My seals came (amazingly) in just under 2 days. They were a bit challenging to mount, but MAN, what a difference! The ease of use, lever catch, and quality of the resulting shots is head and shoulders above what I had been able to achieve with the old seals. Also, VERY consistent from shot to shot. Once again, Reiss, your dedication to pursuing the problem, commitment to product quality and customer service are in a class by themselves. Thanks SO much for your work and caring. (The videos are great too!)
A friend in Belgium made a seal-slip-on tool by cutting off the top of a whisk and making sure the tips of the pins are not sharp anymore (or they would cut / damage the rings of course):
Your suggestion seems ideal, however your picture looks like another product that already has the tines capped with a small bead, known as a "head massager" - some have all the tines at the same length. for example: http://www.imc-miracles.com/images/product/detail/K-HM18A.jpg
What do the seals actually do? And why are in they in that particular configuration: two lower ones whose sloping sides face inwards towards each other, and a single top one with its sloping side facing outwards?
Imagine you are starting to pull an espresso, the lever is down already and the portafilter is in the group. Water from the 4 inlet holes is coming into the space above the puck and filling it up. When you begin to release the lever, below the lowest of the 3 seals you have some air and the shot water. As you release the lever and the piston pushes down, the seal prevents upwards leakage of air so you have maximum pressure and an early 'catch'.
When the piston goes down during the shot, it also covers the 4 inlet holes to make sure that water does not keep coming in.
In the resting position, the space between two top seals covers the 4 inlet holes and the water cannot escape because the two seals there face each other. The water can't go up or down and the system is at rest.
The best seals efficiently close off the space even at very low pressure. The 'normal' seals do that too but just a bit less efficient if any detail (grease, pre-infusion pressure/time) is less optimal.
I think I am going to go ahead and get the plumb in kit for my L1. This will get me to the $$ point I need to get some of the new seals. So, the real question is... do I have to put the seals in my basket, or will they be added automatically. Or, do I need to put a note on the order?
hi james the process is entirely manual, so when i see an order come in for more than £50 i add 3 HP piston seals into the order i send to the factory painfully inefficient, but only 2 months to go! kind regards reiss.
Thanks for that video, very informative. While we are on machine anatomy, I have another question about the brew path.
When water enters the chamber from the four holes, the water has a few paths to take:
* through the coffee puck (ideal path) * back up to spring - this is blocked by a piston seal * back through the TS
It's the last one I'm a bit confused by. Since the chamber is filled via boiler pressure (1.2bar), say the water can't overcome the coffee puck (say too tight grind or something)
Where-then does the water go? Does it go back through the 4 ports and back into the TS and thus the boiler??
Or am I missing something fundamental here?
In the dipper configuration of this group, there is a one way ball valve that prevents backflow through the dipper tube.
But of course this doesn't exist in the TS configuration of the group...
in the L1 pre infusion occurs at boiler pressure, but the extraction occurs at spring pressure (which declines as the shot progresses, as the spring expands to its resting position of course)
the bottom seal has closed off the inlet ports before the brew chamber starts to pressurise above boiler pressure to any significant extent
and, there's no coffee up there
and non return valves in the group neck and thermosiphons do not play nicely together, at least not for very long
I guess I'm trying to understand the original reason for the lever slip...
The water in the chamber has to go somewhere...either the coffee puck absorbs the water (so coffee grind/prep was wrong), or the water is being forced back into the inlet port. If the bottom seal was defective, then water could in theory go into the top of the group, but that would be evident very quickly by water leaking from the top and rusty springs.
But I agree with what you said, the seal will close those off, and I guess that is the point when the lever will 'bite'.
Appreciate your help for this intellectual exercise!
I also received new seals and installed them last night.
I was going to purchase a PVC pipe and slide them over the top of the piston, but I did not have time to go to the hardware store, so I decided to ruin one of my wire whisks.
It was actually very easy to install them with this method.
I received new seals today. Since I had put a set of the old seals on recently, I decided to put only the bottom seal in place (the one nearest the coffee). This seems to have worked fine. The lever grabs lower than this morning, with the same coffee, grind, pre infusion, etc. The EY (measured with Atago refractometer and Coffee Tools) is 1 percentage point higher (21.1%) And it tastes nice. If this combination of seals, old ones around the white teflon guide and a new one below, works in the long term, it could be helpful to those of us who have quite a few pristine old-style seals hanging around.
Fitted new seals a few days ago which are ok but lever was grabbing lower with the old seals. I also fitted the ims 35 screen and the improved pump which I'm really happy with as It runs much quieter.
I struggled a bit with the top seal, I tried using a whisk but the one I used was too small so had to revert to small allen keys. Seals looked undamaged after installing.
Coffee roasted 4 weeks ago, I'm starting a new roast on Saturday, I'll see If that makes any difference.
For those considering the whisk method, don't make my mistake and buy a cheap whisk without first measuring both its diameter *and* the total length over which that minimum diameter is observed.
The first whisk I bought was wide enough at its widest point, but not long enough to straddle the piston without splaying all the tines in every direction. You want one which allows you to grab the tines as they lay against the piston spring and hold them in a uniform distribution around the circumference of the piston. That makes sliding the seal into position much easier.
I ended up having to sacrifice one of my good whisks because the cheap one I bought for this purpose was inadequate. With the right (former) whisk, it's very easy and works well.
Will a darker roast cause the lever to catch higher than a lighter roast?
I have fitted the new seals as well and my lever catches somewhat high, maybe around 11 o'clock. This is probably as high, if not slightly higher than where it caught prior to changing to the custom seals.
I'm using 18g of a medium to medium-dark roast, red light cuts off at 1.20-1.21, and I have experimented with preinfusion times as low as 5 seconds and up to 15 seconds and the lever always catches at the same place.
I did use little Loxeal in the piston and on the seals. Maybe I need to add more.
If I catch every drop of the shot the total espresso weight in the cup is between 40g-44g. I have weighed the prepared VST basket before and after the shot and determined that 15g of water is retained in the puck.
Are all 3 seals equally important in preventing the lever from catching high?
if you grind fine enough and tamp hard enough you will create what i like to call a 'coffee brick' which will be impermeable at boiler pressure
this means that when you release the lever the 9 bar pressure of the spring on the piston causes the water to disappear into the still dry puck, and you observe a high grab of the lever
this will be the case regardless of what seals are fitted to the machine
my suggestion would be to try grinding a little coarser, especially for a darker roast - although what extraction times are you currently running?
for darker roasts i like to pull the shot from the stream early, perhaps with just 20g in the cup - they are easy to push too hard and over-extract (I'm assuming you aren't adding milk)
Comments
Your suggestion seems ideal, however your picture looks like another product that already has the tines capped with a small bead, known as a "head massager" - some have all the tines at the same length. for example: http://www.imc-miracles.com/images/product/detail/K-HM18A.jpg
best wishes,
Matt
When the piston goes down during the shot, it also covers the 4 inlet holes to make sure that water does not keep coming in.
In the resting position, the space between two top seals covers the 4 inlet holes and the water cannot escape because the two seals there face each other. The water can't go up or down and the system is at rest.
The best seals efficiently close off the space even at very low pressure. The 'normal' seals do that too but just a bit less efficient if any detail (grease, pre-infusion pressure/time) is less optimal.
Matt
another barefoot day at the office
All the best!
Just a quick question.
I think I am going to go ahead and get the plumb in kit for my L1. This will get me to the $$ point I need to get some of the new seals. So, the real question is... do I have to put the seals in my basket, or will they be added automatically. Or, do I need to put a note on the order?
Thanks,
James
the process is entirely manual, so when i see an order come in for more than £50 i add 3 HP piston seals into the order i send to the factory
painfully inefficient, but only 2 months to go!
kind regards
reiss.
Thanks for that video, very informative. While we are on machine anatomy, I have another question about the brew path.
When water enters the chamber from the four holes, the water has a few paths to take:
* through the coffee puck (ideal path)
* back up to spring - this is blocked by a piston seal
* back through the TS
It's the last one I'm a bit confused by. Since the chamber is filled via boiler pressure (1.2bar), say the water can't overcome the coffee puck (say too tight grind or something)
Where-then does the water go? Does it go back through the 4 ports and back into the TS and thus the boiler??
