jameswalsh Wrote: ------------------------------------------------------- > course wrong. I am currently contacting all the > effected customers to inform them to disregard the > thermistors and await replacement ones. Did anyone get these replacements or a contact from James? I've tried a few times to contact them through the website and always get an auto-confirmation but never a repby NigeO - Reprappers
ebcdic Wrote: ------------------------------------------------------- > Thanks for your reply. Can you clarify a few > things? I think 'Another' has probably clarified all you need, but didn't mention the FET wiring. > [*] The unswitched +12V - is it reasonable to take > this from one of the IDE disk connectors on the > power supply? That's what I did. Look at the supply, chooby NigeO - United Kingdom RepRap User Group
I updated the instructions on the longboat wiki page and they are working fine for me. the official instructions seem to miswire the FET so it will work but get too hot. I still haven't received the promised corrected thermistor so don't know if that will help too. I hope the instructions get updated or that other builders join in updating the wiki. It's frustrating that there are snippets on aby NigeO - United Kingdom RepRap User Group
Simple question first - do you have endstops fitted? If not, the motors will only move one direction unless you've disabled them in the firmware configuration.h, just checking you've tried both directions. I ask because it puzzled me for a while... Presume you have 12V connected exactly as it was for the test firmware (maybe worth reloading that to double-check it's not just wires disturbed etby NigeO - Reprappers
jez_a Wrote: ------------------------------------------------------- > No, I received 2 thermistors in a zip lock bag, no > markings etc. - I have checked the resistance with > a multimeter, and they both read around 1.7/1.8K > on the 20K scale. I agree that's probably the same as mine, which arrived a week or two ago along with the Kapton tape. Mine was about 2K3 at room temperaturby NigeO - Reprappers
nophead Wrote: ------------------------------------------------------- > The problem you will get is the thermistor will > heat itself, giving a reading too high, assuming > it does not burn out. The data sheet will give the > maximum power dissipation and the self heating > error. Thanks for the warning. As there are new parts coming anyway and no likely damage to other parts, Iby NigeO - Reprappers
Another thought, it looks like the problem is the pullup on the thermistor (4.7K) meaning that at 185C the ADC counts are so low that it's unusable. If I put 100 ohm across the pullup as a better match for the 2K thermistor, the ADC scaling would be right. Any likely problem with that? Worst case power dissipation 1/4W on the resistor, can produce the updated tables with the python script, andby NigeO - Reprappers
Dee Cee Wrote: ------------------------------------------------------- > couldn't properly. We have now ordered the 100k > Epco ones that should have been supplied. [...snip...] > Mark did the right thing and we will be fitting > the 100k Epcos before next use. Patience didn't pay off, in this case! I can't believe it, I shouldn't have waited for the back order (and then was pleasedby NigeO - Reprappers
I've got an almost-complete Longboat Prusa, using the supplied 3mm PLA. The extruder runs but won't extrude. The supplied bead thermistor is approx 2.3K at 20C, different from the 10K calibration on the wiki, so it initially didn't heat at all. I took a guess that it might be as the previous one was noted as being an RS part and this is the nearest, but it doesn't seem to be right. It couldby NigeO - Reprappers