All,

Sorry to broach a topic that is has been discusssed ad nauseum but I'm stumped.

I have been using a PID modified Silvia and Solis Maestro for a couple of years with adequate, albeit slightly inconsistent, results. Using fresh Black Cat. I recently upgraded to a Macap M4 grinder from Chris. I'm now getting consistently sour shots.

With the Maestro, i would just overfill the double LM basket, level the top, lightly tamp (maybe 5-10 lbs), and go. pretty good results.

Now with my new Macap, I'm trying to get more precise. I got a small food scale to be more exact on the amount of beans. I'm using a bathroom scale to try for 30 lbs of tamp. i'm using 17 grams at the moment.

i get a really slow pour for about 10 seconds, too slow, I think. seems the right color at that point.

then it transforms quickly to a blond gusher. not completely blond but it does seem too blond.

if i adjust the grind to be the next level finer or try to add more coffee or try to tamp harder, then i choke my Silvia.

if i adjust the grind to be the next level coarser or try to add less coffee or try to tamp softer, then i get an immediate blond gusher.

i've tried various methods of tamping following advice here but nothing seems to help.

any advice?

I'd suggest starting with a clean slate.

First of all - I'd get rid of both scales. They're probably not helping. Go back to your "overfill and level" style. But... I'd suggest staying with the heavier tamp.

See what happens.
By doing this, you should be able to have a bit more "touch" with the variables and inter-relations.

If you still are having the same problems, tell us what has changed if anything when you get rid of the scales and we'll suggest alternatives.

On an additional note - I've always found the Black Cat to be best from a triple basket.

bpkengor,

I know my Silvia is really picky with the grind that I choose.... Silvia usaually takes a finer grind.

I had similar problems and found that blonding as you dercribed it means either your grind is too coarse or beans too old.

I used to twist my tamp at the end to polish the surface and that didn't help neither.
I'd turn almost 180 degrees and I got some advice to reduce the turning tamp.
It really made a difference!!!

malachi is right: you should keep one variable constant to find out what seems to be the problem.

Black Cat rules!!! Too bad it's not yet available in Canada; the shipping is a killer!!!!

PS: I see that you posted the same question to CG (link). There is some overlap in the two sites' membership, so I suggest posting to the one you frequent most instead of duplicating responses. Thanks...

Dan, thx for the advice. will do.

Thx for everyone's input on this issue. i think i've nailed it. Dan made the following comment:

I'm betting on ..... really bad side-channeling (canted tamp, lost adhesion due to rapping, hard lock-in, or otherwise disturbing the puck).

it turns that i was being casual about rapping the PF from the side with my tamper. i've done it instinctively to knock the ground coffee from the side of the PF. but i had apparently rapping the PF after my last tamp, thus losing the adhesion of the puck. in the past, i was tamping with much less pressure, resulting in a softer puck that was less prone to separately from the PF.

The lesson here, at least for me, is that one must ensure that the water has no place to go other through the puck. otherwise, blond & sour! thx again!

bpkengor wrote: but i had apparently rapping the PF after my last tamp, thus losing the adhesion of the puck. in the past, i was tamping with much less pressure, resulting in a softer puck that was less prone to separately from the PF.

You shouldn't be rapping your portafilter after the last tamp but rather before it. I assume that you tamp twice. In any case, rapping the side is really not absolutely necessary IMHO. I haven't found that it adds anything to the shot, and in more cases than not it is likely to cause channeling.