Destoner

Brett

hey Cosmic, nice destoner. I've just decided I need a project like this so was hoping you'd be able to shed some light on parts you used - in particular the pivoted filter screen and the rubber collar / adapter going from the fan to the pipework. Can you describe what they are or might be able to be found by, and even where you picked them up if possible (as an indication of the type of store where they were found)

Koffee_Kosmo

I like this design CC :thumb:

Brett

ok, so found https://www.bunnings.com.au/rain-harvesting-90mm-easy-clean-mozzie-stoppa_p4814163 One down, one to go 🙂

Brett

Two down. Job almost done. https://www.bunnings.com.au/kinetic-50-190mm-grey-epdm-retrofit-roof-flashing_p4821114 This was NOT the one I used, but it was similar. The one I used was ~$25 and has a square flashing apron around it, and has markings for "75-175mm". Cut the apron off and the first ring on the small end, then a couple of hose clamps later I have a 200mm fan ducted into the 90mm rain pipe. I also bought one similar to this for $25 https://www.bunnings.com.au/move-it-590-x-490-x-126mm-rectangular-dolly_p3961556 and I'll extend the base once I get closer to knowing how large it needs to be stable.

cosmic_couple22

Hi Brett, sorry for the late reply but seems you sorted the right parts to do the job. The hardest thing I found was getting the tube lengths right and the point of entry for the beans. To long and everything just sits in the tubes and or the beans have to be added so slowly you may as well hand sort. To short and everything just blows through at a great rate of knots including the stones. I will have to measure the lengths but I think they were final cut lengths of 150mm. The bean entry chute must be right at the top of the mozzi/stone stopper and only protrude internally a few millimeters so as not to disturb the airflow and beans, the angle must also be as flat as possible to avoid to much air flow returning up the 50mm tube but still enough angle that the beans will discharge into the 90mm destoner tube. I used normal plumbers glue to join pipe but left the join between the stone catcher and the top section dry as occasionally you may need to get in from the top due to a large stone not allowing the spring door to open. For strength of the join for the bean entry chute I used a 90mm pipe hanger down to a 50mm bracket on the other end. All parts came from the bunnings plumbing section, the feed funnel is a down pipe leaf catcher. At the lengths I played around with I can now just freely pour the beans in and never overload the destoner, she never fails to clear the tubes bar 1 or 2 beans and gets every stone every time. I do find using a 10 ounce takeaway cup as a stopper in the feed in funnel helps the beans flow through. Working on some magnets now to ensure no small metal foreign objects sneak through. Let me know if you need any other info.

Brett

Thanks for the reply ! I'm not quite done, and I haven't done any testing of tube lengths or anything, but I think I have it pretty much all assembled for a test run tomorrow. See pic. None of my joints are anything other than twist-tight now, and I have many different length pipes so I can mix-and-match to optimise the flow once I start testing. I decided on a standard 90mm 45* angle join as the inlet, and I have a 22.5* angle before my leaf catcher (yep, I was in the same aisle at Bunnings 🙂 ). I also put a sleeve inside the 45* join so that the beans can only flow in at a certain pace, and it should also help ensure airflow doesn't go up the angle. I have the 200mm fan and that has probably too much airflow in reserve so I hope I should be able to tune in a good balance of flow rate and still leave rocks behind. The missus has been on my case saying I should get some clear PVC pipe so I can see the bean flow - yeah maybe, but haven't yet found some at a reasonable price to justify. Still left to do is properly brace the main pipe to the baseboard. Here's my rough costs: $275 for fan $25 for big rubber reducer $14 leaf catcher/inlet funnel $10 1m length 90mm pipe $15 assorted pipe fittings $9 mozzie stoppa $12 pipe clamp for brace $15 worm drive clamps for rubber reducer both ends $25 dolly ====== $$400 I think that's a bargain, as long as it works 🙂 Thanks again for the inspiration !

mycuppa

It's looking great Brett & Chester. You may also wish to consider experimenting with a slightly longer length vertical lift section as this could assist with debris separation but more importantly if you tune it correctly it may also be less sensitive to the variances in bean shape, size and density, e.g. less fiddling with adjustments for each time you use it. When you have a longer column for the beans to rise inside of a vacuum, it may also assist in stabilizing pressure around the entire surface area of the orifice, rather than differentials (vorticity) that develop across areas of the pipe (it's a bit complicated to explain, somewhat like an irrotational vortex, e.g. particles moving or rotate at different rates to others). Of course, changing that length will mean the airflow pressure needs to be adjusted. A future mod to the design might also consider a vent with filter or sock to catch the fines from the agitation of the beans during destoning. As the beans are brittle and husk will be dislodged, this makes for a cleaner finished product, but alas it will return you back to the start again in tuning flow.

