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Everything posted by caffeinegeek

  1. UK mains voltage has been 230 Volt for a while now and older 240 volt appliances with heaters will be running lower on power output even lower if you are on a long supply line in the sticks? My old bread toaster now struggles to toast bread and the elements hardly glow producing infra red. It's the same problem with older electric oven grills unless they are the 230V red quartz type. I roast with a modified toaster oven fitted with additional heaters normally running from a PID controller with a max output of 1.2kW, but I could go to 2.2kw. I've had to program my own profiles because the profiles for small roasters generally available do not take account of the thermal lag associated with my oven and drum. Temperatures measured inside the oven (air) are higher than larger pro roasters whilst drum and bean temperatures always lag. Changing the bean load from small to 500gm affects the profile, particularly once the roast starts to become exothermic. I have had a roast sitting at the start of first crack for longer than I expected when I started using oven temperatures of <200C. The PV and SV temperatures were both in track but the bean and drum temperature was still catching up. Eventually I had to increase the temperature to around 210-220C for the final roast stage which I prefer to judge by bean color. If you are able to confirm the roaster can reach and maintain this higher temperature, there should be sufficient element power unless the roast starts to become exothermic and then it's time for fans on. I suspect most small capacity DIY roasters have to be learned with a consistent bean load and experimentation to get the best from them.
  2. Hi, I thought I would start this discussion after doing some home roasting. Doing my own roasting I've discovered the roasted weight can drop by about 20% and ocassionally I've had a disaster with an over roast when going for darker. I started thinking: I've tried some of the ready roasted brands in 1Kg bags including those from Costco (Kirkland brand) and been pleased with the good taste, crema produced and consistent grind. If I want to continue with home roasting I can only justify doing it if I can buy bulk green beans 5-10kg and take advantage of the longer storage time for a green been, compared to a ready roasted bean. But when I start to cost what suppliers are charging nothing makes sense? I can buy a reasonable ready roasted bean from cash & carrys for around £8.50 a kg which is a full ready to grind kg with no water weight loss or risk of a bad roast. When I look at the cost of most bulk buy green beans they seem to pitch at over £10 per kg. If I could buy green beens for around £6 per kilo i think home roasting would be worthwhile after allowing for water weight loss and the ocasional bad roast. At the risk of being flamed, what's the point of home roasting, buying the kit, time and electricity cost and how can it make sense economically? My suspicion is green beans in bulk should be really cheap, but suppliers are cashing in on coffee fashion and DIY enthusiasm to hike up prices, whereas a ready bagged and roasted product has more competition on the shelves?
  3. https://coffeeforums.co.uk/topic/48292-when-a-diy-roast-goes-wrong/ I think you could be creating a B*omb! I can never understand why people want to set fire to decent whisky,brandy or bourbon. IMHO If I wanted the flavor I would pour it into the shot? Think of alcoholic spirit drinks as gasolene, would you want it inside a roasting oven? If you wanted to dunk roasted beans in an alcoholic drink after they had cooled from the roaster, that might be different, but I think the outer roast on a bean would make it too hard for alcohol to get through and there's always a secondary risk of explosion in the grinder. As I have already found, there is enough oil in a green been to get a fire without adding to the problem.
  4. Thanks for the tips on crack. I'm looking at what mods I can do to the roaster. At the moment I'm more confident looking visually at the roast and listening for cracks than just relying on PID automation. I'd built in manual overide for heating and fan cooling (which failed on this event) and using manual intervention to control near the crack point has so far given the best results. The issue I've not seen much discussion on is most PID controllers including those with ramp programming are only single channel. Some make misleadingly claims they are more than this by using relay alarm outputs, but this isn't the same as proportional control of temperature for both heating and cooling. The only true dual channel PID controller I've found is Arduino based, using an addon board from the States which isn't easy to get here at an affordable price. With small roasters inluding the popcorn poppers, you rely on air temperature measurements which we know are not the same as measuring bean temperature, but I've not yet worked out how to measure bean temperature with my small drum roaster. My next issue is the drum itself. Peanut roasting drums are a wire drum with lots of open hole area and very little mass. The drum itself isn't going to retain much heat so I'm making a larger drum using thicker perforated stainless sheet. That will allow the drum to be pre-heated and retain more heat before the beans go in. I can easily measure drum surface temperature which I think will be closer to outside surface bean temperature than oven air. But if there's an easy way I'd like to measure bean temperature? PS: Do you think a 500gm bean load is too risky in a small roaster? Clearly the larger the bean mass, the more heat they will store up to be cooled and this increases the risk of a thermal runaway? .
  5. I'm happy to share my bad experiences as well as good to help others. I modified a toaster oven for home roasting. I uprated heater elements, fitted a barbecue spit spindle and motor and mesh peanut roasting drum. The heaters are PID controlled with programmable ramp sequences. I kept all the original front panel controls and over heat protection. Finally, I fitted a huge fan on the rear panel. The fan is the type used for domestic gas boilers and moves a LOT of air. I started off test roasting cheap Santos beans at around 150gm per load then upped the load to 250gm. The oven fan exhaust looped out of my kitchen window and i kept a CO2 fire extinguisher close by. First attempts with air oven roasting gave me an under roasted result so I started tweaking the PID ramps, duration and temperature which aren't anything like the published profiles for professional roast ovens, although the Gene roaster seems close to mine, based on results from their users? By now I hade done 5 test roasts but still needed a darker result. I adjusted the final level temperature to 235C. I found listening for cracks hard because I'm not sure if first crack means the first bean that cracks or hold the temperature and wait for several beans to crack? I was getting more confident now and loaded up the mesh drum with 500gm of Guatemala SHB. I started the routine and watched the bean colour as the oven (NOT bean) temperature was held at 235. The cracks started to occur but I left the temperature set for another minute before starting the cooling phase. I fitted a speed controller on the fan so I could adjust the cooling rate from very fast to something slower. This is fairly easy to do manually by looking at the PID controller present value. THEN DISASTER. The exhaust fan switch/speed controller had failed and the beans were getting darker very quickly. I cut power to the oven heaters but with no exhaust fan I couldn't get much convection cooling through such a small oven cavity. The oven was filling with smoke and its temperature was RISING with heaters turned off. I could see the bean load was now in its exothermic stage and thermal runaway which I wasn't prepared for and the fire extinguisher was last resort. By this time and after I opened the oven door, the house smoke alarms had gone off creating a racket and adding to the confusion. I grabbed a fan heater, switched it to cool and held it in front of the open oven. More smoke everywhere, but the bean load was cooling down at last. When the drum and beans were cool enought to remove, they were as black as black having been self consumed of all oil and were no good for anything but charcoal. And so I learned that whatever fancy PID controller you may have on the heat side, a strong working exhaust fan (and standby fire extinguisher) is an important component to control temperature around the crack point and stop beans going into thermal runaway. I also learned the bigger the bean load in a small cavity oven, the harder it can be to stop thermal runaway! All this is unsurprising when one considers the oil content held trapped inside green beans.
  6. I was surprised nobody mentioned Pannarello? I discovered this is the design of the Delonghi frother I tried with a stainless 6-10mm DIY thread adapter I made from stainless using taps, dies and tube. An expert in fluid mechanics could explain why this design is so good at producing micro foam easily from small milk volumes every time? In fact, you can create microfoam like a soufle which stays in the cup for 10 minutes +. The trick with Pannarello tips is drawing air down the outer sleeve. Not only does this introduce air without any special angles, technique or milk rolling, but the air cools the steam as it enters the milk. This means you do not get a high volume high temperature steam jet entering the milk, bouncing off the bottom of a small pitcher and heating the milk too fast before it gets enough foam. The Pannarello tip takes longer to froth - about 40 seconds. The Delonghi tip I tried has a sliding air shut off and the trick is to cut off air at about 50 deg.C when there is sufficient foam and continue steam heating to the final temperature. This answers my question to my problem - Plenty of perfect milk frothing every time using a Pannerello frothing tip, even with different milk. The best for me so far is Asda own brand full cream.
