300g in a Hottop

[beanflying]

Re: 300g in a Hottop

I hadnt seen your mods in my searching Got to love a nice 555 project.

Drifting a little OT but I looked at the Velleman board as well but I found this one http://www.thesiliconhorizon.com/reflow.htm I had origionally planned to use a toaster oven but picked up a S/hand Hottop instead to save the metal work.

I will start a thread when I find a little time to start playing.

[yoma]

Re: 300g in a Hottop

the D will be electronically switched so you still wont hear a click even with the quiet clinking of the beans going on

Hi beanflying,

My D-model does "click" - the controller board does the electronic switching - of the main power board.  Actually its my own controller board which provides manual roast controls - http://coffeesnobs.com.au/YaBB.pl?num=1172066309/4

Your USB project sounds interesting.

Ive got a Velleman K8055 USB controller sitting around which Ive been planning to wire in to the Hottop.  I initially built the simple controller first to get a feel for controlling the roaster directly.  But it worked so well providing great results - Im still using it 200 roasts later.

Actually I did wire up my notebook to the vellman and a 4 channel temperature logger, but I found it a bit clumsy to use as well as taking up too much bench space and wires everywhere - cant beat a couple of simple old fashioned dials.  In fact I made a note to look at using motorised POTs in my next version.

However with the arrival of the iTouch/iPhone apps, I have been tempted to move the project onto the next stage and use the iTouch/iPhone to monitor/log roasts (and even provide supplementary controls).  I can hide all the controller stuff and wifi with  the iTouch/iPhone.

[beanflying]

Re: 300g in a Hottop

Hi Yoma,

the D will be electronically switched so you still wont hear a click even with the quiet clinking of the beans going on

[yoma]

Re: 400g in a Hottop!

BF: The D and the P *potentially* give slightly less even results than the B because they control the heat by switching the heating power on and off (as the Gene does) so beans can be exposed to much higher temperatures as they pass the element than the drum will ever get to. By contrast the B provides analogue heater control where the output power is actually reduced rather than just changing the on/off duty cycle. So with the D and P a range of (comparatively) very hot and very cold temperatures average out to produce a smooth curve, whereas the B provides continual heat and simply varies how much power is applies to the element to achieve that. The image below is a collection of screenshots of a CRO attached to the heating element of my Hottop B where the power was taken through a full sweep.

I should say that Ive done many roasts with the P controller installed and cant say Ive noticed any marked uneveness, so I dont think the different heating methods necessarily has a great effect on the eveness of the roast, but all other things being equal the B should provide a more even result.

Interesting output - so it chops up the AC cycle (Ill have to research thats done).
So theres no relay on board (no clicking sounds as it switches the heat on/off on my D model).

I use 2 TCs in my hottop.
One is closer to the centre of the drum (just in the bean mass), the other closer to the drum (deeper in the bean mass).

With no coffee in the roaster the one in the center is a few C hotter.
With coffee, they soon converge and remain within 1C.

I wonder what proportion of the heat comes from:
 - the heated drum surface
 - the focused heat along the drum axis
 - heat from the element through the drum

I suspect the combination of the above has an leveling effect to keep the roast even.
When I drop the duty cycle down, I dont see any increase in difference b/w the TCs.

Anyhow - it does a great roast.

[beanflying]

Re: 300g in a Hottop

Hi Greg,

Time to get on to my little USB project . The board and SSR arrived last week but I havnt had a chance to have a play yet.

I had only been running 250g Green for roasts up to tonight but it seems that 300g is OK so I will stick to it for a while.

[gregpullman]

Re: 400g in a Hottop!

... try 400g of Indian Tiger Mountain, which is an A size bean, so nothing like a Peaberry!

Whats the power rating of the newer hottop models?

My old hacked D-model is marked 700W (Ill confirm this with a power meter next roast).

Ive always wondered about running a more powerful heater element / power board to increase roast capacity.

I roast 225 to 230g.  I can get to FC in about 9 minutes when desired and theres head-room to ramp up in the later stages.

My factory B is rated at 740W but I believe the heater elements are unchanged. Its likely the newer motherboard is a bit more power-hungry. The heating elements are plenty powerful enough anyway - in the D the element doesnt run at full power for all that long, and as I mentioned even in this 400g roast on the B it was only running 60% power for most of the roast. Since you dont have a cyclone of air to combat like you do on the Gene, you dont lose anywhere near as much heat so you dont have to put as much power in to get the same amount of heat in the drum.

BF: The D and the P *potentially* give slightly less even results than the B because they control the heat by switching the heating power on and off (as the Gene does) so beans can be exposed to much higher temperatures as they pass the element than the drum will ever get to. By contrast the B provides analogue heater control where the output power is actually reduced rather than just changing the on/off duty cycle. So with the D and P a range of (comparatively) very hot and very cold temperatures average out to produce a smooth curve, whereas the B provides continual heat and simply varies how much power is applies to the element to achieve that. The image below is a collection of screenshots of a CRO attached to the heating element of my Hottop B where the power was taken through a full sweep.

I should say that Ive done many roasts with the P controller installed and cant say Ive noticed any marked uneveness, so I dont think the different heating methods necessarily has a great effect on the eveness of the roast, but all other things being equal the B should provide a more even result.

Greg

[beanflying]

Re: 300g in a Hottop

For additional info. Hottop Model d

Just finished running 3 back to back 300g roasts in my Hottop without any problems. Indian Tiger A 20.30 a few under roasted beans and not all that even (I think a longer warm up might be needed?). PNG Wahgi 22.00 nice even roast. PNG Jikawa Peaberry dumped at 21.30 nice even roast.

