My Lady Duchessa is a rare vintage lever machine built in 1960. Since Doug Garrott beautifully restored it for me, I've enjoyed its ability to tame harsh coffees, making shots with many layers of flavor and moderate mouthfeel. But the only way I was ever able to produce crema for a modern espresso was by assisting the lever. I infer that this machine was designed for coffees available in Italy at that time that included large amounts of Robusta beans, which produce ample crema but a relatively harsh taste.

After successfully adding a booster spring to my Elektra Microcasa a Leva I've worked with Marcio Carneiro to see if I could add one to my Lady Duchessa. He helped me determine the best type of spring and its approximate measurements. Then I searched online and found that Lee Springs carries stock springs close to these dimensions. I ordered the closest two candidates as a sample order. It wasn't inexpensive but cost me about $60 in all for the two springs and a service charge.

Here's the stock spring setup in Lady Duchessa.



We determined the best solution for increased spring strength was not to replace the stock spring, that fits snugly inside the lever cap and the hollow piston. Instead, Marcio helped me spec a booster spring that fits around the original and seats inside the lever cap and at the top rim of the piston. The stock parts of this historic machine are not modified at all, and the booster spring has flattened ends that won't mar these parts. Here's the booster spring, installed:



And today's test shows that it makes very nice crema. This was 15.5 gm of home roasted Guatemalan beans rested for 5 days and ground in a Rio Super Jolly. The crema, flavor and mouthfeel of these shots is very much like the stock Elektra Microcasa a Leva.
The spring I'm using here is the maximum this group can accommodate without interfering with the locking feature of the lever. It is 2.25 inches long where the one that was a bit too strong was 2.5 inches long. Here are Marcio's calculations that include the part number at Lee Springs:

"LHC 162P 0 S: 4mm compression installed, 27 fully cocked (the spring will be 30mm), [approximately] 24mm when sealing and pushing water. That would be from around 3 to 0.5 bar, start to the end of the shot."

The booster spring dimensions are 1.4 inch outer diameter, 1.437 inch hole diameter, 0.162 inch wire diameter, 2.25 inch free length, rate 100.90 lb./inch, solid length 1.075 inch, rod diameter 1.038 inch.

Fantastic, Gary! The Lady is such a charming machine, now she is a strong Lady.

Sorry about the metric dimensions I'm curious if the pressure is that higher but I imagine it would be difficult to measure it.

Márcio.

Carneiro wrote:I'm curious if the pressure is that higher but I imagine it would be difficult to measure it.

Thank you again, Marcio. I'm not so curious about the measurement at this point. The proof is in the crema!

The lever action now feels more tuned to today's coffee preferences without making permanent mods to a collectible machine. I'm glad I modified my Elektra to get richer shots but was somewhat missing the most layered shots with the stock spring. Yes, I can retard the MCAL spring to get that kind of shot. But now the Duchessa provides that shot profile without fuss.

Nicely done!