Django Said:

I've now taken my bistro past the 6 mark point. In fact, I stopped measuring and just cut another 5mm from the plastic part that stops the inner thread rotating, so that the hopper can be rotated even further. I now have a pretty fine grind, comparable to espresso powder bought from the store - I know it tastes bad, was just to play with! The grinder seems fine, and I only ever grind ~14g at a time so aren't too worried about overheating. Hopefully this isn't misplaced confidence!

BUT...when pulling the first test shot, I encountered a problem. Maybe you can help? I tamped pretty hard and then flicked the switch. The coffee started to come through after a couple of seconds (fast) and for a couple more seconds it seemed fine, nice tails etc, but then started pouring frothy, creamy water and filled my shot vessel in a second or two.

Any ideas what might have happened?

Posted March 20, 2012 link

PdM Said:

Hey Guys,

I found another way to modify this grinder without having to cut anything, and it is also reversible should you at some point wish to get the grinder back to its original form.
The other problem with adjusting the grinder so it turns further / pushes the burr further down, is it comes to a stop against the solid mount around the bottom burr, but does not grind fine enough by the time it gets there and adjusting it so it can turn further won't help.

My way, instead of adjusting the top burr to move further down, I adjust the bottom burr up and leave the rest of the machine standard.

After stripping it as per your posts, also remove the part with the motor from its stand off's.
Loosen the nut at the bottom which holds the bottom burr in the gearbox key. NOTE: it's right-hand thread. Also you need to hold the blades - turning the nut against the gearbox can break the gears.

After this is done, remove the bottom burr. You can  now shim the burr up by placing a shim between the bottom of the burr and the plastic spacer beneath it. (use shim stock, or perhaps a copper washer). You will also need to remove one of the washers where the nut tightens as the shaft is no in effect shorter. Take out a flat washer, don't remove the spring washer.
assembled the burr, put the top burr in place and first turn the motor with your hand to make sure the burrs are not touching. If the are, put in a thinner shim.

I shimmed it up 0.8mm (considering going to 0.9m or 1mm just to see how far it will go), but my grind is now very fine and extremely consistent.

Hope it helps.

Posted July 16, 2012 link

PdM Said:

I shimmed it up 0.8mm (considering going to 0.9m or 1mm just to see how far it will go), but my grind is now very fine and extremely consistent.

Hope it helps.

Posted July 16, 2012 link

PdM Said:

On that mod I posted - I recommend actually taking the gearbox apart as well and making sure the ball bearings holding the tension on the drive plate is properly fitted. Just sticking the shaft back in and then shoving it around can cause the drive plate to move. If this has happened you might hear your grinder making a "clacking" noise while grinding. No bigger, just check the ball bearings are in their place.

Posted May 2, 2013 link