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Heatgun FB Build
So I have finally found some time (and gleaned enough parts) to begin my fluidbed build. I'm hoping to be able to roast around 1lb. give or take a little bit and run it off of a 15amp circuit in my garage. I have limited skills and access but have made a little progress. Here's my setup:

single-stage, 120V, Ametek vac/blower (thanks to OGH!)
1500w heatgun element

So far I have housed the heatgun element in an old Starbucks stainless travel mug (at least Sbux is good for something Roflmao) with the fan and switch attachment still intact as to avoid rewiring it to work. Build a rough housing for the blower and attached the heating unit to the blower unit via PVC pipe and rubber coupling.

I will use the original heatgun switch to manually control the low/hi heat options and my blower is hooked up to a variac for speed control. My only dilemna right now is deciding on a roast chamber. I'm torn between a bakearound and a blender pitcher.

Here are some pics:
CharcoalRoaster attached the following images:
3_6.jpg 2_7.jpg 1_8.jpg

Edited by CharcoalRoaster on 09/09/2015 8:55 PM
Comments and suggestions greatly appreciated! ThumbsUp
Good start for sure. Inspiring me to do the same.
Looks great.

I used a replacement globe from a gas lantern for my roast chamber along with some stainless kitchen bits. It may be slightly small to do 1 pound but could probably work with a few small mods.
If you aren't going to recycle any hot air, you won't need the heater switch. With 1500 watts it will be on all the time and your batch size will be limited by the ambient temperature. Just control the batch temperature with the blower control. Be sure and set it up so the blower must be running before the heater and don't ever let the beans stop moving with the heater on. With my heater on 100% and no hot air recycle I can roast 350 grams in 70F ambient and I can run the heater at 70% with 500g loads with recycle on.
Your heater will pull 13 amps and your blower about 4 amps, add 20% for surges and dips your 20 amp breaker will probably blow. Put in a 30 amp breaker if your wiring is 10 or 12 gauge and replace it all if the wiring is smaller..
AS far as I'm concerned you can't beat a Bake-A-Round.
Goog luck...
No oil on my beans...
Ok, I guess we'll see what kind of load I'll be able to handle once I finish everything up. As far as recycling heat I had thought about attempting such a feat but was stuck with one concern - how to get the beans out?

In order to recycle heat I will need to direct the heat that is escaping from the RC back into my blower inlet feeds, right? Do I need to implement a quick lock type connection on that port in order to access beans and recycle hot air? What about chaff collection when recycling hot air?
Reclaiming hot air:
1) First of all I have a two-stage, flow-through, blower. This allowed me to cross-drill the manifold between the blower and the heater, so that, I can run the blower at a high enough speed to keep it cool with the beans moving very slowly. Without those holes heat would constantly build in the blower.
2) My reclaiming system is only a box that hinges up for cooling.
The RC air and the ambient air mix in that box and is drawn into the blower inlet.
3) Cooling and polishing are performed in the RC. During this operation the chaff separates and clings to the 40 mesh screen at the top.
4) The blower is turned off, the screen is tapped, the chaff falls to the top of the beans, and is removed with my little shop vac.If you review my build you will see I went through a lot of hoops to build a chaff collector that sort-of worked but my current system is way more practical.
5) Evac is via a J-tube. Video in post 113 of my build. The picture is in post 179.
Toady's roast 441g of Costa Rican Tarrazu - Ambient = 66F, Heater = 70%, First crack = 10:30, Finish = 12:05 and level = full-city.
No oil on my beans...
a hiccup.

Just to make sure I could get some loft on those beans I threw about 500g into my blender pitcher with some SS mesh on the bottom and the lid on top = no loft at all. As a matter of fact no bean movement at all.

here are some more pics too. I will attach some flex hose ducting or more pvc on the elbow inlet to reclaim hot air once I figure out the RC situation. rough for sure, and hopefully functional soon...
CharcoalRoaster attached the following images:
5_6.jpg 4_7.jpg 3_7.jpg 2_8.jpg 1_9.jpg
Try a perf plate instead. What;s the diameter of blender?
Is the top solid?
No oil on my beans...
Ok, I've got some perf plate material in the garage. I'll give it a try. Diameter is 3" at the base then tapers wider to 8". Lid is normal plastic blender lid that I was planning on connecting PVC to in order to reclaim hot air.
Seems kind of wide at the top. Is the lid vented?
The air that enters the bottom must come out the top.
My inlet to outlet hole total area are a close match.
Then as chaff starts to gather at the top, the outlet is restricted a bit.
No oil on my beans...
I'm sure there is a scientific reason for it that I'm unaware of but why does the inlet outlet diameters need to be identical (as similar) as possible?
It doesn't, but the open area of the RC outlet needs to be near equal
to or larger than the inlet, to move the beans. Because a heat gun's
output temperature is inversely proportional to the air-flow rate, I like to have complete control of it...
No oil on my beans...
Ok so here's a few updates to the build - well a lot of updates actually. Attached is a video of bean circulation which seemed to be pretty good IMO but then again this is my first build so not entirely sure how much movement to look for.

