The sun shone again this morning so ar last I was able to do some proper tests of the modulated sensor in sunlight. With my 3k3 load resistor and the sun shining directly on the white tape, at my 1mm nozzle G31 calibration height, the sensor saturates. If I add a 1k5 load resistor in parallel with the 3k3 (giving just over 1K total load), then the sensor no longer saturates and the reading is aby dc42 - Ormerod
Quoteiamburny @dc42 - that was my original plan and have printed many parts with teeth around the peg, however when the belt is curved that way the teeth on the belt close together and I can't print small enough teeth to fit the tiny gaps, it's not for want of trying I've printed 10+ variations of that type. In that case, how about having just a slot with teeth in it on that side, similar to thby dc42 - Ormerod
Andy, I agree, a digital solution would indeed be better, using an attiny or similar on the sensor board and sending the data back to the Duet via SPI or similar. Of your other suggestions, an R-C filter right at the Duet mcu would help by averaging out the noise - that is why I would like to connect 10nF between pins 74 and 78 of the mcu. A buffer amp on the sensor board would help protect againby dc42 - Ormerod
QuoteKimBrown Right well my question is about the Y axis... Positive Y makes the table come towards the motor, otherwise it follows the diagram on the Printer Interface. That is correct. The movement of the head relative to the bed is in the positive direction i.e. away from the motor.by dc42 - Ormerod
Quotedroftarts You could take the twist out of the belt, then it would go into the lower one. Ian RepRapPro tech support I was assuming that if I did that, the belt wouldn't go round the idler bearing smoothly - but I guess you think it would be OK?by dc42 - Ormerod
Quotedroftarts I have updated the commissioning instructions - ... Can inexperienced and experienced users alike take a look, and tell me if it looks sensible? Does it need more? Looks good to me. My only comment is that I think putting alu or white tape on the x-homing tab should be part of the standard build.by dc42 - Ormerod
@iamburney, thanks for sharing your y-bed attachment parts design. I printed a pair and now at last I have a good tension in the y-belt. There is one aspect of the design that I think could be improved. The belt between the y-attachment part and the y-idler bearing is no longer parallel to the y-axis.This is particularly apparent at y=0: As a result, the total belt length, and hence the tensiby dc42 - Ormerod
QuoteKimBrown LoL then the fun started trying to find the thermistor fault..... Not easy working here in my cabin with just a digital multimeter with probes the size of fingers... Then I remembered I had some safety pins in my bag and used them as probes to get inside the plug. Turned out to be the connector on top of the Hot Head... A splayed socket... fixed with a gentle shove with a safety pinby dc42 - Ormerod
Well I looked at the waveforms on the +5V and +3.3V rails with a scope. First thing I saw was a lot of ringing at about 200MHz, several hundred mV peak to peak. As my scope only has a bandwidth of 100MHz, I reasoned it must actually be somewhat greater than I could see. I was a little suspicious of the input and output capacitors on the LM1117. The datasheet recommends 10uF tantalum at the outputby dc42 - Ormerod
1. AFAIR the snowman is about 5mm thick. You can tell if the print has finished normally, because the bed moves the print away from the print head and the heaters are turned off. 2. The original IR probe is very sensitive to ambient light. Fluorescent and LED light are OK, bright sunlight and incandescent light are not. I have a prototype modulated sensor to alleviate this, and RRP are working oby dc42 - Ormerod
QuoteJamesR10 The other problem, is that at times it prevents me from setting the z to zero and continues to report a plus or minus figure and ignores the G92 command. Any idea what does this? If you have already run bed compensation, then when you enter G92 Z0 it seems to apply the compensation and "correct" the value you set. Hopefully this will get fixed soon (I may even take a look at it mysby dc42 - Ormerod
The resistance of the thermistor is 100K at 25C, so it's most unlikely that you would get a high enough contact resistance to affect the reading. OTOH I had my reading drop to -273 a few times, which indicates open circuit. I had to tighten up the receptacles in the 6-way socket to cure this.by dc42 - Ormerod
I did a bit more investigation. The expansion connector has only one ground pin and it is connected to totally the wrong place to use as the ground return for analog inputs. The expansion connector really needs a separate analog ground pin near the other end. However, the ground connections along the bottom of the board go fairly directly to the processor, so the ground here should be fairly cleaby dc42 - Ormerod
Re x-axis chattering, try putting a bit of white tape on the x-axis homing tab. Also check that the x-carriage can slide past the Z extrusion - I had to file away some protrusions on my x-carriage. I strongly recommend you use the manual bed levelling mechanism to get the bed flat - but you need three 16mm M3 screws to do this. Don't bother supporting the front two corners of the bed, just screwby dc42 - Ormerod
Also, update the firmware on the Duet board if you have not already done so. The current version is 0.57a. Firmware earlier than 0.53 gave less accurate temperature readings.by dc42 - Ormerod
