Meco BBQ Drum Coffee Roaster Details (Why Bother?)

This home-built/assembled device is intended for my personal use - it roasts up to 1.5 lb. of green coffee beans and was made from commercially available components.  This unit required stainless steel metal fabrication and welding, but could have been assembled with a hand-drill or drill press, heavy snips, hacksaw and a pop-riveter.  

I do not advise any person modify an electrical heating appliance from its intended design.  My home-built device is a potential fire hazard and is capable of causing severe burns, electrocution and all kinds of horrible, nasty things.

There is a broad discussion on BBQ grill coffee roasters at alt.coffee; similar discussion is found at Home roast Digest, c/o the Sweet Maria's web site.  I hold all those oxygen-starved, smoke asphyxiated people harmless vis--vis this project...  as you shall hold me harmless if you read one more word.  End of disclaimer.

frontclosed.jpg (95648 bytes) frontopen.jpg (45691 bytes) mountedleft.jpg (58145 bytes) mountedright.jpg (52297 bytes)  drumbottom.jpg (44959 bytes)   drumtop.jpg (33010 bytes)  nomex.jpg (29204 bytes) 
Meco 9309W
electric rotisserie grill $139 approx.
Frontgate.com 
stainless basket set (2)
 $29 approx.
drum installed, left side drum installed,
right side
drum
bottom
drum
top
Nomex quilted batting w/ Nomex cover

A short funnel form permits adding or dumping beans without handling a hot door or latch handle.  I made and fit-tested a Mylar pattern for the funnel (below) before cutting the sheet metal.  Without internal stirring or lifting "fins", beans distributed evenly across the length of the drum once it began to rotate.  They rolled and slid, but did not tumble.  The Meco rotisserie motor (included with the 9309) turns silently at two-rpm; first and second cracks are heard plainly above the ambient noise level produced by distant hawks, mockingbirds and a gentle breeze in the treetops.  The 2 rpm rate keeps beans active enough that there is no scorching or burning during a cycle, even when they are introduced to a very hot drum.  About 70% of chaff fell through the drum holes and accumulated in the bottom of the grill.  No flaring or scorching of chaff occurred given the heating element was not positioned beneath the drum.  Beans roast very evenly, indistinguishable in appearance from an 8-10 minute roast cycle in a Poppery I.  It was possible to view beans through the window and drum, barely, with a flashlight.  Visual tracking of the roast is convenient but not essential.

The design allows the drum to be removed and dumped easily.  Gloves are at hand (pardon the expression) when the beans are transferred to a colander for cooling.  Since a set screw once loosened up (and a hot drum slid off the shaft during dumping) I ALWAYS wear gloves when removing beans.

 

A slight bend of the thermostat improved warm-weather performance.

The size of perforations in the Frontgate.com small wastebasket do not jam (much) with beans in the roasting process (save a few which were oddly shaped, broken or split).  With the heating element rotated along the back wall of the grill chafe falls away from the element and, with a tweaked thermostat, roasting temperatures can be controlled within the 450-575F range.  Non-flammable Nomex insulation allows faster warm-up and more even heat distribution.

basketfunnel.jpg (147652 bytes)

The pattern above forms a funnel to fit inside a Frontgate.com (small) stainless wastebasket.   It is perfect for up to 1.5 lb. of beans on the small Frontgate.com wastebasket.  I do not believe this funnel form will retain more without spillage.  Stainless bowls (with cutout bottoms) may work better and be fabricated more easily (see: www.homeroaster.com).

 

meco warming.jpg (26533 bytes)  meco chaff release.jpg (41820 bytes)  meco looza.jpg (78675 bytes)  meco beans.jpg (99895 bytes) 

Some lifting, tumbling, scrambling fins were an essential addition for improved heating of beans and uniformity of roast.   The pre-heated Meco will run a pound of beans into the second crack in as little as 10-14 minutes it is insulated; first crack in as little as 8-10 minutes.

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An idea to reduce heat stratification occurred while pacing belowdecks.  Cost zero (if you already have a Dremel tool, a slot car motor and hand rheostat controller or an electric paint stirrer):  The Dremel Occasional Fan.  It moves a fair amount of air at Dremel speed #1 and can be introduced through an existing hole in the grill body.  The fan is two-inches in diameter.  The convection idea seemed great until I learned that a tweaked thermostat will create enough heat to go without.

elevators.jpg (66837 bytes)    spout.jpg (16142 bytes)

August 21, 2002
The addition of four drum-width lifting fins (photo above) has turned the corner.  These fins are more like bookshelves.  They are much too wide in the first iteration, cut 2.5-inches x 12-inches then bent 90 degrees, leaving the "shelf" at 1.5-inches wide.  It needs pruning or some large holes punched in it.  Too big or not, lifters put the beans where the heat is.

Another (free) addition was very favorable.  I fashioned a foot long, tapered pouring spout (photo above, aluminum foil over cardboard) to introduce green beans into the preheated grill with the drum rotating.  Without being burned.  Works like a champ.  Introducing the beans in this way means: Lid up - beans in - lid down.  It's quick.  Grill temperature doesn't drop too far.

Elevator width has been pruned down to one-inch; lift height is slightly more than 90-degrees (from bottom) and a constant tumbling motion is achieved.  It looks like an Alp on steroids with twice the smoke.


MonkeyBlend.jpg (67918 bytes)

December 18, 2002
The grill has achieved higher operating temperatures when ambient temperature is low.  For example, when the outside temperature is 30-50F the grill will quickly reach and hold roasting temperatures of 500f or higher; when the outside temperature is 75-90F, the temperature will not exceed 450F indicated at the drum's mid-height. The thermostat, which is outside the body of the grill (inside the variable rheostat), stays cooler in cold weather and forces the heating element to operate for longer periods of time.  The thermostat tweak cure all.

The quality of my espresso is as good as it has ever been - the worst of it is better than 98% of cafe coffee, to be sure.  It is better, but it is different.  A drum roast is different from a popper roast.  I have read that a drum roast is less "bright" than that achieved by a fluid bed.  I find the drum roasts are outstanding.  Since upgrading my espresso machine, I have discovered a lot of flavors and nuances that were once missing.

Conclusions