AssafL wrote:5mm now. It was 3 prior. Remains to be seen that beans don't fall through.

The beans feed into the front and the vanes stir the beans toward the front so prob not a big issue.

Good point!

I just recieved my Quest M3 last week and am enjoying it quite a bit.
I am tinkering with the TC4+arduino and considering gutting the original controls and replacing it with jims P1 design. I would not like however to loose the look of the roaster.
Has anyone done this type of project and could they share photos of end result?
Thanks.

Home roasters.org might help

I'm not sure I know what Jim's P1 design is.

I did the TC4 / PID / SSR mod to mine and I'm very happy with it. I did some testing varying the fan speed throughout the roast and found that I didn't like how it changed the flavor (too much fan brought out more acidity...in a bad way). Now I leave the fan at one speed through the entire roast, including through first crack.

This was the inspiration behind my mod, the only difference was I'm using the TC4/Artisan combo as my PID control instead of the Fuji's.
Another Quest M3 PID modification

Nicely done!

I basically just use the fan to blow off the chaff and then put it immediately back to its normal(for me) operating position; unless I am trying to manipulate the BT quickly.

I basically just use the fan to blow off the chaff and then put it immediately back to its normal(for me) operating position; unless I am trying to manipulate the BT quickly.

+1. I have come to the conclusion that my Quest M3 (MK-II) is at least 95% a conduction roaster, with the fan speed having very little effect on temperature control, beyond brief changes which quickly stabilise. I believe this is because of the very small apertures at the front and the back through which air may flow. Of course, this does not apply to M3s that have been modified to increase the flow of air through the drum. This leads me to wonder whether the simplest modification might be to simply grind off a bit of the drum at the back, without installing a back plate with air holes.

The fan in the M3, in essence, creates a low pressure area at the top front of the drum. This low pulls air in proportion to the amount of gap through the front and back of the drum. Since there is currently not much difference between the two gaps, about half the air in a stock Quest must come in via the back and about half via the front. It would not take much metal removal at the back of the drum to greatly increase the air flow via the back, which air would of necessity flow through the drum and therefore swirl around the bean mass. The limiting factor would be that the larger gap would have to be kept much smaller than a bean, but the drum vanes tend to keep the bean mass toward the front of the drum. Has anyone done this? If so, what was the result. It's not something I want to do with my M3, as I like it as is. But this whole discussion certainly has made me wonder if the Quest could/should be modified to become an entirely different roaster (more convective), or whether the point of diminishing returns favours just a small 'tweak', such as I've described.

I also note with interest the difference in acidity with different fan levels. I had not thought of this and will do some testing. If the increased acidity with the increased fan leads to undesirable acidity, might the tweak I describe make this worse?

My observations differ from yours. With the stock Quest M3 the fan did have impact but it was only at extreme positions. My settings ran from 40% - 70% (on my digital dial). Chaff collection was always 100%.

With holes drilled towards the back - the range i use is now limited to 45-55%, but makes a large difference.

I don't think air increases acidity. I think it helps development and thus reduces acidity for a specific roast.

I can drop 5-10 degrees lower and have manageable acidity now (without having to grind fine and do a 15 Sec preinfusion).

I'll state that the changes make it into a different beast now and takes a bit of re-learning to control.

With holes drilled towards the back - the range i use is now limited to 45-55%, but makes a large difference. I don't think air increases acidity. I think it helps development and thus reduces acidity for a specific roast. I can drop 5-10 degrees lower and have manageable acidity now (without having to grind fine and do a 15 Sec preinfusion).

Good information, thanks. Drilling a bunch of little holes towards the back would achieve more or less the same thing as I was describing by grinding off a bit of the back of the drum. Also, your experience confirms that the fan control would then have a greatly increased effect, which is what I was hypothesizing. Still, I think I'll wait.

I'm guessing that if one adds PIDs to a stock M3 that the heater PID would do all the work and would be easy to control. But, in your modified M3 things get a lot more complicated, as the increased effect of the fan control would/could be brought into the equation. Right? As I said, my M3 is stock (apart from EricS's probes/Artisan). But I'm now thinking about adding a PID at least to the heater, as I see lots of used/inexpensive Fuji PIDs showing up on eBay, where they once cost hundreds of dollars. Would this be a mistake?

Concerning the acidity, I was not saying this is so. My comment relates to another member who posted that he found increased acidity with higher fan on a stock M3, if I understood him correctly. I have not personally detected this despite having once in a while messed up and left the fan on high the whole time.

djbetterly wrote:I'm not sure I know what Jim's P1 design is.

I did the TC4 / PID / SSR mod to mine and I'm very happy with it. I did some testing varying the fan speed throughout the roast and found that I didn't like how it changed the flavor (too much fan brought out more acidity...in a bad way). Now I leave the fan at one speed through the entire roast, including through first crack.

Very nice setup.
Yeah, its the TC4 / PID / SSR design by Jim (don't know last name).
Question, did you include heat sinks in the SSR and how did you manage to fit them?
Did you remove all the stock controls? Would you consider after having done the mod that it is worth it?
Thanks.