HiBREW G64 Plus Grinding Issues and Findings

So if you are here, you have found your way here via my Kickstarter comment. Since I can't post photos there, I will list them here. I'm a busy person so won't spend too much time on this but if you know what you are looking at, you will get the idea.

Recently as others have been getting their G64 grinders, they have observed similar issues; that the grinder just doesn't seem to be capable enough for espresso grinding. Most notably "Benjos" and "Joshua Tan" with Benjos providing the right advice to getting the shims the correct way and Joshua Tan providing some insight about a "wipe zone" which I think makes sense when looking at the placement of my lower burr.

I followed the guide as per the instructions from HiBREW about adding the shim to the lower burr but adding the 0.24mm shim would bring the burrs to their touching point at around a level 25 and adding the 0.21mm shim would bring that touching point to around a level 21, both of which didn't sit well with me.

I then recalled Benjos instructions which was to replace the existing 0.14mm shim on the upper burr which I did as well instead, leaving the lower burr untouched. Using a 0.24mm shim on the upper burr brought the touching point to around level 16 and using the 0.21mm shim brought that to a level 11 so this is the one I stuck with.

In the process of changing out the shim on the lower burr, I did notice something and that was that the burr itself didn't sit exactly flat on the holder. This I think accounts for the "wipe zone" issue Joshua Tan mentioned if I'm not mistaken. Taking a look at the machining of the part shows that there was not enough material removed from it causing the burr to sit high on one side.

If this part is fixed, I believe that not only would the touching point on my grinder be brought down to a lower and more respectable number (maybe like a level 4 like Benjos experienced), but it might also give a more consistent grind.

For reference, as of now with just replacing the upper shim with a 0.21mm shim, I'm able to choke my Breville Dual Boiler with a grind level of 16 with dark roasted beans and 10 bar of pressure. Previously I was not able to do so with even a level 0 so at least it is known that the shim change is required. So it appears there are two issues where you may have a decently machined lower burr holder and only need to change the shim, or you have a poorly machined lower burr holder and need to change the shim and resolve that issue although from my intermediate level experience, the varying grind level from the uneven lower burr holder is not as noticeable as the incorrectly shimmed upper burr.