Or am I missing something fundamental here?
In the dipper configuration of this group, there is a one way ball valve that prevents backflow through the dipper tube.
But of course this doesn't exist in the TS configuration of the group...
Tim
in the L1 pre infusion occurs at boiler pressure, but the extraction occurs at spring pressure (which declines as the shot progresses, as the spring expands to its resting position of course)
the bottom seal has closed off the inlet ports before the brew chamber starts to pressurise above boiler pressure to any significant extent
and, there's no coffee up there
and non return valves in the group neck and thermosiphons do not play nicely together, at least not for very long
kind regards
reiss.
I guess I'm trying to understand the original reason for the lever slip...
The water in the chamber has to go somewhere...either the coffee puck absorbs the water (so coffee grind/prep was wrong), or the water is being forced back into the inlet port. If the bottom seal was defective, then water could in theory go into the top of the group, but that would be evident very quickly by water leaking from the top and rusty springs.
But I agree with what you said, the seal will close those off, and I guess that is the point when the lever will 'bite'.
Appreciate your help for this intellectual exercise!
I was going to purchase a PVC pipe and slide them over the top of the piston, but I did not have time to go to the hardware store, so I decided to ruin one of my wire whisks.
It was actually very easy to install them with this method.
Here are some pictures of the procedure:
If this combination of seals, old ones around the white teflon guide and a new one below, works in the long term, it could be helpful to those of us who have quite a few pristine old-style seals hanging around.
Matt
the improved pump which I'm really happy with as It runs much quieter.
thanks for posting. that's really odd as no one else has reported that. any details?
reiss.
I struggled a bit with the top seal, I tried using a whisk but the one I used was too small so had to revert to small allen keys.
Seals looked undamaged after installing.
Coffee roasted 4 weeks ago, I'm starting a new roast on Saturday, I'll see If that makes any difference.
without wanting to come across as condescending, do check that the seals are facing the right way - top seal down, middle seal up, bottom seal down
what dose are you running?
what pre-infusion time are you allowing?
what boiler pressure are you running? (at what pressure does the red light go out?)
how dark are you roasting? (any chance of an image?)
what angle is the lever now catching at? (any chance of an image?)
kind regards
reiss.
The first whisk I bought was wide enough at its widest point, but not long enough to straddle the piston without splaying all the tines in every direction. You want one which allows you to grab the tines as they lay against the piston spring and hold them in a uniform distribution around the circumference of the piston. That makes sliding the seal into position much easier.
I ended up having to sacrifice one of my good whisks because the cheap one I bought for this purpose was inadequate. With the right (former) whisk, it's very easy and works well.
Seals correct way
14.2g in vst 15g
6 secs pre infusion
boiler pressure just over 1.3
since starting a new beans, lever is now grabbing lower.
Thanks Reiss
I have fitted the new seals as well and my lever catches somewhat high, maybe around 11 o'clock. This is probably as high, if not slightly higher than where it caught prior to changing to the custom seals.
I'm using 18g of a medium to medium-dark roast, red light cuts off at 1.20-1.21, and I have experimented with preinfusion times as low as 5 seconds and up to 15 seconds and the lever always catches at the same place.
I did use little Loxeal in the piston and on the seals. Maybe I need to add more.
If I catch every drop of the shot the total espresso weight in the cup is between 40g-44g. I have weighed the prepared VST basket before and after the shot and determined that 15g of water is retained in the puck.
Are all 3 seals equally important in preventing the lever from catching high?
I changed all 3 seals to the custom seals.
this means that when you release the lever the 9 bar pressure of the spring on the piston causes the water to disappear into the still dry puck, and you observe a high grab of the lever
this will be the case regardless of what seals are fitted to the machine
my suggestion would be to try grinding a little coarser, especially for a darker roast - although what extraction times are you currently running?
Now that I think about it I do feel like my tamp has been getting progressively firmer the last couple months. I'll ease up on it and see how it goes.
for darker roasts i like to pull the shot from the stream early, perhaps with just 20g in the cup - they are easy to push too hard and over-extract (I'm assuming you aren't adding milk)