I built a Bunnzilla for brewed coffee and love it. Now I am getting the espresso bug.
I also have a Preciso. Its very easy to dial in the Preciso, and the micro-adjustments allow me to shorten or lengthen pull times quite accurately.

However, with the Bunnzilla, using the trifecta dial, its so difficult to make minor adjustments.
Out of 8 attemps, one was marginally good.

I have seen modifications made to the Bunnzilla, to give it a fine adjustment dial bored inside of the main adjustment dial, giving microadjustment.
However, would this really turn the Bunnzilla into an espresso grinder, or is it hopeless?

Put another way, supposing you had perfect fine control of the Bunnzilla's adjustment dial, and you could control it, could it in theory at least produce a great Espresso grind?

Since I have $600 invested in the Bunnzilla, I would rather invest another $100 to have a part machined to give fine adjustment control, rather than spending >$1,000 to get a big upgrade over the Preciso.

I can't say much about the Bunnzilla because I have never built/used one. I would try to lower the bar pressure down to 6 bars and see if that slows your flow rate enough to be in a better range for your grinder. Just a though

I've had great results with mine using a lever machine with it! Personally, when it works I prefer it to my K10 or the Mythos I used to have by a fair maigin.

For making it work, preinfusion is a requirement and variable pressure during helps a lot. If you go from dry to 9 bar you'll just make a mess.

BUT, even then, it doesn't always work. Some extreme outlier coffees or coffee older than a couple weeks is going to just gush no matter what. At least in my unit, there's just enough play (not much, but it's there) it can't be aligned quite well enough to choke my machine. It can get too fine with almost any fresh coffee (I've had exactly one outlier so far that even the shop I got it from struggled with), just not enough to choke.

You'll notice I didn't complain about the fineness of adjustment. Because, honestly, it's fine. I want to be able to go finer without burr chime, but I don't need any more fineness in the range I already have. So I'm not so sure your proposed mod hits the right problem. Maybe your unit doesn't have that tiny bit of slack between the outer burr and the shaft so it'd work absolutely perfectly. If you can move it even slightly though, I'd look for a new grinder before going on a modding goose chase.

If you want similar burrs for espresso, the Mahlkonig Tanzania, using the same burrs (minus screw holes) or Ditting kr804 can easily choke any machine after zeroing and have a much better adjustment range. Or so I'm told. Personally I think rather than get a Tanzania I'm going all out with an EG1. But I'm not sure.

thepilgrimsdream wrote:I can't say much about the Bunnzilla because I have never built/used one. I would try to lower the bar pressure down to 6 bars and see if that slows your flow rate enough to be in a better range for your grinder. Just a though

I can't adjust the pressure on my machine.
Roughly half of the shots shoot through too fast and finish in 10-15 seconds
And, roughly half the shots clog my machine, so its a trickle.
Out of 8 shots, only 1 was acceptable, but the difference between this and the other two extremes was about 1/4 of a step on the trifecta scale.
Very hard to repeat.

Thats why I am thinking to drill the main adjustment shaft and put in a micro adjustment. The microadjustment may take a 360 degree turn or two to cover 1 macro step on the trifecta, giving me the adjustability I need.

BTW, with the preciso, I have to adjust quite alot of microsteps to clog my puck, and also quite alot to cause it to gush through.
The same coffee, on the same machine and same pressure, in the Bunnzilla, will go to these extremes with a minor fraction of a step.

CwD wrote:I've had great results with mine using a lever machine with it! Personally, when it works I prefer it to my K10 or the Mythos I used to have by a fair maigin.

For making it work, preinfusion is a requirement and variable pressure during helps a lot. If you go from dry to 9 bar you'll just make a mess.

Do you feel this gives you more margin for error, so you don't need to be as precise with the Bunnzilla grind?
A lever machine I guess would let you "feel" the resistance and choose an appropriate pressure for the grind.
In that case, you have a flexible way to deal with the limited adjustability of the Bunnzilla.

Or, do you feel that the Bunnzilla grind itself, even if you had perfect control of grind, produces a distribution of grinds which give you a narrow operation range?

To my understanding, the Bunnzilla ought to produce a distribution of grinds similar to the EK43. Quite a narrow modal distribution with normal amount of fines.

CwD wrote: BUT, even then, it doesn't always work. Some extreme outlier coffees or coffee older than a couple weeks is going to just gush no matter what. At least in my unit, there's just enough play (not much, but it's there) it can't be aligned quite well enough to choke my machine. It can get too fine with almost any fresh coffee (I've had exactly one outlier so far that even the shop I got it from struggled with), just not enough to choke.

I can choke & gush at will, I just can't get in between. So, this means, the alignment of my machine must be pretty good because just short of whining burrs, I can really, really choke the machine, so it has enough range on the small side.

CwD wrote: You'll notice I didn't complain about the fineness of adjustment. Because, honestly, it's fine. I want to be able to go finer without burr chime, but I don't need any more fineness in the range I already have. So I'm not so sure your proposed mod hits the right problem. Maybe your unit doesn't have that tiny bit of slack between the outer burr and the shaft so it'd work absolutely perfectly. If you can move it even slightly though, I'd look for a new grinder before going on a modding goose chase.

I am in the same boat with regards to being able to go fine enough. That is why I think I need the adjustability, because I don't have the adjustability on the machine side, and I want to be able to very precisely dial in a grind that is repeatable.

CwD wrote: If you want similar burrs for espresso, the Mahlkonig Tanzania, using the same burrs (minus screw holes) or Ditting kr804 can easily choke any machine after zeroing and have a much better adjustment range. Or so I'm told. Personally I think rather than get a Tanzania I'm going all out with an EG1. But I'm not sure.

So, these burrs in those machines produce exceptional espresso, or they produce espresso that is unique to these burrs but not necessary near the best in class? If the burrs are really great for espresso in principle, and the Bunnzilla alignment is considered good in principle, then I would conclude the adjustment is where I need to focus. I agree, it would be much better to have a dedicated grinder like you mention above for espresso and keep the Bunnzilla dialed for brew, but I don't have the budget. On the other hand, the macro adjustment knob on the Bunzilla can easily be machined to enable a microadjustment screw to be bored inside of it.

gobears wrote:Do you feel this gives you more margin for error, so you don't need to be as precise with the Bunnzilla grind?
A lever machine I guess would let you "feel" the resistance and choose an appropriate pressure for the grind.
In that case, you have a flexible way to deal with the limited adjustability of the Bunnzilla.

Oh absolutely. The lever helps a ton.

gobears wrote: To my understanding, the Bunnzilla ought to produce a distribution of grinds similar to the EK43. Quite a narrow modal distribution with normal amount of fines.

I've never used an EK personally, but from what I hear the Ditting burrs don't have that same super sweet shots trick, but can do lower ratio shots while still being good. The Dittings (and Compak, and probably others I don't know of) are more straight unimodal than the EK's somewhat unique thing it has going on.

gobears wrote: I can choke & gush at will, I just can't get in between. So, this means, the alignment of my machine must be pretty good because just short of whining burrs, I can really, really choke the machine, so it has enough range on the small side.

If you can choke it you can probably make pretty good use of it. Try turning the dial reallly slow with two hands. Ignore the notches. Set it between notches or epoxy over the notches on the espresso range if you need to. You will not get a number you can go right back to after using the machine for brew, but it is stepless.

gobears wrote: So, these burrs in those machines produce exceptional espresso, or they produce espresso that is unique to these burrs but not necessary near the best in class? If the burrs are really great for espresso in principle, and the Bunnzilla alignment is considered good in principle, then I would conclude the adjustment is where I need to focus. I agree, it would be much better to have a dedicated grinder like you mention above for espresso and keep the Bunnzilla dialed for brew, but I don't have the budget. On the other hand, the macro adjustment knob on the Bunzilla can easily be machined to enable a microadjustment screw to be bored inside of it.

In my personal opinion, I very much prefer the espresso I get with these burrs to that of other burr types. I've decided this after owning a few grinders simultaneously, and your tastes may differ. The microadjustment screw might be a pretty good option in your case too if yours is well aligned. I have seen it done and it looks like it could also make it more plausible to switch between brew and espresso if you could lock it in place.

CwD wrote: If you can choke it you can probably make pretty good use of it. Try turning the dial reallly slow with two hands. Ignore the notches. Set it between notches or epoxy over the notches on the espresso range if you need to. You will not get a number you can go right back to after using the machine for brew, but it is stepless.

In my personal opinion, I very much prefer the espresso I get with these burrs to that of other burr types. I've decided this after owning a few grinders simultaneously, and your tastes may differ. The microadjustment screw might be a pretty good option in your case too if yours is well aligned. I have seen it done and it looks like it could also make it more plausible to switch between brew and espresso if you could lock it in place.

Thanks for all the feedback. I was also thinking to go stepless but if I add the microadjusment, the steps will actually be useful.
At the same time, I get your point about making really small adjustments, ignoring the steps.
I will try that today some more and see if I can get espresso I like, before making the investment in the micro steps.

Don't waste time and money, even the ditting 805⁄ Tanzania aren't suitable for espresso.

Nonsense. My Tanzania makes quite acceptable EK43 style shots, and actually allows a bit of range for espresso grind. This is an admittedly small sample of one Tanz that might be serendipitously well-aligned. I have tested it only by taste, and not by refractometer. Of course I use a Slayer, so therefore may be cheating. That notwithstanding, I fully expect better espresso from the Monolith Flat or a Compak R120.

I am not certain that Bunnzilla can be as well-aligned as a Tanz could be. As such, it might be less suitable for espresso. It seems worth trying, and at worst you have a great grinder for all or your non-espresso needs. It is also easy to sell if you need to.

The Bunnzilla makes incredible espresso. The R120 makes incredible espresso.