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HTC + TC4C installation questions
BarryR
Top  #26 Print Post
Posted on 10/19/2014 12:38 PM
Right!
With the further info you've all provided, I'd like to pretty much follow OKMed's solution (mostly). I think I'll go with grounded after all for the better response time.
I'd like to use a back (or front) nut to hold the fitting in place rather than relying on the thickness of the backplate.
My remaining questions are:

Do I need to tap the nut (as other's have described for the 1/16th" solution) or can I purchase it (if the latter, what nut do I purchase)? Are there compression fittings that would have a standard (non-compression) thread on the part that I need to secure through the backplate so I could use standard hardware at that end? If not and I need to tap the nut, what nut do I start with and what tap would I need (I'm guessing 1/8" since that's what OKMed used in the backplate)?

I hope I haven't exhausted your patience.
Barry
 
BarryR
Top  #27 Print Post
Posted on 10/19/2014 4:15 PM

Quote

BarryR wrote:
...I'd like to use a back (or front) nut to hold the fitting in place rather than relying on the thickness of the backplate.
My remaining questions are:

Do I need to tap the nut (as other's have described for the 1/16th" solution) or can I purchase it (if the latter, what nut do I purchase)? Are there compression fittings that would have a standard (non-compression) thread on the part that I need to secure through the backplate so I could use standard hardware at that end? If not and I need to tap the nut, what nut do I start with and what tap would I need (I'm guessing 1/8" since that's what OKMed used in the backplate)?

I hope I haven't exhausted your patience.


I found this compression nut on Amazon http://www.amazon...F8+npt+nut
Would this do the trick?
I'm thinking I could make the hole just large enough to pass the male end through, then snug it with this nut (or should I use 2 nuts and sandwich the backplate between them?
Edited by BarryR on 10/19/2014 4:29 PM
Barry
 
BarryR
Top  #28 Print Post
Posted on 11/01/2014 1:12 PM
I think I found a really good solution to thermocouple mounting and would appreciate any feedback.

My plan is to use a 1/4 ips (1/2" OD) threaded nipple (used in lamps), probably the 1/2" long one shown in picture.
I'll then use 1/4" OD 1/8" ID silicone tubing for thermal and electrical insulation.
The plan is to use the omega 1/8" grounded probes (same as OKmed), probably 2" ones.
My uncle (bless him) will then tap two holes in the brass coupling (180 deg apart) for set screws to secure the probes, rather than relying on friction fit (two will keep the probe nicely centered and hold it better).

The silicone tube then goes inside the nipple and coupling and the probe, obviously, goes inside the silicone tube.

Then I need a 1/2" hole in the roaster backplate for each probe. I'll secure the nipple in the hole with a nut on each side and a lock washer. The coupling threads onto the nipple.

Simple, inexpensive, adjustable probe depth, almost no mass inside the roaster and easy to replace the probe if needed.

The main downside that I've found is that I need a 1/2" hole. I think that'll be easy for the BT probe, but it's a bit more cramped for the ET probe. It's probably doable, but there's not much room for error.
If I go to far left (outside) or too high, it might interfere with the drum.

One solution is to mount it on the other side (sort of mirror image to the OEM probe), I realize that it'll be closer to the heating element and may read high (any thoughts?).

Another possibility is to use a 1/16th grounded probe with narrower hardware for the ET probe and use larger probe for BT.

I could also use a 1/8th ungrounded probe without insulation (or buy an OEM probe) for ET (smaller hardware) and the grounded one with insulation for the BT probe.

I also went back to thinking about just using 2 OEM probes (the depth is pretty good though I can probably get a custom probe about 3/8" further into the roaster than the OEM. Does anyone know how the OEM K probes would compare (response-wise) to the omega probes?

