Has anyone ever tried installing a digital timer control into a dosing grinder? i weigh and grind and clear out the doser hopper for each shot. I think there would be good consistency in timing the grind. if the grinder takes approximately 19 second to grind 18g of beans, could i find a timer that would allow me to grind as far down in time to .1 or .01 second intervals and then weight the dose until i get some repeatable results. I was at Stumptown in NYC and the have grinder that have digital timers to control the dose. Can they be retro fitted onto any grinder? I have a La Pavoni Zip with and on off switch, should be easy if i can find the right timer.

Any 0.1 sec digital dark room timer will give... wait for it... 0.1 sec accuracy, more than enough accuracy. Mine's a Gralab 450, which I happily recommend. Cost ~$200. You can actually get a 451, which is a little more timer, for a little less money (~$175) because Adorama seems to have the 451 on perpetual sale. Adorama seems to have the best prices for "new."

You find used, digital darkroom timers on e-bay but they often break in such a way that the timer works as a timer, but not as a timed switch a fault which even honest sellers can overlook. Caveat emptor.

The setup is usually as follows: Plug the timer into the wall, the grinder into the timer, and the timer can be set to power the grinder off and on for any preset duration from 0.1 sec to 99 seconds. Operation begins with the user hitting a switch on the timer.

0.01 sec accuracy would not only be vast overkill, but cost prohibitive.

I'm a little confused by your post (probably me and not you). If you're already single dosing by weight, and looking for better control, then a timer will provide less accuracy than you get with a scale. If you're trying to find a way around the inconvenience of single dosing by weight, then a timer will serve you well. For instance I might keep anywhere between 1oz and 16oz of beans in my grinder's hopper, and use the timer to consistently dose 18g shots.

Timed grinds are accurate enough for nearly all purposes, but be aware they will vary by weight according to grind setting and other factors. If you really want to stay on top of things, you'll keep your scale close and check your weights periodically. If I don't check for a couple of weeks, change beans, go through a couple of grind changes and whatnot, I can get up to 1.5g variance for an an 8sec grind -- even with my very consistent grinder.

0.5g is probably "a lot" of variance. But drilling down, how much of a difference in the cup 1.5g makes depends on a lot of contingencies; too many to analyze here. Also remember, the amount of water in the pull has as much to do with brew ratio as the amount of coffee.

BDL

good and simple suggestion. I was thinking of wiring one in instead of the switch. and yes i am looking to streamline the process. Thanks

I never integrated one but have used a Time-o-Lite M72 with a Super Jolly with great results. It is analogue but still accurate down to about .5 seconds (close enough for this sort of thing,) is physically much smaller than most Gra-lab models and is nearly bulletproof (i used to sell darkroom equipment back in the day - we got lots of Gra-lab timers back for repair but never saw a single Time-o-Lite fail.) I see them sell for as little as $10 and as much as $35 on ebay and they are worth it. I never bothered to mod my SJ timer switch to simple On/Off. I just set it to max time and ran the timer while the switch was still winding down. I do intend to try integrating one of the Delta digital timers into a Major but there's a lot more involved with that in terms of wiring and physical modifications.

"Close enough" is a personal thing. I found that with a Baratza Vario that even 0.1 s and its relatively low grind retention resulted in the dosing being only accurate to a a half a gram or so, with some being off by significantly more. For me, that is enough to change the flavor of the shot noticeably. If your coffee is one that you can stand a gram or so of "waste" on every shot, then you could always weigh after grinding if you are looking for better repeatability in dose.

If you're looking for higher accuracy than a timer can give you, Baratza has commercially available grinders that stop when a given weight is reached. I haven't seriously looked into purchasing a load cell or hacking scale to do that as response time and dynamic repeatability of inexpensive units, at first glance, didn't seem sufficient.

It seems to me that if you want the highest degree of accuracy, then you need to measure the weight of the gounds when you are done grinding, because weighing before you grind doesn't account for loss in the grinder. Measuring by time is a convenience method that is easy to implement as Baratza did for the Vario, but can't really that precise. I have never used a Vario, but there have to be a few contributing factors to the rate that the beans are ground, and changes to any one of them would change the grind rate and produce different quantities of grounds in a fixed amount of grinding time.

mondovino wrote:Measuring by time is a convenience method that is easy to implement as Baratza did for the Vario, but can't really [be] that precise.

With Macap MC4 & MXK and Elektra MXC on 0.1s timers, and a short 0.5s purge, over the course of a week on the same coffee with minimally variant environmental conditions, it's possible to achieve ±0.1g.

Not all coffees are capable of this repeatability. Blends with several varieties are more problematic as are some darker roasts. A weighed dose of a multi bean blend can show the same shot variation as a timed dose if the dose is unevenly 'loaded' by variety.

Large swings in humidity can affect timed quantity. When using weighed doses a change in grind / dose may also be required.

For sheer convenience, dumping ' sum beenz ' in the mini hopper and hitting the timer beats dropping beans 1x1 for a precise weight by a country mile.