mikerobertgodfrey

Thank you!

Thanks!

IGES file should now be on Grabcad.

Unfortunately not. I just don’t have the time... Sorry about that.

See labelled sketch for the key dimensions.

Wow! That looks fantastic. I'm very glad you could make use of the design!

Thanks!

As suggested in the comments, I've since added a brass end to the handle. Simply a plug that is a press-fit into the tube. I could have added a wooden handle but I don't necessarily grip the end of the handle.

I've made mine with the top of the piston flush with the top of the cylinder at top dead centre. When I fill the cylinder, I aim to get the water level about 5 mm below the top so it doesn't overflow if I lift the handle too quickly but I stop extraction before I've run out of water anyway. If you want a larger volume, you could have some space above the piston by making the cylinder longer and pump the lever twice. Hope that helps.

Not yet. It's on my list of things to do. I haven't decided on the best approach for this yet so let me know if you have a good solution.

You are probably right about the threads in the Delrin, especially considering the modulus halves at 100 degrees C.

Thanks for the suggestion. I will give it a try.

I had the same problem when I made the cylinder from solid aluminium - hence the inclusion of the liner. I made the piston to fit the cylinder, so the liner ID wasn't too important. I made my liner ID 41.6 mm but in the CAD it is 42 mm. Make sure you have about 0.2 mm in diametrical clearance between the piston OD and the liner ID, so the piston itself doesn't rub on the cylinder liner and just the o-rings make contact. I would suggest trying 0.2-0.4 mm of diametrical squash on the o-rings, so if the liner ID is 42 mm, the bottom of the o-ring grooves should be around 36.3 mm in diameter for a 3 mm o-ring. Of course, if you overshoot, 3.5 mm o-rings are also a standard size, so you have a fall-back option. I would also try making the piston oversize and testing the fit before finishing th…

I had the same problem when I made the cylinder from solid aluminium - hence the inclusion of the liner. I made the piston to fit the cylinder, so the liner ID wasn't too important. I made my liner ID 41.6 mm but in the CAD it is 42 mm. Make sure you have about 0.2 mm in diametrical clearance between the piston OD and the liner ID, so the piston itself doesn't rub on the cylinder liner and just the o-rings make contact. I would suggest trying 0.2-0.4 mm of diametrical squash on the o-rings, so if the liner ID is 42 mm, the bottom of the o-ring grooves should be around 36.3 mm in diameter for a 3 mm o-ring. Of course, if you overshoot, 3.5 mm o-rings are also a standard size, so you have a fall-back option. I would also try making the piston oversize and testing the fit before finishing the piston (or liner undersize if you are machining the liner to fit the piston).With regards to dimensional stability, the delrin is fantastic. No measurable or noticeable changes to the liner or the o-rings after almost 2 years of making 2 coffees a day. And I find it gets up to a satisfactory temperature after 1 preheat but I usually do 2 preheats by filling the cylinder with boiling water. After 2 preheats, I find the water ends up at around 85 degrees C, and after 3 preheats the water is usually at around 90 degrees C but it's difficult to go hotter. I find it's easier to go hotter with a stove-top kettle, rather than an electric one and using a naked portafilter makes a huge difference, even if you preheat the spouts on a standard portafilter.

Just to add to Hazel's point. I think acetal might work for the piston and valve, just be aware there will be a high contact pressure in the valve piston where the pin goes through. You probably want to make the flanges either side of the o-ring grooves on the main piston a bit thicker too. Stainless 303 would be preferable, but I also appreciate that would be tough to machine. Aluminium is another option but I suspect it would corrode.

Thanks! Sorry for the slow reply, I've been away for a few days. I think Hazel has sorted this issue. The aim is to get the piston as close to the shower screen as possible, but not touching. The piston is stopped by the angled slot in the lever joint, as Hazel mentioned, so it's important to get this right! Let me know if you have any other questions, and it would be great to see a photo of your one once it's finished!

Thanks!

I’m glad you liked it. I didn’t take any footage for YouTube and I don’t currently have any plans to make another one. I would love to sell them but I sadly don’t have the time and it wouldn’t be financially viable for me. Thanks for looking!

