Some people really love their smoothies. We mean really, really, love smoothies and everything about making them, especially the blenders. [Adam] is a big fan of blenders, and wanted to verify that his Vitamix blenders ran as fast as the manufacturer claimed. So he built not one, but two speed measuring setups. Scientific blender measurement method requires one to cross check their results to be sure, right?
Measuring the speed of a blender is all about the RPM. Appropriately, [Adam’s] first measurement tool was an LED based stroboscope. Stroboscopes have been around for hundreds of years, and are a great way to measure how fast an object is rotating. Just adjust the speed of a flashing light until the rotating object appears frozen. The number of blinks per second is then equal to the Rotations Per Second (RPS) of the object being measured.Multiply by 60 seconds, and you’ve got RPM. [Adam] used an Arduino as the brains behind his stroboscope. He wired a dial up on his breadboard, and used it to adjust the flash rate of an LED. Since this was a quick hack, [Adam] skipped the display and just used the Arduino’s USB output to display speed measurements on his laptop.
There are possibilities for error with stroboscopes. [Adam] discovered that if the stroboscope was flashing at a multiple of the blade’s rotation speed, the blades would appear frozen, and he’d get an erroneous RPM value. Thankfully, [Adam’s] Vitamix had asymmetric blades, which made the test a bit easier. He calculated his blades to be spinning at 380 RPS, or 23,000 RPM. Not satisfied with his results, [Adam] brought out Audacity, and ran a spectral analysis of the blender in operation. He found a peak at 378Hz, which was pretty darn close to his previous measurement. Since the blender has a 4 inch blade this all works out to a blade tip speed right around the claimed value of 270 MPH. We’re glad [Adam] found an answer to his blender questions, but our personal favorite blender hack still has to be the V8 blender created by the Top Gear crew. [via HackerNews]
22 thoughts on “Do You Have Any Idea How Fast Your Blender Was Going?”
Do you think this is fun?
Measuring the RPM of a blender?
After hunting and hiring some new pencils at HAD the site is really going down.
Way of the cliff.
If you don’t like the service provided by hackaday I would send a letter to the DOJ and FCC! End the monopoly that HAD has on free cool content that isn’t up to your standards.
While I too feel that the content has been slipping, it probably hasn’t. I remember reading “lots” of great articles “some time ago”, but this week I’ve only read “a couple” so it feels like the quality has gone down, but it’s probably just confirmation bias and I don’t remember how many boring articles there were “some time ago”.
Maybe someone should come up with a hack to analyse the quality of HaD articles vs. time.
Having said all that, I don’t feel this is an article to criticise. The spelling and grammar were above average, and I found it fairly interesting. Not everything is going to be some ground breaking hack. Feel free to go elsewhere, then come back and tell us all of somewhere better, because I’ve had no luck so far.
I do love people who understand that they’re human.
I’m sorry about my first post.
It’s a great article but I just felt that measuring RPM was so obvious that it didn’t need an article.
But it does.
Cool. That’s two relatively simple methods of measuring RPM I didn’t know about.
And I always fear my mothers going to one day ask me to find out if her new blender is good enough for smoothies ;)
he can you induction meter or hall effect meter. lights are outdated
My parents have a Vitamix blender just like the one pictured. They are open loop and the knob only sets the power going to the motor but does not regulate the speed, so the top speed will fall drastically when there is a load on the blender.
My blender is a commercial one from Blendtec (an ICB-3) and it is closed loop, so it will turn up the output power to maintain the RPM on the motor. (I believe their consumer ones do the same.) If you can get a hold of one it would be interesting to see how the unloaded RPM varies from that of the Vitamix blender.
You could probably do an acoustic version that checks for the most common frequency generated by the blender. That should match up with the speed of the motor, although it might be some multiple of it.
“Do You Have Any Idea How Fast Your Blender Was Going?”
Every time I’ve passed thru the kitchen, the blender appears to just be sitting there on the counter, so my answer would be ….. 0mph.
Am I right, I’m right, right?
The task is really simple.
I would go for the sound method.
By far the most easy method thinking about how loud universal motors are in blenders?
Well, I have an iPhone app that measures the RPM of any fast spinning thing… for free. Unfortunately for me, that doesn’t change the fact that this guy hacked a day and I sat all day watching soccer. So score goes 1-0, he wins.
+1 for soccer :)
The thing with RPM measurement is that you need something pulsing.
Be it a switch, hall, IR or sound pulse.
All that is needed after that is just pure math.
360rps would make more sense on a 60Hz mains supply, meaning 6 revs per cycle.
BTW how do they do that? I’m guessing the motor drives the blades directly, not through gears. So that means multiple taps on the motor, or possibly it’s rectified into DC and controlled electronically. Or just directly from DC I suppose.
I’m here 2 years later cos a certain ubiquitous blender, and it’s just a bloody blender not a miracle, is being infomercialled at me right now, and I guessed at the blade being 5cm radius. So a bit of trigonometry with Pi, which I put at 3 because I’m lazy and the Bible says so, gave me 270MPH for the edge of the blade, which is pretty fast, really.
Anyway, how do you get a motor on 60Hz to run at a multiple of 60, say 360rpm? 6 sets of coils just driven in parallel as the stator, and a magnet on the rotor just gets pulled to the nearest one, one after the other? Or use 3 magnets, with 6 poles. I suppose you could have several contacts on the commutator. But that sounds a bit inelegant and inconvenient, nice thing about AC motors is you don’t necessarily need a commutator, cos they wear out.
Almost all blenders use universal motors, which means that there’s no direct connection between mains frequency and RPM. It also means that there’s no need to rectify into DC.
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