Loonster There is ridge that sticks out. That ridge makes contact first. You are not shimming under the ridge, but in the recessed area.
DavecUK As has been hinted at before, the “ in true” mounting surface for the burr is not the recessed area but the rim of the burr.
Thanks to both of you, I may now have a working solution to the challenge of using thinner burr sets in the Duo.
Your astute observations/recommendations showed me where to shim (under the the rim/ridge on the top burr). That, along with Dave’s excellent diagram showing me where the top burr’s teeth needed to protrude helped me arrive at a solution for the Ceado Opal Glide burrs.
These burrs were the thinnest of the collection of 83mm burr sets that I have, being 0.128mm thinner than the stock 151B espresso burrs.
As suggested by @Loonster I used a 0.5mm shim.
I have just dialled the Duo in to 5 on the dial for a light roasted bean measuring 103 on the Tonino scale. 20g in and 40g out in 28 seconds i.e. flow rate of 1.4ml/sec. That still leaves me plenty of runway for even lighter beans, if I want to try them (doubtful).
The burrs produced an exceptional espresso, that would rival an SSP Espresso burr for its brightness and full-on flavor burst.
This is where I placed the shims (ignore the grinds, this was immediately after I ground and the grinds were cleaned thoroughly again prior to reassembly):
Loonster and DavecUK I’m very grateful for the time, effort and brain power you brought to the table for this challenge.
I’ll use the Opal Glide burrs on my bench for a few weeks alongside SSP Espresso burrs so I can compare the differences on a daily basis for a while.
Then I’ll create shims (thinner I suspect) for other thinner burr sets like the DF DLC, Fiorenzato and I’ll post regarding progress.
