Howdy!
I have been wanting to build my own espresso machine for quite some time now, but only recently has the plan jumped forward. The basic idea is a system controlled by an arduino chip, to pull the perfect shot (if you are interested in more of the technical and design info let me know!). I am going to be building my own grouphead. I contacted a local university and asked if I could use their CNC machine. They jumped on the idea when I told them I was a high school student! I will be designing the grouphead on CAD software at home, but I am a bit stuck at the moment. I need to determine a couple of things before I can begin to draft the design:
+what size screen should I use?
+what size portafilter should I use?
+what is the outer diameter of the portafilter basket?
+are the bayonet rings a standard size?
If anyone could help me determine/answer any of those questions, it would be much appreciated!
Ethan

I'd love to ask you a ton of questions but fear this thread will become 100+ pages long; Let's do it anyway!

Why build your own group head? If you do, will you build your own PF handles and baskets? Why not modify an existing group head model? Like an E61 and add a larger or adjustable air-gap to allow for greater pre-infusion times?

Those first questions out of the way...

58MM is the standard most manufactures seem to have chosen...

If you start from scratch you"ll probably have to do some ( well, probably a lot of) work to find fundamental research or you may need to do some of your own...

I imagine that a pressure profile and extraction rate are a.o. Depending on the puck size/diameter which imo is largely dictated by the shot size extraction factor you're after.
Copying stuff others did is fine, as long as you know WHY they did what they did so you can make your informed decisions...

Unless you want the experience of designing your own grouphead, buying a used E61 grouphead would save lots of time and guesswork. They're not that expensive on the used market. For example, EspressoCare used parts currently has one listed for $65 (used) and $200 (restored). If you do decide to go the CNC route, you may want to contact Lino Verna. He designed his own espresso machine, shown below:


See Actively-heated commercial groupheads for more details

I believe he spent a significant sum of money on the fabrication.

Or...go the less is more route and have a look at the example Strietman is making...

Alright, let me try to explain myself.
Why build my own grouphead? Mostly because it seems like fun. I know it will be challenging, but I think I can pull it off. The machine will have an inline pressure sensor, and will sort-of 'learn' how to make the ideal shot. I am considering using a peristaltic pump with thermoplastic tubing, which will be able put out max 12 bar (more than I need). Basically, the machine will run through some test cycles during first use, testing input to stepper motor, and output pressure. Also, with the peristaltic pump and stepper motor, I will be able to precisely control volume.
I will be modeling some parts off of the 58 mm E61 group design. This is just to make it easy to buy parts and such.

Right now, I really need the measurements to a standard portafilter for an e61 58 mm machine. Outer diameter and measurements of the notches that mate with the bayonet ring.

I currently have a couple parts modeled in my CAD software, including a standard e61 gasket, screen, and my group outer-edge.

Where are you located? Maybe someone can send you a portafilter. I may even have one lying around somewhere. I agree with sticking with a standard 58 mm size.

I live in Baltimore, MD. I did just order a digital caliper in preparation for the hours of measuring I will be doing !

Check out this thread -

Custom espresso machine build

Wonder what happened after his accident, he just seemed to fade to black... Shame, as was looking forward to seeing the thing when completed.

Hope Sean is OK, sounds like he might have had a long recovery ahead of him.

Wow, who knew it would be so hard to find a standard portafilter for an e61 machine? Anyone on here have one lying around that they would want to sell for a few quick $?