Scace Thermofilter Temperature Device - Page 7

[AndyS]

At the end of a multi-page discussion of which temperature measurement technique was "more accurate," Greg Scace wrote this:

Time to jump in on this business of which measurement is more accurate or whatever. Let's be clear on what we are measuring when we do the surface thermocouple on top of the cake (ST) or the thermofilter thing (TF).

In ST, you are measuring the temperature of water and coffee on top of the coffee cake. The cake starts cool, and warms up as water percolates through it. The percolation rate is approx 30ml / 25 seconds and the pressure is 9 bars.

With TF you are measuring the water temperature in a warmed, insulated environment as it leaves the dispersion screen. The cake facsimile is preheated. the flow rate in TF is identical to that of ST as is the pressure.


Which is more accurate? The answer is that they are both accurate and if you're using the same measuring equipment, let's say uncalibrated type T wire and the same readout device between the two, then they are equally as accurate, but the measurements are of slightly different things.

And Chris Tacy recently wrote this on his blog:

For example - using the old school methods (pioneered by Schomer et al) for measuring brew temp I had the idea that the Hairbender was best at around 199 or 200 F. Using the Scace [thermofilter thingie], I've determined that the optimal brew temp is more like 197 or 198 F. This is a big difference.

Chris, given the evidence presented in this thread, I think it would be more accurate to state something like: "On machine 'X,' I get the best results with Hairbender when I set it to brew at 197-198F as measured by the Scace Device."

IOW, I interpret the thread to conclude that it's a matter of interpretation whether the espresso is "actually brewing" at 197-198F or "actually brewing" at 199-200F. But it IS important to state how you arrived at the temp measurement. The point of the Scace Device is that someone across the globe can reliably reproduce your measurement. If you're simply sticking a thermocouple into the basket, reproducibility is much dicier.

[miKe mcKoffee]

Yippie I invited a fellow home roaster and recent Silvia owner who lives nearby over to check out the Silvia gasket mod. (I also had a gasket on hand to do his but he didn't have time today, wife duties to attend to, something about a 2 year late 10th anniversary diamond upgrade, which has become highly necessary now do to his recent various coffee related purchases this year like Z&D roaster, HotTop roaster , RK-Drum roaster, I-RoastII roaster, a SECOND Rocky, Silvia and PID mod...) I ordered a PF gauge and thought about ordering Greg's PF temp device, but opted to pass for now. While playing with my Silvia tweaking the pressure via sanding the gasket Greg tells me he ordered one yesterday after reading about my recent styro cup measurements and obvious limitations! (not Greg Scace, Greg who lives a few blocks away) Cool, will have ready access for real temp measurements. Oh, and it's gonna have to be a big diamond upgrade for Trisha 'cuz he's jazzed about the GS3!

[MOSFET]

I haven't read the complete thread. I ask this seriously. Are the materials used in this device all food-grade? My thought would be if there were any chance of trace amounts of cyanoacrylate or other toxic chemicals contacting the machine. Don't want to scare but it's a valid question.

Keith

[miKe mcKoffee]

I haven't read the complete thread. I ask this seriously. Are the materials used in this device all food-grade? My thought would be if there were any chance of trace amounts of cyanoacrylate or other toxic chemicals contacting the machine. Don't want to scare but it's a valid question.

Keith

Interesting question. Suppose to be on the safe side wouldn't hurt to do a cleaning backflush after a temp measurement session.

[malachi]

I haven't read the complete thread. I ask this seriously. Are the materials used in this device all food-grade? My thought would be if there were any chance of trace amounts of cyanoacrylate or other toxic chemicals contacting the machine. Don't want to scare but it's a valid question.

Keith

Have you evaluated the water coming through your portafilters for heavy metals?

[AndyS]

OK, everyone who's used a Scace Device has been very enthusiastic. It makes temperature measurement so much easier and repeatable.

I recently got one, but I noticed some weird things happening. I think I know what the problem was.

If you look at this image you'll see the tip of the thermocouple sheath in the area of the red arrow. The tip is where the temperature is actually sensed. You'll also notice that the sheath runs parallel to the rim of the basket. That is good.

