I want to place a TC (type T, K, whatever) over the lip of my basket and just below the shower screen. Did so successfully with a few TC wires I had (40AWG and thicker) but they always break; either after a few shots or a few days. When I don't lock the PF very hard, so I don't cut them so fast, some of them cause leaks.

Any pointers on a thin(<30AWG?) TC wire that can take the very rough treatment without breaking so fast? Found some good tips here, but not a pointer to the TC wire I'm looking for.

Hi,

I'm guessing it's either thin or resistant, you can't have both. The more robust wires are usually quite thin but have thicker insulation, so it won't work anyway.

Why do you won't to stick the wires between the basket and the gasket? it will break any wire thin enough to fit there sooner or later. If you are using a naked PF you can drill the basket on the side, stick the wire through it and use some epoxy resin to stop the leaks and keep the wire in place.

Regards,
dsc.

Thanks for the reply, Tom.

dsc wrote:I'm guessing it's either thin or resistant, you can't have both. The more robust wires are usually quite thin but have thicker insulation, so it won't work anyway.

Let's hope someone will point to something out there that's at least sturdier than usual.

dsc wrote:Why do you won't to stick the wires between the basket and the gasket?

Forgot to say that so far, even when done this way, the friction with the side of the PF(from the point it enters the grouphead) strips the insulator and eventually breaks the TC. Done this way, it lasts a few weeks with me, though.

dsc wrote:If you are using a naked PF you can drill the basket on the side, stick the wire through it and use some epoxy resin to stop the leaks and keep the wire in place.

Any idea how this would be managed without messing with the coffee cake?

Hi Max,

hmmm you want to measure the water temperature on top of the puck? I would drill a very small hole near the upper rim of the basket and stick a thin TC wire through it. Make it stick a bit up (so the hole has to be at an angle, I'd say around 60deg) so that you can easily move the wire out of the way when grinding and tamping, but make sure you can still lock the PF without too much trouble. Seal the hole with epoxy resin and fire away. I know it might be a bit tricky but it is doable.

Regards,
dsc.

Here is an illustration of some modified baskets. The one on the right represents a setup similar to what Jim Gallt used when he tested the Alex Duetto - Temperature study of Alex Duetto

The thermocouple bead is, IIRC, ~ 4 mm from the bottom of the basket. The basket on the left may be a little easier to drill because you already have a "starter" hole.

Well, guys, thanks for the detailed explanations. But Tom is right, I want to measure the water temperature on top of the puck, everyday, during actual brewing sessions. Ideally, that should happen with a TC wire coming from under the GH gasket, then on top of the showerscreen, then thru showerscreen screw hole to have the TC wires join 1mm below the showerscreen. This works beautifully, for a while, till friction breaks the TC wire, which happens in a few weeks at best.

Now if there's some kind of, reasonably priced, TC wire that can withstand the abuse, at lease for 6 months(my usual gasket change time), that would be beautiful. If not, do you know of any extra insulator that I can apply myself to the parts of the TC wire that get most of the abuse?

coffee.me wrote: ... do you know of any extra insulator that I can apply myself to the parts of the TC wire that get most of the abuse?

I have this great insulation, very supple and strong, only it's made with Bisphenol A. But most espresso fanatics would consider heart disease, or genital mutations in their offspring, a fair tradeoff for temperature stability, no?

coffee.me wrote:... I want to measure the water temperature on top of the puck, everyday, during actual brewing sessions.

What kind of espresso machine do you have? Depending on the answer to that question, perhaps one of Eric's adapters would be a good alternative solution.

On my Alexia (E-61), there is a consistent 3F difference between brew temperature and the temperature indicated on a type T thermocouple fitted into a Svendson adapter.

On the Silvia in my shop, the offset is more like 5F, but still repeatable and consistent.

I am not optimistic that you will find thermocouple material that can be repeatedly pinched between the gasket and the basket. I might be tempted to try modifying a grouphead gasket to allow passing the wire through, and therefore avoid the active pinch point between metal and rubber.

Jim

Jim, thanks for chiming in. Eric's adapters are beautiful but I already use that opening in the GH for other stuff. Oh, and I have a Rancilio S26.

What do you guys think of super glue or a thiiiiin coat of epoxy as extra protection for the part of the wire at most risk? Bear in mind this wire part never touches brew water, as it's the part before the wire goes behind the gasket. Any other thing that's as heavy duty as epoxy but as easy to apply as a thin coat of super glue?

Hi Max,

I'm just curious what are you using that opening for?

Regards,
dsc.

Oh well, I used my last( ) piece of TC wire and replaced the gasket. This time I tried to be "crafty" and curved the wire in all the right places. I also added a piece of aluminum tape to get the wire as far as possible from the way and to protect that part at most risk; not sure if that tape will stick on for long but will replace it if I find a better tape.

On the pic:
(1) This is where the PF ear enters the GH, this is the part of the wire at most risk.
(2) Here it goes behind the gasket.
(3) Out of the gasket and above the showerscreen.



Oh, Tom, currently, I use that opening for measuring brew pressure.

Hi Max,

can I ask how is that pressure setup hooked up? I'm planning to do the same thing soon and was curious how you approached it.

Regards,
dsc.