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n00b questions - 2.2kg FB roaster build
BryanG
I am looking to build a roaster. I am hoping to build a 2.2kg (5lb) roaster, that I hope to be able to do 1lb or 2lb batches in (would be nice). I have been reading the site for several days and am now more confused than ever :)

Motor-
My wife has 3 vacuums in the house that she no longer likes, but I have not thrown out...fate? I keep seeing reference to Vacuum motors for these projects. I have a Oreck and a Dyson, Would this type of vacuum motor do the trick? Or do I need to go out and search for a different motor? I suppose I will control the speed of the fan with the Harbor Freight Router controller, or something like it.

Heat-
I would love to go with GAS, but to keep build costs down, and more simple I am looking at Electric. I have 3 20 amp 115 circuits in my garage ready to go, so I am thinking 1 for all my fans, etc, 2 for heating elements. For heating elements, I see a few different references to heat Gun elements. I was looking at this...
http://www.heatgu...9I182.aspx
Searching the web on the gun it is for is says produces 750 to 1000 degree temps. not sure how that translates to heating the coffee mass. ans I am not sure if that means I need one or two to heat 2.2 kg? How do I mount these in a stainless steal pipe so the elements do not touch the pipe and short?

Roasting chamber-
I am looking at using a wide mouth canning funnel as the base of my roasting chamber, then some heating pipe stock as the remainder of the chamber. If I am reading that correct, that gives me a 4and3/4" diameter roasting chamber. will that work for 2.2kg? How tall do you think it would need to be?

thanks for the help ... I am sure I will hit you with 1000 more questions as I go.
Dan
Not all vacuums will work. What you want is called a vacuum motor. They not only do well generating suction, but pressure as well. It is because of the thin, rapidly turning enclosed impeller they use. Tear down your wife's vacuums and look for this:

www.centralvacuummotor.com/Ametek/116392-00L.JPG

I can tell you that the Dyson does not use vacuum motors, per se, but I have no clue if they could be used to generate pressure suitable for use in a hot air roaster.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
BryanG
looks quite different ... I think this is the one I have...
http://www.ebay.c...232943488b
JETROASTER
Hi Bryan,
The Oreck blower will be of little use.
The Dyson (actually a Panasonic) blower could potentially do 2.5lb.
That blower is a 'flow-thru', vs the one Dan posted, which is a bypass.
Bypass blowers are normally found in central vacs, and are better suited for your project. The 5.7" pictured above might be a bit small.
I use a 7.2" 2 stage (below) for a 5lb machine....it's a bit larger than needed.

You could likely get started with the dyson blower...do a few experiments.
Selfishly, I'd like to see that blower move 5lbs. It would be a nice innovation.
Looking forward to your progress. -Scott
JETROASTER attached the following image:
7_2_2stage_1.jpg
oldgearhead
Welcome and good luck! In general, you will need one Mater Appliance
1520 Watt/750F heat gun element per 1/2 Kg. Also make sure your materials are safe for use with coffee and heat. I know some galvanized
is not safe. I prefer all glass for the roasting chamber. A Corning Bake-A-Round will easily roast and cool 500g loads, but are too small (3.75" dia)
for 1.0 Kg. Something in the 5.0" diameter rage should be prefect if its about 12-16" tall.
]
oldgearhead attached the following image:
bmt_1_4.jpg

No oil on my beans...
RoasterRob
I have used only flow thru blowers, a by pass blower wouldn't work for me without significant mods to how I build roasters.
You can work with either bypass or flow thru, just need to build differently for each.
For heat (without recirc) you would need a minimum of 7kw IMO, I'm not even sure that 7kw would be enough for 5lbs. In warm weather it might be, in cold weather you may not be able to get passed 1st crack.
IMO gas is easier to work with than electric, more reliable and you will have heat to spare.

In my current rig I am using a cheap 1400 watt single stage VC blower and a sievert 2941 gas torch rated at 14kw at 4bar. I can loft and roast 7kg (15.4lbs) of green with this setup. It is definitely running at the limit for heat & loft.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
RoasterRob
Roast chamber ideally 6" dia by 26" tall which allows 10" above roasted mass for spouting. 5" by 16" would not contain 2.2kg of coffee once roasted. Assuming I've done my maths right.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
I am not opposed to going Gas, I am looking at how to accomplish it. The GAS heating chamber appears to be much larger than that needed for electric. My Brother in Law has a commercially produced 10lb unit. It has a pretty darn small heating pipe with the elements in it, leading up to the roasting chamber.
With fire, I am going to need a larger diameter, and I guess a larger blower. Is there somewhere I can read up on the design of these heating chambers, and the transition to roasting?