When I originally received The Device, the sheath was bent down slightly. The sensing tip was about a millimeter or so lower, just about touching the plastic. I believe that silly millimeter made a big difference. It meant that the probe had more of a tendency to report a composite temperature, part hot incoming water and part slightly cooler water that was running along the surface of the plastic. This made the readings artificially low, and it meant the readings were highly sensitive to how warm the plastic was before starting the shot.

I carefully bent the sheath back up so that it was parallel to the basket rim (the photo shows The Device after corrective rebending). My temp readings went up, and they became much less sensitive to the temp of the plastic before commencing the extraction.

I talked about this with Greg on the phone and he agreed that the sheath should be horizontal, not tipped downwards. [EDIT: I don't believe he said it had to be PERFECTLY horizontal, just that it shouldn't obviously tip downwards and shouldn't tip up too much or it might not have sufficient clearance from the shower screen. Hopefully Greg will comment.]

So check your sheaths, everyone.

[HB]

So check your sheaths, everyone.

Thanks for the heads up. The instructions warn about handling:

The Thermofilter is also a precision measuring instrument that is easily damaged by careless handling, and storage. Examples of careless handling and storage include dropping it, bending the thermometer probe, storing an unprotected thermofilter in a toolbox or drawer with a bunch of mean and nasty hammers and wrenches that could hurt it.

Greg may want to add a few words specifically about recognizing the proper position / angle of the sensor. I just looked at mine and it's not easy to judge if the sensor is perfectly parallel because of the viewing angle.

[miKe mcKoffee]

The Thermofilter is also a precision measuring instrument that is easily damaged by careless handling, and storage. Examples of careless handling and storage include dropping it, bending the thermometer probe, storing an unprotected thermofilter in a toolbox or drawer with a bunch of mean and nasty hammers and wrenches that could hurt it.

A tool like this costing as much as it does and requiring another tool costing almost as much to even use it ought to come in a protective case. Being sold bare as it is now is cheap & cheesy IMO.

[barry]

A tool like this costing as much as it does and requiring another tool costing almost as much to even use it ought to come in a protective case. Being sold bare as it is now is cheap & cheesy IMO.

first run of a new product. lots to learn. i know greg was trying to keep the price down and yet still make it worth his time and effort. if you want to add $50 for a case, maybe it should be an option.

[miKe mcKoffee]

first run of a new product. lots to learn. i know greg was trying to keep the price down and yet still make it worth his time and effort. if you want to add $50 for a case, maybe it should be an option.

True, and easy enough to -pick up a $15-$20 padded camcorder case that'll work just fine.

BTW, has the correct diameter/gauge wire been determined for cleaning the brass regulator to return it to 2oz flow. I've tried to clean it without poking something true the tiny hole, and still can now only test about ristretto flow volume... Seems a cleaner needs to come with it in the future.

[barry]

BTW, has the correct diameter/gauge wire been determined for cleaning the brass regulator to return it to 2oz flow. I've tried to clean it without poking something true the tiny hole, and still can now only test about ristretto flow volume... Seems a cleaner needs to come with it in the future.

any tool such as that will destroy the calibration of the hole. it's really really tiny*. if you're having flow problems, check with greg as he's keeping track of these things.

also, iirc, target flow is 75ml in 30secs.



--barry

*a few years back i calculated the diameter needed to restrict flow and was just astonished at how small it was. this creates problems in both construction and use of any such device (my original was a wee tiny hole in a blind filter basket), as any little thing can plug it up. it also brought up an interesting issue: if the equivalent flow requires a hole that small, then the cumulative cross-sectional area of the pores in a coffee puck needs to be similarly small. that juice gets squeezed through some tiny spaces!

[miKe mcKoffee]

any tool such as that will destroy the calibration of the hole. it's really really tiny*. if you're having flow problems, check with greg as he's keeping track of these things.

also, iirc, target flow is 75ml in 30secs.50



--barry

*a few years back i calculated the diameter needed to restrict flow and was just astonished at how small it was. this creates problems in both construction and use of any such device (my original was a wee tiny hole in a blind filter basket), as any little thing can plug it up. it also brought up an interesting issue: if the equivalent flow requires a hole that small, then the cumulative cross-sectional area of the pores in a coffee puck needs to be similarly small. that juice gets squeezed through some tiny spaces!

I wouldn't have attempted running anything through that tiny hole without checking here first, rest assured!

WBC procedure calls for flow of 75ml 25sec +-5sec.

