Results 1 to 19 of 19

Thread: Hottop tipping/scorching

  1. #1
    Senior Member
    Join Date
    Apr 2012
    Posts
    319

    Hottop tipping/scorching

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi there,

    I just wanted to put it out there and see if anyone else is getting the same results as me.

    As per title I've found lately that all my roasts have had signs of sometimes significant tipping. As I've been trying really hard to avoid it in the past few weeks I'm getting mixed results. I started lowering the drop temp ranging from 130C - 160C to see if I was going to get a different result. I've tried extending the roast and giving it a much more gentle rate of rise.

    Today I dropped in at 150C with some Brazil Pulped Naturals using a charge weight of 160g to try and not over load it and I probably got my best results in regards to not so much tipping probably around 30% of the beans have signs of tipping (but this is more than enough to taint and ruin the cup). The profile today was basically 150C drop temp, extended the drying phase, had the airflow on from the middle of drying phase to the end of the roast to make sure there was sufficient airflow. I'm ejecting just before second crack.

    I've tried extending the roast and trying to be more gentle on the RoR, 18-20min roast time.
    I've tried to be a little more aggressive with higher airflow total 12-14min roast time.
    I've tried both of these with higher drop temps of 180C down to 130C.

    I have a feeling the beans are spending too much time on the drum and scorching, I am thinking of removing the drum and fabricating up some new stainless fins to try and replicate the Behmor style agitation fins which I think work great.

    Any thoughts? Has anyone else encountered this problem.

  2. #2
    Junior Member
    Join Date
    Mar 2014
    Posts
    23
    Hi brendogs,

    What machine are you using? Sorry just saw hottop in the subject. The rest of this is not very useful tgen eh. To give background I use an insulated corretto with cover and a bosch 'green' heat gun w/ digital input temp. Also I'm reasonably new to it all as only just ive cracked 15kgs (pun not intended ). My current charged weight is 500g.

    I experienced a few tipping batches and found the biggest impact was air flow rate. I now leave it purely on 2 and just adjust the temp.

    To check if it was the issue I have varied my charged temp between 100 and 209 degrees, tried higher input temps with lower air flow rate and ran initally fan 3 to 100 - 150C. Only thing that caused tipping for me was putting on fan 3.

    Hope that helps.
    Col

  3. #3
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    Brendogs, irrespective of your charge temp.....what is your turn temp?

    p.s. Col.... as per thread title Brendogs is using a Hottop.

  4. #4
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    Quote Originally Posted by chokkidog View Post
    Brendogs, irrespective of your charge temp.....what is your turn temp?

    p.s. Col.... as per thread title Brendogs is using a Hottop.
    My drop temp today was 140C and the turn temp was 70C at 1 min. These are taken from the BT where I do all my datalogging with the hottop.

    Last week I tried a higher drop of 170C with an 80C turn at 1min. When I drop I turn the heat source down to 50% with the fan on half speed to try and steady the first rise so it doesn't gather too much momentum into the drying phase.

  5. #5
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    I'm not familiar with the Hottop..........but

    Is it possible to try to aim for a turn temp as close to 60C as possible?

    Are you able to heat the roaster to (say) 180C, turn heat and air off, then charge the drum as the temp drops through

    160C, turning heat and air back on about 5 seconds after the turn?

    Playing around with this technique might be a starting point to achieving a suitable turn and to solve your issues.

    It sort of reflects what I do in the HG5, same turn temp (60C) but otherwise based on your temps.

  6. #6
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    Yeah I can only try, because it's electric I need to anticipate techniques 2 or 3 steps before it happens. I'll see how it goes tonight and post the results but I think that could be achievable.

    I guess doing this will flatten out the rising curve up to drying phase as well so I can have a tad more control over that. I'll give it a go.

    At what times do you aim to hit the turn? I know the drums are completely different from the HG5 to the Hottop so it's hard to compare but it's good to know.

    I know scorching is mostly caused at an overly hot drum, but when is tipping produced? Is it a mixture of aggressive heat rise and high drop temps? It's tough on the hottop because I can't actually sample beans during the roast and note down when I can see the start of tipping.

    Thanks chokki

  7. #7
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    Tipping is caused by excessive drum surface temp at charge and / or too high a turn temp.

    These events cause rapid, uneven drying especially at the germination end of the bean where sugars are concentrated.

    The tipping marks don't actually show up until late in the roast when those areas roast to a higher level than the rest of the bean.

    Scorching occurs later in the roast when there is too much heat after the onset of pyrolysis, or when

    the sugars start to caramelise; theoretically at 183C but will differ according to your own set up and conditions.

    Facing, where the 'flat' surface of the bean scorches is generally caused by too much heat after 1st crack.

    The ideas I suggested are only that......suggestions. Sometimes things can be learnt by doing something radical.

  8. #8
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    Thanks for that chokki, I'll give it a go tonight and lower the drop and turn temps. I've researched it a hell of a lot and as I've been reading and reading I'm absorbing all this endless information.

    I'm getting closer, the problem is that I think the Hottop is letting me down slightly. The drum doesn't have any fins so the agitation just isn't enough. The beans are spending far too much time on the drum walls so I'll try and work with these drop and turn temps we are talking about but my next project is going to be to remove the drum and add some fins. I've got a 1kg JYR TJ-067 that I'm fixing up and I was hoping that I could try and emulate roasts from the hottop onto that but I just don't think the environments are going to match and give me completely mixed results.

