ISpindel Digital Hydromenter

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aamcle
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Re: ISpindel Digital Hydromenter

Post by aamcle » Sat Jan 26, 2019 6:47 pm

You wouldn't want to be without one.

Aamcle

mattharte
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Re: ISpindel Digital Hydromenter

Post by mattharte » Sun Jan 27, 2019 9:40 am

Are there any still available would be interested in buying one?

aamcle
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Re: ISpindel Digital Hydromenter

Post by aamcle » Sun Jan 27, 2019 9:44 am

You can build one the instructions are on GitHub.


Aamcle

Robhaigh
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Re: ISpindel Digital Hydromenter

Post by Robhaigh » Sun Jan 27, 2019 10:14 am

mattharte wrote:Are there any still available would be interested in buying one?
Yep. Still available. Drop me over a PM with your address .

Sent from my Mi A1 using Tapatalk


chrisr
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Re: ISpindel Digital Hydromenter

Post by chrisr » Sun Jan 27, 2019 4:19 pm

I did the calibration procedure again, using sugar solutions made using my own calculations and not the instructions on the ispindel website. This came out with points that were much closer to the best fit line produced, but the line isn't shaped like anything I've seen for other people's data. It's one of the (infamous) hockey sticks. In fact the best fit line decreases to start with! Which seems a nonsense to me.

I did notice that if I omitted either the top two or bottom two readings I got an almost straight line for the best fit curve.

I've now used all the household sugar, so that brings proceedings to a halt.

I'm going to have to buy a replacement hydrometer, after all. I've lost count of the number I've broken though and I was hoping the ispindel was an unbreakable alternative. I doubt this device is going to replace hydrometers.

chrisr
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Re: ISpindel Digital Hydromenter

Post by chrisr » Sun Jan 27, 2019 6:36 pm

I've noticed that standing on its lid, IE upright, it reports an angle of 18 degrees. That seems a bit out.

I checked the float angle in tap water, measured using a protractor, it's about 15 degrees, 20 at most. However, it's reporting 32 degrees. Could this be why my graph of data points turns up again as it gets to the lower densities?

Is there any calibration of the angle sensor required, or possible? How do you know if it's working right?

I have reset the sensor (the laying it flat thing, Maintenance mode in the WAP config page). Twice. No different. Is it like the sensors in phones, and you have to wave them about to reset them? I tried this but it didn't seem to change anything.

I tried resetting the angle sensor (Maintenance mode) with the ispindel stood on it's lid. Checked angle readings were zero (as near as) then laid it flat. It reported 63 degrees tilt. 90-63=17, which is pretty much the error I originally had when it was stood on its lid. 17 degrees error in 90 degrees? You wouldn't want to trust your life to these things, would you?

aamcle
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Re: ISpindel Digital Hydromenter

Post by aamcle » Sun Jan 27, 2019 8:26 pm

Not to panic, what you want to see is the graph of SG change against time. While it may under lab conditions be possible to calibrate it to achieve the same accuracy as a glass thermometer I wouldn't hold my breath trying at home and then using it in a fermenter with a head of yeast foam.

Even so calibrating and setting counter weights again would be worth while.

aamcle

Robhaigh
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Re: ISpindel Digital Hydromenter

Post by Robhaigh » Sun Jan 27, 2019 9:41 pm

Yep, as aamcle says. These devices are a good indicator but not a replacement for a glass hydrometer.
What they do let you do is see if your brew is active or not, track the changes and see the temp.
This tied in with something like brewpi or craftbeerpi then gives you the ability to control temperature from afar, do your cold crashing etc.

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chrisr
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Re: ISpindel Digital Hydromenter

Post by chrisr » Mon Jan 28, 2019 10:23 am

I'm thinking maybe you're right there: it can report changes in density, but not the absolute density. But that's not how the Tilt sells itself!

