RDT for filter, Ode V1.1 experiences.

MWJB

This isn’t a deep dive into the best weight, or method for applying RDT to your whole bean dose, just my experience in seeing what benefits it may provide.

TL:DR - it makes for a cleaner looking grinder & grinds cup (a very valid reason to do it and why I suspect it has been popular for nearly 2 decades). I didn’t see a significant improvement in dose consistency compared to using the knocker on the Ode v1.1, with 4 knocks per dose. Dose consistency with RDT was better than not using the knocker, or any other measures beyond start & stop grinding on the Ode v1.1. I didn’t see any improvement in workflow as time spent knocking was replaced with time spent poking beans out of the grind cup & down the hopper chute.

Use the least amount of RDT water to achieve your preferred level of cleanliness (for me, this was wetting the handle of a steel teaspoon & stirring dose).

More depth…

I started off by using the 2% (approx) of dose weight suggested in CH Hendon’s recent espresso grinding paper, not because I was expecting any other significant effects in brew time, nor EY - just because it is the only quantifiable RDT weight I am aware of. This equated to 3 sprays from an atomiser bottle and 0.33g per 14.11g dose of whole bean. Dosing cup & lid were visibly wet and beans stuck to the cup & grinder hopper, requiring prodding to send them on their way.

Reducing to 2 sprays (0.21g & 1.5% of dose) and then 1 spray (0.12g & 0.9% of dose) still produced sticky doses. With one spray, on one of 2 occasions, a bean remained stuck in the back of the hopper, behind the mushroom and I didn’t see it until I had brewed the remainder of the dose.

I then tried the wetted bowl of a teaspoon, still sticky doses (0.18g & 1.3% of dose).

Lastly I wetted the handle end of a plain steel teaspoon for about 0.03g of water per dose (approx 0.02% of dose) and this produced less sticky doses, but didn’t eliminate them entirely.

Weighing the dosing cup after dumping the beans into the grinder hopper suggests that, overall, about half of the RDT weight of water never makes it into the grinder. I’ve never seen this mentioned, or discussed before.

My 0.01g scales won’t take the weight of the grinder so I have no idea of how much of the RDT water is lost to the grinder, or makes it out again into the dose. For the gross dose weight out of the grinder I assumed that all the RDT water weight that was on the beans that went into the hopper, remained in the dose. Either way, assuming this, or assuming that the dry (net) weights in & out resulted in the same dose consistency.

These gave an average difference in dose in/out of 0.08g, std dev of 0.11g, cumulatively 0.19g (0.20g for dry dose & 4 knocks on the Ode v1.1). 0.32g extrapolated to 95% confidence level (0.38g for dry dose & 4 knocks on the Ode v1.1). It strikes me that the oft mooted claims of ‘eliminating retention’ (achieving perfect dose consistency) are due to folks using scales that are not able to detect the RDT weight, not accounting for the increase in weight going into the grinder and overlooking the potentially added weight of the grinds out. This is represented in the data as ‘Net dose in vs gross out’.

I use table cloth clips to hold a bag in front of the Ode, so I can quickly brush/knock out any chaff - not the most elegant solution, but quick. Comparitavely, I found the RDT process a bit more frustrating. I won’t be RDT’ing for filter in the future…except maybe for my OE Lido 2 & Lido E grinders (1 drop off of a teaspoon handle & stir beans).

RDT dose consistency

(Scroll the sheet tabs to the right for ‘Fellow Ode V1.1 RDT’)

MWJB

I noticed after the last few doses RDT’d with 1 drop from the handle of a teaspoon, that I was getting better dose consistency than before, with 2 natural coffees (more towards medium than light). So I just carried on dosing with no RDT, nor knocking and I saw very good dose consistency (not more than 0.08g difference)…until I switched to a lighter roast, washed coffee, then I straight away saw 0.30 & 0.54g difference, before returning to the teaspoon handle for the light roast, washed (0.05g difference).

Takeaways are you might not want to RDT every coffee, only those that need it when required.

MWJB

At long last, I have achieved what I regard as dose consistency to 0.1g tolerance. This is the only instance which I have personally seen such, despite it being an ‘industry standard’ according to one YT influencer.

This was achieved with a tiny drop of water (avg 0.04g) from wetting the bare handle of a teaspoon. In one of the 10 grind samples a bean got stuck in the grind cup, in another 2 beans - both needed intervention to achieve this tolerance. I wasn’t going to persevere with it, but with most of my purchases being smaller weights of beans (114g-150g) I though it best to minimise wastage, which it did.