    I'll try a couple roasts tonight and discuss my results.

  9. #9
    Senior Member
    Join Date
    Jun 2011
    Posts
    723
    I use a drum roaster similar to a Hottop and initially had lots of problems with tipping and scorching. I did two things that solved the issues. The first was to reduce charge temp... I charge at 160*C bean temp. The second was to paint the outer surface of the drum with kettle black. The increased emissivity of the setup and greater conduction allowed me to use less power through the roast.

  10. #10
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    Vigorous, constant agitation that keeps the integrity of the bean mass and doesn't spray beans in all directions will

    go a long way to achieving the results you're after.

    The Baby roaster also works better when modded with paddles.

  11. #11
    Senior Member summercrema's Avatar
    Join Date
    Mar 2008
    Posts
    266
    Brendogs, can you post the roasting profile ?

  12. #12
    TC
    TC is offline
    .
    Join Date
    Oct 2004
    Location
    Melbourne
    Posts
    14,665
    Quote Originally Posted by brendogs View Post
    ....I was hoping that I could try and emulate roasts from the hottop onto that but I just don't think the environments are going to match and give me completely mixed results...
    I have always said that a new roaster is somewhat like a new partner. What works for one may not necessarily suit the other. It's takes some getting to know you time.

    Sacrifice some beans and you will learn what the bigger roaster requires to deliver your desired results. It's likely that even the seasoning roasts will help you learn.

    Enjoy

  13. #13
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    Agreed, which is why I deleted a couple of details that are pertinent to my roaster, in my situation, with its unique ambience

    dynamics which apply to the beans I roast and how I roast them.

    This principle applies to everyone.

    Brendogs....I'd worry less about the Hottop and get cracking on your new roaster; solving issues on the Hottop will add

    to your experience but it is the experience and not the hard data that will help with the newy.

  14. #14
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    Quote Originally Posted by chokkidog View Post
    Brendogs....I'd worry less about the Hottop and get cracking on your new roaster; solving issues on the Hottop will add

    to your experience but it is the experience and not the hard data that will help with the newy.
    I would love to chokki but I'm waiting for some part's, I purchased it fairly cheap because it had a blown solid state relay in it because one of the elements shorted. Just waiting on the replacement parts to come in from North Coffee. Once that is ready to go I'll start cranking it over.

    Quote Originally Posted by Talk_Coffee View Post
    I have always said that a new roaster is somewhat like a new partner. What works for one may not necessarily suit the other. It's takes some getting to know you time.
    Does this mean that after the honeymoon period is over it will start contradicting me and telling me I'm always wrong?! I don't know if I'm game enough for this. Haha

    Just about to load the beans in and try a lower and steady turn temp.

  15. #15
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    So I've just given it a go, still got signs of tipping. I didn't quite get it down to 60C, more like 65C. It just didn't want to stop the momentum. Had a very steady rise up to drying phase raised the airflow and then let the roast go up to first crack with the airflow on. first crack developed for just over 1:30 then let it develop for another 1:30 post first crack and dumped. Some of the beans even have signs of facing as well.

    I'm absolutely adamant that the lack of fins is causing this. The beans are basically rolling on the bottom of the drum, barely rising on the side of the drum unless there is a larger charge weight. I'm going to take it out and bring it to work to fit some fins. With a smaller charge weight the beans are spending even more time on the drum face than with a larger charge.

    Rather annoyed that I've been wasting so many beans on this! Grrrrrr

  16. #16
    Senior Member chokkidog's Avatar
    Join Date
    Apr 2008
    Location
    Victoria, Australia
    Posts
    2,096
    I think you've identified the problem, Brendogs.

    Looking forward to hearing how the mod goes!

  17. #17
    Junior Member
    Join Date
    Dec 2012
    Posts
    2
    Hi Brendogs, I have been roasting on a HottopB for about 18 months. I generally load the beans around 75dg but have experimented up to 130dg to try and shorten roast time. Usually roast between 200-250gms and have always had very even roasts.

  18. #18
    Senior Member
    Join Date
    Apr 2012
    Posts
    319
    Ok! So I've managed to get myself a strip of stainless steel which I folded into fins. I decided for my first attempt at this I would replicate the current miniature stock fins and not go with full length fins or anything like that. The fins are 25mm high off the barrel and have done a great job. The beans are spending much more time in the air rather than sitting on the drum base. I did hear a few beans getting jammed somewhere so I may have to manipulate some of the fins so they don't squash beans against anything.

    So what were the results like? Great question!

    I did an identical roast with 200g of Tanzania Machare Estate which in the previous roast had 100% signs of tipping and scorching. They cupped like crap and had a completely carbon aftertaste. Horrid!
    This roast seems to have almost no tipping, I did spot one tipped bean but no others. The roast ran away from me in sections so I will cup it tomorrow afternoon and see how they compare but for my first go I was extremely proud of my little modification.

    I will consider doubling the amount of fins and adding more on the opposite sides of the current fins.

    All in all, can't be happier for my first roast on Prototype v1.

    Have a look at the image below, you can see that I also added a little bend to scoop coffee off the glass face which worked fairly well. I took a video as well so I'll try upload that tomorrow.

    photo.JPG

  19. #19
    Senior Member topshot's Avatar
    Join Date
    Jul 2007
    Location
    Currans Hill, NSW
    Posts
    367
    Behmor Coffee Roaster
    Which model Hottop do you have?



Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •