Help buying a Controller

[MollyFrey]

I have a Paragon kiln and I'm looking to buy a controller. I've been in contact with Paragon but the controller they suggested is over $900, I was hoping for something around $600.

My kiln does have an unique plug, it's a 4 pronged plug, Volts 120/240/3W, Amps 25.9, Phase 1, Watts 6226. The outlet in my wall is 50 amps. The person at Paragon says I need a 50amp controller, but if the kiln is only 25.9, wouldn't a 30 amp controller work? Since my wall has a 50 amp outlet, is that why I should have a 50amp controller?

Thanks for any information

Molly

[Marty]

Digitry.com.
Get a GB1- It may seem like overkill at first but as you ask more from the controller you'll appreciate its features. Elapsed time entry, storage of up to 10 schedules with 14 steps each, ability to link programs for long complicated schedules, alarm capabilities etc. You'll take it from this kiln to your next ones and you'll never outgrow it. No preset nonsense, no 3 key misery.
Not cheap but well worth it.

[Bert Weiss]

You should size your relays and wires to be at least 20% over their rated amperage. So, if you divide 25.9 by .8, you get 32.375. So, you could use a circuit rated for 35 amps. 30 is too small, and most devices jump from 30 to 50.

First of all, I agree with Marty, no argument there.

If you want a lesser controller that is sufficient, you can make your own stand alone controller by buying a Bartlett RTC 1000 board from Bartlett Instruments. You have to add a power supply and put it in a box. I recommend using a solid state relay mounted on an aluminum heat sink and mounted on a plywood board on the wall, away from your kiln. You will need a long enough thermocouple wire to get over to the kiln. You have to be in the do it yourself mode and be able to do things like cut a hole in the middle of a box cover.

[MollyFrey]

Thanks for the suggestions. I'm getting the GB1 from Digitry, saving me $200.

[tob]

Not sure if you've received the Digitry and realized it yet, but you're still going to need a power relay of some type (mercury, electro-mechanicl, or SSR/SCR) to use it with your kiln. The controller Paragon quoted you on has an integral power controller, usually an electro-mechanical relay. The GB1 does not. It merely sends a signal to a separate power control to tell it when to turn on/off.

Just thought I would mention that since it seems that it may not have been clear. It's really no big deal, but unless you already have a power control of some kind, you will also need some additional hardware.

The Other Brad

[David Jenkins]

The Digitry GB-1 manual states, "Some people are used to being forced to describe temperature profiles in terms ramps up and down, expressed as degrees per minute, and in terms of timed soaks. The GB1 relieves you of the calculations required to specify profiles in this arcane manner."

This seems counter-intuitive to me - the schedules I bump into are almost universally given in terms of a temperature target and a ramp rate. It seems that the GB-1 forces me to do a computation, rather than relieving me of the need to do so.

Or am I misinterpreting their programming instructions? [Full disclosure: I really only skimmed the material...]

[Kevin Midgley]

I had the choice when I set up my studio of saving some money and going cheaper or going with Digitry. Worth every penny.
When people claim a ramp rate in a kiln schedule, that assumes your kiln can heat and cool at those rates

You are much better off with a controller like Digitry which will do the automatic holds and adjustments to get to where you want to be time and temperature wise.
With a battery backup unit, the power can go out for a period of time mid firing and it will automatically continue if possible and if not, put you in a holding pattern.
Glass is expensive. A Digitry isn't.

[MollyFrey]

What is a power relay? I have two boxes, one is the digital controller and the other is a box that the kiln plugs into, then the box gets plugged into the wall, which provides power to the kiln.

[Bert Weiss]

What is a power relay? I have two boxes, one is the digital controller and the other is a box that the kiln plugs into, then the box gets plugged into the wall, which provides power to the kiln.

The controller sends a signal to the relay telling it to turn on or off. This is how the controller makes the temperature match the program. The relay is probably in the box with the plug outlet. The relay is wired to the controller, on it's control circuit. The power is wired to the relay and to the kiln elements. The relay is an automatic switch that turns on and off.

[tob]

I had the choice when I set up my studio of saving some money and going cheaper or going with Digitry. Worth every penny.
When people claim a ramp rate in a kiln schedule, that assumes your kiln can heat and cool at those rates

You are much better off with a controller like Digitry which will do the automatic holds and adjustments to get to where you want to be time and temperature wise.
With a battery backup unit, the power can go out for a period of time mid firing and it will automatically continue if possible and if not, put you in a holding pattern.
Glass is expensive. A Digitry isn't.

************

Aside from what sounds like a weird way to program a ramp/soak profile, this describes pretty much any decent temperature controller. These features certainly aren't exclusive to the GB1. What you're describing by "automatic holds and adjustments to get to where you want to be time and temperature wise", sounds suspiciously like guaranteed soak capability (sometimes called "holdback"), which virtually any ramp/soak controller anywhere near that price range has. The same with intelligent power failure recovery. A $70 no-name Chinese ramp/soak controller on eBay might not have these features, but most decent temperature controllers from reputable companies do. I'm not saying the GB1 isn't a decent run of the mill controller. That's exactly what it is. So are a number of other controllers, many with better features (like universal thermocouple input, instead of just two types). A Digitry does have the advantage of being easier to program than most, due to the lack of user programmable options. That may sound like a back-handed snipe at it, and maybe it is a little bit, but ease of use is very helpful for a lot of people.

Regardless, here's my current personal favorite controller, the EasyBake 3000. It stores up to 31 R/S profiles with an overall total of up to 126 segments between them. (So you could have two profiles of 63 segments each, or 10 profiles with 12 segments, plus one with 6 segments, or one with 4 segments and another with 122. As long as the profile total is 31 or less and the total segments used are 126 or less, you can set up any the profiles any way you want.) In the event of a power failure, it has three programmable recovery options when the power returns - abort the program and automatically restart it from the beginning (usually a bad idea), continue the program from where it was interrupted, or hold the existing temperature and wait for the user to intervene. Has an alarm output too. It's at least as capable as a GB1 and cost me less than $5 at my local Goodwill thrift store. (Okay, to be fair, that was only for the oven itself. The controller I mounted in it retails for about $300.) Not to mention it is waaaaay cooler than a GB1 - or virtually anything else. And it makes delicious cookies too...

(FYI for any potential skeptics - both the specs above and the photo below are real. Aside from some minor exposure compensation and cropping, no Photoshopping was involved in the making of this EasyBake 3000 controller.)



TOB