spreadsheet from? I got mine from https://github.com/universam1/iSpindel/ ... md#formula and it is different from yours. Mine only has "Measured Angle", "Measured SG", "Measure Plato" and "Deviation". Your appears to have an extra column called "Hydrometer Readings".

I looks like you have the wrong values in the "Measured SG" column. That column should contain the values that you currently have in the "Hydrometer Reading" column. I think that should solve the problem because your "Measured SG" values are currently about 20 times higher than they should be.

[StrontiumDog]

Where did you get your spreadsheet from? I got mine from https://github.com/universam1/iSpindel/ ... md#formula and it is different from yours. Mine only has "Measured Angle", "Measured SG", "Measure Plato" and "Deviation". Your appears to have an extra column called "Hydrometer Readings".

I looks like you have the wrong values in the "Measured SG" column. That column should contain the values that you currently have in the "Hydrometer Reading" column. I think that should solve the problem because your "Measured SG" values are currently about 20 times higher than they should be.

Got the spreadsheet from the same place, I added the extra column on the right so I knew what measurements I was taking from my actual hydrometer. Should the 'Measured SG' value be the reading from my glass hydrometer or the values from the iSpindel (as they are the values I put in)

Update: Just put the values from the glass hydrometer in the 'Measured SG' column but I get the same formula at the top when I press 'Formel update'

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[StrontiumDog]

Can you post the formula on here that you are using?

Formula I got was;

1295.200171*tilt^2 - 94933.44348*tilt + 1700987.394

When using the readings from my glass hydrometer in the 'Measured SG' column I get the same formula

[StrontiumDog]

You know what, I think I may have solved my own problem........

I have re-downloaded the spreadsheet and the values go from 1.000 down 1.080 whereas I had my values starting with 1.080 going down to 1.000 (does that make sense?)

I have also changed my values from the iSpindel values to my glass hydrometer readings

Does that attached look more sensible now?

[spook100]

I plugged your numbers into the spreadsheet and the resulting formula was
0.011631467*tilt^2 - 0.729792843*tilt + 11.82057081
I have save the spreadsheet with your numbers and you can download it from https://www.dropbox.com/s/fvwi459v64i0b ... .xlsm?dl=0

[StrontiumDog]

Ah thanks!!

I wonder why my formula looks so different?

Was it right to put the glass hydrometer readings in the 'Measured SG' rather than the value of the iSpindel?

This has been so confusing! I will reset when I get home and update on how it looks

[spook100]

I wonder why my formula looks so different?

Was it right to put the glass hydrometer readings in the 'Measured SG' rather than the value of the iSpindel?

Your hydrometer measures the specific gravity and that goes into the "Measured SG" field, as you have done.

You had entered 1.120 instead of 1.020 for one of your SG readings so I guess that is what threw your formula.

[StrontiumDog]

Updated the derived variable and now have the attached....

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[StrontiumDog]

So now things have settled - In plain water at bang on 20 C I have a reading of 0.68 which multiplied by 1000 gives me 680.31 which is close to 1,000 (i.e. 1.000)

My (hopefully last) question now is that in plain water I'm still a way off 1,000 (1.000) so do i need to calibrate it again (now that i know how to!) or is that close enough?

Thanks for all the help, would never have managed this myself!

[StrontiumDog]

Left over night and this morning when checked (at 20 C) I have been able to re-calibrate the 1.000 value so my new value reads 0.32 which is equivalent I believe to 0.323.75 and far less than the .680 value I had yesterday

Guess I'm still after whether or not this is an allowable margin of error or if i need to calibrate again

[StrontiumDog]

In a sugar solution of 1.032 I get 6.73. now realised that this unit is Plato!

When converted to SG using the formula at brewers friend I get 1.026 so recalibration needed I think

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