Things I've Learned While Roasting Coffee

2006-03-21T22:53:00.000-05:00

No matter how much you hope the exhaust fan behind your stove will adequately remove the smoke/odor, your house will still smell for 24 hours after the first time you roast with a popcorn popper.
My outside deck, on the other hand, has excellent ventilation.
Golden Retrievers can hear the difference between an M&M candy and a coffee bean when they hit the floor. They don't like coffee beans. This is probably a good thing.
A Campbells Tomato Soup can is 87% more effective in containing excited coffee beans than one of those short little mushroom cans. Yes, I did just make that number up.
Roasting your own coffee is absolutely worth the trouble.

No caffeine here.

Snatching Excellence From the Jaws of Mediocrity

2006-03-13T22:00:00.000-05:00

Can you really get genuine Guinness-effect espresso extraction from a Hamilton Beach Cappuccino Plus (H-B) espresso machine?

Yes, but I'm not sure you should try.

Some background:

The H-B has a few desirable features:

58 mm Portafilter (not crema-enhancing)
Ulka 41 Watt Pump
Removable Water Reservoir
Double Filter Basket
ESE Pod Filter Basket
Removable Shower Screen
Affordable
Readily Available - Walmart, K-mart, Kohl's, etc.

Here's a shot of the group head.

Now the undesirable "features":

Thermoblock Design
Wide Temperature Variation
Aluminum Portafilter
Low Cup Clearance
Short steam wand (steam stub is more accurate)

By far, the greatest hindrance to making decent espresso with the H-B is poor temperature control. The amount of hysteresis in the snap-action thermal switches is horrendous.

I've added a PID-based temperature controller to the H-B, with great success.

Disclaimer: Do not try this at home. Dangerous voltages are
present. This machine was not intended to be disassembled or modified.

Details:

Yokogawa UT150 PID Temperature Controller (Ebay $45)
Omega Stick-on Type-J Thermocouple (Ebay $6)
Opto-22 Solid-State Relay (Free from a friend-Thanks Rick)
Project Box, Wire, Fuse Holder (Radio Shack)

Here's a look inside. The twisted wiring and the brown thermocouple wire were added for the modification. The controller power comes from the conveniently provided terminal strip.

Taking the top off is not trivial. The two tamper-proof screws are hidden (and tamper-proof). The front of the top is held on with plastic tabs that can't be released once engaged.

Yes, permanent damage is required to get the lid off. Once I decided to drill mounting holes and make wiring changes, this became a moot point. The lid "snaps" back on with sufficient security that this has not been a problem.

This photo shows where I located the stick-on thermocouple near the water entry port on the thermoblock. The brass fitting is the pressure relief from the top of the thermoblock. The insulated line is the steam output. I used some high-temperature silicone adhesive to attach the thermocouple.

I wired the SSR in place of the "brew" thermoswitch as shown here. In the foreground is the steam thermoswitch. I change the setpoint on the controller instead of using the steam switch. More about that later. The steam thermoswitch acts as a safety in the event the control goes "open loop". There are two thermal fuses as well, but they are not resettable.

A view inside the controller housing. The aluminum lid provides adequate heat sink area for the SSR. It barely feels warm under use. I fused the power feed to the controller.

Here's the payoff.

This shot was a bit overextracted since I was trying to shoot photos at the same time. This is Sweet Maria's Monkey Espresso Blend home-roasted in a Toastmaster hot air popper. I've also had excellent results with Intelligentsia's Black Cat Espresso Blend. I use a Solis Maestro Plus grinder.

I have currently settled on a set-point of 212F for espresso. The indicator drops to about 207F by the end of a 25-second extraction. Actually, the temperature dips to about 205F and then recovers to 207F as the controller tries to keep up. I have not measured the actual brew temperature. I've just been experimenting and adjusting based on results.

I always pull a blank shot to heat up the filter basket and cup. By the time I dose and tamp, the temperature is back to 212F. This also quickly brings the temperature back down after steaming.

When steaming/frothing milk, I adjust the set-point to 255F. I crack the steam valve at about 245F to begin bleeding off collected water. If I let it stabilize at 255F for too long, the factory thermoswitch trips and I need to wait for the temperature to drop to 218F before it resets. As long as I continue to bleed off steam, the factory thermoswitch doesn't trip. I can froth enough milk for a 7 oz. cappuccino in about 60 seconds. I have also steamed continuously for over three minutes when making Vanilla Creams for my family with no apparent drop in pressure or temperature.

Silk Purse Espresso

Things I've Learned While Roasting Coffee

Snatching Excellence From the Jaws of Mediocrity