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Kim S

Temperature controller for heat treat oven

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Hi!

I will soon start to build an heat treat oven and I need some advice on what temperature controller to use. 

I have looked on this one https://www.ebay.com/itm/Professional-Ramp-Soak-Temperature-Controller-Kiln-SSR-Kit-Ceramic-Thermocouple/121092751234 Seems to have some of the features I want, but is it any good ? I don't really want to pay hundreds of dollars, but I don't want to buy a crappy one either. So, what do you say ?

 

I am from Sweden, so if there are some spelling errors, that's why =) 

 

//Kim

 

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First question: what do you want to HT?

If you are absolutely sure you are going to need Ramp/Soak, go for a Ramp/Soak controller. If you are unsure at this stage, go for a basic controller. You'll have a pretty steep learning curve ahead of you (unless you are already familiar with PID controllers. This seems unlikely because you are asking the question). 

NEVER buy a controller until you have downloaded the manual from a non-password-protected site, read it thoroughly and understood at least most of it. 

The reasoning is this: you have a steep learning curve ahead of you. If you need to ask for help on this, or another, forum, there are likely to be some folk with enough experience and knowledge of Process Control, and Controllers generally, to help you. However, they are unlikely to be intimately familiar with your specific controller. Being able to provide a link to the manual gives them a reasonable chance of being able to provide specific assistance. 

Some manufacturers put access to their manuals behind a login/signup page. I tend to give up at that point. 

Manuals are difficult and expensive things to write. A manual translated from Chinese into English by an online translation program is not likely to be very helpful. Pretty much the entire value of a controller lies in it being able to control your process. If the manual is not adequate to allow you to set it up to achieve this, the controller is worthless.

Industrial controllers, particularly the ones with higher-end capabilities like ramp/soak, are intended for use by Process Engineers: people who understand both their process and controllers in general. Programming ramp/soak profiles is usually a pain in the neck. The ramp/soak programming is usually set at the same access level as the input type, P,I & D parameters, etc. They are not like the kiln controllers found on the big-name kilns, which are designed to be programmed by an end-user with no real interest in the finer details of process control. These have different access levels for the commissioning technician and the end-user, limiting the amount of damage that can be caused by an incorrect button press.

Ideally, you want a controller with the capability to do what you need it to do, with a good manual, written by someone who writes manuals for a living, in your own language (though if Swedish is your mother tongue, your English certainly seems good enough that you could cope happily with a manual in English). Then you want "real" technical support in a time zone you can live with, also in a language you can communicate in. For me, it needs to be telephone support (ageing Luddite and one-finger typist) but YMMV.

I seem to vaguely recall a few HT oven builds using the linked controller on different forums. If the manual is ok and available online, it might be a good choice.

Alternatives, if you are set on ramp/soak, are the Auber Instruments SYL 2352P, which I have not used myself, but which seems to be highly regarded Stateside. Support is reportedly very good.

My personal favourite is the Automation Direct Solo SL4848VR or the Omega CN7823. These are, as far as I can tell, the same controller with different badges and I buy whichever is cheapest at the time. I have used them on all but the first HT oven I built (7 out of 8 so far). Support from both suppliers is superb.

Omega are  about the biggest name in temperature control worldwide and their technical sales people are extremely knowledgable (and patient, IME): well worth a phone call if you are unsure about thermocouples, etc. 

If you can live without ramp/soak for the forseeable future, a simpler controller really could be a good plan. If you go for a 48mm x 48mm (1/16 DIN) controller format and leave enough length on the wires to reach a different terminal layout, upgrading to a ramp/soak controller later is simple.

 

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Thanks for that thorough reply, much appreciated.


So far I have only made knifes out of simpler steels that doesn't require any complicated heat treat, but I would like to try some new steels that does. So a ramp/soak controller is what I'm after. But they do seem to be a bit complicated to program, so I understand why a good manual is important.

That Auber Instruments SYL 2352P seems interesting, and not to pricey. So my plan for now is

Auber Instruments SYL 2352P https://www.auberins.com/index.php?main_page=product_info&products_id=4:e9e67f295f070e5dd57a29ee9ced26cf 

Thermocouple (spade connector) https://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=22

25A AC SSR https://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=9

Heat sink https://www.auberins.com/index.php?main_page=product_info&cPath=2_48&products_id=244 

3000W heating element https://www.ebay.com/itm/3000W-Pottery-Kilns-Furnaces-Casting-Heating-Element-Coil-Wire-Heavy-Duty-Silver/253703765503?epid=3016423176&hash=item3b11ec3dff%3Ag%3AHKYAAOSwZKRbLGcd&LH_PrefLoc=4&_sacat=0&_nkw=kiln+element&_from=R40&rt=nc&LH_TitleDesc=0|0

 

thoughts ? Is there anything else I should order while am at it ?

 

//Kim

 


 

 

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The Auber stuff should be OK.

I'd forget the element you linked to entirely. It is waaay too thin to last.

I built my first 5 ovens using 16AWG (1.29mm diameter) elements wound from Kanthal A1. These were ok-ish: fine for occassional hobby use, but a couple of the guys who use them to put food on the table had element failures. I then went up to 1.6mm diameter Kanthal A1 and they seem to be lasting better. 

I got some of the Far-Eastern elements off ebay, just because they were so cheap that I had to check them out. They really are very thin indeed. They also appear to be continuously-wound and then cut from a roll. To get connection tails, you'd need to unwind some of the coil and twist it to make the tails. I've just dug one out and measured it at about 0.65mm diameter wire. 

My advice is to go no thinner than 16AWG, thicker if possible, and to use Kanthal A1 or equivalent. The price will, of course, be considerably higher than that of the thin ones on ebay. 

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