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Thread: Hottop bean mass temperature probe

  1. #1
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    Hottop bean mass temperature probe

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    This is just a topic split from http://coffeesnobs.com.au/YaBB.pl?num=1236075603/45#45 so as to not take that thread too much OT.

    Quote Originally Posted by 695C454F1B1A2C0 link=1236075603/47#47 date=1236576405
    Quote Originally Posted by 0411060413160F0F0E020D630 link=1236075603/45#45 date=1236514557
    my probe is the shaft below it and the hole at the bottom was my first attempt! *
    Have any posts been made on installing a probe from this location Greg? *I cant find anything on the Things Coffee knowledge base. *Would be much appreciated!
    Not yet. Theres info on the web in general about running a probe through the bean chute cover but I wanted a more elegant solution. Its certainly helped a lot with my roasts and being able to see exactly what the bean temps are doing, and makes experimentation that may affect the environmental temp but not the bean temp a lot easier. It was originally just something for my own use but I can see how it could benefit others too. The problem is that since it involves opening the unit right up it will void warranty, so its not something we can officially recommend our customers do!

    As to the poll, one option if the interest is there is to do the install as our end with a Handy Andy meter and probe so your warranty stays intact. Obviously theres the cost of the meter and probe, and then the install time so I dont know what it will work out to but $250 is a ballpark figure. You could do it yourself for less if you were prepared to void your warranty. Would be interesting to hear your thoughts, regardless of whether youre actually looking for a Hottop at the moment.


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    Re: Hottop bean mass temperature probe

    Hi Greg,

    sounds like a good option to have available but also worth doing would be a thermocouple only option for those of us with K type meters already from other things. Also opens up using or not using CS version 1 or 2 meters and logging software etc.

    If you want to add another option to the poll I would vote for the thermocouple only version finished to a pair of 3mm binding posts for ease of connection.


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    Re: Hottop bean mass temperature probe

    I wasnt sure how hard it would be to find just the probes but if we could that would be an option. Poll adjusted just for you BF! :)

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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 4B4C48474F455040474E290 link=1236648700/1#1 date=1236652211
    If you want to add another option to the poll I would vote for the thermocouple only version finished to a pair of 3mm binding posts for ease of connection.
    beanflying....

    There is just one problem with that idea.... and that is extra "junctions" can effect the accuracy of the readings....

    Ideally the two thermocouple wires should be run (in the same material) all the way to the junction at the meter.... and that is where the thermal compensation takes place.

    If you introduce other connections (of dissimilar material to the thermocouple leads) they are, in effect, extra junctions which will produce current proportional to the temperature at that point..... and quite possibly produce significant error.....

    I wouldnt really advise doing that - but to always run continuous leads all the way back to the meter (if you want accurate measurements!)

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    Re: Hottop bean mass temperature probe

    Vote given ;)

    Granted more connections is a bad idea but any voltage losses with gold on gold pins at very low currents shouldnt be to bad, it will certainly be repeatable for readings. The other option would be to supply k type with the 3mm bannana male plugs fitted as it suits most meters (a few use other types). These are fairly easy to source and are about $12-15 each.

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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 3631353A32382D3D3A33540 link=1236648700/4#4 date=1236661010
    ranted more connections is a bad idea but any voltage losses with gold on gold pins at very low currents shouldnt be to bad
    Its not the voltage loss.... that isnt a problem. It is the junction of two dissimilar metals (the thermocouple lead and the copper, brass or whatever metal the connector is) which produces yet another thermocouple..... and depending on the temperature at that point the junction generates current...... And it is the current generated by that junction which creates the problem......

    If you look at professional meters..... they extend the temperature compensation right to the point where the thermocouple leads change to normal copper.... to overcome the inaccuracies.... but we dont need that level of complexity.... just run the chromel and alumel leads (K type) *back directly the the meter (the meter is the reference junction).... the reference junction has built in temperature compensation at the point where these leads plug in.

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    Re: Hottop bean mass temperature probe

    I did mention similar metals partly for that reason, no change in material doesnt cause a problem and gold or silver for that matter (I think the flat bladed thermocouples connectors use silver) have very low electrical resistances.

