Neat modification. ;)
Where did you get the gauge from ?.. most of the ones i see cost $65 - $80 for the gauge alone.
I am a self confessed coffee snob after getting right into the art of coffee making since my wife bought me a sunbeam 4800c. The 4800c took me a long time to figure out how to get descent shots of espresso from it. My journey so far...
I started off with ground coffee beans from the supermarket (yuch!). Then bought a Kyocera hand grinder for $70 online and I think its pretty good at grinding, I know there is a lot of discussions about paying big bucks for a good grinder and admmitedly I havent tried an expensive grinder yet, however I recommend the Kyocera that Im using and think it works very well.
After a fair bit of searching and advice from this website from other people trying to get good coffee from their machine, I purchased a descent tamper (the plastic one that comes with the 4800c is fairly useless) and an unpressurised basket (also recommend). I also bought espresso shot glasses so I could easily measure the extraction volume within the 25-30 seconds
The biggest thing I noticed was getting freshly roasted coffee beans from Newtown and the taste was so good as compared to the store bought beans. Then I was given a Tempo popcorn maker as a present and found out about roasted coffee beans with them at home. Bought green coffee beans so cheap and wow!, for anyone not roasting at home, please do -* it has made the biggest difference to my home coffees!!
Now, i make pretty decent enough shots but found my machine wasnt consistent as it relied on my tamping pressure to adjust the pressure at the brew head. One coffee would be nice, then I would maybe not press slightly as much and the next shot would not be as nice. It frustrated me so much I nearly gave up on it. I think the sunbeam 6910 is the same on its extraction functioning, then I found info about OPV valves.
I decided to buy a Vibiemme Domobar bypass valve and also a gauge so I knew what pressures I was adjusting to, and piped them in after the pump and before the Thermoblock (the thread was the same). I have now set the pressure to 10 bar and so far, the bitterness is gone and the shots are consistent and very nice. It costs only about $60 odd bucks to upgrade and makes a big difference. Also, the pressure drops immediately after extraction and stops spurting out when removing the portafilter (must be the valve letting air in?). I made an access hole at the side where the valve is and i can easily slide a screwdriver in and can now adjust the pressure without stripping down the machine again.
Many people seem to go for name brand machines and say to save up to get a Silvia, but I cannot afford to pay that much for a coffee machine for starters and on a technical level, its a machine that has valves pump etc so can be modified to at least get better shots. Im not saying my machine pulls shots like a silvia or anything but Im happy with the results and am posting this to show other cheap model espresso machine owners that this is a cheap, easy mod that can make a big difference to their machine. I was so fed up with getting inconsistent shots that were always slightly bitter due to the high pressures from my machine but am now very happy with the results. I havent really found anyone modifying cheapish machines and recommend this.
If anyone wants any more info please ask and here are some pictures of it fitted to my 4800c. Also, if anyone has an advice for me on bettering my coffee making, please let me know !!
Neat modification. ;)
Where did you get the gauge from ?.. most of the ones i see cost $65 - $80 for the gauge alone.
I got the the Vibiemme valve for $39.75 online from stefanos espresso care. However, I was later contacted by Disave espresso parts in Vic, I could have gotten an expobar valve for $25.50 + $5.50 postage.
Stefanos sell gauges from $30 upwards but you can get 16 bar pressure gauges online from RS components in NSW for $14.50 upwards. I got mine on ebay for $20 which is another option.
Have you thought about doing a PID temperature controller mod to your machine?
Yes, the thin copper pipe does lead to the temp gauge and it came with the temp gauge. I searched for espresso pressure gauge on ebay but i might have been lucky as i don't see any there at the mo. You can find my temp gauge with a pipe from stefanos espresso care with pipe for $44.95. But you can easily get one a lot cheaper from rs components.
I got a 3 Ways 1/8" BSP Tee female brass coupler adapter and two 1/8"Bsp Male to 1/8"Bsp Male adapters which were a couple of bucks each. The threads are a perfect match. I then had some plumbing pipe sealant which goes around each thread and dries quickly to prevent leaksge. Then just some return hose and cable ties which were both about $1 from hardware store.
NOTE: i had to very slightly cut the male part of the valve down a fraction so when i screw it into the pump it doesn't press against and damage the pump (I learnt that from someone's post who modified their 6910)
I've deffo thought about how i can temp adjust but because it's a thermo block system and not a boiler i'm not sure if it can really be done well but i'm open to suggestions.!!!!
The thermoclock system has a fairly quick path once heated to the group head and I've gotten an accurate temp gauge and measured the temp directly coming out during an extraction and i get 92 degrees which i think is fairly good. I froth my milk first and then run water through the group head for about 5 secs and then extract. Once extracted the milk is ready to be added straight away which keeps a nice flavour to the espresso.
