iTopSpin

Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: 1 2 All   Go Down

Author Topic: Recording laser tachometer for automated spin-decay curve capture  (Read 2314 times)

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages

A while back, ortwin pointed me to the UT372 recording laser tachometer as an affordable solution for automated spin-decay curve capture. You can download the PDF manual and Windows software at this link for inspection if you like.

Got the red UT372 below for $66 on Amazon. Seems to be well-designed and well-made. Tested the USB recording functionality for the first time today, and I'm happy to report that it works just fine on Windows 10!



After opening the bare-bones software on my laptop and connecting to the UT372 via the included USB A to USB B cable, I spun up the top shown and started collecting (time,RPM) data points at 1-second intervals. (The sampling rate is adjustable.) Then I exported the data to a file for processing in Excel.



The export files bear ".xls" extensions but are really tab-delimited text files, not Excel files per se. Nonetheless, Excel will open them after some complaining. Another 5 minutes of work, and I had this raw spin-decay curve and exponential fit (dotted line). The blank RPM values in the table were obvious outliers that I deleted manually to keep Excel from plotting them.



Plan to use exponential lifetime as a figure of merit for comparing top performance going forward. This top's 46.3 s lifetime is very short by endurance top standards. But over my entire LEGO top collection, it's pretty middle of the road.

Still streamlining my workflow with it, but you can get an idea of what's involved from this video...


« Last Edit: June 08, 2021, 07:02:47 PM by Jeremy McCreary »
Logged
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

ortwin

  • ITSA
  • Hyperhero member
  • ********
  • Posts: 1490
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #1 on: June 08, 2021, 02:31:49 AM »

Great to hear that it does what it should!
So that bicycle courier from China was going fast to deliver it to you?
A few days ago,  I promised myself I will also order one as soon as I reached my 25 minutes goal. 
That thread on the back for the tripod sounds good also. My current tachometer also has one, but it didi not come with one. My friend suggested it and made it. It proved extremely useful ever since. Could you just drop a quick picture of the backside with that "threaded metal hole" visible? You could just modify the first post, I will find the picture.
Thank you for the review!

Logged

In the broader world of tops, nothing's everything!  —  Jeremy McCreary

ta0

  • Administrator
  • Olympus member
  • *****
  • Posts: 14323
    • www.ta0.com
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #2 on: June 08, 2021, 09:28:26 AM »

Having entered decay data by hand in the past, I fully appreciate the usefulness of a data logging tachometer. I've got good and bad stuff from China, so thanks for taking the risk for us.
Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #3 on: June 08, 2021, 07:03:47 PM »

The back of the UT372 has a brass hole with a standard 1/4"-20 tripod thread.

Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #4 on: June 08, 2021, 08:48:33 PM »

Having entered decay data by hand in the past, I fully appreciate the usefulness of a data logging tachometer. I've got good and bad stuff from China, so thanks for taking the risk for us.

The Chinese seller on Amazon opened the package before shipping and removed the software and 4 AA batteries listed as "in the package" in the printed manual that came with the tach.

After calling them on it, they offered me a 60% refund if I'd agree not to return it. Since the tach itself looks new, I accepted. That was yesterday. We'll see if and when the refund appears in my account.

Fortunately, you can download the software, and there are several other sellers on Amazon.
« Last Edit: June 08, 2021, 08:54:43 PM by Jeremy McCreary »
Logged

ortwin

  • ITSA
  • Hyperhero member
  • ********
  • Posts: 1490
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #5 on: June 21, 2021, 08:41:09 AM »

. ...I promised myself I will also order one as soon as I reached my 25 minutes goal....
I did not order mine yet because  I still did not reach my 25 minutes goal.
But I am positive that I will get there eventually, so I want to suggest to you, Jeremy, already to think about "standard settings" each of us should use so that the data and the curves can be compared easily. Maybe even some template, excel or something, where we can bring our measurements in to?
Some fields would be needed to be filled in: time, date, location, equipment, author, comments, ....

