@Chert If I was doing it for just myself I might replace the solid-state relay and control it directly. You are correct there is one solid-state relay for each knob. However I wanted to design something that could be attached to a brand new roaster and not compromise whatsoever the design principles or safety mechanisms. And this is what evolved from that. I'm super happy with that. On the comment on whether one might get a better heat curve with direct control. To be honest, I don't think so. Not much and perhaps not worth doing. I can make my curve look a lot smoother with extra Artisan-Scope smoothing by the way and cheat others do. It turns out, the control is very tight and very responsive with the knob. I wouldn't think one could get more than perhaps 10 or 15% better and I don't think that would be tasteable in the bean with the level of control we're getting now. With this system this machine literally does things that multiple five figure machines can't hit easily. I think that's impressive. So anyway kind of long, but that's my thoughts on that. I hope that at least makes sense. I wanted to honor what Ken built.

@Msimanyi - Very kind of you to say thank you so much for the response. I do appreciate it.

Thanks so much for the response.

I've been curious since I looked under the hood of a artisan 6 years ago. Then pid and SSR for boiler heat control was well established and artisan was already to go for roaster control of hot tops and such but the coffee crafter team and my acquaintance who owned one weren't interested. So I never heard of anyone taking control of those SSR s by logic level controls. I might check that Facebook fluid air group.

Your solution looks great. I envy you the time a bit since I have the motor and cards to work out a gas knob system like that (as others have led the way here) for my huky but haven't gotten it done.

Would be happy to help you with your project or offer approach suggestions if you need it. Sounds fun!

It takes a while to dial the PID in. I personally went through about 20-30lbs of coffee before I arrived where I did (and that's doing 8oz/1lb roasts). The nice thing about the solution here, is it works with anything with a knob (like a gas knob) and can be scaled up to larger servos. It just depends if that's the desired approach.

Hi Lexingtonian,

I've been thinking about doing the same thing to my 3-e... Would you be willing to share the great work you've done and provide a bill of materials and 3D printer CAD files?

Thanks!