As some here know, I have a 1lb commercial Sample Roaster that has been significantly modified since its purchase from Roaster's Exchange, which has the unlikely website URL of roastersexchange.com
If you know of any roasters in need of their unique skill set, don't hesitate to call them:-) But I digress.
Prior work on this roaster has included replacing the anemic burner that was shipped with it (per suggestions I got from Barry --- Thanks!) and custom fabrication and installation of a smoke hood, as smoke comes out all over the place from this thing, especially through the tryer hole.
Previously, I've monitored roast temps with a thermocouple (TC) mounted on a custom wood stand that I fabricated from scrap wood leftover from other things; this worked well however was a major PITA due to the need to put the TC stand on the cooling tray which coincidentally had to be used for other things such as cooling beans, which meant I needed to continually remove and replace it in use, and the TC would take time to get back up to temp for the next roast. I also needed to remove it before the roasts were completed as I wanted to use a tryer to look at beans towards the end of the roasts. There was also an uncertainty factor about when to introduce beans for the next roast since I try to let the drum cool off below 400F before new beans are put in, to reduce the risk of roast induced defects.
Six months ago I had an idea about permanently mounting a TC in the roaster, whose design is not very conducive to this, as the only nonrotating entry point was the tryer hole itself, which among other things is needed for introducing green beans and dumping them at the end of each roast. In addition, the drum rotates in the hole and the probe can't get too close to the opening or it will be damaged by the drum, but there is a need to preserve the size of the tryer hole since beans have to go in and out through it in this roaster design.
I determined that this installation was feasible and after talking to Greg Scace, got a recommendation to go with Omega for the fabrication of the custom sheated TC. The rep I spoke with from Omega was very helpful on the phone and seemed to understand well what it was that I wanted to have made. After some discussion we came up with measurements and a design, when I told him what I was working with, how I intended to mount it (attached to the outside cover of the drum), and the requirements for it and its wiring to withstand temperatures up to at least 500F. We were able to get this whole thing made for about $50, which I thought was very reasonable. I knew I would have to bend the TC sheath tubing several times, which was also a consideration in the materials and thickness of tubing used.
A few weeks later I received the custom fabricated TC, but various other things and reservations about how to actually execute this thing put the project way behind. A number of times I actually decided not to proceed with it as I became convinced that the project was apt to end in failure. For one thing, the stirring vanes in my drum are HUGE and if the probe was put in with the wrong orientation it would get chewed up quickly and destroyed. I tried using a bent hanger to simulate the bent TC in the drum and became even more convinced that this was a very dicey proposition. For one thing I was not convinced that I could attach the external part of the TC to the outside of the drum in a way that would stay put and would not get in the way while roasting.
The project went on the back burner.
A few days ago I was in a Lowes and got an inspiration to use some small pieces of copper tubing cut with a hacksaw, and some JB Weld (aka "redneck epoxy") to hold the TC in place. Yesterday, I cut off pieces of the copper tubing (about 1/2 to 1/3" in length) and proceeded to do the installation with the copper as a guide and the JB Weld to hold it all in place. I needed to revise the bending of the TC inside the drum to avoid the large drum vanes, but otherwise the project came off as well as I could have hoped for.
Here's a picture of the drum from an angle on the side showing the TC attached with the copper and JB Weld:
as you can see, the tip of the installed TC is in the bean mass:
This shows the old standing TC in place as well as the permanently installed TC
Here you can see both TCs in the drum with beans being roasted:
Here is a plot of temperatures datalogged during roasting with both Thermocouples in place; as you can see, both give more or less the same information. There is no data for the Tryer Hole (on a stand) TC during the period when there were beans in the cooling tray from the prior roast.
As you can see, the tryer hole is used for other things!
And finally, a view of how the roaster now looks with the permanent TC in place, right after a bean dump:
Perhaps this will give some of you some ideas you can use, and if not, I hope you found it at least a little bit interesting. Like all successful mods I've done, it really has paid to think a long time before actually doing anything.
ken
