Post By TampIt
EM6910 + BCG820 +VST report
Hi guys, just thought I'd report my findings after upgrading from my much loathed EM440 grinder (that comes with the em6910 box package) to Breville's Smart Grinder Pro 820. This is my first time making espresso at home for a while since the EM440 blades wore out within months to the point where espresso was not an option - one plus side was it gave me some much needed aeropress experience to satisfy my caffeine needs.
After about 300g of beans, I manage to get a tasty pour on:
- VST 15g filter, dosed at 18g
- BCG820 19.2secs, fine espresso setting on 2.
I did some reading and there seemed to be a lot of recommendations regarding VST dosage to stay close to the recommended dose within 1g. However, I found on the em6910 it just was not having it and I needed to updose to 18g so as to not produce a watery shot (and it was nearly gushing at nearly the finest setting). I didn't take note of the output in mls or grams, but on my em6910, longer extraction times (about 40 secs) seem to favour the desirable thick honey/syrupy pours with great taste. I did read somewhere that the vst filters take much longer to blonde than to traditional filters, I moved the cup away at around 30secs for a double ristretto and it was delicious. It's also a relief to know that burrs have room for adjustment on the BCG820 since I needed to go all the way to grind setting 2, though I was using fairly fresh beans <7days.
I hope this serves as a reference point to helps others on their coffee journey who took a similar path. The forums have certainly helped me a lot.
Originally Posted by lightandeasy
Yes, the VSTs take longer to blond, however with some medium SOs balancing the cup can be a challenge. Preinfusion seems to be almost essential with a VST - the timing is always worth a tinker (just start the 6910 "normal preinfusion" and cut it immediately after the preinfusion finishes, then restart it after a few seconds). Depending upon the roast, anywhere from 25 to 40 seconds "post preinfusion" may work well for you.
FYI, my experience with VSTs (6910, 7000, La Pav 2 group, LM Linea & Strada) is that VSTs will give a good result if you match the dosing & the grind over a fairly wide range. I would suggest two other things for you to play with -
1) Try grinding finer / dosing less - 15.4g seems to be optimal on my machinery (perhaps your grinder needs a shim?).
2) Try progressive tamping (lighter tamping in several stages). I find tamping about 2mm at a time helps slow the VST's "extra flow rate" down. The first tamp is critical if you "go naked p/f" as it will reduce / remove spraying and pour a lot more consistently.
Enjoy your cuppa
Thanks for your tips TampIt,
will definitely be trying the preinfusion you suggested and progressive tamping (hard to break habit with a single tamp from cafe environment). I've realised my tamp is not wide enough for the vst basket and have been having a lot of issues channeling down the sides resulting in terrible terrible tasting coffee. So I will stick with the stock basket and tamp for now until I can afford a better tamp
So... you're saying you tamp 5-7 times per shot?
Originally Posted by TampIt
Originally Posted by Vinitasse
I usually do two if I am pushed for time*, three (single) or four (double) light tamps when dialling in a new setup and/or new roast. I rarely need to overdose as this tamping method slows the shot down enough to suit a VSTs extra flow - which gives a lot more control to the "VST shot" compared to any other method I know.
* Extra info, probably relevant:
1) I also use "flat base / tapered sides / exact fit in basket" tampers and naked p/fs exclusively with VSTs (mine or cafes). When using a naked, a good level initial tamp means I rarely have spraying issues. I was taught that tamping method in 1970 or early 71 to tame gushers when "under the pump" at a cafe by a northern Italian gentleman / guru. When I told him about Schomer's "single 30 pound tamps" (some years later) he just snorted and said "only for dark roasts". As I was doing mainly lights and mediums back then (and now) I found the 30 pounds / single tamp was never as good "in the cup".
2) LM used the same method when designing their Swift grinder. They use around 8 pounds tamping pressure in 1mm increments. The advantages of using a machine makes that more practical...