  7. Hi all, can somebody tell me what is the outside diameter size (mm) of the steam tube on a Gaggia Classic? Thanks
  8. Thanks, I can try that. I agree it may be possible to find a technique and work fast, so I'm prepared to take longer then move up to more holes if I want faster steaming? I'll try blocking up a hole, but this will change the steam distribution as both holes are offset from the tip centre. With the single hole tip resting at the popular angle on the jugs pour lip, then moved to the side I'm getting a good swirl action in the milk without the ultra rapid fast temperature rise. I've been working on the principle that if I can produce plenty of good quality micro foam, I won't have a problem producing less, whilst tip depth can still give me heated milk without foam? I don't want to hog a thread about milk when coffee aficianados concentrate on shots. But it's frustrating when you think milk should be the easy part.
  9. So now I believe this problem arises using a commercial machine which is more suited to high volume coffee turnover in a busy shop? The volume of milk being frothed or steamed with microfoam will be a lot more than the single cup volumes I'm starting with. My Fracino Contempo 1E has a large 7 litre copper boiler, therefore plenty of steam volume maintained at the optimum 1 bar pressure. With their standard 4 hole steam tip and milk volumes around 125-150ml, the superheated steam volume and capacity to heat a small amount of liquid is huge.150ml of milk at 7 deg.C can reach 70 deg.C in less than 10 seconds. Frothing requires the physical action of 'rolling' the milk. My standard steam wand has no air admittance port I could find to mix air with steam and getting the right air mix is down to tip technique. But such a high steam volume will cause rapid heating of the small milk volume first, allowing insufficient time to roll the milk and consolidate air into it before it reaches the optimum 60-65 deg.C. In the hands of an experienced Barista it may be possible to get these small milk volumes frothed o.k. But since I've started looking carefully at the quality of frothing and many online videos, I see there's a large variation in results obtained for cappucino and latte, which are not obvious just looking at the top surface of the finished cup. I can make froth but microfoam, steamed milk that pours like Guinness looking active in a glass with micro bubbles rising upwards and stable has eluded me? Advice so far has been to concentrate on milk, temperature and technique. It's true that getting good results from a small milk volume is hard but why? - It's because the steam heating is too fast to control the amount of air through the milk stage at around 50 deg.C, although I agree it's possible with the right technique if you can work VERY fast. I decided on 2 approaches to test my theory: My steam wand with a 4 hole tip pushes out steam fast and furious, so I can't see any issue with the boiler but I can easily change the steam tip. The second test would be to try a sophistocated steam tip designed to allow air to mix close to the tip. Ideally I wanted a commercial quality steam tip. I found a steam tip spare sold for the Delonghi ECAM 22.320.SB. This is mostly plastic with a 6mm angled steam tube, a single 1.2mm hole and clever nozzle and air admittance, but won't plug in directly to a 10mm OD wand. This was my first alternative test nozzle temporarily fitted to my steam tube with silicone pipe and clips. This nozzle is a concentric design. The steam jet itself is specially moulded and there's an outer tubular 'shield' through which air is admitted. I think the idea is you don't need to incline the tip, just sit it below the milk surface and the shroud draws in air above reducing the problem of large air bubbles forming and breaking at the surface. This is similar to how a gas blow lamp or bunsen burner works. In just 2 tests with no special technique I could produce gloopy long lasting Guinness like foam in 150ml of cold milk taking about 40-50 seconds. My second approach was to try a Rancilio Silvia V3 single hole tip and compare results with the Delonghi frother. What I disliked about the Delonghi frother is its multiple components that are not so easy to clean as a standard tip and it's more domestic quality parts than solid all metal commercial. The Silvia V3 single hole tip produced the lower steam volume and much slower temperature rise I was looking for and therefore easy to find the transition temperature where the milk would roll and keep rolling a lot longer. As with other standard steam tips, it relies on technique to angle and position the steam tip in the jug, but it's far more controllable. For a commercial coffee shop, the steaming time of up to 50 seconds per 150ml is probably too long, but the foamed milk quality is excellent. The Delonghi frother still had the edge as it was pretty idiot proof and very little skill is needed, apart from looking at the digital milk thermometer. I have decided to cut the standard 10mm steam pipe about 150mm up from the steam tip and fit a threaded stainless adapter. This will allow me to fit the Delonghi frother, revert back to the standard tube and different tips, or experiment with my own version frother using an outer shroud like the Delonghi. I hope this helps those using commercial machines at home struggling with milk frothing to get good results. As I get more practice with the single hole tip, I may move back to 2 or 4 holes, but at the moment I like the control I'm getting with single hole and time to froth is less important to me than the result.
