Re: Ultrasonic Z-height sensing? February 22, 2014 06:55PM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 23, 2014 04:57PM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? February 23, 2014 05:30PM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 25, 2014 12:16PM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? February 25, 2014 12:40PM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 25, 2014 05:15PM |
Registered: 10 years ago Posts: 300 |
Quote
dc42
How temperature-stable is the reading you get from it?
Re: Ultrasonic Z-height sensing? February 25, 2014 06:00PM |
Registered: 10 years ago Posts: 14,672 |
Quote
Radian
But can you clarify for me what you mean about the threshold? Do you mean that the threshold value set by G31 should be obtained by recording the difference between max. and min readings found experimentally?
Re: Ultrasonic Z-height sensing? February 26, 2014 05:14AM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 26, 2014 09:45AM |
Registered: 10 years ago Posts: 2,472 |
Re: Ultrasonic Z-height sensing? February 26, 2014 09:49AM |
Registered: 10 years ago Posts: 42 |
Quote
dmould
I wonder whether you could use the extruder thermistor reading (with the hotend cold) to aid in applying temperature compensation to the ultrasonic reading? I have noticed that if a cold nozzle is moved over a hot bed (e.g. to manually zero the Z height), the hotend temperature reading rapidly increases as the extruder is heated by the bed.
Re: Ultrasonic Z-height sensing? February 26, 2014 10:41AM |
Registered: 10 years ago Posts: 2,472 |
Quote
jy_oc_hx
Quote
dmould
I wonder whether you could use the extruder thermistor reading (with the hotend cold) to aid in applying temperature compensation to the ultrasonic reading? I have noticed that if a cold nozzle is moved over a hot bed (e.g. to manually zero the Z height), the hotend temperature reading rapidly increases as the extruder is heated by the bed.
In theory this is a vey good suggestion but i think i have read in another thread, that i can't find at the minute, that the hot end temp sensor is designed for the top end readings and the lower range of readings it gives can fluctuate and vary quite dramatically. If i come across the thread again i'll update this with a link. But if i am wrong please correct me.
Re: Ultrasonic Z-height sensing? February 26, 2014 10:56AM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 27, 2014 09:17AM |
Registered: 10 years ago Posts: 300 |
Quote
dc42
Radian, did you attempt to measure the change in oscillation frequency as the probe moves towards the bed? It occurred to me that this may be another way of height detection. I was thinking of trying a one-transistor Colpitts oscillator (operating at the parallel resonant frequency of the transducer, rather than the series resonance that we are both using at present) and then frequency-counting in a microcontroller.
Re: Ultrasonic Z-height sensing? February 27, 2014 10:22AM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? February 27, 2014 01:48PM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? March 03, 2014 04:12PM |
Registered: 10 years ago Posts: 300 |
Quote
dc42
One snag is that there has been a run on 10mm 40kHz ultrasonic transducers since I built the prototype, and neither Farnell nor RS has any in stock. This may delay the Kit 5s till sometime in April, unless I add £3 to the price and source more expensive ones from Mouser, or ship the Kit 5s without the transducer.
Re: Ultrasonic Z-height sensing? March 03, 2014 05:12PM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? March 04, 2014 09:24AM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? March 04, 2014 10:12AM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? March 04, 2014 12:30PM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? March 05, 2014 07:33AM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? March 06, 2014 11:42AM |
Registered: 10 years ago Posts: 300 |
Quote
dc42
If your first peak is at 6.4mm transducer face height and the second one at 11mm, then your half-wavelength is 4.6mm, and you should get another, larger peak at about 1.8mm face height if your transducer was lower. As this is such a low value, I suspect that your maxima correspond to my minima, and vice versa. This may mean that your oscillator is operating at the parallel resonant frequency, not the series one. Components L1 and C1 will also affect the resonant frequencies, as does the 4.7mH series inductor in my drive circuit. Does your oscillator still work if you increase L1 to 4.7mH and omit C1?
Re: Ultrasonic Z-height sensing? March 08, 2014 03:31AM |
Registered: 12 years ago Posts: 227 |
Re: Ultrasonic Z-height sensing? March 08, 2014 05:06AM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? March 08, 2014 12:35PM |
Registered: 12 years ago Posts: 227 |
Re: Ultrasonic Z-height sensing? March 08, 2014 02:47PM |
Registered: 10 years ago Posts: 14,672 |
Re: Ultrasonic Z-height sensing? March 10, 2014 06:10AM |
Registered: 10 years ago Posts: 300 |
Re: Ultrasonic Z-height sensing? March 10, 2014 06:18AM |
Registered: 10 years ago Posts: 48 |
Re: Ultrasonic Z-height sensing? March 10, 2014 06:39AM |
Registered: 10 years ago Posts: 300 |