Brett

mycuppa wrote:

It's looking great Brett & Chester. You may also wish to consider experimenting with a slightly longer length vertical lift section as this could assist with debris separation but more importantly if you tune it correctly it may also be less sensitive to the variances in bean shape, size and density, e.g. less fiddling with adjustments for each time you use it. When you have a longer column for the beans to rise inside of a vacuum, it may also assist in stabilizing pressure around the entire surface area of the orifice, rather than differentials (vorticity) that develop across areas of the pipe (it's a bit complicated to explain, somewhat like an irrotational vortex, e.g. particles moving or rotate at different rates to others). Of course, changing that length will mean the airflow pressure needs to be adjusted. A future mod to the design might also consider a vent with filter or sock to catch the fines from the agitation of the beans during destoning. As the beans are brittle and husk will be dislodged, this makes for a cleaner finished product, but alas it will return you back to the start again in tuning flow.

Re the longer column, after my first two experiment loads yesterday I was actually going to try a shorter one - I needed to use more airflow than I expected to get the flow of beans over the top, and by reducing the length of that section I was expecting I'd be able to use less air speed but still achieve separation of garbage and good. I also have to tune the length of the shield at the 45* entrance, as it still seemed to affect the airflow and bean transport too much (I might even go with a cutout that I can adjust in some way to see how that plays out) I do like the idea of a filter to catch more chaff and fines, but I am pretty lucky that even on a really chaffy natural processed coffee I don't end up with too much of that coming through on the beans once into the cooling tray. My sock on the outlet (not shown on pic) did catch a few small flakes of chaff so it's doing something there as well I guess.

cosmic_couple22

Thanks for the input mycuppa :thumb: Brett, I found I achieved better bean flow when I moved the entry point as close as possible to the swing door trap, also I switched out the 90mm y section to the 50mm feed, again created better control. Good job though and pleased you took my project and made it work for yourself. Let us know how its going. For me a very capable destoner for just under $400, has made my weekly kilos far easier to manage. Anne Cooper showed me an idea of a large earth magnet on a cooling tray arm for collecting any foreign metal matter, not cheap at $240 but works a treat.

FreshCoffee2

old (wrecked / no cost etc) speaker magnets, placed anywhere convenient in the path of the roasted coffee from cooler to destoner.

mycuppa

magnets are an interesting concept, but not new. A few years ago I evaluated Loring's 35kg Kestrel platform. At the time, Loring did not have available any type of de-stoner solution. Their approach was to implement a rare-earth magnet (not sure which type) on the mobile weigh loader for the green coffee transport to the roaster's hopper. I really liked this system - it was a mobile trolley with integrated weigh scale, powerful rare earth magnet and fast, effective loader. Being the skeptic, I saw first hand small stones being isolated on the magnet - remember, this is on the raw coffee side. I'm not sure how effective this solution would have been long-term and I'm sure a 3rd party destoner could have been bolted-on. Loring have since developed a traditional destoner. One day when I have time I will play around with these rare earth magnets specifically for raw coffee handling.

grundemp

Hi all, I've been trying to build a destoner and have tried several fans but not much success so far. I was wondering if you can share your fan specifications please so I can find a fan that is powerful enough to lift the beans. The problem I'm having is that when I insert the mozzie filter I end-up with too much back pressure which is not enough to lift the beans up. Any advice is much appreciated. Thanks Peter

askthecoffeeguy

got any photos of your setup? might be easier to troubleshoot if there's a visual to refer to? best, pat

mycuppa

The specifications of my 3x De-stoner systems are proprietary, commercial equipment designed by roaster manufacturers and built for specific platforms, e.g. 30kg, 50kg and 60kg systems - the motors are all 3 phase, variable speed units - it's not domestic equipment...... hence it's not relevant to your application, e.g. 250kg per hour throughput. A de-stoner design needs to have multiple control points, e.g. speed of motor (fan pressure), size of throat (entry point), ratio of perforated tray area (separation zone) and an important "make-up" air vent that provides air stream into the flow of product as it rises vertically in the column or chamber. Many designers overlook the "make up air" and rely too heavily on adjustment of fan pressure, which is a critical oversight..........when sufficient product falls (or builds up) in the separation zone (perforated tray) it can indeed "choke" from not having enough free air to mix with the product in lifting. You may find that by creating a "vent" between the fan motor and the separation zone, it will allow the flow of product easily.

[deleted]

Probably the simplest design I've seen for a domestic situation, is via the use of a Vacuum Cleaner that you can vary the speed of. Using a bucket and a pickup nozzle, you adjust the speed of the VC until all beans are picked up but rocks and other denser materials are left behind... 🙂 Several designs can be found on a number of coffee forum websites, etc... 😉 Mal.

askthecoffeeguy

My Sunbeam Cafe Series grinder has been 'put out to pasture' since chewing a stone through the blades the other day - now it can't grind fine enough for espresso, so I'm using my massive Fionzorato coffee grinder in the kitchen at home - seems like over kill but it makes for great coffee - so what can you do !