Skywalker roaster... | [275] |
Skywalker, the AL... | [195] |
Dereks 1-2Kg drum... | [115] |
Skywalker Roasts | [92] |
SR800/SR540 Fan C... | [82] |
3d Printed Fluid Bed Roaster
|
|
Linnaeus |
Posted on 11/20/2017 10:22 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Hi All, I recently submitted a 3d printed roaster here: https://forum.homeroasters.org/forum/viewthread.php?thread_id=5392 Now I am attempting a fluid bed design. Core Components: 1) 18V, 120W portable vacuum motor + PWM controller + 2.5" cold air intake filter 2) 1800W ceramic heat gun element - nichrome with narrow ceramic channels. Should conduct more heat to the air at the expense of added static pressure. 3) Fuji PXR4 PID + 4" probe + SSR 4) Bake-a-roun Pyrex Tube!!! It is a DIY fluid bed after all The rest will be made with a refractory concrete made by Rutland. I have used this mix in a few other projects and am very happy with it. To prevent dusting from bean impacts I'll be sealing the lower roast chamber with a ceramic adhesive stable up to 1200C. Should bind any small particles to the surface and prevent contamination. Early pic of the mold being printed. It is inverted here (and in the following three photos) so you are looking at the roast chamber upside down. Finished mold for lower roast chamber. This is a not-insignificant print. Total height is 180mm (the exact limit of my printer). Print time was 36 hours and in total 280 grams of filament was used ($4). Filled with concrete mix, bit of rain. A temporary guide in place used to mount 4" bolts into the base. These will be used to mount the lower roast chamber to the control box that will sit below. Printing a compression chamber for the vacuum housing. This is a bit of a lossy / non-ideal design. It will guide the air from the vacuum outlet (which right now is tangential to the rotation of the radial compressor and route it to a 30mm opening that will mate with the lower roast chamber intake. Bonus: This was made for an earlier iteration where I was trying out an axial compressor. This is the final stage which includes stators and a turbulence reduction cavity. It worked and boosted the dynamic pressure, but the total length of the axial compressor was close to 100mm and required at least 40-50mm gap beneath (not accounting for a filter). The entire design was too tall. The radial compressor overcomes this by taking air in at a right angle. Will post more pics as it comes together ;) Edited by Linnaeus on 11/20/2017 10:35 AM |
|
|
JackH |
Posted on 11/20/2017 2:12 PM
|
Administrator Posts: 1809 Joined: May 10, 2011 |
This looks great! I don't think anyone else is building something like this. Please keep us updated. Looking forward to seeing it roast! ---Jack
KKTO Roaster. |
|
|
btreichel |
Posted on 11/21/2017 1:09 AM
|
1/4 Pounder Posts: 185 Joined: May 07, 2007 |
Interesting. I have an airflow prototype 3-d printed. Never thought about printing molds. |
|
|
Linnaeus |
Posted on 11/21/2017 10:25 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Quick update. So, I made an error with this mold and printed an infill for any support pieces touching the build plate (you can see it in the first image of the mold print in progress). The result is that the "bowl" for the roast chamber was one giant chunk of plastic that was not easy to remove. I have tried one round of baking it out, which worked rather well - but has left a bit of a residue. I'll have to fire the rest of the plastic off (either in the oven or a fire pit). Additionally, in trying to burn the plastic out I heated up the block a bit too much (430F) before all of the moisture had been baked out. This has resulted in some small cracks. I've sealed the cracks with rocksett, they are barely visible and should not impact the strutctural integrity of the finished part, but the OCD person in me wants to start from scratch. upside down Right side up The bowl showing some of the PLA residue The ABS vacuum guide Next to the 18V 120W vacuum Wired up to the PWM - works a treat. Some of the other parts lined up and ready to go Next step is to print the lower housing which will encase all of the electronics and support the roasting chamber above the vacuum housing. I will embed the heatsink for the SSR in the intake path for the vacuum housing. In this way, I'll have active cooling for the SSR and will (VERY SLIGHTLY) increase the intake air temp. Edited by Linnaeus on 11/21/2017 10:30 AM |
|
|
Linnaeus |
Posted on 11/22/2017 11:08 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Baked out the remainder of the plastic residue and was able to fit the glass top and heating element. Fit is very good with no wiggle room on either. The heating element has a mica sheath to prevent conduction within the refractory. |
