Decent Espresso Machines (DE1) - Any thoughts?

[matth3wh]

John, this is all sounding great! The extra time in testing is paying dividends in important areas that will help to deliver a better / more refined product that you and the team are happy with and that should lead to a greater experience for your customers. Sounds like a recipe for success there. All the best to you and the team. Might have a convert here.

[>decentespresso]

Decent Knockbox now 50% larger

Two weeks ago, I received a one-off (CNCed) version of our knockbox design. While it was nice looking, I found that its capacity was in the 6 to 8 pucks range, which was too little. To top it off, the knockbox looked teeny tiny next to our espresso machine, which itself is not that large either. I don't think there's that much of a market for ultra-compact knockboxes! Also, the small size meant that it was possible to bang the back of the knockbox when using it, and you can see a scratch in the photo below from my head barista Edison demonstrating this to me <sigh>.



We've now tried 30%, 40% and 50% larger sizes, and I think I like the 50% size the most, because:
- this gives us a capacity of about 22 coffee pucks
- the relative size of the knockbox next to our espresso machine is better.

Unfortunately, now I can't prototype this at a reasonable cost (it'd be cost to $1000 to make with CNC), so I'm going to to pay for a sheet metal stamping mould, and hopefully the size will be good and the mould can be used. :x

The render below is the 50% larger version, with a portafilter in there for scale.

[level3ninja]

Looks like a better size. For reference it's a similarish shape to the Breville knock bin, which unlike some of their machines is built to last. I have one and I think it's pretty much the perfect size and shape for home use. I empty it once every week to week and a half, which would be 14-20 pucks and it's not quite full at 20. If you compare your size to the Breville one I reckon that's a good benchmark, though you wouldn't want to go any larger than it.

[>decentespresso]

Revisited: getting an even water flow into the coffee bed.

Occasionally, we've seen "cavities" in our spent coffee puck, after an espresso shot, that look like hot water came through harder than elsewhere. Ideally, we want water to come out of the group head shower in an even way, so this has been something to solve.

We think that this problem is caused by how the holes on the group head shower are oriented. If you rotate the shower a bit, the holes can lie directly under where the water is coming out, and thus you'll have an uneven water distribution. We thought the problem was possible hole alignment between the shower and the shower screen, and that might contribute, but definitely getting the water to flow through the shower evenly is the first priority.

By the way, this is what a shower looks like:



and this screen sits on it, right on top of the coffee bed.



To test this theory, we loosened the screw, rotated the group head shower slightly, and voila! the holes-in-the-puck problem went away.

However, I don't think that's not a great solution for you guys, because it means everyone then has to worry about how these holes align if they take this apart to clean it. We thought that it'd be better if the hot water entered the group head as close to the center as possible, so that it has a better chance of flowing out everywhere evenly, and in such a way that hole alignment didn't matter.

Below is an annotated CAD drawing of our solution. The water path now has a little "cave" that redirects it very near the center, and in such a position that no shower screen holes will ever be below it.

FYI that hole on the far left is for flushing the dirty water out at the end of the shot. We have a separate water path for that so that we don't soil the clean "making espresso" water path.

And FYI #2, we're likely going to redesign that shower, rather than using an off-the-shelf part, to have more holes in it, so that water enters in a more distributed manner into the shower screen.

[>decentespresso]

Looks like a better size. For reference it's a similarish shape to the Breville knock bin, which unlike some of their machines is built to last. I have one and I think it's pretty much the perfect size and shape for home use. I empty it once every week to week and a half, which would be 14-20 pucks and it's not quite full at 20. If you compare your size to the Breville one I reckon that's a good benchmark, though you wouldn't want to go any larger than it.

Thanks for the tip. Could I trouble you to give me a height and width measurement on the Breville, for comparison?

Of all the competitor's knockboxes out there, Breville's is the one I think is most elegant looking. Their design has class.

Whoops, just found it on Amazon:

• Measures 6-4/5 by 7 by 7-1/4 inches

[level3ninja]

Here's some more measurements just in case: Imgur: The most awesome images on the Internet

[MattyRay]

Regarding the knock box, this is where even a cheap 3D printer would make sense. For well under your $1K CNC'd price, you could purchase a 3D printer and print a full size sample. It might not be as strong as the production version but at least you would be able to hold it and check sizing etc.

Cheers,

Matt

[>decentespresso]

Regarding the knock box, this is where even a cheap 3D printer would make sense. For well under your $1K CNC'd price, you could purchase a 3D printer and print a full size sample. It might not be as strong as the production version but at least you would be able to hold it and check sizing etc.

I used to outsource my 3D printing to a people-with-3D-printers-at-home web service (I forget the name), and my first hire in Hong Kong was Alex Chau, who did great 3D prints and who I met this way. He would touch up the 3D prints w/o telling me, but I could see the filing marks. Great attitude toward quality!

Unfortunately, our knockbox is now larger than most 3D printers (including Alex's makerbot) will print. He could make it in two pieces and glue it together, but it'd be a bit shabby looking.

Besides, we really need to (literally) bang on it a while before I'm comfortable making 500 of them.

We do use 3D printing a *lot* here, and we have a graveyard of previous designs that's pretty interesting.

[blend52]

I really do not understand why you are wasting your skills , time and resources on designing another knock box ?
The returns have to be trivial
surely the focus should be on final details and testing, testing, testing, to find the inevitable bugs in the Espresso m/c.

[TampIt]

I really do not understand why you are wasting your skills , time and resources on designing another knock box ?
The returns have to be trivial
surely the focus should be on final details and testing, testing, testing, to find the inevitable bugs in the Espresso m/c.

