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Jhead MK V thermistors

Posted by dslc 
Jhead MK V thermistors
May 04, 2013 04:27PM
The Jhead reprap wiki page lists the EPCOS 100k B57560G104F as the thermistor (for the MK V at least). I ordered one of these recently (from a reputable supplier), however, and neither the thermistor nor the size of the thermistor mounting hole match the B57560G104F dimensions (2.4 x 4.1 mm for the glass bead).

Does one anyone precisely which thermistors are being commonly supplied with these hot-ends? E.g., how about this Glass bead NTC G540 thermistor: [radionics.rs-online.com] ? The bead dimensions on this thermistor are 0.8 Dia. x 1.4mm - which seems much closer to the hole machined on the Jhead I have.

Semi-commercial engineering | Reprap diary
Re: Jhead MK V thermistors
May 04, 2013 05:50PM
if i remember correctly there are 2 different versions of the mk v. They are designed for different thermistors because the original was discontinued by the manufacture. Are you sure you have the correct one?
Re: Jhead MK V thermistors
May 05, 2013 08:05AM
Thanks! I didn't even notice that the MK V-B uses a different thermistor. The supplier didn't specify whether it's a MK V or MK V-B they are sending me - but I guess it's probably the newer one.

Semi-commercial engineering | Reprap diary
Re: Jhead MK V thermistors
May 09, 2013 02:50PM
One more question if I may (not related to J-head hot-ends specifically) ...

Is there any significant drawback to using a 200k thermistor as opposed to a 100k thermistor? (I realize that I will have to update the thermistor table in the firmware.)

I ask because the only source I can find for the thermistor I'm looking for is out of the 100k versions.

Semi-commercial engineering | Reprap diary
Re: Jhead MK V thermistors
May 09, 2013 03:22PM
I'm also having an issue finding out what table to use.

I recently got a MK V-B, and it came with a thermistor.

I have no information on which one it is.

I know it's ~100k at room temperature, and it was ~30k at 50deg C
Re: Jhead MK V thermistors
May 10, 2013 11:02AM
from maker blog, the MK5b use :

Part Number: 104GT-2
Manufacturer: Semitec
Description: NTC 100k ohm 3%
Tolerance: 3%
Data Sheet: High Heat-Resistance and High Sensitive Thermistor
Diameter of Glass Bead: 1.35mm +-0.15mm
Length of Glass Bead: 3mm +-1mm
Lead Length: 45mm +-1mm
Lead Diameter: 0.15mm to 0.18mm
If using Sprinter firmware, select temperature table #5.

Now, good german copies of the J-head use yet another thermistor. This one is
honeywell 135-104QAD-J01 or 135-104LAC-J01 and should use the table #7 of sprinter
The latter is easy to identify, it is an inline cylinder one with a lead on each side like a resistor, not a bead.
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