Pid controller

[Hammerfall]

So if I buy a pid controller( part syl-2342 I saw Stacys sticky), and a ceramic hi temp thermocouple, what else do I need? I'm not exactly sure what powers it, or if it needs a heatsink.  I know I need to drill a hole in my forge and place the probe out of the path of the flame, then line the hole with In my case mizzou. How deep does one want the probe? Any help would be fantastic.

make sharp things

[Hammerfall]

My main question is do I need a heat sink and is a 10a relay enough. Also how deep to put the probe.

Here is my parts list. Does this look good?

 

[Hammerfall]

Last question. Can the switch be used to turn the pid on and off. I'm an electrical dummy.

[WayneCoeArtistBlacksmith]

Some PIDs are battery operated and some plug in.  I mounted mine in a gray electrical duplex box with a solid top, I cut a hole in one side for the PID to mount in.

This is my information on pyrometers:

How I got my Pyrometer.  September 15, 2015 by Wayne Coe

 

I have had a number of people ask me about how to get a Pyrometer like mine so I decided to write up this little sheet.

 

I have the PID that you can find at this URL. 

http://www.lightobject.com/JLD7100-PID-Temperature-Controller-P44.aspx

There are a number of other companies that sell this PID and there are other PIDs also.

Last year I paid $28.42 including shipping but now I see that it is $28.95 plus shipping.

With this PID you must also supply your own power cord so there is another expense, unless you can source a power cord from an old extension cord or something similar.

 

For the Thermocouple you can use this URL.  http://www.omega.com/pptst/TJ36CAXL_NNXL.html

These come in 12” and 18” probes.  For a 12” probe you can  order a TJ36-CAXL-14U-12.  I just priced that out and it came to $44.00 plus shipping.  Remember that the reading comes from the very end of the probe only.  The tip of your probe needs to be in the area that you are measuring the temperature.  In the case of a Ribbon Burner that would be in the center of the burner.  I have mine lying on the floor of the forge. 

 

I mounted my PID in a double outlet box and used the plastic outdoor type box which is gray and is waterproof and dust proof if you use a cable gland for the connections.  I ran both cords out through the one cable gland.  Keep in mind that the probe is somewhat fragile when hot.  You need do devise a method of securing the probe in the forge and the PID so that they don’t fall or otherwise get moved around while you are working.  I drilled a hole in a fire brick to extend the probe through and mounted the box to my forge stand.

 

Good luck and Let me know how I can help you.

Wayne

 

[Latticino]

The PID controller (Proportional, Integral, Derivative feedback loops from the differential between measured temperatures and setpoint) appears to have more capability than you need if you are only looking for a pyrometer type readout for forge interior temperature.  The PID controller will also give you outputs that can control things like Solid State relays, contactors, SCR and the like to modulate, or turn on and off, a power source for heating the chamber the sensor is measuring.  If you only want a readout a digital temperature indicator will be enough (though if the controller is cheaper or more available it will certainly also give a readout).

One thing to be cautious about is that the normal type K thermocouple is not really rated for the above 2300 deg. F and potentially caustic (if using flux) environment of a typical forge.  You really should use a type R or S, but they are prohibitively expensive.  If you must use a type K, I recommend getting the thickest thermocouple you can reasonably afford and using a ceramic sheath (like you have listed).  You will also need type K thermocouple wire to go between the probe and controller/meter.  If you use normal wire you will throw off the reading.  Be careful to follow the instructions regarding the thermocouple wire as the two wire materials inside the shield are different and need to be hooked to the correct terminals on the thermocouple.

Not really enough information to evaluate whether the switch will suffice to turn on your controller, but I would have to say it is likely that it will work fine.

[timgunn1962]

As Latticino says, the PID controller is a controller. You don't specify what it is that you wish to control, so it seems likely that you are just using it as a pyrometer (temperature display)?

It's not a problem to do this, but you may need to trawl through a lot of setup parameters to make it do what you want.

If it is "just" a temperature readout you want, an ebay search for "DM6801A" will bring up a handheld type K pyrometer that gives very few opportunities to get things wrong and costs under ten bucks delivered (though you'll also need a 9V battery). It takes a type K input and reads temperature in either DegC or DegF (there's a button to toggle between them).