+1. I have bought several Oz made Grindensteins for smaller cafes - I think they also make much larger ones. My personal oldest one is probably over 20 years old by now and it still looks new. A moderate pressure water jet keeps it pristine over the years, and the centre "knock piece" is still unmarked - although these days I use VST baskets and knocking pucks out is a distant memory (they flick out now). Short of running over it with a large truck or feeding it into the intake of a jet engine I cannot see how you would destroy it.

Oh, the home one costs about $A30 with a wide choice of colours. If the aforementioned Breville is half as good, the whole global market for a knockbox must be worth, oh, let me see, a few peanuts.

John (DE), it reminds me of an old screensaver "Shouldn't you be doing something more productive?" - like getting the espresso machine manufactured so I can buy one?

TampIt

[>decentespresso]

John (DE), it reminds me of an old screensaver "Shouldn't you be doing something more productive?" - like getting the espresso machine manufactured so I can buy one?

I understand that your interest is in our espresso machine, and that's great, but we currently have a full line of coffee accessories (12 different kinds of products) at https://decentespresso.com/ and we sell a lot of them. Our most popular accessory is the "competition milk jugs" https://decentespresso.com/milk_jug but our digital milk thermometer is a close second https://decentespresso.com/milk_thermometer

I have 3 full time employees dedicated to our accessories business, and it's helping pay the bills for two years of espresso machine R&D. These accessories bring cash in the door, every day, and boxes go out.

Having a functioning accessories business has meant that we've had to fully build out our logistics, supply chain, manufacturing relationships, fulfilment, order handling, tracking, tech support and accounting systems. Most of these systems were primitive and bug-ridden when we were first launched them, but they're now fairly mature.

These are all things we'd need to have a well run espresso machine business, and it means that when we ship our espresso machine, the rest of the company will be totally ready for it. If we had no product except for a not-yet-shipping espresso machine, none of this would have been built out. I'm working off the assumption that our espresso machine will be a success, and I don't want to be a victim of its success.

[gc]

I understand that your interest is in our espresso machine, and that's great, but we currently have a full line of coffee accessories (12 different kinds of products) at https://decentespresso.com/ and we sell a lot of them. Our most popular accessory is the "competition milk jugs" https://decentespresso.com/milk_jug but our digital milk thermometer is a close second https://decentespresso.com/milk_thermometer

I have 3 full time employees dedicated to our accessories business, and it's helping pay the bills for two years of espresso machine R&D. These accessories bring cash in the door, every day, and boxes go out.

Having a functioning accessories business has meant that we've had to fully build out our logistics, supply chain, manufacturing relationships, fulfilment, order handling, tracking, tech support and accounting systems. Most of these systems were primitive and bug-ridden when we were first launched them, but they're now fairly mature.

These are all things we'd need to have a well run espresso machine business, and it means that when we ship our espresso machine, the rest of the company will be totally ready for it. If we had no product except for a not-yet-shipping espresso machine, none of this would have been built out. I'm working off the assumption that our espresso machine will be a success, and I don't want to be a victim of its success.

Good to see this. While there has been great concentration on this forum to whatever issue you serve up and the clear interest of everyone in a high quality long lasting machine, perhaps an even bigger factor in longevity of the machines we buy is how good and sustainable your business plan/team is. So the above comments at least allude to cash flow and the development of a distribution system that works - at least for small, low tech items. Naturally, I'm full of optimism in the hope of having a great machine but my friend the financial analyst was sadly, a lot more pessimistic

[>decentespresso]

Finalizing the water tank design.

This week, we're finalizing the water tank design, so we can send it out for manufacturing. For at least the first 500 machines, we'll be using porcelain (ceramic). While it is heavier than other options, it's totally food safe, even in quite hot water, and totally dishwasher safe : lots of other material aren't.

We've previously allowed the water tank to slide out the front and the back. However, I'm blocking the back-fill because I've now had two employees think they're being helpful and unplug the 220V power plug as another person fills the water tank. That has them holding an open electrical wire inches from pouring water. Not good.

Banning filling from the back gains us 100ml of capacity because I can get rid of the little 1cm rim on the back. It also avoids the problem of the tank sliding out when you lift the DE1.

From the front, we've always had a little rim



that you squeeze with your fingers to pull the tank out.



However, ceramics are glazed and very rounded, and it's not been very easy to grab this. If we make the rim bigger, it becomes easier, but at a significant cost in water tank capacity (100ml for 1cm). There's also a ceramic deformation problem that if we have a rim on the front, we need to have a symmetrical rim on the back or the tray will deform when drying.

So, I've decided to remove all rims from the drip tray, which gains us 200ml of water capacity (bringing us up to 2000ml) but now we need a dependable way to get the water tank out.

My favorite idea is to put the tank on runners, so you push it in, hear a click, and it stays put. Then, push it again to have it pop out. Here's a video of what I mean:

However, that's going to take some R&D to get right, and I want to kill all the R&D that I can so that we can move to shipping.

Jeffrey's low-tech-but-just-works idea is to have a metal "pull tab" like so:



placed to the left of the water tank:



a little tug of the finger:



tugs the water tank out.

We've also considered button a metal "collar" around the entire water tank, so you pull that, or a strap, but this pull tab seems the most simple.

I'm soliciting ideas now, so let me know what you think of this, and if you have any other (simple) suggestions!

[roburu]

I like the pull tab idea, hopefully the way it's attached to the tank is solid and it's not in danger of coming apart during transport or use.

[>decentespresso]

Now building beta 7

David in Seattle is building our beta 7 machine now. It's crazy how much cleaner the design has become with a few months of iterations!



And we have new iterations of the group head and main mixing chamber (the amber colored part) made now and ready to slot in.