    Also the word repeatable is important in the case of K type thermocouples as they are not the most accurate device by any stretch. I actually find the supplied environmental sensor in the Hottop is very consistent in its readings even if it is not necessarily a true indicator of bean temp. Learning to drive what you have is as important as the ability to compare one to another.

    Seems there is only 2 options in common use so offer either flat blade lead termination or bananas and you will cover most cases. And offer a meter and probe option as well. Replacement later down the track if required is simple as well rather than having to terminate internally.

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    A_M
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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 43687F684B090 link=1236648700/3#3 date=1236659782
    Quote Originally Posted by 4B4C48474F455040474E290 link=1236648700/1#1 date=1236652211
    If you want to add another option to the poll I would vote for the thermocouple only version finished to a pair of 3mm binding posts for ease of connection.
    beanflying....

    There is just one problem with that idea.... and that is extra "junctions" can effect the accuracy of the readings....

    Ideally the two thermocouple wires should be run (in the same material) all the way to the junction at the meter.... and that is where the thermal compensation takes place.

    If you introduce other connections (of dissimilar material to the thermocouple leads) they are, in effect, extra junctions which will produce current proportional to the temperature at that point..... and quite possibly produce significant error.....

    I wouldnt really advise doing that - but to always run continuous leads all the way back to the meter (if you want accurate measurements!)
    I agree... totaly with the comments from JavaB.

    If one looks at good connectors, you will find that they are particular to the thermocouple type..

    However it does not mean that the HT could have the thermo couple fitted with the right length lead and connector attached. Thus you could plug into any suitable meter. If you wanted to extend or modify... Then the supplier would not be liable for any errors that might / could be introduced.

    Further more, at the end of the day it is an indicator and trend analysis that most are looking for. If any one attempts to do a direct compare and starts defining exact temps... Then they have missed to whole point. Too many variables.

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    Re: Hottop bean mass temperature probe

    As per AM, JB and others.....

    If a t/c option is considered to be viable as an option, you can procure dedicated t/c sockets for the more common t/c types.... J, K etc. If a dedicated plug and lead is also supplied, this could then be configured with the most appropriate connection system on the Meter end so as to be compatible with the CS Standard DMM for example. There are a number of adaptors, usually available from instruments suppliers, that are relatively easy to obtain for use with a number of common meter connection posts/sockets.... :)

    Mal.

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    Re: Hottop bean mass temperature probe

    My own installation just has the probes lead hanging out between the chassis and the control panel. Looks pretty aftermarket and agricultural, but no inaccuracies and the simplicity of it was manifest when it did some time at The Coffee Barun for some demos - Mark was able to just plug his existing multimeter straight in with no adapters or anything. But Im still not really happy with the aesthetics of a neatly finished Hottop with a lairy yellow lead hanging out - for myself I can live with it but not if youre going to sell it as an official solution.

    Interesting comments anyway guys, keep them coming! [smiley=thumbsup.gif]

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    Re: Hottop bean mass temperature probe

    Here are some pictures of my mod to the Hottop with the new CS DMM :)
    I hope the attached file workes :-?

    It was simple and it works :)

    Warren.



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    Re: Hottop bean mass temperature probe

    Great work Warren, almost identical setup to my installation! No doubt an inspiration for other like-minded roasters. It really helps to see the effect of the on/off nature of the P - you can definitely make a difference by minimising the length of the off portions of the program, or even surfing the controller a bit with the up/down buttons to keep the heater on a bit here and there when required to smooth out the lumps and bumps.

    Greg

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    Re: Hottop bean mass temperature probe

    Thanks Greg,

    For interst, here is a real time temperature comparison between the Hottop readout and the DMM readings (CS Roast Monitor)

    Its intersting to see the difference and the changing differences

    The differences supprised me the first time I used the DMM :o

    Now Im getting a handle on tweeking the Hottop ;)

    Warren.


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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 2F342B2833342F5B0 link=1236648700/10#10 date=1236680024
    Here are some pictures of my mod to the Hottop with the new CS DMM :)
    I hope the attached file workes :-?

    It was simple and it works :)

    Warren.
    Interesting a model E ?

