Which thermistor

Hi all,

I'm collecting parts for my build and am struggling to pin down which thermistor to acquire.

On the wiki I only see generic references. Now I appreciate that the thermistor settings can be calibrated but all the ones I am finding are rated around -55 to 150 degrees C.

As the nozzle needs to heat to 250C for ABS this seems to be too low. (Or can the thermistors handle more?).

Please help advise me.

Thanks,
Craig

You need something like this [uk.farnell.com] it has a 300C rating.

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[www.hydraraptor.blogspot.com]

the part you need is B57560G104F

If you can't find the EPCOS B57560 series there are lots of other choices. The Digi-Key online part selector, for example, has a good selection of 100K thermistors with an upper limit of 250 to 300 degrees. They should all work fine in an extruder.

All,

Thanks for the feedback, I have now been able to track down the right part. Each time I searched I couldn't find the right thing which I put down to my own inexperience at buying electronic parts.
I kept finding the lower rated parts.

Cheers,
Craig

I use the Honeywell 135-104LAF-J01 (Farnell Nr 1383986) in my printers, I have not had any failure and printers must have gathered thousands of hours of printing time:

www.3dp-tools.com

hey people

Is there a reason we are looking at 100K Ohm thermistors?

I have found this one which has a tolerance of 1% and is only £0.42 as opposed to this one which looks more like the standard one but costs £2.36.

Is there any reason or pitfall in using one over the other besides cost?

Thanks

I'm not aware of any reason why the £0.42 device would not work. The axial arrangement of the leads might make it a bit more difficult to attach securely without shorting, or not, depending on the approach you take. I'll note that the leads are much thicker than the leads on the more expensive bead style device, but I don't think in this application the difference would be significant. Most likely you will have to generate a new lookup table for the firmware, but otherwise I believe it should work fine. If anyone knows better please speak up.

The specific £2.36 device that you've linked is not actually a good choice as it has a specified upper limit of 200C and you really want a device that has an upper limit of > 250C (300C is probably a better choice).

... i use mostly PT100 for their linearity and measuring range from -50 to +600 centigrades, but they're pretty expensive

But when asking at Heraeus you can get some samples, so i received some even more reliable ones in cylindrical ceramic housings with 2mm diameter and measuring range until 800 centigrades for free

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madscifi Wrote:
-------------------------------------------------------
...
>
> The specific £2.36 device that you've linked is
> not actually a good choice as it has a specified
> upper limit of 200C and you really want a device
> that has an upper limit of > 250C (300C is
> probably a better choice)
...

Yea - it seems that thermistor's data sheet or data PDF states that it is good for measuring temperature up to 300 Celcius. It is also the one listed by part number by james villeneuve and Nophead, so I am guessing it is the Mouser details that are incorrectly captured.

So how difficult is it to generate a new lookup table for the firmware. Will I need any special equipment? If so it would probably be more cost effective to go for the standard glass bead one.

AgeingHippy Wrote:

> Yea - it seems that thermistor's data sheet or
> data PDF states that it is good for measuring
> temperature up to 300 Celcius. It is also the one
> listed by part number by james villeneuve and
> Nophead, so I am guessing it is the Mouser details
> that are incorrectly captured.

That is why one should always read the datasheet, just like i did should have done. Sorry about that.

> So how difficult is it to generate a new lookup
> table for the firmware. Will I need any special
> equipment? If so it would probably be more cost
> effective to go for the standard glass bead one.

The thermistor page has a link to a program that will generate the table, and see the following page for instructions on determining the relavent parameters to feed the program.

Hi,

Me again. I'm busy programming my extruder controller (eventually, yeah I know, I'm taking my time).

Anyway, I bought the B57560G104F recommended above. From what I can make out, the standard table in the latest firmware (20100702) seems to match. It is described however as RS Thermistor 528-8592, which comes back as B57540G0104J.

Can anyone confirm of the table is the same? Or if not, does anyone have the correct table (which we could add to the wiki - where it should be if this is a recommended thermistor) for me (to save me having to figure out how to create it myself from the script).

Thanks,
Craig

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