In regards to the torch, I have natural gas in the house, but it is low pressure. It appears you all are using high pressure to power your torches. Is there a low pressure torch, or do I need to look at Propane?

So much to learn :)
RoasterRob

Quote

BryanG wrote:

I am not opposed to going Gas, I am looking at how to accomplish it. The GAS heating chamber appears to be much larger than that needed for electric. My Brother in Law has a commercially produced 10lb unit. It has a pretty darn small heating pipe with the elements in it, leading up to the roasting chamber.
With fire, I am going to need a larger diameter, and I guess a larger blower. Is there somewhere I can read up on the design of these heating chambers, and the transition to roasting?

In regards to the torch, I have natural gas in the house, but it is low pressure. It appears you all are using high pressure to power your torches. Is there a low pressure torch, or do I need to look at Propane?

So much to learn :)


For the "furnace section" a 6" dia pipe approx 24" high. Room for the VC blower and torch directly above the blower with at least 11" or more gap to the RC perf plate. For 5lb coffee a basic VC blower about 1000 watt 5" dia single stage would work fine as long as your perf plate is not too holy. Basic layout similar too my original "Heath Robinson" roaster on Ed Needhams site http://www.homeroaster.com/rob.html
The RC on that one is only 650grams - 4". For 2.2kg RC would need to be 6" x 26". With that furnace section you could easily in the future build a new RC that will do at least 4kg with no other changes. (possibly just need to put in a slightly gruntier VC blower). I'm running a 7kg RC on a later version of that Furnace section, same burner (Sievert 2941) and 1400watt VC blower.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
Rob, do these roasting chambers need to be made of such heavy gauge steal? It seems to be a bit of overkill. Could one be build out of sheet metal (non galvanized)?

I see a lot of the home roaster made of heavy pipe,, it seems so heavy...
RoasterRob
Sheet metal would be fine. The RC does need a bit of weight in the bottom to keep it down unless you want to lock it down with some kind of latch or a bayonet type of connection etc. I have used materials that i have easy access to. The weight has never been an issue. It was however easier to fix the VC blower in a 6" sch40 pipe than in a 6" ss pipe. The sch40 pipe is 157mm id compared to 150mm ss 1.5mm wall with id of 147mm from memory.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
The cone part of the roasting chamber seems to be the hard part to find.
This is only 5" diameter, 30 degree slope, would give me flexibility on the opening hole size ranging from 1.5" up.

Would this part work?
http://www.racepa...=JOD-96-SS
RoasterRob
Don't need a cone if build an asymmetrical flow RC.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
Rob,
in the asymmetrical, I have a tube, angled screen near bottom, with holes in 1/2 to 1/3 to push beans up that side, replacing beans slide from above ... hummm.

not sure why I never pictured it.

Question... heat chamber leads to the roasting chamber, full 6"diameter opening between the two? limiting factor, and I guess forced pressure to move beans is number and location of the holes in the slanted screen/plate piece (that has a specific name I am sure)...

hummm, this is more interesting now, much easier to build...I have looked at your builds, why have I not seen the difference int he Roasting chamber before now. UGHHH

Now now I just need a 6" stainless tube for the RC, about 26" and then a 6" steel tube to house the heating chamber... and then a coupler slide one onto the other... this became much more obtainable now. Thanks for hitting me with the Clue by Four. :)
RoasterRob
The perforated section is flat and approx 20% by area of the tube cross section area. Only the slide plate is angled, I use 45 degrees. I have used gravity to hold the RC down just need enough weight in the RC. Gravity has worked fine for the 650 gram and 2.3kg RC. My 7kg RC needs extra weight.
I have just made sure the furnace section has a flat plate welded to the top. The bottom of the RC I usually have a short section of sch40 pipe that has been skimmed on a lathe. That first roaster I also had a short section of pipe slide up the inside of that pipe on the bottom of the RC. Hole at top of the furnace section is about 80mm. Still using about that size hole on my 7kg RC. The VC blower has only got about a 35mm inlet hole.

