Notifications
Clear all

MinTemp error  

  RSS
drpeej
(@drpeej)
Trusted Member
MinTemp error

My printer is in a coldish garage and every time I switch it on I get Err: MinTemp Bed and is totally locked.  

If I play a heater on it for a minute or two it can be started up normally and then prints perfectly.

The temp of the bed was 16 deg C just now and that was cold enough to trigger the error

It seems a bit pointless to warn me of this when the bed hasn't even been heated yet

Is there any way to suppress this error or set the trigger temperature a little lower?

Posted : 27/03/2020 3:39 pm
holmes4
(@holmes4)
Estimable Member
RE: MinTemp error

The only way to adjust this is to use a custom firmware build, where you set BED_MINTEMP in configuration_Prusa.h to a lower value.

Posted : 28/03/2020 4:01 pm
drpeej
(@drpeej)
Trusted Member
Topic starter answered:
RE: MinTemp error

@holmes4

OK Thanks.   Thats a bit of a faff so I'll probably just keep a heater handy.  Wouldn't it be a good idea to have it as a configuration setting?

BTW - where can I find the firmware source files if I decide to go down the custom route?

This post was modified 2 years ago 2 times by drpeej
Posted : 28/03/2020 4:55 pm
drpeej
(@drpeej)
Trusted Member
Topic starter answered:
RE: MinTemp error

I found the necessary file on Github.   However I am puzzled because it appears to be set as follows:

#define BED_MINTEMP 10

I presume the 10 refers to 10 deg C

As I said,  mine raised a MINTEMP error at a temp of 16 deg C

Has the value already been reduced in a later build than I am using?

My current FW version is 3.8.0-2684

Posted : 28/03/2020 5:13 pm
holmes4
(@holmes4)
Estimable Member
RE: MinTemp error

It does, but there's a comment elsewhere that the actual value is higher. I changed mine to 5 and eliminated the problem. 

You may have a similar issue with the hotend mintemp. In this case, it doesn't even look at the Celsius value but instead the "RAW" value.  Change that to 1004 and that should take care of it.

Posted : 28/03/2020 8:35 pm
RedDawg
(@reddawg)
Reputable Member
RE: MinTemp error

I was having the MIN TEMP BED problem a few days ago myself. All Live Chat could suggest was upgrade F/W, full factory reset, bad thermistor, etc. I convinced myself that the thermistor was PROBABLY bad, but before ordering a new one and waiting waiting waiting, I decided to have a look at what would be involved in installing a replacement. Since the printer was already inoperative because of the inability to navigate the display menus (described in a more recent post, and now fixed), and it looked like it was going to be some time before a new thermistor would arrive, I went ahead and removed the print sheet and the bed below (9 screws). What I found was pretty surprising and I guessed it to be the problem: The thermistor is coupled to the underside of the bed with what appears to be nothing more than a square of Kapton tape (or something very similar) and pressed into place. Probably because of repeated heat cycling, this tape square had developed a "bubble" and looked like it was not keeping the thermistor in good thermal contact with the bed. I pressed and burnished the bubble as best I could around the contours of the underlying thermistor, put everything back together and NO MORE MIN TEMP BED errors! Prusa needs to evaluate this assembly technique for better long-term adhesion of the thermistor to the bed. If it happens to me again, which I expect it will, I think I will try to inject a small amount of thermal grease through the tape in the vicinity of the thermistor using a hypodermic needle, followed up by some Bondic (UV-cured bonding adhesive) in the same area. This same issue could also lead to higher-than-calibrated bed temperatures or even bed temperature run-away as the thermal contact between the bed and the thermistor continues to deteriorate. As always, YMMV.

1. "Creativity is the sudden cessation of stupidity." and "Any problem can be solved with the materials in the room." -Edwin Land, inventor of the Polaroid Land Camera. 2. "If I can't fix it, it isn't broken." -Me....
Posted : 29/03/2020 11:31 pm
holmes4
(@holmes4)
Estimable Member
RE: MinTemp error

@reddawg That's interesting, but not the issue here. The problem is when the ambient temperature is below the firmware's cutoff for MINTEMP. You turn on the printer, and it immediately complains about MINTEMP_BED and makes you do a reset, after which it complains about MINTEMP_BED. If you can get the bed to start heating, you're fine. I had taken to running a hot air gun (on low) at the bed for 10-20 seconds to raise the temp enough to get past the error. Since making the adjustment in the firmware, I don't have this problem anymore.

I have my printer in my basement where, during the winter (and early spring), the ambient temperature is around 58F, which the stock firmware thinks is too cold.

Posted : 29/03/2020 11:36 pm
MisterMaker
(@mistermaker)
New Member
RE: MinTemp error

Sorry for the bumb but it is getting colder here now. My Printer is in an enclosure which is not heated, but the printer is easily able to heat this enclosure up. But the min:temp error stops me from doing this, which is stupid. This should only be triggered when starting a print, not at boot!

Posted : 31/12/2020 9:45 am
holmes4
(@holmes4)
Estimable Member
RE: MinTemp error

@mvdh

I agree, but if you don't want to edit the firmware sources and make a custom build, you can do what I sometimes do and run a hot air gun (or hair dryer) towards the build plate and extruder to warm them up enough to let me get to the preheat function.

Posted : 31/12/2020 10:06 pm
Share: