Kossel XL - Migrating from Marlin to reprap firmware
bearer last edited by
Too early for quick maths, 12 to 16 is close, but close isn't good enough indeed!
The Max carriage travel is used only to limit the length of homing moves, so the exact distance is not critical.
The difference between 80 and 100 steps/mm is 20 vs 16 tooth pulleys.
The default speed and acceleration limits in the configurator are quite conservative, so increase them if you know your machine can handle higher values.
Thank you all for the very helpful and quick replies !
The last concern I would have is the Beta values for the thermistors,
for the hotend I just selected the e3d hotend preset since I have an e3d v6 but I have no clue what the coefficient is for the bed thermistor and have no reference for the model, is it ok if I leave it as default (4138) ?
where did you buy the bed from?
if you leave the default your temperature will be off.
for low pla (60C) the temperature difference can be a few degrees, assuming the common thermistors used. you could work with that.
higher than that can lead to bigger temperature differences.
@veti I just realized that in Marlin, I have both TEMP_SENSORs set to 1 and the comments say that "1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)". So I assume that "pullup" is the Beta coefficient and so I will set the bed's one to 4725 too so its the same as the hotend's like in Marlin.
Makes me think one could do a simple script to migrate from Marlin to RRF.
marlin thermistor values are actually in the code
// R25 = 100 kOhm, beta25 = 4092 K, 4.7 kOhm pull-up, bed thermistor
wylley last edited by wylley
Oh ok, this is really confusing so both of my thermistors were at 4092 K but the configuration tool sets it to 4725 when I select the e3 hotend preset which happens to be really close to the pullup. So what should I do ? Put both at 4092 like in Marlin or maybe only change the hotend's one to 4725 ?
if you have an genuine e3d hotend then yes you need to set B4725 and C7.060000e-8
most clones v6 hotends do not use a semitec thermistor. for those you do not set it to B4725 and C7.060000e-8
@veti It is a genuine one so I had the wrong Beta coefficient for years, good to know, thank you. I'm guessing leaving the bed at 4092 K like it was in marlin should be fine.
Veti last edited by Veti
I'm guessing leaving the bed at 4092 K like it was in marlin should be fine.
yes. If it worked before it should be fine.
It is a genuine one so I had the wrong Beta coefficient for years
dont forget about the C coefficient. you need to set it as well as that changes the temperature calculation to the steinhart-hart model. A Beta value in steinhart-hart model has a different meaning.
wylley last edited by wylley
@veti After some research I've found that both of my thermistors had the wrong beta coefficient on Marlin since e3d says to use the TEMP_SENSOR 5 (wich has 4267 K beta value) and that my heatbed thermistor looks like a cheap chinese one with 3950 beta value. So I've put the e3d preset B4725 and C7.060000e-8 for the hotend and B3950 C0 for the heatbed on RRF.
I guess the manufacturer didnt care about the +-150 difference on both thermistors and just went with TEMP_SENSOR 1 on Marlin.