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  1. #1

    Thermometer purchase...?

    Hi

    Been looking to buy a thermometer to measure accuracy of my CTC...

    I have an IR thermometer but its useless for measuring hot end and bed temps - it reads pitifully low which is probably down to reflections I guess.

    Anyone found an "ebay" special that does the trick?

    I would prefer a probe type device - preferrably with the "meter" too - so I dont need to go use a multimeter with a K input....

    TIA


    David

  2. #2
    Technologist LuckyImperial's Avatar
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    Unfortunately you'll have a hard time getting an accurate temperature relative to the thermistor that's inserted into the heat block. The surface of the heaterblock is quite a bit cooler than the internal thermistor location.

    You could always try buying your own thermistor and measuring it's resistance and then doing the conversion on your own.

    http://www.mouser.com/ProductDetail/...2FPgvFdg%3D%3D
    http://www.atcsemitec.co.uk/gt-2-glass-thermistors.html

  3. #3
    Thanks Luckyimperial

    My thermistor is bolted on the outside of the heat block (CTC) - so is probably part of my problem.

    My IR is a Fluke, so you would have thought it would have read it ok, but its terrible for this application.

    I guess I will but a probe type K and use my multimeter (which has a K input).

    I thought there must be a "forum favourite" thermometer that peoplke would use...


    David

  4. #4
    Staff Engineer Davo's Avatar
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    Have you tried to apply some high temperature, flat black paint to the surface you wish to measure with your IR?

  5. #5
    Technologist
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    Easy way to check basic accuracy is to check the ambient temp and then compare it to the temp readings on the CTC.

    I found them to be very accurate for the thermocouple on the hotend. Not sure what yours has, but mine uses K-Type thermocouples, so they are a known quantity. I did replace the thermister on the bed, as this was reading about 10C low.

    TBH, people get quite hung up about the exact temp instead of seeing what works for them and then sticking with it. I use an indicated 230C for ABS and 210 for PLA and Ninja Flex.

  6. #6
    Guys - thanks for the replies and ideas!

    My lead in to this was clicking extruders, so I questioned the temps.

    The thermistors are K type and I ave ordered some new ones. My guess is that they are over reading the temperature... causing the restriction to feed.

    I just wanted a thermometer so i can be really sure, and with Sailfish, understand there is no way to calibrate them unless I use washers between the thermistor and the heat block (which seems to do the trick!).

    I had not thought of black paint - thats worth a shout... not sure with the Ir I would have a big enough "black" target though....


    Will let you all know...

    David
    Last edited by BestGear; 05-09-2017 at 10:50 AM.

  7. #7
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    Reading your other post, I don't think this is anything to do with temperature, but poor filament drive. I have posted a solution I know worked on my CTC in your other thread.

  8. #8
    Super Moderator curious aardvark's Avatar
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    I use a cheap ir gun on my heat bed - pretty accurate. Just don't stand the other side of the room while measuring :-)

  9. #9
    Engineer Marm's Avatar
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    Ir guns will work fine on the bed, but not pin point targets. The simple explanation is that they measure a cone of temperatures out from the sensor. Think shotgun not rifle. So aiming it at the heated bed, you'll get the average of the entire heated bed, which is what you want. If you try to aim it at the extruder, then unless you are almost right up against it, you get readings from the air and framework around it.

    If you want a simple way to test the hot wnd's temp, get a multi meter that can do temps (everybody should have a multi meter in their toolkit), and attach the thermocouple.

  10. #10
    Staff Engineer Davo's Avatar
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    OP, are you using an IR camera, with different temperature zones rendered in different colors?

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