The first image shows placement of the Piezos under the insulating blanket and the high density foam, the kind that the Tevo Black Widow was packaged in. I don't know what the insulating foam is but it has to handle the bed temps and is covered with a heavy duty aluminium foil so the contact signal is damped by the foil. The second image shows the relative diameters of the various piezo disks anby Chowa - General
Here are some pictures of my rig early version. Please note that I have used shielded cable from the piezo and grounded at the electronics.. Image on right shows the insulating blanket underside of bed. Although I have the 20mm and27mm (green) only 1 piezo is active for testing. Stefby Chowa - General
My thots, save your money get Simon's V2. just love it. Forget the clones. No more offsets, no more poor registration of probe points. Just exact posistioning . Stefby Chowa - General
Yes Simon, very happy with the results. Will post pictures as soon as I find my camera that has the build on it. I need to take the bed apart to install the 41mm piezo to check it out. I came to your site out of sheer frustration with the BLT leveling thing that sometimes worked and is now in the scrap box. If you remove the s from the preceding, you will get the message. Looking forward for yourby Chowa - General
14:27:08.243 : M48 Z-Probe Repeatability Test 14:27:08.243 : Positioning the probe... 14:27:11.446 : Bed X: 200.000 Y: 120.000 Z: 0.255 14:27:13.727 : 1 of 5: z: 0.286 mean: 0.2862 sigma: 0.000000 min: 0.286 max: 0.286 range: 0.000 14:27:16.009 : 2 of 5: z: 0.281 mean: 0.2838 sigma: 0.002500 min: 0.281 max: 0.286 range: 0.005 14:27:18.274 : 3 of 5: z: 0.283 mean: 0.2835 sigma: 0.002062 min: 0.281by Chowa - General
I have used a single piezo mounted in the center of the carriage plate connected to the V1.22 board using shielded wires from the piezo. My build plate is wider than it is deep and it has a type of foam, my insulation faced with aluminum foil. There was no lack of sensitivity I have a video of it homing and also doing a mesh bed level. Must have been sitting on horse shoes that day as the whole sby Chowa - General
IDris Is the schematic available with the one shot? I'm in the process of building one on perf board want to experiment with band pass filter to get rid of low frequencies as the setup as exists is sensitive to someone walking or some other move event. My setup (under bed) is also very sensitive in the Y axis. Consider old tech such as LP vinyl records using dynamic pick ups which used shieldedby Chowa - General
I think of the piezo as a very sensitive microphone. I have noticed erratic flashing of the blue led by placing my hand near the piezo /wiring. Using a length of shielded cable salvaged from an old cd rom drive ,there was no effect. The power supplies in 3d printers are terribly noisy along with the mechanical vibratons. The one shot you are proposing should be an excellent solution. Good luck.by Chowa - General
Q1 assuming this is for mounting electronics I'm using the T nut and m3 screw Q2 Yes, very useful as the blue led is normally off Q3 Yes,yes,yes!! Definitely yes. 500ms adjustable for now A free bee -a bandpass filter using that spare op amp section and spare ground pin for the shielded sensor piezo cable. Since we are basically using audio freq it may be useful to limit the band width. Steveby Chowa - General
I like that idea very much. What drive current are you using for the Nema 17 pancake motor? I found that using the default DRV8825 drivers that the motor was operating extremely hot. I have not as yet run this extruder with the TMC2100 watterrot genuine but can't find the drive current for the Tevo branded OEM Will continue further work with the underbed mount sensor. Steveby Chowa - General
The BW is all metal. I can tap the table and it picks that up. I'm using one 20mm piezo in the center of bed hot glued to the support carriage. Sensitivity is not the issue in my opinion. For my application using more than one sensor is not practical, tho I have drilled and tapped 4 holes for that possibility. My bed has a foam insulation covered with aluminum foil which is a V4 bed. So heat is nby Chowa - General
Yes, the shielded cabloes appear to work well, don't have a scope to do anything . This is eating into my beer budget. I've replaced the stock motor /gear train with a Tevo Titan clone with a Nema17 stepper and saved over 500g of weight on the gantry. Need to adjust the driver as motor got very hot in a 1hr run. The B W uses one motor to turn 2 lead screws with a belt. Don't have specs as to whaby Chowa - General
The BW uses drv8825 driversso will try the genuine watterott and tune them to specs. BTW was it you who created the adjustable underbed Holders? If so is it on Thingiverse.com? Also rewired the cable from the pcb with shielded and from the piezo as well.by Chowa - General
I'm waiting for the heat sinks to arrive for the TMC2100 watterott drivers to see if microstepping calms things down.by Chowa - General
That scope you admired goes for usd 390. Nice to have but a new Printer?by Chowa - General
Has anyone considered using toothed idler pullies with the same pitch as the drive Belts? It may reduce mechanical noise as the belt teeth would fit in better than using smooth pullies which could cause sub or hypersonic vibrations. The scope pictures are great but the piezo signal is clamped by the 2 input diodes to ca 0.7+ - Vdc by D1 and D2 to the input of the differentiator IC1a. The serverby Chowa - General
I was referring to not use surface mount components, rather than thru hole mounted and soldered. Perhaps bad choice of wordsby Chowa - General
IDRIS OK, that schematic must be for V1.22 board and pins 5,6,2 are ground and a good place for the shielding connection. Is there a pcb for discrete Components? Suppose I could breadboard the circuit. Would be nice if the schematics were identified with the board versions. Steveby Chowa - General
Looking at the 13/09/2016 schematic it shows a 1kOhm resistor going to ground. I think a shielded cable from the piezo to the board would aid in noise reduction as well as a shielded one going to control board. The cheap PLUS are quite noisy so some ferrite beads could be useful. Don't have a scope do do any real analysis. BTW, am interested in your adjustable mounts for the piezo underbed mounby Chowa - General
Ground grd not qrd, my bad.by Chowa - General
His All One question regarding the V1.22 board is the qrd pin electrically the same as the led - ? I need a spare pin for the shielding. Have been following the discussion with interest. BTW, that drilled 20mm piezo that you sent Dj, I was able to sand the rough edge with P400 paper. Have not tested as yet want to see if the hole makes it less sensitive. My initial test with one piezo and shieldeby Chowa - General
Well, good news, I connected the piezo with 2 wires shielded a length of 25cm the shield connected to the DC -. No capacitive effect Now to get more shielded wire and hook up the other three. Could also use ferrite beads to choke off any other noise. Something to try later.by Chowa - General
Hello All I have been playing with a 20 mm piezo and have noticed that when I place my hand close to the sensor input wiring the blue led flashes uncontrollably.Suspect it could be a static charge from my body. Am not using shielded wiring from piezo to the input of the board. Since I do not have a scope to see what noise is being generated. The circuit is very sensitive and responds to a lightby Chowa - General
Looking fwd to the next batches for my BW. Sby Chowa - General