Baens very cool after the standard cooling cycle around 40 degrees.

[yoma]

Re: 400g in a Hottop!

... try 400g of Indian Tiger Mountain, which is an A size bean, so nothing like a Peaberry!

Whats the power rating of the newer hottop models?

My old hacked D-model is marked 700W (Ill confirm this with a power meter next roast).

Ive always wondered about running a more powerful heater element / power board to increase roast capacity.

I roast 225 to 230g.  I can get to FC in about 9 minutes when desired and theres head-room to ramp up in the later stages.

[yoma]

Re: 300g in a Hottop

If youre upping the fan towards the end of the roast you may see a temp increase as the beans dry out / go exothermic.

Spot on!  I measured the fan effect near the end of a roast.

[gregpullman]

400g in a Hottop!

On another note, why stop at 300?! Removing my Things Coffee warranty honourer hat and donning my traditional experimenters hat, after doing 350g of Peaberry a couple of weeks ago I decided to be silly and try 400g of Indian Tiger Mountain, which is an A size bean, so nothing like a Peaberry!

As you can see it sure was a pretty full drum, the beans were really backing up on the right side of the drum, beans were more likely to get pushed into spots they normally wouldnt end up (such as at the top of the drum support) and it was harder for chaff to escape. I ended up maintaining 60% power to the end of the roast, which ended up taking about 23 minutes. It could have been quicker if Id kept the power higher for longer. I expected the cooling tray to overflow and it got close, a few escaped but it still managed to contain them all which is a surprisingly good result.

The roasted beans were fairly good - a little more tipping and divots than usual, probably due to the beans being that much closer to the element, and a slightly more uneven roast, but overall not as bad as could be expected. Of course, as a supplier of Hottop roasters we wouldnt formally recommend roasting such a large volume as this, it may void warranties and cause your car tyres to burst, but from an experimenters point of view it shows 400g of a large bean is entirely possible in a Hottop, even if the results arent quite as even as can be achieved with the more recommended volumes.

500g here we come!

Greg0g

[gregpullman]

Re: 300g in a Hottop

Its mainly there to get rid of the smoke but it obviously gets rid of some heat at the same time. If youre upping the fan towards the end of the roast you may see a temp increase as the beans dry out / go exothermic.

[yoma]

Re: 300g in a Hottop

... my standard recipe for a 250g roast is 100% power and no fan to about 140C, then drop back to 70% and 1/4 fan until about 165, 70% and 1/2 fan until about 180, 40% and 3/4 fan until about 192 (around FC) and then 40% and full fan from there on...

What effect does the fan have on a roast?
I generally never use the fan other than to cool down the unit after a roast.
On one occasion, I measured the temp. changes caused by the fan via my on T.Cs in the bean mass.
It uped the temperature (more O2?).
Thanks
-yoma

[T.D.]

Re: 300g in a Hottop

Thanks again for the awesome deal and great service Greg. Im sure youll also be pleased to see that the AUD has recovered a little in the last week or so.

Thanks for the info on the different roast settings. Ill have to start taking some notes in anticipation of receiving my new baby! 8-)

[gregpullman]

Re: 300g in a Hottop

Youve done well to get it at the price you did! Settings were quite different TD; my standard recipe for a 250g roast is 100% power and no fan to about 140C, then drop back to 70% and 1/4 fan until about 165, 70% and 1/2 fan until about 180, 40% and 3/4 fan until about 192 (around FC) and then 40% and full fan from there on. Others work on different recipes but that works for me - you could try 80% power until about 155 for example. Naturally these figures will vary from region to region, from power supply to power supply and from unit to unit, but theyre what I initially aim for and then fine-tune it as the roast progresses to compensate for the variables.

With the 150g roast it was a fair bit of making it up as I went and it wasnt as smooth as I would have liked but if I was to do it again Id have a much better idea of what to do. This is from memory so take the figures with a grain of salt. IIRC I started at 100% but dropped back to 80% around 110, then dropped it back to 60%, then 50% around 165 (temp was still climbing too fast). Around 175 it was still climbing a bit quicker than I wanted so wound back to 30% (Id never gone that low before) but the roast stalled about 182, so I went back up to about 80% to recover it and once it had started rising again I went back to 40% which took it through smoothly to the end. Fan speeds were roughly unchanged.

If I was to do it again Id try to start at 70% (to lessen the chance of tipping, not that there was any but there was no need for that much power that early as it just created a beast I then had to contain), then drop back to 50% around 140C and 1/4 fan, 1/2 fan around 165, 40% power and 3/4 fan around 180C and full fan around 195 (slightly higher full fan point as the lower bean volume will translate to less runaway as the roast approaches the end). However as I mentioned above, your own settings may need to be different to mine (or what I might suggest) but theyll at least give you somewhere to start.

A classic trap for young players (er, Hottop B owners) is to panic and try to rush changes in too quickly before the last one has taken effect. You can safely assume with anything you do on the control panel that youll need to wait at least two minutes before you have enough data to get some idea of the longer-term effect. As you build your experience you can predict what changes you need to make for what end result.

Good luck!

Greg

[T.D.]

Re: 300g in a Hottop

Thats an interesting experiment Greg. How much did the roast settings change for the large and small roasts. I have a bunch of PNG peaberry so might be a good excuse to try a big roast with them. Cant wait to receive the hot top, very excited!