Thanks to John B's pioneering and Tom C's encouragement, I decided to modify a Bunn G3 and add Ditting 804 Burrs. The G3 was never used commercially (a total lie), and is quite old, but seems to work ok. The relay is an old fashioned one with contactors rather than a SSD.

My goal was to make a case that would stand about 12" high and otherwise as small as possible. It still isn't small and it still is kind of ugly, but it's growing on me. I used oak that I planed to 5/8". I'm glad I didn't go thinner. The machine is extremely heavy and the joinery has to be strong.


The rough case. Nothing glued up yet.


Case trimmed down a bit, but still rough.


Motor mount with capacitor holder. I ended up relocating the capacitor holder to the side of the box. Luckily I have a right angle attachment to my drill.

This motor mount has legs and is screwed to the case from the inside. Again, using the right angle attachment. I've had it for five years and never needed it until now. No exposed outside hardware. I drilled the mount to use the existing vibration dampening rubber hardware.


Motor roughly in place.

I decided to keep the existing switch and cut a rectangular hole for it. This sort of thing is very easy with a Forstner bit to make the wood behind the switch very thin. I also did this for the cord strain relief.

I took the existing ABS black plastic funnel and cut most of it off. It works, but I will definitely make a better funnel that makes use of the space.

I had trouble removing the existing burr that was glued with coffee oil in place. Removing the entire burr holder from the motor was very simple and then it was easy to tap out with a punch from the other side. Took a few seconds. I soaked the mount and I'll use a flexible shaft to smooth the coffee exit path which retains the original sand casting roughness.


I next made the spacer that goes with the top burr, which is the burr that doesn't turn and is marked by Ditting, "Top". I used a piece of old cutting board as the material. I decided that food safe plastic would be better than metal for a bunch of reasons, none of which matter much. It's hard to hold a thin ring without distorting it in the lathe, so I first made a press fit for the burr and then used the old Bunn burr as a mandrel to hold the plastic and turned it down to fit the burr holder.


Grubby cutting board.


Using an old burr as a mandrel. Very handy and easy.


Mounted spacer.

I'll finish fabricating the coffee exit chute out of stainless steel tomorrow and finish things up, hook up the electrical, which I hope I don't do wrong in a day or two and test it.

------
I made the exit chute today.

As with painting and soldering, welding prep is more time consuming than the actual work. I only needed to tack weld the corners. If I had welded a nice bead along the joint it would have distorted the steel so it wouldn't have been at all flat. It's plenty strong with just the corners and sits nice and flush.

I also smoothed the aluminum opening that was rough from the sand casting with the hope that it will discourage grinds from accumulating.


A set of transfer punches makes this sort of work easier; you can use the existing chute to locate the holes. Even so, I had to stretch them a bit on the mill because I kind of messed up the measurements of the angle of the chute. I might make a new one later. It didn't take very long. I used a Foredom flex shaft and those who use Dremels should grab one if they find a used deal. They are much better for many applications except for portability.


The smoothed area isn't perfect, and I might polish it.
Before:

After:


Tomorrow I'll make the cover, wire everything and see if it works.

-----------------
I assembled the grinder today. The plastic spacer I made was too thick and would have caused a disaster if I hadn't noticed before turning on the grinder. There has to be enough clearance for the wings of the moving burr holder. See:

Press fitting with a 5 Ton arbor press -- bit of overkill.


The auger was badly scratched. Obviously an accident which might also explain the terrible condition of the burrs. Maybe someone tried to break it in by feeding nails through it.


I decided to use an oil finish followed by beeswax. So far its just the oil, which is tea seed oil (not to be confused with tea tree oil), which is a high flash point cooking oil.

I replaced the flat head screws that hold the burrs with allen head cap bolts (screws) which are easier to put on or off and shouldn't strip. [If anyone needs a set, PM me]. I also replaced the black bolts that hold the dial assembly on with stainless hex head cap screws just because.




I buffed the stainless exit chute which came out pretty good.

The thing is very heavy, pretty quiet and very, very fast. I still have a few details to attend to, but it now works (I didn't use the relay after all, thanks: Ira). My first cup was drip and thanks to cognitive dissonance, it made the smoothest, sweetest cup I've ever made.



--------------------------
The recent storm in N. California knocked my power out, so I had the opportunity to try my Arcade Crystal wall mounted grinder to compare against the Ditting burrs. The Arcade did a credible job grinding the coffee. 30 grams in about 30 seconds. Much slower than the motorized grinder. The burrs are similar in size, though the Arcade burrs are conical.

The Arcade cup was significantly more bitter, and also less layered, which probably means more fines. The grind size seemed similar. It wasn't very bad, but definitely not as good.

That's a great looking project, Dan. I look forward to seeing this one-of-a-kind Bunn/Ditting woodie take shape.

That will be a Bunn with class. Bunns' and furniture, I never thought about the 2 together when related to coffee, but it will be nice and the 5/8" is a good idea for a larger glue joint surface area.

Have you decided how you're going to finish the wood? That joinery is fantastic.

*Edit

I see your updates. Looks nice! The Trifecta plate will clean up the front plates appearance even more. I have mine but still haven't put it on.

DJR wrote: In another post, I tried to find out what the relay really does and I'm still not sure. Bunn cheaped out on everything about the grinder, so they would not have thrown it in for fun. I suspect that it is related to the bag switch which isn't a normal solid throw type switch. Anyhow, I think I'll bypass the bag switch and still use the relay for good luck.

I told you how it works in the last post of the other thread. If you don't want the relay and you get a suitably rated switch, you don't need the relay. Follow the wires, one of the wires from the motor goes to neutral and the other one goes through the relay to the hot. All the switches do is operate the relay.

Ira

I understood and appreciated your explanation. But I wonder why they added to their cost by using a relay? Any thoughts?

The relay latches when the bag switch is depressed and the on switch is pressed and released.

Ira

The grinder is pretty much done. I have an issue to solve regarding the exit chute. At espresso sizes the burr carrier acts as a fan and blows the coffee around. I might have to make something to fix that. Other than that, it works well.

Final Size in Inches:

Width: 9.75
Height: 10.75
Depth: 14.25

DJR wrote: I have an issue to solve regarding the exit chute. At espresso sizes the burr carrier acts as a fan and blows the coffee around.

I think that's the real reason for the cleaning lever, it keeps the grounds from blowing around. When I tried holding it up for a day or two, the grounds went everywhere.

Ira

After further testing with cardboard baffles, it seems that it is not air from the burr holder that is acting like a fan. Instead it is the pure velocity of the ground coffee being spit out from the burrs at high speed, and into the chute. So, I think the OEM clacker is actually a damper that slows down the coffee velocity by making the coffee force open the chute damper. It's spring loaded. In mine, at least it is 'normally closed' and the coffee forces it open. Mine might be broken however.

I'm going to make a chute with a gravity, rather than spring loaded damper which will have a knob that will allow some clacking to knock free any stuck coffee. I'll try to make it in the next day or two unless there is another solution (for example a special container to contain the coffee as it comes out).