How to make a Thermometer Clip for an Air Popper Coffee Roaster

Also see some alternative mounting ideas in our article on Adding a Thermometer to an Air Popper, and our Hearthware Gourmet Tip Page

Our Thermometers are on the Roaster Accessory Page (By the way, digital thermometers on a stem do not work well for roasting -the head is not meant to be exposed to such heat, and the digital readout goes black on you).

You need a good 550 degree thermometer to roast with a stovetop popper like the Whirley Pop (Theater 2), and referencing temperature to determine your “degree of roast” in any roaster is a plus. The Cooper 550 degree Small Thermometer is made as a pocket type, with a 1 inch and a 5 inch stem (a perfect stem length for poppers and most roaster appliances). Cooper Instruments makes better thermometers than the types we used to stock (Comark and Pelouze), and the face on the Cooper is easier to read. It can be easily re-calabrated too using the nut on the shaft (instructions included). Dialface thermometers should not be submerged in water while cleaning, and the face should not be exposed to high heat. If you notice the divot on the shaft about 2 inches from the tip … well, from that point down the thermometer is “sensing” temperature. Keep that in mind because ideally you want the shaft to contact the coffee directly, not just sit the air (although this is useful too, such as an air roaster of any type since in the final roast stages the air and coffee temperatures are very close).

  • To add a thermometer to the Whirley Pop, drill a hole in the top equidistant from the centerline (the hinge), and the rim, on the side that clips shut to the rim (so that it is not in the way as you are adding or removing the coffee). Do you really need a thermometer clip? Well, not really, but if the dial face is moving around while you are cranking, it makes it hard to read. I would try to undersize the hole a bit so the thermo fits snug, and see if you can do without a clip. Also, Ken Davids book, Home Coffee Roasting, has instructions too.
  • To add to a Hearthware Precision – enlarge one of the holes in the top of the chaff collector with a 5/32 or 3/16 drill bit. Drill slowly to avoid cracking the plastic. Drop in the thermometer. To suspend the tip of the shaft in the coffee without touching the metal at the bottom of the roast chamber, you may need some spacers. A clip doesn’t seem as necessary as with others. For a Hearthware Gourmet, see our Gourmet Tip Sheet.
  • For a Freshroast you can chose a drill location that will get the tip into the coffee but not touch the glass sides or metal bottom of the roast chamber. Be very careful drilling though any plastic parts of the roast chamber on the FreshRoast -the plastic is hard and cracks easily! (I use a flexible thermocouple on the Freshroast, so admittedly I have not mounted a rigid-shaft thermometer in this roaster yet.)
  • The Caffe Rosto and Alpenrost are a bit tricky. I use a flexible thermocouple in both, but I have used a rigid-shaft thermometer in the Alp. The problem is twofold: you need to drill through the bean hopper in the end, and through the wall of the roaster so the shaft goes directly into the open end of the drum. The coffee doesn’t meet the thermometer shaft very often but I did get good readings with this method. The other problem is that you have to slide the thermometer out of the hole each time you need to open and close the Alpenrost lid. I have not mounted a rigid shaft thermometer in the Rosto yet but you can either go in from the side of the roast chamber or it might be possible to remove the roast chamber lid’s knob, and go in right through the hole in the top!
  • Click here for Air Popcorn Popper installation. Note: that page has my old mounting hardware method, the tee-nut. Also, Ken Davids book, Home Coffee Roasting, has instructions too.

Making a Simple Thermometer Clip

I would try to drill your hole so the thermometer fits really snug …then you don’t need a clip to fiddle with. But if the thermometer is moving around during the roast and you can’t read it, try this clip:

What you need:

  1. A piece of flexible spring steel – the easiest place to get this is from steel pallet strapping. Check out the dumpster behind your local lumber store. They still use the steel strapping for lumber.
  2. Drill and bits: possibly 5/32, or 3/16. Actually, the one I use (and it’s perfect for this) is a #25, which I think is a machinist’s sizing scale.
  3. Wire snips or sheet metal snips
  4. Pliers

1. Here’s what you need. I have a metal hole punch, but you can drill the holes in the steel. It should be really thin stuff.

2. Trim a 3-inch piece of the thin steel strap. While you’re at it, make a few between 2-3.5 inches. What the heck?

3. Punch or drill 2 holes, about 1/2 to 3/4 inch from each end. The holes can be bigger than

4. Make a 90 degree bend 1 inch in.

5. Make a 45-degree bend 1-1/2 inch from the other end

6. Pinch the two ends together while sliding the clip up the shaft. If the holes line up too well, it won’t do it’s job. You actually want the holes to be a bit out of line so when you release tension, it grips the thermometer. The cardboard in the picture is simply meant to represent the popper/roaster…

My Old “Tee-Nut” Method

What you need:

  1. 8/32, 9/32 or 10/32 Tee Nut -local hardware store
  2. High Temp RTV Sealant -auto parts store
  3. Drill and bits: possibly 5/32, 7/32, 15/64, 1/4, details below.
  4. Wire snips or sheet metal snips

What to do:

  1. First of all, Tee Nuts have little barbs that need to be clipped off with the snips.
  2. Try to size the Tee Nut to the diameter of the thermometer shaft you will be using. If it is not a really tight fit, don’t worry.
  3. Open the RTV sealant and, with and coat the inside (threads) of the Tee Nut. This will help the thermometer grip and fit snug. I use a small nail to coat the threads. The idea here is to be able to remove the thermometer, so don’t block the hole with the sealant.
  4. Drill a hole in the popper hood with a diameter a tad larger than the outside diameter of the Tee Nut shaft.
  5. Put 3 dabs of RTV sealant under the collar of the Tee Nut and fix it in place on the hood. Let it all dry before forcing the thermometer into place for the first time.

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