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05/23/2022 10:46 AM
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HTC + TC4C installation questions
BarryR

Quote

GreenBean wrote:

I see that you have started a thread on another coffee forum discussing this same subject i.e. advice on installation of thermocouples in your Hottop. It is difficult to follow your current thoughts on what you propose to do across the two threads. There are many different approaches possible and you have received good advice from a number of contributors. The solution proposed by okmed looks good to me provided nylon ferrules are only used on the cold side of the fitting. My views on what I perceive to be your current proposal are:

1. There is no substitute for dismantling and measuring your Hottop with your proposed solution in mind. I believe Hottop have made changes to the design of key elements such as the drum. Measuring your own Hottop is the only way to be certain that your solution will fit.

2. Choose the thermocouple length to allow maximum safe protrusion into the roast chamber. This will provide the most accurate readings. The drum drive motor can be disconnected to allow the insertion or removal of the thermocouple.

3. My view is that 3 mm diameter probes offer the best compromise of smooth output, speed of response and robustness (of the sheath and thermocouple wires). 1/16? thermocouples will work but you should expect less smooth temperature and RoR curves and may have issues with breaking thermocouple wires.

4. Fibreglass insulation provides good thermal insulation to the thermocouple wires but is not ideal to insulate them electrically from any mains connections within the roaster. To ensure a safe installation you should route fibreglass insulated thermocouple leads through suitable silicone sleeving/tubing.

5. The rear wall of the Hottop is too thin to provide a robust threaded connection to the fitting although okmed reports good results so far. The connection may well fail after a time. In this case you would still have the option to fix it with J B Weld.

You have asked if RoastLogger will graph the fan and heater settings. I have deliberately made the decision not to chart this information as I believe it encourages users to think, and attempt to control their roaster, based on elapsed roast time. Elapsed roast time is a poor indicator of roast stage and attempting to control a roast based on this produces poor results. I have covered my views on this in several posts on other coffee forums. In summary, RoastLogger allows you to control the roast by making changes to the heater and fan based on bean temperature. This produces much better control of a roast and more consistent results in the cup. RoastLogger provides a simple set of tables that allow you to script the changes in settings. These changes are applied exactly as scripted in each roast and RoastLogger indicates when each change is applied. Charting this would not provide any additional useful information.


Again, thank you all for all the info.
I was concerned about the "cross-posting" issue though I kinda stumbled into it.
A helpful post above led me to the HB threads, so I asked some questions on those threads on HB. I'm not sure how I should have handled it differently. I guess by commenting on those threads here (though I wasn't sure that those members would respond here).
Sorry if I violated forum etiquette.

This probe thing is way more complicated than I'd imagined. Before I delved, I figured I'd just be buying 2 probes, drilling and installing. Though I'm a good DIYer I'm not an engineer and don't know some of the terms and details and never worked with probes, thermal insulation and the like.

Isn't fiberglass an electrical insulator?

In regards to the other info above:

1) I realize I have to do it myself, measure, etc, but had hoped I could figure out the parts before disassembling otherwise I'll pretty much have to take it apart, figure it all out, put it back together and then order the parts.

3) Oh well. Looks like I have to rethink this all. : )

4) Isn't fiberglass an electrical insulator?

5+) I only wanted the fan and heat indicators as a reference to make it easy to review, see what the roaster was doing and then make changed either to the profile before the next roast or during the next roast on the fly, but I'll see how it all goes when I finally get this mod done.
Barry
 
GreenBean

Quote

BarryR wrote:
4) Isn't fiberglass an electrical insulator?

Yes, fibreglass insulated thermocouple leads use thin layers of woven fibreglass which is adequate for most circumstances but they are susceptible to being ?punctured? by sharp edges. When routing such leads through a roaster containing exposed mains voltage connections you should, for your own safety, ensure that the thermocouple leads can not come into contact with these connections. The easiest way to do this is to route the thermocouple leads through more substantial insulation sleeving.
homepage.ntlworld.com/green_bean/coffee/smilestore/8.gif
Izzo Alex Duetto | Gaggia XD 2 Group | Mazzer Super Jolly | La Cimbali Max | Solis 166 | Hottop P | Hottop B | French Press (several) | Aeropress (collecting dust) | Kettle modded (added digital thermometer)
 
BarryR
Thanks GreenBean and everyone else.
Based on the advice in this post, I'm reconsidering going with larger diameter probes as you suggest. Hopefully, this weekend, I can reach a decision and order everything.

If I do go with wider probes it seems two major options are either the XCIB-K-3-5 that seems to be highly regarded in the various threads
or the HTTC12-K-18U-2-GG (1/8" ungrounded probe).

The XCIB is 6.4mm diameter with an exposed tip, so I imagine this would combine the benefits of ungrounded (not needing grounding) with the rapid response time that the exposed tip provides.

The HTTC 1/8" (ungrounded), would probably be easier to mount (it's narrower) but would not have the above XCIB advantages. It's also cheaper.

1) Do I have this about right?

2) Has anyone mounted the XCIB type without the epoxy? If so, which thermocouple or other method was used.

3) If I use the 1/8th" HTTC type, I can use 1/4" compression fittings, right?
Any down side? Is there room? Would brass be a problem (Stainless seems very expensive for this).

4) I recall on poster epoxying a sleeve but then holding the probe itself in place with basically friction fitting in a silicone (or such) sleeve. Wouldn't this tend to shift?

5) I believe the XCIB is stated to be very durable but for the BT probe, wouldn't the beans constantly banging into the exposed tip put it at risk for breaking?
Barry
 
BarryR
Sorry.
I reread OKMed's post and see he pretty much answered #3 above.
Barry
 
GreenBean

Quote

BarryR wrote:
...The XCIB is 6.4mm diameter with an exposed tip, so I imagine this would combine the benefits of ungrounded (not needing grounding) with the rapid response time that the exposed tip provides.

The XCIB thermocouples have an exposed tip which is insulated from the collar and braiding so they do not require further electrical insulation. The rapid response time due to the exposed tip is a disadvantage for this service. A slower response is desirable to obtain smooth output as discussed in previous posts in this thread.

Quote

BarryR wrote:...Has anyone mounted the XCIB type without the epoxy? If so, which thermocouple or other method was used....

I am not aware of anyone doing this. I think the best and easiest way to fix these thermocouples is to J B Weld them directly to the rear wall.

Quote

BarryR wrote:...I recall on poster epoxying a sleeve but then holding the probe itself in place with basically friction fitting in a silicone (or such) sleeve. Wouldn't this tend to shift?...

Silicone tube can grip the thermocouple tightly If the tube and the fitting are sized correctly to provide a tight fit. If a tight fit is not achieved then the bean probe would certainly shift. The solution used by okmed resolves this by using a nylon ferrule in a compression fitting to compress the silicone tube against the sheath.

Quote

BarryR wrote:...I believe the XCIB is stated to be very durable but for the BT probe, wouldn't the beans constantly banging into the exposed tip put it at risk for breaking?

The XCIB thermocouple uses quite thick wire with a substantial bead at the hot junction. This may not be as robust as a 3mm stainless steel sheath but is sufficiently robust for the service.
homepage.ntlworld.com/green_bean/coffee/smilestore/8.gif
Izzo Alex Duetto | Gaggia XD 2 Group | Mazzer Super Jolly | La Cimbali Max | Solis 166 | Hottop P | Hottop B | French Press (several) | Aeropress (collecting dust) | Kettle modded (added digital thermometer)
 
BarryR
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

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
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
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
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

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
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
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

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
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

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
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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