|
|
Linnaeus |
Posted on 11/23/2017 8:57 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Below is an assembly of all the pieces designed thus far: |
|
|
allenb |
Posted on 11/23/2017 11:57 AM
|
Administrator Posts: 3851 Joined: February 23, 2010 |
Quote JackH wrote: This looks great! I don't think anyone else is building something like this. Please keep us updated. Looking forward to seeing it roast! I agree with Jack, I've never seen anyone doing 3D printing for molds and making operational fluidbed roasters from them. This looks like it would be a whole lot less hassle without having to fabricate sheet metal parts. But, one would have to have the expertise in programming the printer. Very nice indeed! Allen 1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
|
|
|
btreichel |
Posted on 11/23/2017 7:49 PM
|
1/4 Pounder Posts: 185 Joined: May 07, 2007 |
If you can do the cad drawings, there is software that slices it up for printing. |
|
|
Linnaeus |
Posted on 11/24/2017 9:37 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
I don't really have any metalworking skills, and have always been jealous of the cancellation/sheet creations that people are building. But I do love 3d printers. There is no other tool that makes engineering prototypes so accessible to a hobbyist. |
|
|
Linnaeus |
Posted on 11/25/2017 9:44 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
More assemblies - working on the base now and fit for the PID/PWM... not too happy with what I've come up with as it will be a bit bulky, but want to pull the trigger soon so that I can get this operational. The rear intake will have a cold air filter mounted ontop - it's serious overkill, but will go towards preventing any buildup / fires without adding restriction. Probably would have been better to just 3d print a mesh cylinder and put a nylon over it. |
|
|
Linnaeus |
Posted on 11/25/2017 10:57 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Some screen grabs of the first half of the enclosure. |
|
|
Linnaeus |
Posted on 11/25/2017 12:21 PM
|
Newbie Posts: 49 Joined: September 12, 2017 |
And with a mock up of the 2nd half of the housing: And with the rear intake filter + PID/PWM: Edited by Linnaeus on 11/25/2017 12:28 PM |
|
|
snwcmpr |
Posted on 11/25/2017 3:53 PM
|
1 1/2 Pounder Posts: 925 Joined: March 03, 2011 |
WOW!!
--------------
Backwoods Roaster "I wish I could taste as well as I wish I could roast." As Abraham Lincoln said "Do not trust everything you read on the internet". |
|
|
Linnaeus |
Posted on 11/26/2017 6:46 PM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Wanted to show off a little design element that makes me happy. The SSR heatsink is ducted into the vacuum intake path. I hope that this will prolong the life of the relay by keeping it super-chill, and also give the tiniest little boost to my ambient air temps :) It's starting to come together - here's where the vacuum housing connects to the roast chamber. This part is printed in ABS with a flange also printed in ABS. Unlike the PLA, which has a glass transition temp of 60C, ABS has a tglass of 85-90C and won't really deform until 105C or so. Finished printing the base out as well. The PWM fit is a little loose - so I'll be printing a little frame to keep it secured. I'm applying an epoxy + copper powder (real metal powder) to this piece. When cured it can be buffed up and aged. Will post those pics tomorrow. |
|
|
renatoa |
Posted on 11/27/2017 12:36 AM
|
Administrator Posts: 2980 Joined: September 30, 2016 |
Too much care for the SSR, for my 1400W element it runs cool enough without any heatsink, about 40C degrees. I would be rather worried about the real specs, when such 40A unit stopped working in my roaster, opened it and was surprised to find inside a 16A triac, which make a cinic joke the 40A engraved on the case... Be also aware that when these SSR die, they don't break the circuit, conversely, they short, so you will have full power without any control, other than mains switch or unplug from the wall faster than a fire break out. Roasters: DIY: TO based IR 200-640g
Moded commercial: Skywalker, Dieckmann RoestMeister, Nesco, popper(s). Electrics: TC4ESP, MS6514, USB/Artisan/Apps, PID controllers Grinders: Arco, Xeoleo ghost burrs, Krinder, vintage PeDe Dienes, MBK Feldgrind Brew/presso: ALM pour over, Arin lever, Staresso Mirage, Hario Cafeor dripper, Flair, Kompresso, Rota Aeropress, Gaggia Mini |
|
|
Linnaeus |
Posted on 11/27/2017 5:50 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Thanks renatoa, In testing, this ssr ran between 45-55c. Every little bit helps ;) and with enough cooling a 16A triac could probably handle 18+ amps. Heat is the enemy of all electronics.
