Building a lever machine.... from scratch - Page 6

A haven dedicated to manual espresso machine aficionados.
User avatar
FotonDrv
Supporter ♡
Posts: 3748
Joined: 11 years ago

#51: Post by FotonDrv »

bidoowee wrote:Nice work!
I can see it would be hard to get the right amount of adhesive into the hole.
In any case, the result is super.
Thank you. This one was the most comfortable to use, hard to believe but true. When I sold this machine the new owner wanted it in lieu of several others from which he had to chose.

That Light at the End of the Tunnel is actually a train

jontyc
Posts: 124
Joined: 11 years ago

#52: Post by jontyc »

bidoowee wrote: jontyc - thanks for the information - that is helpful. I know that ABS can be welded with solvent, is easy to vacuum form and I guess it is now the goto material for (hobby) 3D printing. I didn't know that it could be cast however. Do you happen to have any links/info about the process? I have to admit I'm a little baffled by the plastic handles on the machine - I see some traces of injection molding on the portafiler handle (which isn't original), but there are no longitudinal mold lines visible on the other parts and they don't look like they have been refinished.
I only found two or three portafilters indicating ABS and stopped searching, I can't say it's the case for all. Lego however is ABS and injection molded. No links on the process sorry, I simply needed to get a lever handle's density for a simulation.

User avatar
bidoowee (original poster)
Posts: 265
Joined: 8 years ago

#53: Post by bidoowee (original poster) replying to jontyc »

Lego! Of course. All those hours I spent as a kid and I forget that it's made of ABS.
Thanks again.

jontyc
Posts: 124
Joined: 11 years ago

#54: Post by jontyc »

ABS does get rubbery at 105 °C though - I guess that's reasonably safe but not a huge margin. I wonder if a high-temp variation is used.

User avatar
FotonDrv
Supporter ♡
Posts: 3748
Joined: 11 years ago

#55: Post by FotonDrv replying to jontyc »

And the foam products can get toxic when they get hot, the isocyanurates in particular.
That Light at the End of the Tunnel is actually a train

User avatar
bidoowee (original poster)
Posts: 265
Joined: 8 years ago

#56: Post by bidoowee (original poster) »



At the end of last week I received the prototype of the group body from the foundry. There was a little confusion with the shipping and the package got left on the doorstep of my office overnight! Very fortunately, despite spending the night on a busy street, it was still there the next morning. I have taken quite a few measurements and, although there are a couple of small problems, I am very pleased with the result. I put the new body into my stripped-down machine with the rest of the original group parts to limit the scope of the testing. The first results were a little worrying: even after a good warm-up, there was a constant flow of water past the lower piston seal. I took a closer look at the piston and decided to replace both seals, which, though they were working fine in the old group, are a couple of years old. Success - no more water past the seal. My suspicion, though I haven't tried to measure this yet, is that there is a certain amount of error in the alignment of the cylinder bore with respect to the top of the group. If the axis of the bore isn't perpendicular to the surface that the rest of the group parts are bolted to it will mean that the axis of the piston wont be parallel with the axis of cylinder. It also makes sense that a pair of cylinder and piston parts that have lived together for decades would generate a unique wear pattern on the seals. I may also add a PTFE (Teflon) guide ring to the piston which will greatly increase the concentricity of the piston with respect to the cylinder.

Finding a good fit for the portafilter seal was another small adventure. The groove for the seal has a couple of out-of-tolerance dimensions which will have to be addressed in the next production run. This means that there is less space (both axially and radially) than is needed for the generic 73mm x 57mm x 9mm Viton seal. To solve the problem for now I found an 8mm silicon seal for another machine (rancilio silvia i think) which is considerably softer and fits quite nicely.

To make a a long story short: I made coffee on Friday. With old beans and without re-calibrating the grinder the results were actually pretty good. Now that the body has been tested, I can start on the rest of the group parts.

User avatar
pizzaman383
Supporter ❤
Posts: 1730
Joined: 13 years ago

#57: Post by pizzaman383 »

Very, very nice!!
Curtis
LMWDP #551
“Taste every shot before adding milk!”

User avatar
bidoowee (original poster)
Posts: 265
Joined: 8 years ago

#58: Post by bidoowee (original poster) »

Thank you!

User avatar
FotonDrv
Supporter ♡
Posts: 3748
Joined: 11 years ago

#59: Post by FotonDrv »

pizzaman383 wrote:Very, very nice!!
+1.

I really admire your level of expertise and follow through!
That Light at the End of the Tunnel is actually a train

User avatar
wreckfish
Posts: 137
Joined: 12 years ago

#60: Post by wreckfish »

This is a really impressive endeavor. Thanks for sharing your progress on this.