Kossel XL - Migrating from Marlin to reprap firmware
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@bearer said in Kossel XL - Migrating from Marlin to reprap firmware:
If the marlin board was configured for different microstepping that would account for the difference in steps pr mm.
not from 80 to 100. thats 25%. You cant get that with a different microstepping settings.
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Too early for quick maths, 12 to 16 is close, but close isn't good enough indeed!
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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.
HTH David
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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.
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@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.
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marlin thermistor values are actually in the code
// R25 = 100 kOhm, beta25 = 4092 K, 4.7 kOhm pull-up, bed thermistor
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@Veti
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
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@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.
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@wylley said in Kossel XL - Migrating from Marlin to reprap firmware:
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.
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@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.
