Popcorn Popper Chimney for Coffee Roasting

As noted before, I’ve been using a hot air popcorn popper to roast coffee. The tin can “chimney”I was using to keep the beans from flying out was a little short. For a while I had it extended with some metal foil tape, but the tape was not holding up well.

I had some extra sheet metal around and a Pop brand riveter from a yard sale so I tried to extend the can a bit.

I wound up with an extra drilled hole where one of the rivets didn’t take (a poor artist blames his tools, but really that rivet gun is lousy). It looks relatively durable.

It doesn’t add a lot of height to the can itself, but because the added diameter keeps the can from extending deep into the popper it effectively adds a good amount of height to the chimney. The week’s roasting was already complete when I made the thing, so operational testing will have to wait.

Recirculating with an Immersion Chiller

I’ve already mentioned my new homebrewing system.  One feature I made sure to include was recirculating the wort with an immersion chiller.  Like a counterflow or plate chiller, this provides for very efficient cooling.  But it retains the advantages of an immersion chiller regarding easy sanitation, by dropping the chiller into the boiling wort for a few minutes.  The key is a pump to recirculate the hot wort over the chiller.

The copper immersion chiller is connected to tap water as normal.  The recirculating flow keeps the hot wort flowing over the chiller for improved efficiency.  In this picture I’ve raised the outlet above the surface to visualize the wort flow (normally I would try and keep it submerged to reduce hot side aeration).  A pump connected to the outlet of the kettle accomplishes the recirculation.  A six inch piece of half inch stainless tubing helps direct the flow and provides weight to keep it contained in the kettle – don’t ask how I learned that lesson.

Growing barley for malting

After growing hops for a few years, I thought I would try growing some two-row Conlon barley to have a go at turning it into malt for brewing.  I probably won’t get a lot of product, but it should be a neat experience.

Not surprisingly, the seed looks very similar to malted barley grain.  I’ve planted most of this pound in a few stray spaces in the garden.   We’ll see how it goes.

Rancilio Silvia Portafilter Gasket Replacement

Poort Miss Silvia was still laboring with the original brew system gasket that seals the portafilter against the body of the machine.  After six years of almost daily use, a replacement was in order as it was prone to leaks.

I knew the old gasket would be difficult to remove but I had a few dental pick style tools ready.  This is what it looked like after removing the diffusion screen:

You can seen a channel worn around the diameter of the gasket where it was crushed by the portafilter.  The diffusion screen was badly grunged up and there’s a stained pattern of holes on the brass behind where the screen was.

The old gasket was hardened and brittle in spots.  I wound up using a chisel at times to cut the material.  Here’s the remains of the old gasket next to the new gasket:

The cheap Harbor Freight tools didn’t stand up to the job very well – the dental picks bent easily and the chisel was damaged too:

Once the old gasket was out I ran the machine before reassembly to make sure no old gasket material would be trapped behind the diffusion screen.  I didn’t expect it to shoot a stream in a forward direction.

Getting the new gasket in was relatively easy and it was nice and squishy compared to the old one.  I won’t wait six years to do the next replacement!

New Brewing System

The lovely Mrs. Nerdly Endeavours treated me to an awesome birthday present of a new homebrewing system.  I wound up sourcing a Blichmann Top Tier stand, burners, and shelf from a local shop and the kettles, pump, fittings, etc. from an online source.  Here it is squeezed into a nook in our backyard.

I used my existing rectangular cooler as a mash tun, adding a 10 gallon kettle and burner for hot water and a 15 gallon kettle and burner for boiling the wort.  The pump is to move the wort into a fermentor and for recirculating chilling with a counterflow chiller (more on that later).

The Blichmann stand requires DIY plumbing of a propane gas manifold which was actually pretty easy.  I made the mistake of getting a five foot length of black iron pipe at first which was too long – four feet was perfect.  My two-burner system came with all the required plumbing parts apart from the long pipe itself.

Thermometer Calibration

I received some parts for a new homebrewing system & thought I’d better calibrate the thermometers to ensure the desired mash conditions, where temperature is critical.

To start, I heated water to approximately mash temperature and put it in an insulated mug.  I used a reference mercury thermometer and a Thermapen™ for reference, plus the thermometer being calibrated.

It’s difficult to see in the photo, but the mercury thermometer and the digital thermometer agreed to within about +/- one °F.  The photo was taken after I adjusted the analog dial brewing thermometer (a Blichmann Brewmometer™), also to within about a degree.  Let the zymurgy begin!