Edited by Linnaeus on 11/27/2017 6:04 AM |
|
|
Linnaeus |
Posted on 11/27/2017 7:57 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Testing the fit of some of the parts. Was able to loft about 200g of test beans. Will need to seal the joint between the vacuum and roast chamber with silicone though - the ceramic element did cause a lot of back pressure. |
|
|
Linnaeus |
Posted on 11/27/2017 9:48 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Not totally happy with the finish, but here's a little background on the process. The finish is created using a 2 part resin and a powdered copper that looks like this: The resin is mixed, and then the copper is added. Once dried the finish looks like this: The piece is then buffed using a piece of 000 steel wool. After buffing the part it looks like this: I may add one more coat with a black dye in the resin, or I may just drop some black shoe polish on top. One of the challenges is that when buffed with steel wool, the copper shines up, but the resin dulls a bit. Giving it a bit of a haze. This can be corrected by adding more copper to the resin, but it gets very thick and difficult to paint. |
|
|
Linnaeus |
Posted on 11/28/2017 7:02 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Did some more testing, and to get the highest pressure rating possible I will have to seal with silicone. Unfortunately, this means that the connection between the vacuum housing and the roast chamber will be semi permanent. If I approached this project again I would make a larger flange inset in the refractory RC and coat it with high temp silicone. That way the two parts could be easily separated for maintenance. Here's a little pro/con. Most vacuum motors have way too much airflow, when you dial them back, they lose the majority of their pressure rating. The ceramic heating element used here adds a significant amount of static pressure (con). The pro is that the radial compressor can be run in it's optimal power band. I would guess that I get about 50 cfm through the heating element - but also get 8-10 inches of pressure. The other pro here is that the high air pressure within the heating element means that there is a higher air density. Higher density means more air molecules in contact with heated surfaces and a higher heat transfer rate. In many fluid beds the limiting factor is getting enough heat transferred to the air before it comes in contact with the beans. The limiting factor in this design is the airflow through the element. Once it's all sealed up I will do a test of the maximum green coffee volume that will fluidized. Keep your fingers crossed for 500g. |
|
|
Linnaeus |
Posted on 11/30/2017 2:19 PM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Very frustrated today. I went to test my heating element, and found that it is only drawing 400 watts, despite being specced as a 1600W - 120V element. Lesson learned, I should have tested this before assembling / siliconing parts in place. Now it's going to be a major PITA to remove the element / clean up silicone / remove the gasket between the RC and the vacuum housing. On another note - here is an image of the final air intake assembly And the probe mounted (lower left) + heating element mounted / wired up (center) I also printed a little flange so that the PWM would sit flush |
|
|
allenb |
Posted on 11/30/2017 4:42 PM
|
Administrator Posts: 3851 Joined: February 23, 2010 |
Running the numbers it looks like they may have shipped you a 220 volt element which would run at around 480 watts at 120 V. Allen 1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
|
|
|
Linnaeus |
Posted on 12/01/2017 7:26 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Looks like that, Allen. The coil measures about 30 ohms, which is about 1600w at 220-40 rms. I have a bigger problem though. The shallow roast chamber side may be too shallow - the beans do not slide down towards the heating element. Also, the 120w vacuum may not be powerful enough to push through the ceramic element and much over 100g of beans... Hmm... Well, I guess it would have been greedy to want this to come together so easily. |
|
|
Linnaeus |
Posted on 12/01/2017 8:33 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Pretty happy with the look / assembly. Just hope I can figure out a perf plate design that will work. |
|
|
coffeeroastersclub |
Posted on 12/01/2017 10:07 AM
|
Pounder Posts: 535 Joined: May 26, 2009 |
Believe it or not you may want to restrict the airflow coming out of the exit area of the element. By doing so it will create a higher pressure area yet on a smaller area under the beans, causing a spouting of the beans. I encountered the same issue as you when first developing an air roaster (spouting type). What I mention was the solution. So what you would do is cut out a piece of stainless steel in a circle, the diameter of which is the exit circle you now have. Then cut a hole in the middle of it about half the diameter of the original circle. Affix somehow. You may need to do a couple tries with different sizes of holes cut till you get it just right. Len "If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
|
|
|
Linnaeus |
Posted on 12/01/2017 10:30 AM
|
Newbie Posts: 49 Joined: September 12, 2017 |
Hi Len, I'm going to give that a shot. In addition to the top holes, I was considering leaving a small air gap on the edge to inject a blanket of air under the beans as they fall back to the central heating location / get them out of the static coeficient of friction range. Any reason why I shouldn't use aluminum? Higher heat conductivity might scorch the beans? Also, any best practices for hole positions? Thank you for the help! I need all I can get. Edited by Linnaeus on 12/01/2017 10:35 AM |
|
Jump to Forum: |
Thread | Forum | Replies | Last Post |
---|---|---|---|
Skywalker, the ALM chinese one pound roaster | Other Roasters | 196 | 03/28/2024 12:40 PM |
My first popcorn mod roaster (vahegan) | Fluidbed Roaster | 48 | 03/24/2024 12:04 PM |
Fatamorgana electric drum roaster | Other Roasters | 2 | 03/24/2024 10:03 AM |
Dereks 1-2Kg drum roaster build | Drum Roasters | 116 | 03/14/2024 7:16 AM |
Bellwether Roaster | Drum Roaster (Store Bought and Commercial) | 31 | 03/08/2024 9:28 PM |