Hi All,

I am trying to dial in my grind so that I am using exactly 18g of espresso in my double PF (Rocket R58 standard). My grinder (Compak K10 Fresh) currently puts out grinds such that when I sweep and weigh them, I am getting to about 18.5g, even using a concave sweep tool. I would like to lower my dose, which I believe would mean making the grind coarser. But, at the same time, I don't wish to increase my flow rate as I would like to keep the approximate rate I have now, which is producing a 60% ratio. So, how do I reduce the dose but not increase the flow rate?

Thanks,
--David

To reduce dose and maintain flow rate, you need to tighten, not loosen the grind.

This doesn't make sense to me. If I tighten the grind, I will be able to fit *more* in the PF, not less. That should increase the dose, not reduce it. Can you elaborate on exactly why you think it will reduce the dose?

Thx.

Flow rate is regulated by both the amount of coffee in the filter basket and the grind setting. The flow is reduced if you add more coffee and/or grind finer. The flow is increased if you reduce the coffee dose and/or grind coarser.

Dose and grind can be changed independently of one another, and should be determined by experimentation. Ignore how much coffee you can cram into the basket. The "correct" dose is whatever yields best results in the cup.

You also can't dose by weight and volume at the same time. You say you want exactly 18 grams in your basket. You can't say, "I want exactly 18 grams and I want it to come to precisely this level in the basket." It just doesn't work that way.

Lowering your dose is going to increase flow rate, and in order to maintain flow rate at a lower dose, you need smaller particle size so there's more resistance to the water flow.

That makes sense, but here is the problem. I am not single dosing. I grind to overflow the basket then swipe. Currently, I am swiping to 18.5g. If I make the grind tighter, using this method I will get a larger dose.

I should make it clear that when I say flow rate, I am referring to getting the weight I desire out of my timed shot. So, I want to put in 18g, and get out about 30g of espresso in 25 seconds, yielding a 60% ratio.

Then you are not dosing by weight. You're dosing by volume, so forget what it weighs and grind so you get the flow rate you want with a full basket.

Or, dose by weight, grind to get the flow rate you want, and forget what the volume is. Otherwise you'll drive yourself crazy chasing your tail.

What matters in the end, is the taste in the cup.

trihard wrote:I grind to overflow the basket then swipe. Currently, I am swiping to 18.5g. If I make the grind tighter, using this method I will get a larger dose.

I should make it clear that when I say flow rate, I am referring to getting the weight I desire out of my timed shot. So, I want to put in 18g, and get out about 30g of espresso in 25 seconds, yielding a 60% ratio.

Brew ratio, as you know, is computed by weight, not volume. You have already discovered that overfilling and swiping the basket does not give you a consistent dose weight. Changing the grind makes a difference. So does the bean blend, and how long it's aged. And let's be honest: there is no way you can accurately dose to within 0.1g by overfilling the basket and swiping.

If you insist on dosing by volume, you also eliminate a powerful way to tune your extractions. Light roasts, for example, often require a lower dose and finer grind to avoid excessive sourness.

Unless you are working in a busy cafe, and workflow dictates speed at all costs, I recommend you weigh your coffee dose. Sure, it takes a few extra seconds. But it will help with both consistency and fine tuning the taste in the cup.

Back to post 1.

Two answers.

One. You're using the Fresh. Can't you adjust it to give you 18g and then you just need to worry that everything stays in the pf?

Two. Let's do it your way. What concave tool are you using? Scottie Callahan tools or similar? If that's the case then you can easily adjust for a +/- 0.5g. You do that by adjusting your swiping technique.

Let's say you sweep with the tool exactly upright.. You'll get 18.5g. If you swipe with the top of the tool tilted AWAY from you, you'll compress more coffee into the basket and get 19g. If you tilt the top of the tool toward you, you'll remove coffee out of the basket to get 18g.

Just make sure that you start upright from the center of the basket and tilt as you come closer to the edge. Imagine a pendulum movement.

Dose by weight, not volume and use a nutating tamp or a bowed finger or chopstick to distribute the grinds in the basket.