If you really want a permanent thermocouple, the 8-gauge one with ceramic sheath is a pretty good option for the reasons Latticino mentions. It is worth noting that type K thermocouples are particularly prone to "drift" when used at temperatures above about 1000 degC (1832 degF) and it would be a mistake to assume that a permanently-installed Type K will remain accurate for very long at typical forging or welding forge temperatures. Things are not nearly so bad at typical Heat-Treating temperatures

The SYL2342 controller has relay outputs. If you are looking to control the temperature of a forge using a HI-Lo burner arrangement, it would be a good choice. The Hi stage solenoid valve would be powered through the output relay.

It will not directly trigger an SSR though. For use with an SSR, you'd want the SYL2352 instead, which has a 12VDC pulse output intended to drive an SSR.

SSRs are usually used where short cycle times are required and tend to be better suited to electric heating than to gas-fired systems.

If you are not controlling anything, you will not need the SSR.

The learning curve for controllers tends to be steep and mistakes can get expensive. I've been lucky enough to make most of my mistakes at my employers expense.

My personal preference for forges is for a long hand-held thermocouple which can be inserted while the forge is adjusted and then removed while the forge is in use. 

This allows the temperature to be measured at different places in the forge. Unless specifically designed to provide a very even temperature throughout, most forges have quite large temperature variations throughout the chamber. Color can be a good indicator of the even-ness, or otherwise, of chamber temperature but it's nice to be able to put numbers to it.

Examples of forges designed for even heating are dedicated Heat-Treating forges and vertical welding forges intended for welding billets of pattern-welded steel. Both of these examples are fairly specific to bladesmithing, though there may be other applications I am unaware of. 

Given that we are in the HT sub-forum, it seems fair to assume that the OP is either intending to run a forge designed for Heat Treating or is intending to use a general-purpose forge for HT.

In my experience, once the burner is adjusted there tends to be little temperature change at any given location unless a further burner adjustment is made so I usually take the thermocouple out when forging but keep it in when Heat-Treating.

My preferred thermocouple is an Omega KHXL-14U-RSC-24. This is a 1/4" diameter Mineral-Insulated handheld thermocouple assembly, 24" long below the handle, with a culy cable terminating in a miniature plug which fits almost all type K pyrometers (including the DM6801A and TM902C). The junction is Ungrounded and the sheath material is Omega's proprietary "Super Omegaclad XL", rated for use to 1335 degC, 2440 degF.

The upper end of the range is good for checking that forge temperatures are adequate for welding high-Carbon steels.

TBH, most of the time I actually use otherwise similar thermocouple assemblies with type 310 stainless steel sheaths because I can buy these much cheaper from the supplier we use at work with no shipping costs. They don't last nearly as well at the higher temperatures though. 

Apart from the drift issue, the main reason I don't like permanently-installed thermocouples in forges is that they are fragile and, to give useful information, need to be positioned where the workpiece will be positioned. This makes breakage pretty much inevitable for someone of my limited skill. 

Omega have a lot of information on their site about temperature measurement and control and it's worth a look. A good starting point is http://www.omega.co.uk/prodinfo/thermocouples.html

I used to carry a printed copy of the Labfacility Temperature Control Handbook back when the world was young. Everything you could want to know about temperature control in one slim volume. The .PDF can be found at  http://www.controlsdrivesautomation.com/orgfiles/ZORGF000011/IPE/Enhanced companies/labfacility/Temperature Handbook.pdf

 

I use the DM6801A pyrometers myself now, having previously used TM902Cs, also from ebay. The TM902C only reads in DegC so there's even less chance of operator error and I tend to think in degC so don't miss the degF reading. I was quite happy with them intil last year when I had a batch of ten of the TM902C handheld pyrometers that were fine up to 800 degC (1472 degF), but had increasing errors once above that temperature.

They didn't look quite like the 30 or so "good" TM902Cs I'd had previously, but the visual difference was not enough to show in an ebay photo and I decided it was safest to use something else. I have access to a calibrator at work and always check any personal instruments with it. That's how I found the bad ones.

All the earlier ("good") TM902C units were as accurate as big-name units costing much more and the half-dozen or so DM6801A units I've tested so far have been similarly accurate.

 

 

[Hammerfall]

Thank you Tim.