    It also appears to have a cover of sorts around the bean dump flap and spring.. Mine does not have that..

    I will mod mine as soon as the dmm arrives and post same pics, so you can see the difference..

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    Re: Hottop bean mass temperature probe

    Hehe, yeah Ive got quite a collection of those myself from different controllers, batch sizes and other variations. Sometimes the env sensor can fool you but the bean mass probe never lies. If youre going to experiment around a fair bit Id be encouraging you to look at the B control panel rather than the P (not that you want to hear that now but still!)

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    Re: Hottop bean mass temperature probe

    Mmmmmm.... dont know where that model E came from.... the rest of the controllers are all Model P.... as they should be.....

    Quote Originally Posted by 6673646671746D6D6C606F010 link=1236648700/14#14 date=1236681720
    If youre going to experiment around a fair bit Id be encouraging you to look at the B control panel rather than the P
    Yep, definitely agree with that. The P, being very automated, doesnt let the user do much (other than to monitor what it is doing).... where the B gives far more manual control to the end user.... and it can be tweaked (in real time) during the roast.

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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 0510070512170E0E0F030C620 link=1236648700/0#0 date=1236648700
    Not yet..... .....hear your thoughts
    Thanks for moving this to a new thread Greg.

    I have a P model at the moment and having read Randy Gs notes on the chute cover mod, felt that measured temperature would likely be elevated by radiant heat warming the probe itself. To this layperson, it appears that your probe location is a more elegant solution that would measure temp of the bean mass more accurately.

    I answered no to the poll because apart from being a touch exxy, I do enjoy the challenge/experience of doing such things myself. Nevertheless, the preservation of the warranty is an enticing argument.

    Quote Originally Posted by 160D12110A0D16620 link=1236648700/10#10 date=1236680024
    Here are some pictures of my mod
    Great job mate. And on behalf of those about to follow in your footsteps, thank you!

    I think Id like to see my probe lead depart the casing from the back, but thats just personal preference I guess.



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    Re: Hottop bean mass temperature probe

    I found I can surf the temps on the P controler in real time :)

    For my favourite SOs, I can save the end result, maybe change a one or two segment times and recall the profile before roasting again.
    All I have to do is watch and tweek the temps up or down as required ;)

    There is a lot less guess work now :)

    Warren

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    Re: Hottop bean mass temperature probe

    Quote Originally Posted by 11243D376362540 link=1236648700/16#16 date=1236683306
    I have a P model at the moment and having read Randy Gs notes on the chute cover mod, felt that measured temperature would likely be elevated by radiant heat warming the probe itself.

    If you check most probes.... both the solid ss probes and the bead type... you will find only the very tip of the probe (where the actual junction is) responds to the heat. There is very little conduction of heat along the probe to that point. So if the far end of the probe is in a cooler position (topshots mod) or in a hotter position (Randys mod) it makes no noticeable difference to the readings.

    I check all roasters using the chute probe (cant go drilling extra holes in customers roasters ::)) and the probe can be well over 100C (about 140C) at the end of preheat.... but as soon as the beans are introduced the indicated probe temp drops almost instantly as it touches the room temp beans.... even though the rest of the probe is at 140C....

    So there is not too much to worry about other than to ensure the pointy bit (the very end of the probe) is in the bean mass..... however you get it there!

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    Re: Hottop bean mass temperature probe

    Behmor Coffee Roaster
    Quote Originally Posted by 06292022350A26292620222A222933470 link=1236648700/13#13 date=1236681517
    Quote Originally Posted by 2F342B2833342F5B0 link=1236648700/10#10 date=1236680024
    Here are some pictures of my mod to the Hottop with the new CS DMM :)
    I hope the attached file workes :-?

    It was simple and it works :)

    Warren.
    Interesting a model *E ?

    It also appears to have a cover of sorts around the bean dump flap and spring.. *Mine does not have that..

    I will mod mine as soon as the dmm arrives and post same pics, so you can see the difference..
    I think the cover is a more recent addition although I think mine has the same thing. The KN8828E is just what the P was originally called but theyre the same thing. Well spotted though Watson! ;)



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