I think my volume problem was/is two fold. First very small, too small to be seen, blockage and incorrect opv pressure.

I pulled three 25sec pouring each into Pyrex measuring cup. Total 75ml for THREE 25sec pulls! Ok, again removed brass fitting, flush and lightly tapped up side down. Didn't see anything come out other than water. Reinstalled flow fitting (with new teflon tape) and pulled 3 more 25sec. This time 150ml total. Better. Next pulled 3 30sec for 200ml total, very close to spec.

Looks like routinely need to take off brass fitting and flush tap out. (Yes, I maintain a regular, anal even, cleaning regimen with Silvia!)

Remaining problem now likely I have Silvia opv set dead on 9bar no flow. Recent reading leads me to believe I should have the no flow pressure .5 to a full bar higher (no flow setting .5 to 1bar higher than when pulling shot) Haven't gone back inside to remove and file the second gasket some more, figured I'd do it same time doing the rope heater mod.

[barry]

Remaining problem now likely I have Silvia opv set dead on 9bar no flow. Recent reading leads me to believe I should have the no flow pressure .5 to a full bar higher (no flow setting .5 to 1bar higher than when pulling shot) Haven't gone back inside to remove and file the second gasket some more, figured I'd do it same time doing the rope heater mod.

if you're using this with a vibe pump, then yes, your flow rate will be dependent upon things other than the scace device.

[miKe mcKoffee]

if you're using this with a vibe pump, then yes, your flow rate will be dependent upon things other than the scace device.

Yes, I'm not Andy, my Silvia still has a vibe pump! And since I've gotten a deal on a Bric' she'll likely never know the joys of rotary...

[gscace]

Greg may want to add a few words specifically about recognizing the proper position / angle of the sensor. I just looked at mine and it's not easy to judge if the sensor is perfectly parallel because of the viewing angle.

It shouldn't be sensitive to angle, but I would expect the wrong answer if it contacts the plastic insert.

-Greg

[gscace]

I wouldn't have attempted running anything through that tiny hole without checking here first, rest assured!

WBC procedure calls for flow of 75ml 25sec +-5sec.

I think my volume problem was/is two fold. First very small, too small to be seen, blockage and incorrect opv pressure.

I pulled three 25sec pouring each into Pyrex measuring cup. Total 75ml for THREE 25sec pulls! Ok, again removed brass fitting, flush and lightly tapped up side down. Didn't see anything come out other than water. Reinstalled flow fitting (with new teflon tape) and pulled 3 more 25sec. This time 150ml total. Better. Next pulled 3 30sec for 200ml total, very close to spec.

Looks like routinely need to take off brass fitting and flush tap out. (Yes, I maintain a regular, anal even, cleaning regimen with Silvia!)

Remaining problem now likely I have Silvia opv set dead on 9bar no flow. Recent reading leads me to believe I should have the no flow pressure .5 to a full bar higher (no flow setting .5 to 1bar higher than when pulling shot) Haven't gone back inside to remove and file the second gasket some more, figured I'd do it same time doing the rope heater mod.

Mike:

There have been a couple of thermometers that have had flow issues. In Bob Yellin's case, and in yours too I reckon, errant teflon tape used to seal up the connection between the orifice and the filter was the culprit. Disassemble the cap from the filter, remove the teflon tape from the threads, clean / flush out everything really well, and reassemble. You can use teflon tape for the reassembly, but I've started using Loctite 222 as a sealant. Loctite 222 seems to be a good solution because it solves the problem of stray teflon bits and the joints can be easily disassembled. Loctite 242 is a stronger version that can be used as well. Do not use red (271) or green (292). Neither of these can be disassembled without lots of heat.

The filter will filter out things down to 0.003 inches in diameter. That's good enough to prevent clogging of the orifice, so you shouldn't have any more trouble once you have it straightened out. Filter life (how long until the bronze gets clogged up) is gonna be related to how clean you are when you use the thermometer. Use it on a clean machine.

WRT a zoomy case - so far I've been making them in batches of 25 at a time. It's pretty much a cottage industry at the smallest of scales. If people want to pay an extra $50.00 for a case, well I'll go about supplying them. I'll have to see.

If you don't feel comfortable disassembling the thermometer, you can send it to me and I'll sort it out for you. Lemme know.