  10. With the stock 4 hole tip it takes about 12-15 seconds for the milk to go from 7-70 deg.C steaming at 1 bar. I think I might be getting somewhere because I'm sure now my technique is fighting the huge amout of steam coming out and the fast temperature rise. Somewhere around 60 deg.C I start to get the large bubbles and after that large bubbles just keep coming. This morning a Breville steam tip arrived. It's the one with the plastic push up and down sleeve to select hot milk or cappucino. It's short stubby 'L' shaped steam tube is 6mm OD whereas my Fracino is 10mm OD and 8mm ID. With some temporary silicone tubing, I attached it to my steam wand, plunged it into supermarket semi skimmed milk. It took longer and the temperature rise was slower but I got nice micro foamed milk from a small starting volume of about 125ml. Now I know this frothing tip is a designed venturi and sliding the selector just covers the air hole. I dismantled it and the single tip hole was about 1.2mm. I'm not trying these things to compete with baristas, but then single cup coffees with small volumes of milk with no waste is my challenge. If I was frothing 250ml + milk each time I think it would be easier. I bought some Cravendale whole milk and tried it with the stock 4 hole tip. The cold milk swirled with more turbidity, but that might be expected anyway compared to semi skimmed. The small volume frothing result was similar but the foam seemed more stable and sat longer without collapsing, but then this milk is twice the price! So I'm back wondering about trying a single hole standard type steam tip first to give slower heating? I shall also be engineering the Breville steam tip with a more permanent connection to my standard steam wand and do it in a way that allows me to go back to the standard tip. Mods always need a revert back exit plan! I'll let you know with some photos how it's working out if I don't give up fighting the Captcha.
  11. Regular supermarket fresh semi skimmed - Waitrose, Sainsbury - they all give me the same results. But I'll give the Cravendale full fat a try if they are using better cows.
  12. Thanks for the 'tips' (pun!), I've watched several videos but they don't tell you what to do when you don't get the same result at the end? My milk volume is 100ml which added to a single shot fills my latte glasses. That small milk volume might explain why I'm generating bubbles and coarse foam at the surface? I don't see why there should be objections to using a wine cooler? Mine is compressor driven with tight control of temperature, adjustable down to 4 deg.C, has a smaller space without the door always being opened for access to food and now we drink more coffee than wine.
  13. Thanks, I've made a small step in progress: I do use a thermometer and aim for 65 deg. C & no more than 70C. I changed the steam wand tip from 4 hole to 2 hole. Most fridges of the Eco kind like ours set their fridges to 10 deg.C when the Eco button is pressed which is a trap for the unwary! I could drop the fridge temperature but the wine cooler will do 5 deg. C which is a smaller space and doesn't get the same frequent use as the kitchen fridge. The problem as I see it now is my milk volume is too small for single cups causing the milk to heat up and aerate too quickly due to the small volume. The larger air bubbles are getting through faster before I get nice micro foam. The larger bubbles tear the milk fat apart and once this stage is reached there's no more micro foam . A larger pitcher gives better results because the frothing to final temperature can be slower and I'm doing good cappucinos, but the micro bubble froth for latte is still eluding me? Once the milk starts to froth I'm getting larger froth bubbles sitting like foam on top of the milk. Just for an experiment I've ordered a Breville auto frothing tip to try on my 10mm steam wand to see if getting air into the milk through a venturi tip design gives a better froth. I'm also aware that steam tips come in different hole sizes as well as the number of holes. I think my problems arise because I'm not in a cafe business frothing 1/2 litre of milk at a time. Just to give me an idea, how long should it take for a given volume of milk in your pitcher to reach temperature? I didn't think frothing fresh milk for micro foam would be so hard. The boiler is putting out steam at 1 Bar with no water after purging the wand and the only thing left can be the tip, how air is mixed and my technique?
