Mendel: what termistor to use for heat bed?

Just got my Mono Mendel kit a while ago and have been slowly (but surely) building it, but yesterday while soldering the heat bed thermistor I messed up and ruined it.

So now I'm trying to find out which thermistor is being used by default in the Mendel kit. I know it's possible to use ones that are different but I'd prefer not to mess around with calculations, tables, firmware and what not for my first build. I'd like to be able to follow the guide exactly as is.

So I know I need a "glass bead 10k thermistor", but the ones I find have different properties, like for example their maximum operating temperature. Normal values seem to be 125º, 200º, 300º etc, but I can't seem to find any information on the one used in the kit.

I've found these on the internet:

[uk.rs-online.com] (max. 250º)

[es.mouser.com] (max. 300º)

Any help would be much appreciated!

-Tako

Edited 1 time(s). Last edit at 04/19/2013 08:57AM by quintesse.

Incorrectly set thermistor can show you +30C more than it is, you will force extrusion, and bam hot end damage or stuff like that.

That is to say, if you skip messing with thermistor, in the end thermistor will be messing with you. Your choice.

Afaik there is no default, but i think first used were 100k, and that or 200k even are probably better at high temps. Its rating better be 300+C, the one with 250C i wouldnt trust.

And 20% tolerance means that you have a thermocouple ready to calibrate its thermistor table, otherwise its useless. If you dont have means to read real temperature then you cant customize it, then you are better with something aiming to 0.1% tolerance which is gonna be more expensive. But if you have a thermocouple you customize your own thermistor table and that should be best thing to do either way, and only then you can use something like +/-20%, since you customize it then doesnt matter what error it has from the rest of its batch.

First of your links i believe points to a product series that was widely used for reprap before, but i think with 100k value.

Edited 3 time(s). Last edit at 04/19/2013 10:34AM by NoobMan.

Force extrusion? This is for the heatbed, not the extruder, The extruder uses a 100k thermistor like you said, but the heatbed only uses a 10k one. And the first one I link to, the max. 250ºC one, has a tolerance of 5% which seems okay, doesn't it? Or does the heatbed get really hot as well?

Oh yes i missed the heated part. So if you already have 100k for hotend, why not get same for heated bed. Probably this one

Yes, I bought a similar one, but a 10k version (because that's what was in the kit so I didn't want to change that).

But that was before someone pointed out to me that the list of components in the build instructions actually give a brand and type number: Semitec 103gt-2 ( [es.mouser.com] )

So I ordered that one as well, just to be on the safe side.

Anyway, thanks for your help!

Edited 1 time(s). Last edit at 04/19/2013 03:02PM by quintesse.

OK.

Btw, welcome to reprap forum.

Dont hesitate to post here. Whatever your problem is, we are guaranteed to make it more complicated than it was initially.