Does that make sense to you? It would be better to have that at the beginning before everyone has 50 files but comparing the files to those of other people becomes unnecessarily hard due to small incompatibilities.




Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #6 on: June 21, 2021, 12:32:50 PM »

...think about "standard settings" each of us should use so that the data and the curves can be compared easily. Maybe even some template, excel or something, where we can bring our measurements in to?
Some fields would be needed to be filled in: time, date, location, equipment, author, comments, ....

Does that make sense to you? It would be better to have that at the beginning before everyone has 50 files but comparing the files to those of other people becomes unnecessarily hard due to small incompatibilities.

Wow, having 50 raw spin-decay curves (SDCs) to analyze and compare -- beyond my wildest dreams!

Ideally, we'd use Excel files to share the raw (time,speed) data so that anyone could analyze it.

Personally, I'd find the following useful:
1. Experimenter's name
2. Date data was acquired. Time if necessary.
3. Name of top.
4. Enough low-res photos of top to show its shape and aerodynamic properties.
5. Top description, including any noteworthy features not clear from photos.
6. Pertinent top dimensions, with reference to photos as needed for clarity.
7. Known or estimated mass properties, including mass, CM height, and moments of inertia if known.
8. Tip details, including material and estimated radius of curvature over contact patch.
9. Plot of raw SDC in RPM vs. seconds.

I'd really like the graph to include an exponential fit -- including the associated decay constant or lifetime and R² goodness of fit. I think we'll learn a lot from seeing how much the measured SDCs differ from their best exponential fits.

Finally, would love for all data other than speed (in RPM) to be in meters, kilograms, and seconds for direct comparison and easy analysis without conversions.

Likelihood of getting even half of that wish list = zero, but a template might help.
« Last Edit: June 21, 2021, 09:22:49 PM by Jeremy McCreary »
Logged

ortwin

  • ITSA
  • Hyperhero member
  • ********
  • Posts: 1490
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #7 on: June 30, 2021, 02:41:49 PM »

Received mine today.
Mostly everything works fine as far as I tested.
The thread for the tripod is a bit far off center. That makes it too unbalanced for my little tripod: It tilts to where it wants to, not to where I put it. So I need to use my large tripod.
Other than that it is Like Jeremy said a matter of streamlining the work with it.@Jeremy: did you by any chance prepare a template for SDCs?I think we should also agree on some sampling rate. What would you recommend from your experience so far?

« Last Edit: September 19, 2021, 01:24:51 AM by ortwin »
Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #8 on: June 30, 2021, 05:37:11 PM »

Received mine today.
Mostly everything works fine as far as I tested.
The thread for the tripod is a bit far off center. That makes it too unbalanced for my little tripod: It tilts to where it want to, not to where I put it. So I need to use my large tripod.
Other than that it is Like Jeremy said a matter of streamlining the work with it.@Jeremy: did you by any chance prepare a template for SDCs?I think we should also agree on some sampling rate. What would you recommend from your experience so far?

I'm having good luck with a short, highly articulated Delkin bipod with big suction cups for feet. Bought it years ago for my heavy DSLR but never found a good use for it till now.

You and Iacopo might settle on a sampling interval, but it would surely be way too long for most of my tops. So far, I've been using 1 s.

A more practical sampling standard would be to collect ~100 samples per SDC. That should provide plenty of resolution for our purposes.

Might start on a template next time I measure a batch of raw SDCs. But you said your spreadsheet skills are poor, and I don't know where Iacopo stands in that regard. So, realistically, who would use it?

Also, some potential SDC providers may not have Excel. If free web-based Google Sheets can import the data files and has the necessary plotting and curve-fitting functionality, might be a better alternative.
« Last Edit: June 30, 2021, 06:30:12 PM by Jeremy McCreary »
Logged

Bill Wells

  • Hero Member
  • *****
  • Posts: 263
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #9 on: October 15, 2021, 01:49:04 PM »

UT372 recording laser tachometer

Jeremy, I believe you saved my bacon again. I ordered and received the UNI-T UT372  Tachometer but could not find how to record RPM. Now I'm realizing there should have been a software disk also. No there was none. I see you have posted a link for software? I have not yet gone to the link, thought I would check in with you first. Trying to avoid further frustration  :(. Do you have further suggestions before I go down another rabbit hole?

Many thanks for your help
Bill

Logged
It's not worth doing if you're not obsessed about it.

Iacopo

  • Immortal Member
  • *********
  • Posts: 1722
    • Spin tops by Iacopo Simonelli, YouTube channel
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #10 on: October 15, 2021, 02:48:57 PM »

But you said your spreadsheet skills are poor, and I don't know where Iacopo stands in that regard.

I never used a software for making spreadsheets.

I am not planning to buy the UT372, but I could change idea, it depends on my future needs. 
I have a good laser tachometer, but it dosn't record the data, I don't use it often though.
Logged

Bill Wells

  • Hero Member
  • *****
  • Posts: 263
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #11 on: October 15, 2021, 03:09:01 PM »

I am not planning to buy the UT372, but I could change idea, it depends on my future needs. 

I use a standard laser tachometer and the stopwatch feature on my iphone. And pencil and paper to record RPM each minute.
So far am not happy with the UT372, Maybe I will like it better if I can make it record automatically.

I use a spreadsheet, Excel, to record data and plot curves. Works very well for me.
Logged

ortwin

  • ITSA
  • Hyperhero member
  • ********
  • Posts: 1490
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #12 on: October 15, 2021, 03:47:11 PM »

...
I use a standard laser tachometer and the stopwatch feature on my iphone. And pencil and paper to record RPM each minute.
...

I use a spreadsheet, Excel, to record data and plot curves. Works very well for me.
Even without recording there can be a little advantage using the UT372:  You don't need the stopwatch feature on your phone, the time shows at the same time as the RPM in the display. To restart that a t zero, press the R/C button twice.
Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3784
    • MOCpages
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #13 on: October 15, 2021, 04:17:01 PM »

Affordable automatic recording via USB and the tripod mount are the main reasons to buy a UT372.

You have to download the simple Windows recording software separately. Among other things, the program controls sampling rate and exports the data in CSV files that Excel is happy to import.

Then you process the data in Excel.
Logged

Bill Wells

  • Hero Member
  • *****
  • Posts: 263
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #14 on: October 15, 2021, 05:59:41 PM »

Even without recording there can be a little advantage using the UT372:  You don't need the stopwatch feature on your phone, the time shows at the same time as the RPM in the display. To restart that a t zero, press the R/C button twice.
For my latest test runs today I used the UT372 and its time feature. It was a benefit! Have not yet downloaded the software.
Thanks for the the re-start info.
Logged

Bill Wells

  • Hero Member
  • *****
  • Posts: 263
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #15 on: October 24, 2021, 01:26:50 AM »

UT372 recording laser tachometer

Well finally got mine figured out. But it wasn't any 5 minutes. Had to interpret some Chinese instructions first.
So far have not used the tripod mount. I look around for a stack of boards just the right height.



.
Logged

ortwin

  • ITSA
  • Hyperhero member
  • ********
  • Posts: 1490
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #16 on: October 24, 2021, 02:25:20 PM »

...

Well finally got mine figured out. ...

 
Sorry that I have to be picky on this issue, but I think the correct way to put this would have been : Wells finally got mine figured out. ...
Logged

Bill Wells

  • Hero Member
  • *****
  • Posts: 263
Re: Recording laser tachometer for automated spin-decay curve capture
« Reply #17 on: October 24, 2021, 04:02:14 PM »

Sorry that I have to be picky on this issue, but I think the correct way to put this would have been : Wells finally got mine figured out. ...

Ortwin, glad to have you here :D
Logged
Pages: 1 2 All   Go Up