  14. Thanks, that ties up when I said frothing 2 cup volumes seems better. But if you want just one cup of coffee, do you froth more milk and throw milk away? I suspect the best milk froth occurs when the milk is coldest and my small milk volume heats up too quickly? I think I will try some milk in my wine cooler which is at about 7 deg C and a lower temperature than the fridge. When I do the hand hold temperature check I find my coffee seems too cool? Perhaps that is how it should be compared to boiling water over instant. I was in Italy last year during Winter and the first Latte I had seemed too cold for my taste, but I was told the Barista had been taught by his parents over many years so I wasn't going to argue! Does your milk froth pour out of the jug nicely or stick around the sides like mine?
  15. I can only comment on my 'all manual' method where I have control over all the elements. I use a Mazzer Jolly grinder I modified to provide adjustable timed bursts. 4 bursts gives me a single shot load which I frequently check for weight, but I can tell from the finished tamped height if it changes. I aim for and get a single shot time of 20 seconds with 8 bar pump pressure. The shot times change according to which shop beans I use, how dark they are and how old they are, so I want to start roasting my own. The Mazzer micro grind adjuster only needs a very small change to optimize the grind and pour time. I watch the crema as the shot comes out and occasionally I will extend the shot if I think there's some more left. IMHO the grinder and the grind are the biggest factors in achieving consistent shot times. If I'm lazy and the shot drips out slower taking up to 40 seconds, I might leave the grind settings as they are.
  16. Hi, I have an old 'traditional' machine with a 4 jet steam wand and normal steam pressure at 1 Bar. Whatever type of cold milk I use, frothing starts producing what I think you all call the micro foam. I personally find the milk to cool for my present taste and keep frothing longer until I hear the tone change from the steam wand. At this point the milk gets hit by lots of large bubbles and can rise to twice the starting volume, but the froth then seems too coarse with too much air and collapses quickly. I am generally frothing a small volume sufficient for a single shot cup or latte and I can get some better results starting with a larger volume of milk. Whatever I do, I can never get any improvement and produce a more solid froth for latte art, although what I produce seems to be like the coffees I get abroad in the run of the mill bars ( not Costa!). Where am I going wrong? Is it a limitation of my machine? Do good milk frothers always use air injection or special steam tips or higher steam pressure? Another problem I have is the froth sticking to the inside of my stainless frothing jugs. I've checked inside and they are not highly polished which I think would allow the froth to slide out better? Are there better frothing jugs? I've noticed some commercial places spooning out their froth rather than pouring it.
  17. My old Fracino failed last week. Symptoms were : 1. Normal pump pressure for start of brew. 2. Nothing from brew head. 3. A few seconds after selecting expresso type, all leds flashing and audible alarm. There was no 'click' heard from the group solenoid so I suspected the error alarm was caused by lack of water flow being measured to the brew head. Tested the solenoid coil Parker YB09 P/N 304398 and found it open circuit. Ordered new coil. D.c resistance measured @ 900 ohms. Warning: Do not power these coils unless they are fitted on the valve stem, otherwise excessive current will flow! I wonder if others have had to replace the group head solenoid coil? My old coil was stamped Tu=50 deg.C, whereas the new coil had no temperature markings. I looked in the Parker catalogue and all coils for this valve VE128 V have a 50 deg.C ambient temperature rating. On my Fracino machine the group head temperature is maintained by syphon flow and the solenoid is directly coupled to the brass body components. I would expect the ambient temperature around the solenoid to be above 50 deg.C? My valve has a stainless U channel cover over the valve so I might consider replacing it with polished perforated stainless sheet. I checked the Parker catalogue for alternative higher temperature coils, but there were non.