@TMD_RS436: I don't think a UV tube would affect the sensor significantly, it's the IR in the sunlight that is the problem. @Dennis, @Treth: yes, if I put an attiny or similar mcu on the sensor pcb, then I could arrange for the output to be 800 to 900 at the calibration height, thereby minimizing the effect of the Duet electronics noise on the reading. This is assuming that the 3.3V supply at thby dc42 - Ormerod
Quote9600 Also, when attempting to print something the fan duct pushes the bulldog clips off the bed as it moves to one end That is unfortunately intrinsic to the design. See item 7 in my unofficial troubleshooting guide at . For the sensor hitting the bed before the nozzle does, see Ian's reply. You can also adjust the sensor height a little because the screw holes in it are a little oversize.by dc42 - Ormerod
According to you can print PLA direct on glass, if it is heated to 70C. Has anyone tried this?by dc42 - Ormerod
I didn't perceive a problem with the plywood ribs or with the fit between the front rib and the bearing, but the MDF bed support was sagging at both back corners. So I kept the ribs but replaced the MDF with a 3mm aluminium triangular bed support. I had already fitted bed leveling adjustment screws as described in the manual bed-leveling instructions. It's level to within about 0.1mm now, exceptby dc42 - Ormerod
Ray, that's interesting! I also found the z-rod was wobbling. Watching it, it was clear that the problem was not that the rod was bent, it was that the bottom of the rod was not concentric with the bearing. I assumed I had fettled the z-driven gear unevenly to make it fit. So I printed a new z-driven gear, and used a hammer to put a nut in it instead of fettling it. The new one wobbles just as muby dc42 - Ormerod
QuoteTMD_RS436 @dc Why not fit the bare minimum value in series with a pre-set resistor that way you can adjust it with the arm at its maximum height and adjust it to reduce the ambient/sun light and then do the test for the Z sensor. And by having the bare minimum fixed resistor you will be protecting the emitter if you went to low with the pre-set. SMD Pre-sets are rather small. Just an ideaby dc42 - Ormerod
Hi dmould, Yes the thermistor reading code has changed. The old code under-reported the extruder temp at low temperatures and over-read it at high temperatures. However, the code for reading the IR sensor has not changed at all. Perhaps your sensor has shifted position, or the connector is coming loose? The screw holes in it allow for quite a lot of movement.by dc42 - Ormerod
Yesterday I painted the x-carriage around the sensor black, as per dmould's suggestion. I was sceptical, because even if some light either gets through the x-carriage or reflects off it, it stand to reason that ambient light reflected from the target area on the bed will also be a problem. But I felt I had to try it. Today the sun came out briefly, so I did some more tests using the modulated seby dc42 - Ormerod
I'm not too surprised by your results, for two reasons: 1. The datasheet for the thermistor from the manufacturer (Honeywell) is very poor, all it gives is dimensions, nominal resistance (100K) and resistance tolerance (+/- 2%). Their catalog also gives "Resistance ratio" but doesn't appear to define that term. The thermistor beta value quoted by Digikey will be measured over a particular temperby dc42 - Ormerod
QuoteRadian dc42, obviously there's a finite budget involved and one use for it might be to source a better PSU. I agree with you that very few qualities are critical for powering a 3D printer but there will always be "lowest common denominator" PSU's like RRP ship. Pitching into a slightly higher price bracket won't necessarily return a better PSU. Droop on the 12V rail is all we need to eliminaby dc42 - Ormerod
Another way to increase the power to the heated bed would be to replace the ribbon cable by something with lower resistance. Three pieces of this cable wired in parallel would, by my calculation, have less than half the resistance of the ribbon cable, and increase the bed header voltage by around 0.2V. What I haven't worked out is how to prevent the cables getting tangled. It needs something likby dc42 - Ormerod
I think the discussion about regulation of the PSU is a bit of a red herring. The Ormerod doesn't need a well-regulated PSU because it has 2 regulators on board for the electronics, and the actual voltage on the 12V rail is not critical. The issue is that the output voltage of the supplied Ace/Alpine PSU drops somewhat below 12V under load, and when printing ABS (but not PLA), this and the resistby dc42 - Ormerod
QuoteSlinBin What else is not read at startup ? The whole of config.g is not being read at startup. So this also includes the network settings, which explains why you can't connect over Ethernet. As 3D-ES says, ditch the SDHC card supplied and use a good one instead. I picked up a 4Gb Class 10 Maplin own brand one for about a fiver.by dc42 - Ormerod
I have no experience of the Mendel, but I think the big advantage of the Ormerod is the Duet electronics, which has a much more powerful processor then the Melzi electronics used on the Mendel, built-in USB without going via serial and with flow control, and built-in Ethernet. This should eventually provide a lot more more functionality, when the firmware catches up. But I expect the Duet electroby dc42 - Ormerod
QuoteRory166 Just found overclock selling Alpine psu cheaper than ACE. 500w alpine less than 10 pound including vat. The one RRP has been shipping is the 550W one, £10.99 from overclock. They also have the Corsair CX430 (the non-modular version of the CX430M that I am now using) at £34.50.by dc42 - Ormerod