Any thoughts?
BarryR attached the following image:
hottop_thermocouple_mount.jpg
Edited by BarryR on 11/01/2014 1:22 PM
Barry
 
BarryR
Top  #29 Print Post
Posted on 11/02/2014 7:27 AM
I cut a 3/4" round piece of refrigerator magnet and stuck it on the back wall for the roaster. If I got the hole PERFECTLY in place for the ET probe it would work but no room for error, so the only option with this set up would be to put the ET probe on the other side (near the heating element), but I'm assuming that's a bad place for it.
Barry
 
smico
Top  #30 Print Post
Posted on 11/02/2014 8:44 AM
Have you guys considered RAG's solution:
http://homeroaste...post_45922
I am champion of improvisations, but if I would need to do it again, I would do it exactly like that.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
BarryR
Top  #31 Print Post
Posted on 11/02/2014 9:00 AM

Quote

smico wrote:

Have you guys considered RAG's solution:
http://homeroaste...post_45922
I am champion of improvisations, but if I would need to do it again, I would do it exactly like that.


Yes. Strongly. Might still end up doing that but I wanted to try to use 1/8th inch probes which might hold up better, which led me to OKmed's solution but I'm concerned about whether that will loosen up over time.

That led me to weeks of deep contemplation, the solution I gave above which I thought would work well, but then I realized it's too crowded for that.
Barry
 
BarryR
Top  #32 Print Post
Posted on 11/02/2014 1:21 PM
OK. This time I might really have the solution.

It turns out 1/4 ips tubing is way wider than I need and 1/8 ips has an ID of about 1/4.

So, 1/8 is what I need and the hardware pictured below should work nicely.
I'll need to drill a 3/8 hole and the hex head is only a little over 1/2 inch so it'll fit nicely inside the roasting chamber. I'll but a washer & locknut on the back side to hold it in place. Then thread the coupling.

The coupling has a set screw which will pinch the 1/4 inch OD X 1/8 inch ID silicone tubing to hold it & the 1/8 inch thermocouple in place.

Probe depth can be adjusted and replacement (if ever needed) is easily done.

I'll let everyone know who it turns out.
BarryR attached the following image:
thermocouple_solution.jpg
Barry
 
smico
Top  #33 Print Post
Posted on 11/02/2014 3:29 PM
I used to use 1/8 inch probes, fixed on the back wall, but they were quite slow to respond. Not critical for BT, but kind of annoying for the ET measurement.
Truth to be told, I simultaneously switched to insulation from the back-wall, and to 1/16 inch probes, so I don't know how to attribute which change had more effect.
Your solution seems simple and effective.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
BarryR
Top  #34 Print Post
Posted on 11/02/2014 3:36 PM

Quote

smico wrote:

I used to use 1/8 inch probes, fixed on the back wall, but they were quite slow to respond. Not critical for BT, but kind of annoying for the ET measurement.
Truth to be told, I simultaneously switched to insulation from the back-wall, and to 1/16 inch probes, so I don't know how to attribute which change had more effect.
Your solution seems simple and effective.

Thanks. It took me lots of google searches to find what I needed.

If I find the 1/8 probes to slow, I could switch to 1/16th on the BT and just use additional or different silicone tubing.
Barry
 
smico
Top  #35 Print Post
Posted on 11/02/2014 4:05 PM
Would it be possible to tap the hole in the back-wall, and thread just a few threads on the outside of coupling so you can screw it flush in? I am not sure if the back-wall is too thin... Your uncle might know.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
BarryR
Top  #36 Print Post
Posted on 11/02/2014 4:49 PM

Quote

smico wrote:

Would it be possible to tap the hole in the back-wall, and thread just a few threads on the outside of coupling so you can screw it flush in? I am not sure if the back-wall is too thin... Your uncle might know.


It might work but I think it's not ideal. okmed did tap for an npt fitting and it worked for him.

I chose this way because it's more secure than tapping into the panel.
Since I'm using the 1/8 ips nipples with a small hex head, it shouldn't be a problem fitting.
Barry
 
woodchuck
Top  #37 Print Post
Posted on 11/03/2014 9:58 AM
Sorry been traveling so late to the party. Not sure if this will help but I just JB welded a couple of rivet nuts into the backplate and RTV'd the probes into the nuts for a tight airtight fit.

Cheers

Ian
woodchuck attached the following image:
tc-2.jpg
Roasters: TJ-067, Hottop with TC4C and RAF Mods
Espresso: LaSpaziale VII/Macap M4 Grinder
Pour over: Bonmac Pro Cone
Press: Bodum
 
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