  18. I've been using my Mazzer Jolly a while now with the funnel mod. Static on grinds isn't too bad, but there's always some grind left behind to fall out several minutes after filling the filter. Static is produced on the grind because the beans have been roasted and are so dry they are a high voltage electrical insulator. After mechanical grinding, the grind particles take on an electrostatic charge helped by oils from the beans acting as another good insulator. Electrically, your ground coffee is similar to high insulation plastic: Once the grinds have taken on the charge they will be attracted to any earthed part of the grinder. I don't get the grind shower and spatter some get, just a small amount left stuck to the inside of my funnel which drops down later. The closest analogy is charged laser toner sticking to the collector drum. The amount of static you get and its nuisance will depend on the dryness and depth of roast. A very dark roast will lightly carbonize the beans and they should take on less static. A mild roast with some oils remaining will be a good static charge retainer. After some searches I found what is frequently referred to as a 'hack' requiring water to be dropped on some kitchen tissue and then 3 or 3 drops squeezed out into the been hopper. This introduces humidity or water vapour on to the beans which is relatively conductive to static charge and stops the grind particles taking on a static charge and sticking together. It was after reading this that I thought the logical cure for bean static had been missed. And so I removed my small size hopper from the grinder and waved the steam wand over the top a couple of times. With the lid replaced on the hopper, there was humidity trapped inside and no static after the grind, even a few days later. Since anybody sincere about getting good coffee should have a decent grinder and steam wand, it seemed the logical way to avoid static and get consistent grind weights for each shot.
  19. There are more knowledgeable people here than me but I have been all over my old Fracino. I regard it as having a cloned E61 head with their added solenoid removing pressure to drain. I didn't spot it straight away but what surprised me the second time I was dissasembling their group head was the tiny circular stainless steel filter screen in a chamber on the top after the brew water inlet. This is followed by a jet with a VERY small orifice of about 0.7mm dia. This was a surprise when you look at the size of everything else. But explains how the small amount of brew water passing through the portafilter basket is kept at near constant pressure during the shot pull. The gauge is on the brew water flow output before the jet. I only see a small change in pressure when a shot is pulled and I can now see why. It also explains where the generally quoted figures of expected water volume come from when a shot is pulled with an open portafilter. The brew water volume delivered is determined by the pressure set on the pump, the size of the jet and the time water flows. If we time the flow over 25 seconds for say 9 Bar pressure, the amount of brew water delivered to an open filter should be similar machine to machine. This also assumes the pump pressure control is good and maintaining its pressure when loaded. A good point was made about mains water inlet pipe kinking, This aspect of the design on my Fracino was really bad and took some time to get a kink free routing. A rotary pump using a mechanical pressure off loading valve needs the pump to be fully charged on the water inlet side to allow it to regulate the set pressure under all load conditions. A kinked pipe could starve the pump and reduce outlet pressure when needed for the shot. I agree that if pressure is not reaching the filter basket it can only be lost in a few circumstances - The pump pressure is 'sagging' which should be evident on the gauge, water is being bypassed via the OPV, water is going to drain (visible) or if the group head has this small jet like mine it could be partially blocked? On my Fracino I had to buy an unusual long reach metric socket to remove it for cleaning. I've been looking at these pressure gauge modded blind portafilters and I'm not happy with them for my Fracino? When my shot starts, the flow meter is expecting some (small) flow as brew water is sent through the charged puck. If no flow is sensed, my machine goes berserk into alarm mode and the same thing happens if I try a rubber blanking disk. I've concluded the only way to get a useful pressure reading is to measure pressure in a fully charged portafilter as it is passing brew water. Unless you drill holes into the group before the filter basket you can't do this. One way I'll try is to fit a needle valve after a pressure gauge fitted on a blind portafilter. For my test I shall swap out a 3/8" spout. The out flow from the needle valve can then be adjusted to be the 25 second discharged shot volume. The presssure reading will then be more representative of real life because it will correctly show if the pump pressure is sagging (in my case) after the flow jet, whilst my machine is working under its normal conditions with a measured flow and no alarms. By adjusting the needle jet I should be able to simulate finer coffee grind to see how well the pump pressure into the filter basket holds up. These blind portafilters are everywhere on Fleabay with just a pressure gauge attached. Somebody please tell me why these are so popular for fault finding when they don't allow normal water flow? If other group heads have a small jet orifice like mine, there will be an unstable pressure reading as the brew water through this jet is pushing against a relatively large volume of trapped springy air.
