HB wrote:When I have time, I will plot some of them. Unfortunately I only have a Fluke 54-II without the datalogging software, so I have to key in each data point by hand into Excel. I posted the last series of videos to offer insight into the process behind a review, not show specific results.

cannonfodder wrote:Like Dan, I do not have the software to do the downloads and hand key into Excel from the Flukes memory to create the chart. I actually brought my meter to work today so I could key in data for a flush chart using Eric's thermocouple adapter.

I know what you guys need for Christmas!

No really, plotting data is about as much fun as drinking Starbucks. While a graph is helpful (and you will see plenty floating around here), there is a lot that can be seen pretty well in a video and is also quickly captured with a minimum of fuss. Dial-up speeds notwithstanding (ouch, RandyG!).

I did some data logging tonight and keyed in 300 or so data points for the graphs. I decided to bracket some flush and rebound times. All data collects were made with a minimum of a half hour between collections.

Measurements were taken with one of Eric's E61 group adapters with a T thermocouple on a Fluke 54II.

I started with a flush to 205 with a 20 second rebound


Second sequence I flushed to 207 with a 20 second rebound


Third sequence I decided to go with a shorter flush and shorter rebound, I flushed down to 209 and a 10 second rebound.


Lastly (I was running out of coffee), I went back to the 205 flush target and prolonged the rebound to 30 seconds.

jesawdy wrote:there is a lot that can be seen pretty well in a video and is also quickly captured with a minimum of fuss.

- Assuming the video site is not blocked at the perimeter.
- Ever try to overlay a couple of videos?
http://www.ielogical.com/coffee/RoastLogger.xls imports datalogger files, plots the shots / roasts and will stack up to 10 shots on a comparison graph with a minimum of fuss, as in no ytpo's

Randy G. wrote:6+ years with Silvia, Dial-Up...

Man, you ARE into PAIN!

I was going to add some labeling to the graphs and parse them out in a different format to clear them up a little. Your shading is correct.

I ran the shots for temperatures not to drink. The shots were running 28 seconds, give or take one, for two ounces. That is not necessarily where I stopped the shot. Some ran long just because I let them but the flow rates were the same so the data is valid.

The Domobar Super appears to be tuned to run in the midrange of the shot temperature (195-205).

The flow restrictor in the Super keeps the group in the 200 or lower range most of the time. I believe that keeps the groups flattest brew temp in that 198-200 range. When I try to run higher, I get a rapidly downward slopping profile. That slope levels off in the 198-200 range.

If you prefer coffee's that work best at higher temperatures the flow restrictor may need opened up a little to help heat the group to the 205 range. You could also adjust the heat exchanger injector length to further tune the machine for higher temperatures but that is more work than most home users are willing to go through IMHO.

The machine is displaying the classic E61 hump temperature profile. The graphs I posted have an exaggerated hump at the beginning because of the point of measurement.


E61 adapter with thermocouple

I have a few questions for you guys:

1) I know this is probably coming, but it would be helpful to have readings from a thermofilter to compare to Dave's graphs using the TC adaptor so we can see what the results in the cup are like. You didn't say whether you tried the shots from your "testing" or how they were.

2) Have you noticed whether it takes longer for the group to get to stabilize at operating temperature after a shot or series of shots or when first starting up? (Actually, this brings up another question I've had which is what "normal operating temperature" for an E61/HX design should be if it's being used as it was designed and not overheated, but we can save that for later. ) I wonder what effect the thermosyphon restrictor has on this. It seems like the GH would cool off after a shot or several shots and it might take longer to get back to operating temperature with the restrictor. Does this make sense?

3) Any idea whether having the patent on the original E61 design means the VBM has the same, larger chamber #3 in the GH design as discussed here?

I'm just wondering how the design of this machine affects it's behavior and whether it is markedly different from other machines, like my Anita. Thanks for an interesting review and all the hard work you guys do!

Justin

I was asleep at the wheel, sorry about the delay Justin. The titans have been taking most of my time.

jgriff wrote:I have a few questions for you guys:

1) I know this is probably coming, but it would be helpful to have readings from a thermofilter to compare to Dave's graphs using the TC adaptor so we can see what the results in the cup are like. You didn't say whether you tried the shots from your "testing" or how they were.

