I've tried taking a video of the parallelism check, but the viewing angles are so awkward (I have to check the DTI with the use of an inspection mirror) I was faffing about with the camera and focus for a good few minutes and 90% of the video was rubbish, out of focus etc. So here's some photos of the setup used for the check:

https://www.flickr.com/photos/tompjagiello/16509287929/

and the results in form of a collage:



I've used 8 test spots, starting with 3 o'clock and stopping every 45degs, the shaft was rotated using the motor as I can set the speed to however slow I want it (I believe this was close to 10RPM). As you can see a design which allows for adjustments is far better than relying on machining tolerances (unless you have a super advanced machining centre offering super precision at which point you don't really care ).

Rgds,
T.

Some more prototyping parts arrived, here's a shot showing the fluff coming out:

https://www.flickr.com/photos/tompjagiello/17300113616/

No further messing about is required, no WDT, just tamp and pull. Retention is <=0.1g.

T.

what about production?

That's a hard topic to crack, but I might have some more info in a month or so.

T.

What's innovative about this grinder? What sets it apart from the various maker/hacker grinders that have been shown before (aside from actually being shown)?

The adjustment is all via a push of a button (no collars), there's no threads to worry about, no locking rings / mechanisms. You can easily come back to an old setting and the adjustment is repeatable down to 0.01mm. The burrs remain parallel down to less than 0.01mm across the whole range of adjustment (espresso to brewed).

Regards,
T.

dsc wrote:The adjustment is all via a push of a button (no collars), there's no threads to worry about, no locking rings / mechanisms. You can easily come back to an old setting and the adjustment is repeatable down to 0.01mm. The burrs remain parallel down to less than 0.01mm across the whole range of adjustment (espresso to brewed).

That's interesting. I'm picturing a rack and pinion mechanism in my mind. What kind of method/mechanism do you use to true up their faces to such tight tolerances?

It's built-in adjustment or simply tolerances on mounting holes and appropriate joints. Shimming is always an option if you have an existing design and something doesn't fit as it should, but if you design well from the ground up, such measures are not necessary.

Rgds,
T.

I had posted something about how aging affects the density of the beans and how that can indirectly affect grinder output.. if you really don't wanna tweak the time as the beans age.. i think weight based will be really awesome

Just my two little cents..

I'm fully aware of the cons of a timer based system, although I've switched to single dosing and ditched the weighing system idea for now. It's just more convenient in a home environment to single dose imho.

Regards,
T.