  20. Thanks, another one for the ideas mix! Wifey wants to chuck it out as it gets less use now. Ours is a single pot and paddle size. I think I'd like the paddle larger and turning slowly, but these things might be trickable. In some of the vids the paddle is throwing beans all over the place. My breadmakers are both fan assisted and at first look it seems to me you need to drill a load of 5mm holes in the container. I'll put a temp probe in mine and see what temperatures its reaching. I guess the acrylic cover will limit max temp but then popcorn poppers use a similar material. Of course the ultimate would be a breadmaker already designed with a coffee roasting option on the menu! There are heat guns around now with digital control of air temperature and air speed adjustment. I'm interested in seeing whether they can produce much of a hot air vortex like the poppers, although I suspect their small fans won't be good enough. In that vid. you can see just how much smoke is produced from the larger bean loads. Definitely not for the kitchen and shows how smoke extraction (and a fire extinguisher) is v.important
  21. This may be of interest to those who are into modding and technically challenged! Like most things on the internet, you need to know what you are doing with mains electricity and be technically competent to try this out. These old Fracino machines aren't wrapped up in microprocessor control and I love what you can do with them. I decided after some intial experiments to add pre-infusion to the shot. Pre-infusion stops the sudden spurt you get when the 9 Bar pump kicks in. I suspected this initial pressure hit was causing channelling and not giving full shot extraction from my filter basket load? I had started with the 'standard' 7gm load but found nearer 8-9 was needed, despite doing a lot with the grind. Pre-infusion seems to expand and consolidate the grind in the basket, hence some experimenting with grind fineness and overall shot time is needed. More efficient extraction is probably not a commercial factor in a busy coffee shop, but if you are going the extra mile sourcing green beans and home roasting small amounts it should be. Your machine may not work like mine, so you have to do some checks first to see if it is suitable. If you can disconnect the pump connector, hit a shot selection on the front panel and brew without error alerts, then a mod, like mine is possible.The Contempo 1E only has 2 sensing functions and neither relate to pump operation, pressure, or current draw. So you can confidently change what the pump does during a shot. In the ideal world you would have a vane type pump which could be controlled to ramp up its pressure for 'X' seconds when you call the shot. Unfortunately, the Fracino uses a rotary pump capacitor start motor and it is either on or off. - but it is a very strong reliable pump! My mains water inlet pressure is 4 Bar. The object of my schematic design is to hold off starting the pump for 'X'seconds after the shot is called to wet the dose at 4psi. The Fracino flow meter is still active throughout, but you do have to re-calibrate the shot time and grind. Setting the 'X' off time needs some experimenting but I'm starting with 5 seconds. The schematic allows 'X' to be adjusted from 1-15 seconds. 4-5 seconds is about the time it takes after calling the shot for the first drip to appear from the porta filter. Why did I build my own timer rather than use something off an auction site? My schematic is universal and accurate for different types of mains timing application and I know it works because I've used it for controlling bathroom fans. It has a very small profile, doesn't use a relay or need a low voltage power supply and doesn't have components that could overheat inside the Fracino cabinet. Also the pump is switched 'zero crossing' which is a lot softer starting than using a relay and better for the and capacitor pump life. With 5 second pre-infusion my filter basket load has gone down from 8-9gm to 7gm for the same flavor intensity. I'm using less ground coffee and that can only be good. With such a simple addon controller for the pump I am unable to vary the pre-infusion timing for double shots etc, maybe I have to find a 'one setting fits all' compromise? In software it would be easy to change the pre-infusion time according to the shot duration. Newer Fracinos offer the pre-infusion option, but mine didn't. I'll post some photos here but as I said, you need to be comfortable building live mains circuits safely and be technically challenged. I'm just about done on this mod. now and moving on to the home bean roaster project. .