Hi. Unfortunately, Solidworks files are never backwards compatible, which means you need Solidworks 2018 or later to open the files.

Sorry for the delayed reply. I've included links to all the parts you need to purchase in the supplies list. I bought them all from The Espresso Shop which is a UK supplier but they do offer worldwide shipping.

No problem. Let me know if you have any more questions along the way and good luck!

It shouldn't matter if the liner is Acetal homopolymer or copolymer (I used copolymer because that was what I could source. I'm based in the UK, so I was able to source my Acetal from "The Plastic Shop": https://www.theplasticshop.co.uk/acetal-rod-40mm-50mm-60mm-65mm-70mm-75mm-80mm-90mm-100mm-diameter.html.It doesn't have to be Acetal. There might be alternatives (perhaps Teflon?). Just make sure the glass transition temperature is well above 100 degrees C, is it thermally insulating and food safe. Hope that helps!

Thanks for reading! Frame alignment waschecked in two ways. One way is to sight along the length of the frame in sucha way that you can see the relative twist between the seat tube and head tube.This is a common technique used in woodworking, typically with 'winding sticks'.This method is surprisingly sensitive but doesn't tell you about the twist ofthe rear dropouts relative to the head tube. The other method simply involvedputting it back into the jig and checking for alignment relative to theclamping cones, since that was made accurately and everything on the jig couldbe checked with a straight edge and square. The usual method using a bigsurface table is unnecessary for a small number of frames in my opinion (unlessyou happen to have a huge surface table already).I did face off the BB…

Thanks for reading! Frame alignment waschecked in two ways. One way is to sight along the length of the frame in sucha way that you can see the relative twist between the seat tube and head tube.This is a common technique used in woodworking, typically with 'winding sticks'.This method is surprisingly sensitive but doesn't tell you about the twist ofthe rear dropouts relative to the head tube. The other method simply involvedputting it back into the jig and checking for alignment relative to theclamping cones, since that was made accurately and everything on the jig couldbe checked with a straight edge and square. The usual method using a bigsurface table is unnecessary for a small number of frames in my opinion (unlessyou happen to have a huge surface table already).I did face off the BB and HT. I had the luxury of a BB facing/threadingtool for the BB but for the HT, I used the boring head when I was boring it inthe mill. That way I could be certain the faces were parallel to the bore.I looked online for some drawings for the disc mount position andthen set it up in the mill using a wobbler to get the boss position accurate. Hereare the drawings I used (page 59): https://www.servicearchive.sram.com/sites/default/files/techdocs/gen0000000005504_rev_e_frame_fit_spec_2018_road.pdfJust so you are aware though, I think the boss position is 2mm too far out in these drawings (I had to machine a custom adapter to compensate).This might be because I used through-axle (Syntace x12) dropouts instead of QR though– not sure.My BB was pre-threaded. On my first bike, it didwarp, and I had to use the BB threading tool. On my second one though, I had nosuch problems. I used to work at a bike shop (Cycle Republic) and they wouldhave been happy to clean out the BB threads for cheap (I’m assuming most bikeshops are similar), so that’s always a fall-back option if the BB does warp andyou don’t want to spend the money on a threading tool

Thank you! I made a quick video: https://youtu.be/PfPWta_hi9E

Thanks! Here's a short clip: https://youtu.be/PfPWta_hi9E

Possibly. I decided to cut it to length first because it's easier to squash it parallel without extra tube attached but it might be worth trying it your way.

I’m glad you liked it! Good luck!

All good advice, thanks. I used standard nitrile O-rings, which as far as I am aware should be OK but I agree it's a good idea to use properly approved O-rings. With regards to the grease, I just used natural products in the cylinder (e.g. butter & olive oil) but I doubt their longevity and effectiveness.

I see your point. I might make a wooden handle or a brass end.

Thanks for the suggestion. Tried that too but it didn’t work.

Thanks!

I didn’t have any particular plans to sell them but I will let you know if I do!

Thanks for reading. With MIG welding, it's very easy to blow holes through thin metal (the tubes are only 0.4 mm thick in places); hence why I decided to braze instead.

Haha. I wouldn't drink what I meant by IPA...

Thanks for looking! I will hopefully get round to writing up the jig assembly soon.