Caravel 3.2 impressions

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armindillo
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#1: Post by armindillo »

I just got a new (to me) Arrarex (or possibly Giubel) Caravel version 3.2 with all the latest and greatest advances before they gave up making them.

Instead of adding to the Caravel mega-thread, here is a new thread. Moderators please let me know if adding to the mega-thread would be more appropriate.

The machine is almost in "like-new" condition. I used to not be a fan of the gray color, but the paint is amazing at hiding chips. It took me 2 days to even notice that some paint is missing in the middle of this picture:
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armindillo
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#2: Post by armindillo »

It is known that there was some cost cutting going on as the models changed.
These are screws holding on the rubber feet on 3 different machines:




Left is from a VAM 1.0 (1960), middle is Caravel 1.2 (1968) and right is Caravel 3.2 (1976).
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armindillo
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#3: Post by armindillo »

It was not surprising that the action of pumping the piston was not as smooth as on my older machines but I found it was mostly due to a pin within the piston that was half falling out:

After replacing it with a bolt things work much more smoothly:
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armindillo
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#4: Post by armindillo »

But the big question is, how is the espresso?
I did a comparison with VAM 1.0, Caravel 1.2 and Caravel 3.2. The first 2 basically produced the same result so here are the 2 caravels. The "halloween" Caravel 1.2 runs on 120V so I set it up outside in parallel with the new Caravel 3.2 that uses my transformer.



The coffee and the grind are the same, home roasted Honduras something-or-other ground on my Kornkraft hand grinder. I suspect the new Caravel will do better with a coarser grind.
The lever on the new caravel goes all the way down and never really encounters much resistance, but it would bounce up most of the way due to the springy air between the puck and the piston. When I hold the lever down, eventually coffee comes out and with enough pumps I get an espresso without crema.
On the older caravel, the lever goes down part way and encounters resistance. I push hard and start getting crema, 2 more pumps and I'm done. That's my normal routine.

The taste from the new caravel was not terrrible (by my standards). I've been experimenting with lighter roasts and am always surprised when today's espresso tastes less bad than yesterday's. I'm still getting used to the idea of aging the coffee until it gets drinkable.
So the new caravel shot was a bit bland but not offensively bitter. Strong lingering aftertaste of dried-leaf-pile.
On the other hand the older caravel shot had a strong flavor of meyer-lemon and much less dried-leaf-pile aftertaste. One of my better efforts!

I'm assuming that the big difference is the amount of air that is trapped between the column of water and the piston. The older Caravels have a seal at the bottom of the piston and the newer one has the seal attached to the cylinder so it ends up being at the top of the piston when the lever is down. There is lots of air between the sides of the piston and the cylinder.
I did my best to keep the temperature the same on the 2 shots (around 92C).
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drgary
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#5: Post by drgary »

Armin,

Thank you for posting this as a separate thread. Here it'll be found. In the megathread it would blend in with everything else.

It's great to see a comparison between different versions. I wonder if this one simply needs a coarser grind?
Gary
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What I WOULD do for a good cup of coffee!

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Bluecold
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#6: Post by Bluecold »

Does the v3.2 pistom have a hole? I'm not entirely convince that the extra air volume plays a huge part. It can't be that large of a volume, since it's a very thin ring.
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armindillo
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#7: Post by armindillo »

I tried a much coarser grind in the 3.2 Caravel and that reduced the wait for the coffee to drip through but there is no way I can get crema with the low pressure I'm able to get on the piston.
I'm always bouncing on a pocket of air, no matter how much I try to fill the cylinder with water.

I decided to measure the extra space by holding the whole thing upside down, forcing the seal around the hole closed and filling the space up to the end of the cylinder with water from an eye dropper. I weighed the amount of water.
I found the 3.2 Caravel held about 10ml, my 1.2 Caravel held 6ml and the 1.1 VAM only 4ml.

The only explanation I can think of for the sponginess is the extra 4cc of air.

This is the Caravel 3.2:

This is the VAM 1.1. The end of the piston is bigger and the hole is smaller than on the Caravels:
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armindillo
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#8: Post by armindillo »

For fun I took pictures of the inside of the cylinder on 4 different machines. You can see the early design with no hole in the piston and 2 rows of holes to let water into the cylinder, up to the last design with the 2 O-rings and a slot between them to let water into the cylinder.


The following is a Caravel 1.2



Note that in the final design, there is no need for the inside of the cylinder to be smooth. It has a seam running down the side of it and dimples where it is spot-welded to the boiler. I'm sure that reduced the manufacturing cost quite a bit.
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armindillo
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#9: Post by armindillo »

The temperature regulation on the Caravel 3.2 is also different. Since the thermostat is attached to the body of the machine and not the boiler, the heating element being on has less to do with the water temperature.
Starting from cold I found that the element would shut down when the water is around 92C. The water would still heat a bit as the body cooled and eventually the element would go on again, bringing the water to a boil before shutting off.
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armindillo
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#10: Post by armindillo »

OK, I figured something out.

Bluecold is correct that the extra air around the piston in the later design does not amount to much.
I think what messed me up is the extra looseness in the linkage preventing water from fully filling the cylinder.

I lifted the lever all the way up and wiggled it back and forth and kept getting gurgling noises.
I managed to get more water into the cylinder than ever before and finally conquered the ridiculous sponginess.
With more pressure I managed to get a bit of crema.
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