I'm just about ready to wire up my machine but I came across some issues whilst checking the resistance. The thermistor in the hot end is giving me ~140Kohm while the thermistor in the bed is giving ~100Kohm(as it should), both at room temp. Can anyone explain? Secondly the bed heater is giving me 1.4Ohm when in the manual it says it should be 1.2 - will this be a problem? And also, I've noticed one of my limit switches dosn't seem to be doing anything when I press the button(it dosn't make a click sound). I not really sure what the function of the limit switches are but I presume they are a precautionary measure to prevent damage to the machine if the calibration is off or something? Do I need a new limit switch? Any help is greatly appreciated. Thanks https://reprap.org/forum/read.php?292,283879,283879#msg-283879 Fri, 11 Sep 2026 21:22:18 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?292,283879,294795#msg-294795 https://reprap.org/forum/read.php?292,283879,294795#msg-294795 nophead Mendel90 Tue, 14 Jan 2014 17:17:23 -0500 https://reprap.org/forum/read.php?292,283879,294777#msg-294777 https://reprap.org/forum/read.php?292,283879,294777#msg-294777 tforde90 Mendel90 Tue, 14 Jan 2014 16:47:31 -0500 https://reprap.org/forum/read.php?292,283879,294690#msg-294690 https://reprap.org/forum/read.php?292,283879,294690#msg-294690 maximum value of Z not the minimum.]]> neildarlow Mendel90 Tue, 14 Jan 2014 14:23:54 -0500 https://reprap.org/forum/read.php?292,283879,294638#msg-294638 https://reprap.org/forum/read.php?292,283879,294638#msg-294638 M119 gives the result:
"x_min:L y_min:L z_max:L"

Why is it z_max instead of z_min?]]> tforde90 Mendel90 Tue, 14 Jan 2014 12:58:34 -0500 https://reprap.org/forum/read.php?292,283879,289069#msg-289069 https://reprap.org/forum/read.php?292,283879,289069#msg-289069 tforde90 Mendel90 Sat, 04 Jan 2014 10:21:45 -0500 https://reprap.org/forum/read.php?292,283879,288808#msg-288808 https://reprap.org/forum/read.php?292,283879,288808#msg-288808 nophead Mendel90 Fri, 03 Jan 2014 19:21:42 -0500 https://reprap.org/forum/read.php?292,283879,288736#msg-288736 https://reprap.org/forum/read.php?292,283879,288736#msg-288736 BSBMX Mendel90 Fri, 03 Jan 2014 16:23:52 -0500 https://reprap.org/forum/read.php?292,283879,288667#msg-288667 https://reprap.org/forum/read.php?292,283879,288667#msg-288667
Have you subtracted the resistance of your meter leads from the bed resistance?

I don't think 1.4R will be a problem as the wires always add a little to the actual resistance of the bed so it tends to measure a bit more at the Melzi end.]]> nophead Mendel90 Fri, 03 Jan 2014 14:13:26 -0500 https://reprap.org/forum/read.php?292,283879,288637#msg-288637 https://reprap.org/forum/read.php?292,283879,288637#msg-288637 The thermistor problem fixed itself I'm now getting ~100kohm for both.
I'm still getting 1.4ohm instead of 1.2 for the bed heater tho. Will this be a problem?]]> tforde90 Mendel90 Fri, 03 Jan 2014 13:21:30 -0500 https://reprap.org/forum/read.php?292,283879,288080#msg-288080 https://reprap.org/forum/read.php?292,283879,288080#msg-288080
Two ways I can think of damaging them: one is over tighten the screws (but I would expect that to break the printed part first) the other would be overheat them while soldering so the casing melts and the contacts move. Do the solder tags look like they have moved?]]> nophead Mendel90 Thu, 02 Jan 2014 16:16:36 -0500 https://reprap.org/forum/read.php?292,283879,287953#msg-287953 https://reprap.org/forum/read.php?292,283879,287953#msg-287953 tforde90 Mendel90 Thu, 02 Jan 2014 11:15:41 -0500 https://reprap.org/forum/read.php?292,283879,283901#msg-283901 https://reprap.org/forum/read.php?292,283879,283901#msg-283901
not just to prevent damage. when you turn it on, before starting the print, it will home, the motors will run to the end, untill they touch the swich. that's how they knw where 0 is.
are you sure it is doing nothing, check with the ohmeter .
sometimes you may not hear the click. get a voltmeter, and check resistence between legs when the switch is pressed or not. (should be 0 resitence in one case and a break in the circuit in the other)
or check it in software - page 67 of the manual
(or just wire a 9v battery and use your tounge like we did before DVMs)]]> avishalom@gmail.com Mendel90 Mon, 23 Dec 2013 14:46:07 -0500 https://reprap.org/forum/read.php?292,283879,283879#msg-283879 https://reprap.org/forum/read.php?292,283879,283879#msg-283879 Secondly the bed heater is giving me 1.4Ohm when in the manual it says it should be 1.2 - will this be a problem?
And also, I've noticed one of my limit switches dosn't seem to be doing anything when I press the button(it dosn't make a click sound). I not really sure what the function of the limit switches are but I presume they are a precautionary measure to prevent damage to the machine if the calibration is off or something? Do I need a new limit switch?
Any help is greatly appreciated.
Thanks]]> tforde90 Mendel90 Mon, 23 Dec 2013 14:13:42 -0500