Secondly is a finished pic of my roaster. I am able to handle 1lb loads pretty easily, but I think that's where I would max out. Last night I did a test roast but stalled out when some chaff clogged by reclamation point near the blower. As a result I didn't have enough juice to finish off the roast but learned where some hot air was escaping and have since closed those off. Today I built a cyclone chaff collector out of an old kleen kanteen, some pvc, and a mason jar for collection. I included some fine ss mesh at the output on top and siliconed in a perf plate baffle directly underneath (no pics - sorry I forgot before installation) I ran a quick test and beans circulated, air circulated, and everything seems to be functioning properly. Hopefully, was all the silicone cures I can run another roast.

CharcoalRoaster attached the following image:
I did have some times marked down during the roast before the clog and with 3/4lb I hit yellowing right around 8:30. If everything would have been cool I was guessing I would've finished the roast around 15-17min. How's that as far as roast time is concerned? About the same as I was getting in my GeneCafe.

One last element I want to add is a temp probe in the BM. I have a type-k thermocouple/digital thermometer but not a probe. Any suggestions on a decent probe out there to build into the roaster?

It's on sawhorses right now but on the ground it'll stand about 3ft tall - it's a ridiculous monster, kind of ugly, but once it starts to breathe fire on those beans I'll be a happy camper roar
Today's Roast 445g Kenya AA
Ambient = 71F
Yellowing = 3:30,
First crack = 10:00,
Finish = 11:45.

I still maintain PID, chaff collectors, and BMT probes are a waste of time....
Edited by oldgearhead on 09/24/2015 7:57 AM
No oil on my beans...
Sadly, I was forced into adding a chaff collector because it was clogging up my roaster :-)
My roast chamber is a Bake-A-Round tube. It is 14.5 inches tall and 3.4 inches in diameter. I use a generic 40 mesh convex screen to trap the chaff in the roast chamber. I do have to reduce the load from 450g to 350g with a few dry-processed beans. However, it works perfectly for most beans.
oldgearhead attached the following image:

No oil on my beans...
I think my heating element died. After a couple weeks off of the build I sealed some air leaks and went to fire everything up. The blower was working great but when I flipped the switch for the heating element I didn't feel any heat at all. Checked the plug connections and everything was as it should be.

Is there a fuse or anything on those salvaged heatgun elements I can check to see if it blew or are there visible symptoms of a burned out element?

Check for a fracture in the coil itself. Cheers, Scott
Thanks Scott - sure enough there was a break in the coil where it touched the metal enclosure it was housed in.

I replaced the element with a new one and made sure the same problem wouldn't occur again.

My next question is re: amperage, power, etc. I have great bean circulation and am recycling heat. My chaff collector is working like a champ but my roasts are still taking too long. I am thinking that because my only circuit available to run my roaster on is only 15amps that I'm not running on full power.

I think I remember reading here somewhere that without larger amp circuits blowers/heaters won't be operating at 100%. If this is the case, then would this potentially explain my roasts stalling out after 15-18 minutes?
Just put a temperature sensor or thermometer where the beans are normally located, run it for 6 minutes at 40 CFM without beans, and record the temperature. If you don't have an air flow meter try to duplicate the lowest blower speed that just keeps the beans moving very slowly. I use a 30 amp 120V circuit and the above test gives me
500F at 75% power on the 1550 watt heater...
No oil on my beans...
You can check your voltage at the element with power on. If it's low, your going to have a corresponding power drop. Use either thicker wires or shorter ones to get your voltage up, if that's the case.
Bad coffee prevails when good coffee roasters stand by and do nothing.
Ok probably a naive question I asked earlier re: power considering one of the components to my build may be the cause of the seemingly low power production.

I have separate plugs for the vac blower and the heating element. The vac motor is plugged into a variable speed controller. Both the speed controller and the heating element unit are plugged into a 3-way splitter on the end of a 15' extension cord. This way, I thought, that all I need to do is plug in the extension cord anywhere in my garage and I have power while being able to cut either the fan or heater off independently.

After reading through more of the posts I think that either the extension cord, splitter, or combo of the two is reducing the power to my element.

Could this be true?
Lots of maybs:
1) Distance of plug from circuit breaker
2) Gauge of wire in the wall
3) Wire gauge of extension cord
4) Length of extension cord
5) Amount of loss in electrical controllers

Is the garage circuit breaker tripping? What size is it?
My first thought is your current is escaping through heat from either
the extension cord, the connectors, or both. Feeling the cables or using a heat sensor right after a trial run might locate the problem.
No oil on my beans...
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