I had mentioned earlier that I was holding off doing the graphs because I was waiting for a Scace II thermofilter. Unfortunately they are in short supply so I decided to press on with what I had. When it arrives I plan on running one or two more graphs with both the thermofilter and E61 adapter. The shots I pulled were with old garbage beans. Leftovers from a pound of this and a pound of that so they were not fit to drink. I simply ground fine enough to get a properly timed shot and went at it.

2) Have you noticed whether it takes longer for the group to get to stabilize at operating temperature after a shot or series of shots or when first starting up? (Actually, this brings up another question I've had which is what "normal operating temperature" for an E61/HX design should be if it's being used as it was designed and not overheated, but we can save that for later. ) I wonder what effect the thermosyphon restrictor has on this. It seems like the GH would cool off after a shot or several shots and it might take longer to get back to operating temperature with the restrictor. Does this make sense?

The first part of the question: It takes longer to stabilize in the heat up phase. The machine needs a good 45 minutes to heat, an hour is even better. Shot to shot, I was able to outpace the machines recovery ability. If everything is ready, I can bang out shots pretty quickly. I would guess around 100 seconds from shot to shot. After the third shot it did need a few moments to recover. If you pace is more like a double every 3-4 minutes, I believe the machine would keep pace until you ran out of coffee.

My intra shot flushes were all but non existent. I would give the machine a quick 3-4 second flush just to clean off the shower screen while I was tamping. Then lock and go. If you are making milk based drinks, pull two doubles, froth your milk and serve them, then pull the next two, milk etc. At that pace it keeps up just fine. I ran the machine at work for a while. I could knock out 6 drinks back to back using that technique.

Second part of question two, the normal operating temperature of an E61 group. Ideally, that would be the brew temperature you wanted, or slightly higher. On my Isomac, which does not have a thermosyphon flow restrictor, the idle group will heat up to the 212F range. That requires a very long cooling flush before I pull my first shot. As long as your brew water is the correct temperature, the group should maintain close to that temperature. If the brew water is too cold then the water will leach heat from the group until equilibrium is reached. Same holds true if your water is too hot. The group will leach heat from the water in an attempt to equalize.

3) Any idea whether having the patent on the original E61 design means the VBM has the same, larger chamber #3 in the GH design as discussed here?

I'm just wondering how the design of this machine affects it's behavior and whether it is markedly different from other machines, like my Anita. Thanks for an interesting review and all the hard work you guys do!

Justin

I don't know. I have not taken the group apart that far. I would have to ask a service tech for that one. What I can say is that the group preinfusion timing and pressure profile is common.

I can tell you that Dan (HB) has some interesting things planned for that grouphead he got from 1st-Line. So that question may get answered in the future.

cannonfodder wrote:Second part of question two, the normal operating temperature of an E61 group. Ideally, that would be the brew temperature you wanted, or slightly higher. On my Isomac, which does not have a thermosyphon flow restrictor, the idle group will heat up to the 212F range. That requires a very long cooling flush before I pull my first shot. As long as your brew water is the correct temperature, the group should maintain close to that temperature

Hi Dave,
After getting my machine working properly, I'm still at a bit of a loss about my temperature, or actually I should say, the accuracy of my new boiler gauge. As detailed in my post, I am now running around .8 to .85 bar which after an hour of idling is reading about 209 to 210 on Eric's thermometer grouphead adapter before flushing. I am roughly doing a 25 second flush and stopping at about 206F and pull my shot about twenty seconds later. The shot bottoms out at 200/201F in the last 10 seconds.

I dialed my machine up to 1.1 bar and the group then idled way up at 214/215F. The shots also were too hot up around 203/204F (I know there is a slight difference between puck temp and Eric's group temp (somewhere between 1 and 2 degrees higher from my understanding).

The espressos are great, and really that is all that matter, but I'm just intrigued by the fact that your group seems to idle at a much lower temperature and you are set at 1.1 bar. Is there any adjustment to the thermosyphon restrictor (I'm unfamiliar with how they operate)? I plan on getting an omega meter and thermocouple adapter from Eric some point to make more accurate data (gotta love that datalogging) but any thoughts would be appreciated.