Mine does not appear to accurately indicate the density below 1030(-ish), as it starts to be affected by the 17 degree sensor error. So it's not going to be of much use in showing when a fermentation is nearing completion.

I wouldn't expect these cheap little modules to be spot-on accurate, but an error of 18% would seem to me to make them absolutely useless.

Can anyone else tell me what their ispindel reports as the angle when it's stood on its lid?

aamcle
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Re: ISpindel Digital Hydromenter

Post by aamcle » Mon Jan 28, 2019 10:30 am

I'm tempted by CraftBeerPi I've loaded it and checked that it works on my Pi but that's all.

I have a GF so I don't need it for the hotend and I use a STD to control the fridge as a result there would not be a lot of benefit except that I would have some fun building it.


Aamcle

mattharte
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Re: ISpindel Digital Hydromenter

Post by mattharte » Mon Jan 28, 2019 2:55 pm

[quote=Robhaigh post_id=840927 time=1548580461 user_id=18118]
[quote="mattharte"]Are there any still available would be interested in buying one?[/quote]Yep. Still available. Drop me over a PM with your address .

Sent from my Mi A1 using Tapatalk
[/quote]

Arrggghhh waiting for PM to become active for my user ....will have to get active posting

chrisr
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Re: ISpindel Digital Hydromenter

Post by chrisr » Tue Jan 29, 2019 8:36 pm

Making some progress … I replaced the accelerometer sensor board, and I am now getting tilt angle readings from just under 90 degrees (when the tube is laid flat) to just short of 0 degrees when the tube is vertically upright. So I think now there’s a good prospect of getting a series of sensible calibration values.

So, based on my issues, I’d advise the first thing any new Ispindle owner should do is to run the zeroing procedure (under Maintenance), then look at a few tilt angle results and make sure you get 90 degrees (or as good as) when the tube is laid down flat, and 0 when it’s stood upright. I doubt you’ll be able to make accurate density readings unless it's accurately reporting the tilt angle.

Now I need more sugar…

chrisr
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Re: ISpindel Digital Hydromenter

Post by chrisr » Thu Jan 31, 2019 12:44 pm

I've run through the calibration again and got much better looking results.

I've read on another site (from someone that appeared to know what they were talking about) that the calibration curve should be shaped like a tan curve. A steep angle in the high densities, flattening in the middle, then steeper again at the low densities. The effect is very gentle though, not as pronounced as tan.

This being so, a cubic polynomial will be a far better fit to the curve than a quadratic. The Tilt uses a cubic calibration curve. The Excel spreadsheet will only give you a quadratic solution, and only for plato. If you go to the online one, at http://www.ispindel.de/tools/calibratio ... ration.htm, this will give you a cubic, as well. Also, you can choose whether the output of the function is degrees plato or a specific gravity.

My calibration data is:
Tilt SG
20.1320 1.000
28.7163 1.006
35.2877 1.011
37.8370 1.015
46.4764 1.020
52.1650 1.030
56.9744 1.040
62.8403 1.057
66.0515 1.071

Also, I found the answer to a previous question I posed: "I noticed the ispindel doesn't settle 'straight', the drawer is at an angle in two planes. Would that affect it?"

Ideally, the ispindel should tilt in one plane only, as the software does not take into account two planes of tilt. By which I mean the top-most edge/end of the plastic sledge should remain parallel to the surface of the liquid. IE, the tube should not have any roll component as it floats in different densities of liquid.

A few degrees out is unlikely to affect it much, but if the sledge ends up tilted significantly sideways this will affect the calculation of tilt angle. Adjust the position of the weights to keep it straight.

markpeace
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Re: ISpindel Digital Hydromenter

Post by markpeace » Sun Feb 03, 2019 1:11 pm

Hi Rob - I’d be interested in buying one of these off you if you’ve still some available?

ridleyrumpus
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Re: ISpindel Digital Hydromenter

Post by ridleyrumpus » Thu Feb 07, 2019 6:27 am

I would ve interested too.

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