  22. Thanks, I'm adding another option to the project. The stainless peanut roasting baskets for BBQs are being sold on Fleabay, I have a couple coming to try out. I've also discovered IKEA's stainless cutlery storage container. They come in 2 sizes and 2 of the smaller ones code 300.118.32 can be joined together to make a 11.5 dia X 26 roasting drum (£2 ea). Sadly their 8mm holes are too large and I will try them out as 'formers' with a wrap around stainless mesh. I already have a cheapo toaster over which I modded with PID for reflow soldering and I can get 2 of the IKEA drums inside running off a 5V Chinese spit roast motor. For reflow I needed a faster controlled cool down than the internal recirc. fan would give, so I fitted a gas boiler flue fan on the back. It pushes a lot of air through and should work well to give rapid cooling of the roasting drum. Run in short bursts it will also pull out smoke. I added an extra 800W of IR quartz heating tubes and it has plenty of heat wampum. When I've finished it should look something like the Behmor 1600 costing less than £40. Smoke and chaff are things to look forward to and work around, but I'm hoping they will be manageable for 1/2 kg or less max bean load. Behmor use an open type basket drum similar to the BBQ peanut roasters, but I'm not sure yet if a drum with more density like the IKEA would be more stable holding heat, even with pid controlling the air flow temperature.
  23. I've realised that unless you buy beans direct from a roaster, you can't guarantee their freshness and their freshness deteriates very quickly. For home use I want little and often which makes mail order buying expensive and wasteful on white van deliveries. Now I'm moving to home roasting to roast a rolling 2 weeks supply and always have fresh beans. Here's what I'm trying out at the moment: 1. 1200W popcorn popper, fan motor driven separately and heater PID controlled. - First tests look good for 80gm loads, tedious for 500gm. Interesting wind vortexing on these machines. 2. I have 2 stainless peanut roasting baskets that will fit my gas barbecue rotisserie. Precision temperature control could be challenging or impossible to achieve? 3. I have a 2000W temperature controlled heat gun with lcd temperature readout to play with when I can find a 'pot' giving the right floating air vortex with a chimney (any ideas?). I now appreciate roasting fire hazards, not necessarily from the roaster machine but the beans - chaff that gets lit and flies around! If the gas barbecue is successful that ticks the boxes for safety with larger roast loads. Next up could be a modded tumble dryer! Popcorn poppers seem 'popular' and get a lot of discussion here. But has anybody done anything yet with gas barbecues? If all you need is a rotisserie, peanut basket and digital thermometer, that could be simple and cheap to set up?
  24. I build from scratch and adapt quite a few different designs of electronic thermometer and PID controllers. I usually want a stable fast reading response and my personal preference is for 'K' type thermocouple sensors because they are extremely small, fast responding to temperature changes, handle a wide temperature range accurately and are not susceptible to interference pickup. You can buy 'K' type thermocouple probes in various thread types fairly cheaply and any electronics readout part will be compatible. The readout displays used to be very expensive sold commercially but now you can pick them up cheaply with an lcd display, powered by an AA battery and accurate to +-1 deg.C. Look carefully at the metal 'sheath' around the sensor itself. If it is substantial then it could have thermal inertia and be slow responding. In some situations like car cooling systems and ovens you want that, but if you are measuring liquid flow, fast response is better at showing what's really happening. Of course, when the hot brew water hits the puck and massive porta filter body, brew water input temperature won't be the same as that passing through the coffee. I'm just about to add pre-infusion to my basic expresso machine. The thinking is you reduce channelling because the initial lower pressure flow through the puck consolidates the coffee ready for the 9 bar high pressure hit (if you aren't ramping up pump pressure). It also has the advantage of stabilising the coffee temperature in the filter before the main brew stream arrives. I did some simple tests with a switch on the pump and whereas I was using an 8-9 gram single shot load, pre-infusion for 5-10 seconds appears to give the same strength with a smaller 7gm load. I shall build an electronic timer to do some more tests.
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