I am now measuring the amount of ground coffee i use which is another factor that once i keep constant can help me find the right flavour i like. I've found 18 grams works well for my taste.
The beauty with this mod is I can adjust the pressure easily for my taste and have consistent shots. Let me know if you need anymore info !!
This is my first post on this forum.
The best thing about this thread is that I love it when people modify 'el-cheapo' machines (coffee machines or otherwise) to perform better than their intended purpose - congratulations and 11 out of 10.
The reason I came across this thread is that I purchased a 4800c yesterday on evilbay for $23.30 aus - a good buy I thought, but I can't seem to get a decent cappuccino out of which is my preferred drink.
I already have been using a crappy little Breville ESP2 which I thought I had mastered and got some bloody good cuppa's from, but the 4800c is something else.
Sorry I can't offer anything else but to acknowledge that 'Life is too short to accept drinking sh*t coffee' and it doesn't have to cost the world!
I agree that life is too short to drink crappy coffee at home, i'd rather go out and buy a descent coffee. The 15bar machines can be very temperamental with the bitterness so that's why i modded it to get 9.5 bar and it tastes a whole lot better and doesn't cost an arm and a leg. Actually the Rancillio silvia has the same ulka vibe pump as the 4800c so when modded it should extractat exactly the same pressure at a fraction of the cost.
Do you roast at home?? i recommend an el cheapo popcorn popper and roast at home and wow, tastes better than some coffee shops when you get the knack right!!
the first thing you need to do to a 4800 is toss the pressurized baskets and get a Krupps double with a Krupps group head seal, you will start getting decent shots right away.
The pressure mod is unreal! I like the sound of that!
OH yeah, then you need to spend way more $$ on a grinder with the money saved withg the cheap modded machine.
I apologise to the op if I have hijacked this post but the "Coffee God" said it should be ok.
I did a fair whack of research (mainly on this forum) and soon realised that 'I don't know Jack'!
Thanks for the info on the pressurized baskets - I had no idea, but has been confirmed upon further reading. I'll take your advice, and from many others on the benefits of a decent grinder, as at least a good starting point.
I just hope the tax man and child support agree.
could you have just drilled the hole for the screwdriver and adjusted it by taste?
looks good, i've just OPV'd my Breville BES820 but have yet to set the pressure and still need to fix the leaks.
a problem i'm having now that i'm wondering if you encountered is that my steam pressure is now much lower, as the OPV is still drawing pressure away from the pump output when steaming.
did you notice this effect at all? i'm not sure what to do to rectify it without implementing a split output from the pump that i can switch from one side to another to either use or bypass the OPV.
It' just just my opinion but i think it would be fairly hard to adjust by taste to get the exact pressure as only a very slight adjustment on the valve screw makes a large pressure adjustment, but it could be possible to do. I mean taste is the main thing and if you adjust and it tastes better, sure. It would take a few trial and errors. Actually, if you placed the hose coming from the valve pressure relief into a measuring glass and measured the amount of water filling the glass each shot, you could use this as a method of measuring how much you adjustment (if that makes sense).
I haven't noticed any problems with steam pressure at all with my machine. I would of thought that the 9-10 bar pressure set on the valve would be more than sufficient for just steaming some milk and the valve shouldn't let in any more air when the system is operating. However, my machine may work differently to your when steaming. Sorry i can't help any further.
I had trouble with leaks with mine too but i used plumbing pipe sealant and it worked perfectly
I'm wondering if sunbeam is uses BSP and NPT? If we use the wrong trend type, that would explain the leaking?
turns out the steam problem was caused by the steam diverter valve and body. there was some bad seal in there somewhere, stripped it down, replaced arm o-ring and it's back to good pressure. even better than before the OPV i think.
Were you using a single floor basket before you did the OPV mod?
I have the same machine and with just the basket mod and a really good grinder the shots taste really good, I was told that the pressure mod was not necessary?
Any Idea what the pressure is normally before you changed it?
I need to decide if I should do it or not, thanks
also in the photo it looks like you have a chromed brass group handle, it there one around to fit this machine?
La pavoni use a 51mm Group handle, I wonder if it fits? would be nice to have a naked with a tripple basket for restrettos
Last edited by C-man; 1st October 2012 at 10:47 AM.
As i mentioned in the first post, I did upgrade to a single floor (unpressurised) basket and found that it helped a lot alright. I just seen your post of the triple basket mod you did - looks good. I find though if i pack the double up good, I get around 21 grams which is around a triple anyway.
I did upgrade to a single floor basket before the mod and the shots did taste good alright but the key thing with the OPV mod is..