-Greg

[skyryders90]

There have been a couple of thermometers that have had flow issues. In Bob Yellin's case, and in yours too I reckon, errant teflon tape used to seal up the connection between the orifice and the filter was the culprit. Disassemble the cap from the filter, remove the teflon tape from the threads, clean / flush out everything really well, and reassemble. You can use teflon tape for the reassembly, but I've started using Loctite 222 as a sealant. Loctite 222 seems to be a good solution because it solves the problem of stray teflon bits and the joints can be easily disassembled. Loctite 242 is a stronger version that can be used as well. Do not use red (271) or green (292). Neither of these can be disassembled without lots of heat.

Greg -

I got a thermofilter recently, and after ~1 day of use the flow rate has dropped all the way down to roughly .5 oz in 30 seconds, and the flow comes out of the hole at a tilted angle. This is one the thermofilters that did not use teflon tape. Any ideas on what might clog it? If I disassemble it, do I have to somehow clean off all the loctite before I can use teflon tape to seal it (I don't have any loctite)?

Any thought/advice would be appreciated.

Thanks!!

-Steve

[gscace]

Steve:

Sounds like an orifice what needs cleaning out and sounds like I didn't get the downstream side of the filter sufficiently cleaned. I can clean it and send it back to you, or I can tell you how to do it. Your call. Email me at gscace@earthlink.net, or phone me at two four zero two five two zero two four two and I'll fix you up one way or the other.

-Greg

Greg -

I got a thermofilter recently, and after ~1 day of use the flow rate has dropped all the way down to roughly .5 oz in 30 seconds, and the flow comes out of the hole at a tilted angle. This is one the thermofilters that did not use teflon tape. Any ideas on what might clog it? If I disassemble it, do I have to somehow clean off all the loctite before I can use teflon tape to seal it (I don't have any loctite)?

Any thought/advice would be appreciated.

Thanks!!

-Steve

[gscace]

Mike:

There have been a couple of thermometers that have had flow issues. In Bob Yellin's case, and in yours too I reckon, errant teflon tape used to seal up the connection between the orifice and the filter was the culprit. Disassemble the cap from the filter, remove the teflon tape from the threads, clean / flush out everything really well, and reassemble. You can use teflon tape for the reassembly, but I've started using Loctite 222 as a sealant. Loctite 222 seems to be a good solution because it solves the problem of stray teflon bits and the joints can be easily disassembled. Loctite 242 is a stronger version that can be used as well. Do not use red (271) or green (292). Neither of these can be disassembled without lots of heat.

The filter will filter out things down to 0.003 inches in diameter. That's good enough to prevent clogging of the orifice, so you shouldn't have any more trouble once you have it straightened out. Filter life (how long until the bronze gets clogged up) is gonna be related to how clean you are when you use the thermometer. Use it on a clean machine.

WRT a zoomy case - so far I've been making them in batches of 25 at a time. It's pretty much a cottage industry at the smallest of scales. If people want to pay an extra $50.00 for a case, well I'll go about supplying them. I'll have to see.

If you don't feel comfortable disassembling the thermometer, you can send it to me and I'll sort it out for you. Lemme know.

-Greg

Hi:

I must add to these instructions a caution that one must use teflon tape or a teflon pipe dope that is compatible with plastics service (NOT PVC GLUE EITHER) when reassembling the orifice / filter assembly to the plastic insert. Loctite is not compatible with plastics and doesn't seal like it's supposed to. The consequence is that the reassembled thermofilter will leak from the plastic insert connection and you'll have to scrape hardened loctite from the threads on the orifice / filter and remake the connection correctly.

To be very clear - Loctite 222 or 242 to make the connection between the filter and the orifice. Teflon tape for making the connection to the plastic insert.

-Greg

[Abe Carmeli]

IMO, even if not exactly the same, the results are still representative (there has been a discussion about that here on HB). And, I'd expect rather more variability with coffee than with the GC device.
Wolfgang

I wish that were true, it would have made life easier for all of us. But in my experience, the intrashot result as measured with the Scace is sharply different than when measured with a T/C in the coffee puck a-la Schomer or by snaking the T/C over the lip. Scace will show a much wider temp variance than the coffee method. The coffee itself attenuates the reading. As an example, a stock home machine will show a 5f intrashot with Scace, while with coffee, it will show around 2-3f.