Cheers,
Kaelin

That is odd. I have my machine idling at 1.1 bar and with Eric's adapter (I have the fancy steel braided thermocouple version) I do not recall ever getting more than 205F on the Fluke. When I flush the temperature spikes which is to be expected and shown in the above flush graphs.

The gauges on the Domobar Super are not of 'exceptional quality' but functional. The gauges are plastic with a chromed plastic accent ring but accurate enough to do the job. The only way I know to verify would be trying another gauge or put a gauge on the steam wand and open the steam valve to check the reading. The pressure in the steam wand should be equal to the boiler pressure gauge. But that would be a pain to rig.

The thermosyphon restrictor is a fixed disk mounted in the upper thermosyphon line. It is installed when the group is put together. I have seen a photo of a commercial HX that had an adjustable restrictor in the thermosyphon line. You could tune the group by turning an adjustment knob. To change the restrictor in the Vibiemme you would have to remove the group from the machine.

Another thought, you are in Canada; I wonder if this is a US market mod and not present in the Canadian version. Although on my Isomac, which does not have a restrictor, the group temperature climbs higher than what you are seeing.

Dave - what you are saying about the US market Vibiemme is EXACTLY what I was thinking. Recall the multiple posts here and on CG about Australian Expobars having a 2.5 mm thermosyphon orifice installed and US Expobars running "hot" with no restriction.

Also, the ECM Giotto and the Vibiemme Super Domobar are ESSENTIALLY the same internally yet, AFAIK, the Giotto does not have a thermosyphon restrictor.

Kaelin - If you still have your old pressure gage, I will be happy to check it against a very accurate 0-30 psi (~ 0-2.0 bar) gage I have.

erics wrote:Dave - what you are saying about the US market Vibiemme is EXACTLY what I was thinking. Recall the multiple posts here and on CG about Australian Expobars having a 2.5 mm thermosyphon orifice installed and US Expobars running "hot" with no restriction.

I will have to drop Stefano an email and see if he can answer that question.

cannonfodder wrote:To change the restrictor in the Vibiemme you would have to remove the group from the machine.

The restrictor (61 / 62) is in the TS / boiler connector. No need to remove the group from the machine.

My boiler is currently set to an uncalibrated 231.5 / 0.65bar and the group idles at a calibrated 200

cafeIKE wrote:The restrictor (61 / 62) is in the TS / boiler connector. No need to remove the group from the machine.

Interesting, I thought it was in the upper thermosyphen line at the group connection. I may perform a little surgery just for my own personal edification. And pass on a few photos for the others that would like to see what a flow restrictor looks like.

I have been working on taking some shot photos for my friend Tony and his revamped Caffe Fresco web page. I switched to the VBM this morning and the espresso gods smiled on me.

That is a 3 ounce shot with a 16 gram dose of Ambrosia, mindbender of a shot. Try getting more crema in your shot than that!

cannonfodder wrote:I may perform a little surgery just for my own personal edification. And pass on a few photos for the others that would like to see what a flow restrictor looks like.

No surgery required

Vibiemme Flow Restrictors

cannonfodder wrote:Try getting more crema in your shot than that!

Duh! Pull 4 ounces

the guys at expobar said that the teflon restrictors will not build up scale like the brass ones.

this is why they use the teflon ones.

i think the restrictor is key. the one in my pulser has it working great. i recently switched to a vetrano and it seems like it needs a restrictor as well. or a smaller one.

jon

RegulatorJohnson wrote:the guys at expobar said that the teflon restrictors will not build up scale like the brass ones.

OTOH, if a brass one builds up enough scale, the group will be stone cold.
A sure fire indicator that a descale is in order.

erics wrote:Dave - what you are saying about the US market Vibiemme is EXACTLY what I was thinking. Recall the multiple posts here and on CG about Australian Expobars having a 2.5 mm thermosyphon orifice installed and US Expobars running "hot" with no restriction.

I got an email back from Stefano about the restrictor. The importer/distributor is responsible for the its installation as well as the size of the restrictor. So you could get a Domobar Super without a thermosyphon restrictor. However, if you got the machine from 1st-Line there should be one in there.

The only way I know to verify its presence is to remove the case and detach the thermosyphon line and look. Unfortunately, that could void your warranty. So check with your vendor prior to taking a wrench to the machine.