DIY themowell from 1/4" tube

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clearwaterbrewer

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I have made some 1/4" thermowells from tubing I got from grainger..http://www.grainger.com/Grainger/Tubing-3ADU9

I used a hacksaw to cut 4 angled notches in the tip and bend over into a round shape, TIG shut, and grind/polish smooth.. not happy with the time taken to make them and with the appearance of them..

Anyone use a lathe and some sort of tool to 'spin' or 'turn' them down to a rounded point? Was thinking some small bearings mounted in a MT-2 tailstock for my micro-mark lathe... (similar to a knurling tool) I have lots of ideas, just wanting to see if anyone has put them to practice...

optionally, anyone seen pre-fab tubes that are cheap (less than $5 for 6-12")?

-mike
 
how well do those fit in 1/4" compression fittings, 1/4" is 6.35mm...

edit: I guess it is easy enough to use a 1/4" MFL washer(less than 1/4") and drill out the 1/8"NPT-1/4"flare fitting to just over 5mm...
 
I have made some 1/4" thermowells from tubing I got from grainger..http://www.grainger.com/Grainger/Tubing-3ADU9

I used a hacksaw to cut 4 angled notches in the tip and bend over into a round shape, TIG shut, and grind/polish smooth.. not happy with the time taken to make them and with the appearance of them..

Anyone use a lathe and some sort of tool to 'spin' or 'turn' them down to a rounded point? Was thinking some small bearings mounted in a MT-2 tailstock for my micro-mark lathe... (similar to a knurling tool) I have lots of ideas, just wanting to see if anyone has put them to practice...

optionally, anyone seen pre-fab tubes that are cheap (less than $5 for 6-12")?

-mike
I havent done this yet but my idea was to turn a piece of stainless rod or some such so that there is a short shaft that will fit inside the tube and there will be a step up to match the outer diameter. Do a fusion weld around the seam and clean it up in the lathe and maybe turn a slight point on it.
I like the spinning idea. I am thinking a small bearing mounted in the end of a piece of stock that could be held in a tool holder.
 
I assume you've seen the Brewers Hardware probe ends that many of us use? Wasn't sure what kind of ID dimension you need.

I saw the $14 and up thermowells, but not the temp probe ends... not sure what the difference is... Thank you, $14 was too steep for needing them in quantity...

Those $3.50-6" and $3.75-8" closeouts look good... I ordered 4 each.. I would like to spin them myself in the future, so if anyone comes up with a tool or procedure, let me know..
 
I think the thermowells have a large enough ID to hold the probes or a probe from something like a Johnson controller.

The probe ends are large enough for individual sensors like a one-wire sensor or anything else in that package size.

Darrin's stuff is pretty well made. I've given up trying to make anything he sells already as I know mine wouldn't be as good.

Not sure how you're using these but check out how he does the compression fittings by drilling through them and them using o-rings as a seal. Works out real well when in a mash tun so you can easily back them out of the way while stirring in your grains.
 
When I have to shape something round that is not critical but want it to look good I just chuck it into my cordless drill then grind it to the shape I want by hand. A bullet nose is really easy and can turn out great. You can use sandpaper to smooth it. Then take it to a buffer if you want it shiny.
 
I think the thermowells have a large enough ID to hold the probes or a probe from something like a Johnson controller.

The probe ends are large enough for individual sensors like a one-wire sensor or anything else in that package size.

Darrin's stuff is pretty well made. I've given up trying to make anything he sells already as I know mine wouldn't be as good.

Not sure how you're using these but check out how he does the compression fittings by drilling through them and them using o-rings as a seal. Works out real well when in a mash tun so you can easily back them out of the way while stirring in your grains.

I buy the 10-packs of 2P237 fittings from grainger and drill them for 1/4" in the lathe to get a straight hole:
Male-Connector-2P240_AS01.JPG


then I use a 1/8" long piece of 1/4"ID plastic tubing as the ferrule, but my next order, getting some 2CGH8 PTFE(teflon) ferrules :
Ferrule-2CGJ1_AS01.JPG


I use these EPCOS B57500M0103A005 thermistors for my BCS.. both Newark and Digikey have them for <$3.00

4607328.jpg


and a few of these GE Sensing MA100 thermistors that are about $5 from Newark, but only 2mm in diameter, that fit in meat probes for use in my smoker, as I like to see the brisket temp vs smoker temp graph from the internet ;-)
4580075.jpg


so without tubes, I am at $40 for 10 sensors... if I get the tubes at $4, I am at $8 per sensor, and I know exactly the parameters of the thermistor and can use the same parameter thermistor in several ways, not being tied to what the person who made the sensor used...

here is tubing enough to make 10 probes, average length 7.2" total would be only ~$5/probe :)
Tubing, Welded, 1/4 In, 6 ft, 304 SS
Tubing-3ACR6_AS01.JPG
 
You can use a ball or knob turner on your lathe to get the end perfectly round. They aren't that hard to build.
 
those are for cutting, right? (that is all that I see) here is what I am talking about... just on a larger scale.. all I need is the skill, and the hat... that is one bad hat!

 
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I used a piece of soft copper and plugged the end with a short piece of 00 ground wire. Ground it smooth and haven't had any problems sense.
 
Just now, I tried turning the end shut with a cheapie Harbor Freight bit and running the lathe backwards:
turningtube1.jpg


It chipped the bit, but not really where it is important, and it did make the diameter larger and will have to turn that down.

It seems that motion of the tool across the surface with some pressure works better than a lot of pressure...
I believe a multi-angle approach is needed.. and that is how I got the last little bit... running it in more than across.. I think a small bearing mounted on a tool may do the trick...
turningtube2.jpg
 
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