This link shows my original Heath Robinson prototype roaster on Ed Needhams site.
http://www.homeroaster.com/rob.html Looks like a pile of junk ( actually it was a pile of junk before I turned it into a roaster).
Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
Thank rob, I am now reading through a Google Groups conversation you were part of years ago. So much great info.

Here is my wild dream ... a single Roaster base that I can swap out the propane burner to adjust max heat, and adjust with adjustable regulator, and control on the Vacuum Motor speed.

Then have a few different size Roasting chamber that I can swap around based off the need (small batch, test roasts, big run) I would love to see 1lb, 5lb and 10lb chambers. that would maximize my versatility with a single roaster.

One thing that has me concerned, is that you mentioned in a post that you could do the burner swap, to increase heat, but there were other issues. What may I need to be considering?

I am looking at this motor...
http://www.graing...Pid=search It seems big enough to lift 10lbs, but can it be throttled down to deal with just 1 lb?

Does this sound unreasonable?

I love the idea of your I read somewhere to mock them up with plastic and cardboard first to test. I can get 6" ID PVC pipe to mock up a 5lb load. how do you simulate the lfat plate and angle? I am guessing the angle can be cardboard, but the flat plate will have significant pressure on it. Do you use some sort of PVC fitting to do that, and drill the holes in it?

Thanks for all your experience and sharing it!
RoasterRob
The sivert 2941 burner with 1 to 4 bar reg worked for 650 grams thru to the 7 kg RC I use now. 7 kg is about the limit.
That VC motor is a bypass unit, if your fitting it in the bottom of pipe a flow thru unit is what you need.
I used steel perf plate and card board angled plate fitted inside the stainless steel pipe I intended to use as the RC. I also have a wood & cardboard sivetz box roaster still sitting in the garage.
If you are copying my setup (incuding perf plate layout) you really don't need to test a mock up.
search FB roaster on youtube. The RC I'm using there is the 2.3kg unit.

Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
BryanG
Rob,
Translating from metric to silly american keeps confusing me. GREAT news on the 2941, that makes it easier. I do have a question on that, it is hard to find info on how to set them up.

They sell the torch head, the neck and then a handle. Is the handle necessary? Or can we take the neck to the hose coming from the propane regulator? IF we have to have a handle, is there something I can look for to find a cheaper version or used one that I can adapt to the burner head? propane is not something I use except for my grill in the yard.

As for the VC motor, I was thinking of placing the motor not in the base but along side fed by a 2" pipe to feed the heating chamber and then using the intake to cool beans... (question, if air is pushed in perpendicular to the direction of the RC, will tat create too much turbulence, or do I need a 90 in the base of the HC to push the air up?)
I am looking at this:
homepages.paradise.net.nz/loenhout/roaster4.jpg
and this one, little nicer looking.
homepages.paradise.net.nz/loenhout/rver3.jpg

The main reason for that, it is easier for me (I lack a machine shop) to fabricate hooking the motor up this way, rather than trying to figure out how to mount the motor into a pipe and seal it up good, creating mounting brackets, and the like. Maybe in the future on my v2 or v3 design :)

Hope you do not mind me working with your proven designs. :)

Thanks again,
Bryan
roastedgourd
Bryan,

I recently finished a roaster based on Rob's design. I used the 2941 and did not buy the handle. Instead, because the threading on the burner doesn't fit any standard American pipe fittings, I had a machine shop make a custom adapter to go from the burner to standard black pipe threads. It cost me $40. It's beautiful and works great but if I had it to do again, I would solder a short black pipe nipple onto the burner and be done with it. Problem solved for less than $2. I run straight from the adjustable pressure regulator to the black pipe, which runs straight into the burner. It's a simple setup and it works fine for now.

For the vacuum, I'm using a amatek bypass blower similar to the one you linked to above. I built a separate box for it and run it straight into the side of the furnace chamber at the bottom. I did not use a 90 elbow to direct air up. I've had no problems pushing over 5lbs. (my goal) of beans with this setup.

Hope this helps!
-Ian
BryanG
silly question, what is the diameter of the heating chamber pipe?

Ian thanks! Got pics? I love to look at these things...
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