Here's some more modification ideas for the Quest M3; simply adding high temp thermal insulation to the outside of the roaster. It certainly helps stabilize the ET a bit better and requires less babysitting of the MET during the roast to a certain degree. I didn't really have to change my roasting technique, it just made it a bit easier to profile all together.
A fairly easy and reversible modification that only costs about $30. It took me about an hour, but that was partly because I was taking pictures and tiptoeing thru the task. Parts from McMaster-Carr are:
9379K93- Ultra-High Temp Foil Faced Insulation Strip
7594A8-Extreme Temp Aluminum Foil Tape * ( in retrospect, wider tape would be helpful as well)
Tools required: Utility shears, N95 dust mask, disposable nitrile gloves, flexible measuring tape.
I spent a good deal of time trying to figure out which materials to choose as far as utilizing the material without having to trim and modify it too much. Knowing that it would essentially be fiberglass, I didn't want to have to carve it up much and have particles everywhere. The foil faced insulation strip is exactly 3" wide, and the drum, is just a hair over 6" long, so I knew I could get the job done by simply lying 2 sheets parallel to each other and securing it with the foil tape. You can see from the photo below that the insulation isn't very well attached to the foil. It's a bit fiddly getting it to behave the way you want.
It's relatively self explanatory, but a few tips are to carefully fold over the ends of the insulation to help trap the fiberglass and give you a clean edge to tape down.
It's not glued to the aluminum and easily slips off. I'll likely go back and run one strip around the horizontal exhaust tube as well, but I used up most of my aluminum tape, so I'll save that for likely later on in the day after I go to the hardware store for some other unrelated things I need, I'll pick up another roll of aluminum tape. This roll was only 1" wide, and it's not the most adhesive stuff in the world, so in retrospect, I'd go with a wider tape.
The drum diameter is 54cm, I cut each strip at 57cm and still had a slight gap ( unimportant for the most part), the gap is out of the way, underneath the bottom. I took the wire cage off, set it aside, and also unscrewed one side of the lateral drum mounts at a time, meanwhile I supported the drum with my Cafelat tamping stand and a microfiber towel, which just happened to be the perfect height to support it all without any undue flexing.
Sliding in one at at time and taping it in place along the drum face, midline, and rear. I worked around till I had both pieces wrapped and gently tapped, paying close attention to the midline seam. and taping everything down well.
Then replacing the wire cage and gently squeezing and tightening the aluminum tape down where small gaps appeared. The wire cage holds everything in place nicely and still secures well, but I might pick up a few wider washers, since on one side, I had to screw them in a bit lower, where the gaps between the individual wires are wider. It probably won't make a difference, so I'll just watch it for a while and add them if I feel like I need to.
One thing that reinforced the fact that I need to use a wider tape than the 1" was the fact that the lower areas were quick to come unsecured and hang a bit. But the 1" tape was nice for the detail work of securing it down around the drum face and rear, to prevent the insulation from being exposed to my roasting environment. After the wire cage is back on, it's easy to go back and push and tuck around to close everything off nicely.
I ran three roasts (it's super early in the morning and I was awake, but I didn't feel like making it a super long roasting session), but it was quite apparent that this helps stabilize the ET a bit and it allowed me to get thru a profile without as many tweaks to the heat. Sequential roasts were nice in that, I was able to see a dead straight ET/ MET prior to charging my next roast. It also gave me a good extra minute or so between roasts without loosing heat. I usually re-weigh my cooled beans and update the Artisan profile so I can save it, before moving on to the next roast, and this modification allowed me to do all these little tasks without worrying about my ET caving down or soaring up. And this was with the fan running at 4.