Adding an airlock to a corny keg

I have a keg of homebrewed Dubbel style beer that is a little disappointing, so I thought I’d inoculate it with some souring bugs to funk it up.  But it was already in a keg and pretty well fermented out – why not leave it there?  It might build up a lot of pressure so some way to vent it is desirable, such as an airlock.

The first few Google results for fitting an airlock to a 5-gallon Cornelius style keg (“corny key”) looked excessively complicated.  I had some old tubing that I managed to stretch over one of the outlet ports by soaking it for a bit in really hot water.  The airlock plugged right in.

I’m using WYeast 3278 which has “Belgian style ale strain, a sherry strain, two Brettanomyces strains, a Lactobacillus culture, and a Pediococcus culture.”  Should be interesting.


Rebuilding the Rancilio Silvia steam valve

I’ve had my excellent Rancilio Silvia (“Miss Silvia”) espresso machine for seven years now and the steam wand developed a dribbling leak.   Time to rebuild that sucker!

I ordered replacement o-rings and seals from 1st line and was happy to get the parts just the day after ordering them, despite just using ground shipping.  Most of the work in rebuilding the steam valve went as described here, though there were a few things worth pointing out.

It is important to back up the flare nut fitting when removing the steam valve from the solid copper tubing connecting it to the boiler, to avoid twisting and kinking the solid tubing.  Here’s a photo with blue-handled wrenches (the top one is out of focus):

I used a couple of cone wrenches that had previously seen service in rebuilding bicycle wheel hubs (a side benefit of having too many endeavours is having a bunch of related tools that could serve other uses).

The steam wand itself was stuck hard and it took a lot of force to remove it.  It has an odd plastic bit where I expected an o-ring.  This photo shows the degraded plastic bit alongside the o-ring I replaced it with:

I removed the degraded black plastic bit when I rebuilt it.

Here is a test before I re-assembled the housing.  The PID controller I’d added years ago for temperature control is resting at the bottom left – I had to pull it out to access the steam valve.  The boiler has wooly ceramic insulation installed to try and protect the electronics in the PID

No leaks!  Hopefully Miss Silvia will provide many more years of service.

Roasting Coffee

So Mrs. Nerdly called me saying she found a hot air popcorn popper at Community Forklift for $5 – should she buy it for roasting coffee?  Why not!

Years ago I’d used a Zach and Dani’s roaster (now Nesco) when I lived in an apartment – that roaster had a nice feature of an “afterburner” to reduce the inevitable smoke from roasting coffee.  But it crapped out as the belt driving the auger started slipping, and I junked it after stripping out some parts for my junk salvage box.

This new device is a Presto Poplite model 04820 (or as it says on the bottom of mine, 0482007) and fairly powerful at 1440 Watts.  I guess there was a glass top or something at one point for popcorn, but no matter that it was missing.

I started with some green coffee beans from the fantastic Sweet Maria’s: Espresso Monkey and another espresso blend, “Espresso Workshop #21 -The Satpura Fold.”

I did four batches, two of each blend, each using about a half cup of green beans.  I put an open-ended food can on the top of the roaster as a chimney

With about half a cup of beans, I lost a few beans blown out the top, but I like to think they were mostly sickly light dried-up beans.  It did a nice job blowing the chaff out.  Definitely something to be done outside!

The end results looked nice and I look forward to tasting them tomorrow.  I got about 11 ounces by weight of roasted coffee from the four small batches.

Incidentally, I would swear I got a caffeine buzz from being near the coffee as it roasted.

Homebrew Stir Plate for Growing Yeast

I make beer, which requires yeast, preferably lots of yeast. Normally I buy yeast prepared by commercial labs that cater to homebrewers, but I make 10 gallon batches so I would buy two packs of yeast and even then wonder if I had enough.

After reading this piece by Dr. M.B. Raines (showing that continuous stirring generates about ten times the number of yeast cells as compared to just aeration), I was convinced to build a magnetic stir plate to help grow yeast and save some money.

I used a 120mm computer fan with a LM317 voltage regulator to adjust the speed using this simple circuit:

Details on the circuit can be found here. The component values aren’t critical. I used some capacitors I had around and aimed to keep the ratio of the values of C1 and C2 about the same.

I attached some rare-earth magnets to the fan with a hot melt glue gun and stuck the works in a plastic project box.  People say a metal box won’t work, but I’ve used metal-topped stir plates in the past, so I’m not sure.

The potentiometer worked well to control the stirring action over a range of speeds. I don’t have a hemacytometer to count the cells, but it seems to work well, making the starter medium much more cloudy and giving a vigorous fermentation.