jimseven posted some nice pictures of the Bunn burrs a while ago. I have an LPG with this burr set.

http://www.flickr.com/photos/jimseven/3 ... hotostream

another_jim wrote:Bunn LPG. 81 mm burrs, 15 inches high, lid removed and with a single dosing skirt and ground coffee tray

Jim, could you provide some more detail on the "single dosing skirt" ? My biggest hangup with the Bunn is the popcorning and the back ledge where coffee beans like to hang out. I've been meaning to cut up a plastic soda bottle or something to make a bean silo -- but if you already have a solution that works, I'll gladly borrow.

Thanks.

I use a deli tub with the bottom cut out. It's just as makeshift as a soda bottle. The base of the hopper is faceted, so a round rim creates some gaps -- the trick is to pick a bottle size that slides easily over the motor, but doesn't protrude over that sintered (?) metal top of the grind chamber.

The best solution for someone who can fabricate parts, I think, is a two piece assembly.

1. a tube that slips easily over the motor case,
2. and a funnel that is mounted to the hole where the beans enter the grind chamber and flares up and out beyond the diameter of the tube, and seals up to the column onto which the motor is mounted.

The tube would drop down and close the funnel. To grind, lift the tube, spoon in the beans, drop the tube, and grind. That would improve the feed and eliminate stray beans

For a grind catch tray, get a plastic BUNN brew basket, around $15 (I have the stainless on my brewer, surprised to find out they are around $80). Put a paper filter in the plastic basket, slide it in and grind away. The grinder is made to hold the BUNN brew baskets. You can take the paper filter out with the coffee in it and pour it into your press pot. Or you can hole saw a 1 inch hole in the bottom of the basket and put a small catch container under it. You end up with a perfect fit funnel that slides right into the basket rails on the grinder.

I am enjoying my grinder. I have been turning off the espresso machine on the weekends and brewing good old coffee. I am getting much better cups from the bulk grinder than I ever did from opening up the grind on my espresso grinders. The bitter has gone away and I am getting a relatively clean and sweet cup. A little more body would be nice, but not having a couple thousand to spend on something like one of the Mahlkönig it works quite nice.

It's interesting how the grinder (and I guess all bulk grinders) works at different roast levels. I did all my previous testing at cupping roasts, which are very light roasts stopped at the end of the first crack and which have no roast flavors at all. These are roughly the same for all grinders, so it was difficult to tell which ones were better.

The situation changes rather dramatically when doing production roasts, even lighter ones, where the roast goes on long enough for distinct caramel and toasty flavors to develop at the bottom end. Here the espresso grinders fall down, even when sifted. My hypothesis is this: roast flavors are more prone to over extraction tan acidic flavors, and it is in the darker roasts that good bulk grinders make the most difference.

Don't take this too seriously: I'm still exploring and haven't done any formal testing, But it does look like for brewing, grinder differences may depend on roast differences.

jiitee wrote:For your reference: Some close-up pictures of the lower burr of Mahlkönig Tanzania (the upper burr is similar).

Wow, they look extremely well made/finished burrs. I've just bought a used Ditting off eBay, I'll pull the burrs off that (its had flavoured coffee, so will need a good clean everywhere anyway) and snap a shot for comparison when I get it.

gyro wrote:Wow, they look extremely well made/finished burrs.

They indeed are. Before these my previous "close-up" experience with grinder burrs was with the Mazzer Mini-E and compared to those these felt almost ethereal (there's not even holes in them as they are held in place by magnets instead of screws). Grind retention is very low - just after cleaning I've measured 0.5 grams difference with what goes in and what comes out (after this it gets less as the circular groove next to the inner perimeter of the lower burr fills up - that gathers the most stuff).

But if I'm not mistaken, these burrs cannot be resharpened like most other Ditting/Mahlkönig bulk grinder burrs. Thus I'm taking very good care that I put only beans inside.

gyro wrote:I've just bought a used Ditting off eBay, I'll pull the burrs off that

Regarding disassembling and cleaning Ditting is very generous with the availability of schematics: http://www.ditting.com/schematics.htm

jiitee wrote:But if I'm not mistaken, these burrs cannot be resharpened like most other Ditting/Mahlkönig bulk grinder burrs. Thus I'm taking very good care that I put only beans inside.

Yeah, I think anything bigger than 80mm can be resharpened by the looks of it. I had a feeling the magnetic ones were 80mm? Very cool really. I understand some of the Mahlkoenig burrs are actually double sided, so you can just flip them over when they are getting a bit dull. Not sure what models have that feature.

http://www.dittingswiss.ch/en_products/ ... rview.html

I'll see when mine arrives, but its supposedly only had around 15kgs through it, coming from an unsuccessful business venture. Time will tell on that one, but it looks like new...

Cheers, Chris

The BUNN burrs are rather chunky in comparison. They spec them as having a Rockwell hardness of 66, which is darn hard steel. It would take a lot, and I mean a LOT of coffee to dull them. Something like a little piece of volcanic pumice would just get pulverized and the grinder would would just keep on grinding.

cannonfodder wrote: It would take a lot, and I mean a LOT of coffee to dull them.

No idea what the Dittings are made of, but just found this claiming 25000lbs of coffee before you need new burrs. Sounds a massive amount, but even if you take only 40% of it, its still a massive amount!

http://www.ditting.com/compare_models.htm