1 consistency - with the pressure directly depending on the exact tamping and grind every time, you can pull a good tasting shot but with any slight change in either tamp or grind, the flow might be slower/quicker and the shot would taste different. With the OPV mod, no matter how light you tamp or grind, the pressure will be set to 9.5 bar and won't go over and shot taste is more consistent. Before the mod, the pressure would read around the 12-14 bar range
2. Bitterness - Although I was getting decent shots, i found there was always the slightest bitterness taste no matter how good the shot was. Since the OPV mod that bitterness is gone.
I just use the standard group handle that came with the machine.
Just to note, if you're happy with your shots, just leave it as is. I've had my machine for 3 years now and was never completely happy with my shots and with the added parts that were cheap enough and didn't take long to fit, i have a more consistent better tasting shot machine.
Thanks for the reply karl_
Hmm, Every shot from even expensive machines I have tasted had a slight bitterness to them I guess?
I think I will do the mod, if you were doing it again, which OPV would you order? the Expobar?
Great Mod. A quick question about machining the OPV so its not pressed against the pump - can you point me in the direction of the thread that was contained in? I post a rough set of guidelines of how you got it done? This seems the part that has potential to cause the most grief.
I find that with my really good grinder and the single floor basket I get good shots for the first 15-20 seconds,
then after that I guess the pressure builds causing the shot to speed up, blond, and go bitter, If I keep the shot restretted to no more than say 18 seconds
it is sweet but I am not getting the full dose. Hopefully the OPV mod will fix that.
to measure the correct amount that you need to cut off if you aren't sure, just put something into the pump outlet up to the point that it just doesnt touch that internal piece, mark it off then compare that length to the OPV inlet and cut off the excess. it should be around 3-5mm i think.
I guess you want to make sure that the ajustment for the valve is easily accessible and easily adjustable. Mine is easily adjusted with a scredriver and when i screwed my valve in, it faced against the wall nicely for me to just drill out for adjustment access.
Also the thread is important, that's one reason i got the Vibiemme Domobar as the thread was the same so it easily bolted in (1/8" BSP thread).
I reckon the expobar valve should be fine, i guess whatever valve is a decent make and cheapest
Your right, this is what has the potential to stuff up the pump from what I read in the thread.
It's nic's stuff: » BES900 and the brass OPV… Nic's Stuff
Have a look
Now I can't wait to do this mod!
the pressure is too much! I can't take it anymore! PRESSURE!
It's gettin to me! AHHHHHHHHHHHHHHHHH
I would like to stick with what worked for you to simplify but can't seem to find Vibiemme here unless someone else know where?
I see a cheap pressure gauge, but don't understand how it can be 16 bar and have 20 divisions on it? also I guess you need to buy the thin copper tubing seperate?
here is the link http://australia.rs-online.com/web/p...auges/7008878/
Thanks to Karl for all the help,
I have everything on order now.
the next mod will be to control the pump speed during extraction, to allow for pre-infusion at 9 bar and lower pressure extraction in the back half of the pour
around 5-6 bar just enough to keep the small trickle coming. The result is trying to copy what a good lever machine does.
I still get flow at the very slowest setting even though you can barely hear the pump (very quiet). And the pressure is variable from about 1 bar to 9 bars (where the OPV is currently set). And it is very smooth (even though in the video my gauge is jumping all around - I think I had air in there).
I have been getting the best espresso I've ever had - very different from what I was getting before. And it has really widened the range of coffees I can use for espresso. I'm now doing some lighter roasts that would be way too bright if pulled at 9 bars. When I start out at 9 (just bring it up to 9 bars long enough to get the pour started) and then back down to 4-5 bars to keep the pour barely trickling, I get much more creaminess and rich deeper tones in the cup and much less of the citrus peel.
Sunbeam mod 001 (Large).jpgSunbeam mod 002 (Large).jpg
I managed to get it done, the plumbing was easy, just Teflon tape and no leaks first time.
Cutting through the Stainless steel casing was a bitch though!
yeah, shots are very smooth now, and the pump is very quiet too.
Thanks to Karl for all the help.......
Hi C-man, I'm considering doing this to my Breville ikon (not sure if it will all fit?).
Just wondering what parts you went with in the end and the costs?
I used the same parts Karl suggested, he listed them above
cheers C-man - which gauge did you get, RS Components?
I've decided I'm going to attempt this with my E4800.
Was shipping expensive from stefano's?
C-man, it appears you used the Vibiemme valve from the photos. Did you try and get the Exopar from Disave espresso parts?
jet black espresso in sydney has a generic expansion valve listed on there website for $25.60. But its unclear whether its adjustable like the Vibiemme.
hey jimmi ,i ordered the valve and Gauge from Stefenanos
just before Christmas cost $99.20 all up and took just over a week to arrive i think postage was $14.50