Replaced thermocouple

[S.TImmerman]

Hello,

I had a drop of glass land on it and replaced it. its just a small hotstart pro by skutt. The first 2 times the glass balled up (frit in a mold) at 1350/10 so i know its going way too hot. It was so easy to replace and im wondering if i did it wrong. I ordered it from skutt so i know its the right one. I have some small pieces to do and i hate using my larger kiln. Once i do some test firing is there a way to calibrate it? could it be installed wrong? If the two prongs are in the opposite holes they should would it make it fire VERY hot? I'm thinking it was close to 1600 to boil into the mold.
I should add, it does follow a schedule and come down - it just fuses too hot.
thank you

Sheree

[Bert Weiss]

The leads are color coded. wire them up the same way they were. There should be a note on the controller for which goes where. Any Type K thermocouple should work. However all thermocouples are not created equal. If you can see the weld at the tip, you have a cheap, short life model. My personal recommendation is an inconel sheathed 1/8" diameter. I have been using a set of these, for over 20 years. I have noticed recently that I am not getting as much heatwork as I used to, considering the temperature I programmed. It is time to replace them. No big deal though. They are still working for me. I recommend buying from Krumor in Ohio. They are a primary manufacturer and will sell to you directly. Google them.

[S.TImmerman]

Thank you Bert,

I had called Skutt and told them what kiln I had- It was relatively cheap 16.00 with shipping. Im surprised they would sell me something that would not work in the kiln they sold me. It was a two pronged - i viewed this to changed it http://www.skutt.com/video/6_b.thermocouple.html

which one would you suggest? http://www.krumor.com/glass-industr (Forgive me, I don't see a k model)


Its my smallest kiln a hot start pro http://www.skutt.com/glass/products/starter.php

Thank very much!!... I just checked, there is fine weld on the tip. I wish I had asked , I just trusted they would sell me good one. Had I known to ask I would have bought a better one!

S

[Tony Smith]

With all due respect to Bert, Skutt is in the business of building kilns for the glass industry (us). I would contact them and give them a chance at correcting the problem with the thermocouple. I'm pretty sure they only use K-type thermocouples, and any K-type thermocouple should work. It doesn't have to be Inconel sheathed which is typically used in a corrosive, industrial environment and costs many times what a bare thermocouple costs.

Tony

[Morganica]

Sheree, when you call Skutt, ask to speak to Perry and tell him what's going on. He's the engineer who frequently handles customer support issues, and he's talked me through some really wacky problems.

The thermocouple you got could be defective, or it could be installed incorrectly, but I doubt that Skutt sold you an inferior choice for their kiln. I once accidentally pushed a thermocouple deep into its hole in the firebrick when laying up a piece, and the firing cycle went nuts--possibly something along those lines could be happening to you, too.

[Bert Weiss]

With all due respect to Bert, Skutt is in the business of building kilns for the glass industry (us). I would contact them and give them a chance at correcting the problem with the thermocouple. I'm pretty sure they only use K-type thermocouples, and any K-type thermocouple should work. It doesn't have to be Inconel sheathed which is typically used in a corrosive, industrial environment and costs many times what a bare thermocouple costs.

Tony

Tony and Cynthia. This is fairly simple. Yes all Type K thermocouples work. Bare wire exposed thermocouples have relatively short lives. Inconel sheathed ones have very long lives. The latest quote I have from Krumor was a year ago, and a 6.5" long sheathed thermocouple with 6" long lead wires cost $26.50. extension lead wire is .63 per foot. The ones I am using are actually 23 years old. How old is the $16 Skutt supplied one that failed? (when I first started buying inconel sheathed thermocouples they cost around $16.)

In my observation, most every kiln manufacturer cuts corners by using less expensive components, that are not in the best interest of glass fusers. The initial cost for the kilns becomes less, but they do not last as long or work as well as they could. In my opinion, no kiln should use mechanical relays for temperature control, they are very unreliable, yet most do.

Sheree You need to match the length of your existing thermocouple. The quote I gave was for: Type K Thermocouple, 1/8" dia, ungrounded, inconel. For $29 they will add a stop that keeps it in place and does not contact ground. Krumor makes everything custom to order. If the hole you have is too large, you can stuff it with fiberfrax fibers.

[Morganica]

Tony and Cynthia. This is fairly simple. Yes all Type K thermocouples work. Bare wire exposed thermocouples have relatively short lives. Inconel sheathed ones have very long lives. The latest quote I have from Krumor was a year ago, and a 6.5" long sheathed thermocouple with 6" long lead wires cost $26.50. extension lead wire is .63 per foot. The ones I am using are actually 23 years old. How old is the $16 Skutt supplied one that failed? (when I first started buying inconel sheathed thermocouples they cost around $16.)

In my observation, most every kiln manufacturer cuts corners by using less expensive components, that are not in the best interest of glass fusers. The initial cost for the kilns becomes less, but they do not last as long or work as well as they could. In my opinion, no kiln should use mechanical relays for temperature control, they are very unreliable, yet most do.

Sheree You need to match the length of your existing thermocouple. The quote I gave was for: Type K Thermocouple, 1/8" dia, ungrounded, inconel. For $29 they will add a stop that keeps it in place and does not contact ground. Krumor makes everything custom to order. If the hole you have is too large, you can stuff it with fiberfrax fibers.

You know, I've got a $1,100 raincoat* that's really gorgeous--all the seams have been hand-bound with silk tape, the lining is so perfect I could wear that coat inside out, there's all kinds of special detailing, etc. I've also got a rain hoodie I picked up at Costco for $40. The seams are raveling, the fabric's cheap and if one pattern matches anywhere on that coat I'll eat it.

But it keeps the rain out just as well as the fancy coat. The fancy coat is 'way overengineered, and unless you're into spending a bunch of money, it's not the smartest way to design a product.

So, yes, this is fairly simple: Why spend the extra bucks if you don't have to? Inconel sheathing is no guarantee that the thermocouple won't break. We need to be careful about announcing that a manufacturer/vendor is doing something shady or against customer's best interests unless they really are doing something wrong.

BTW, I've got the original bare wire thermocouple in my Skutt GM1414, the kiln is about 14 years old and in that time has gone from mechanical relays to a hybrid arrangement to mercury switch. I've beaten that kiln nearly to death with drying out molds, long-term casting and near-continuous firing for more than a decade...and my cheap, bare wire-exposed thermocouple is still accurate.

I know this because I test it with a datalogger that has used inconel and bare-wire type K thermocouples. Those thermocouples get dragged in and out of kilns, buried in witness blocks and occasionally stomped on the floor. Both types break, so I'm not gonna spend the extra bucks on fancy thermocouples. (And, in fact, when you get into tricky castings that require witness blocks, you're more than likely going to be throwing away at least one of the thermocouples at the end of the project, so it's silly to spend more.)

---------------
*That I picked up on eBay, barely worn, for $85. eBay is an amazing place to pick up a great wardrobe.

[Tony Smith]

Where's my LIKE button?


Tony

[JestersBaubles]

In my experience, if a thermocouple is connected backwards, the temperature reported will go down with increasing temperature, not up (granted, my experience is with dataloggers).

So it just occurred to me, where is the reference temp for the thermocouple on a kiln? On the controller board? Just curious... never thought about it before (I guess that's kind of a belated thought given that I work with TCs every day ...).

Dana

[Morganica]

Bullseye has a nice piece on using thermocouples: http://www.bullseyeglass.com/images/sto ... tes_07.pdf

And yes, they recommend Inconel sheathing...for dataloggers, which get a lot more wear and tear.

[S.TImmerman]

Hello everyone, you all are so wonderful! Perry emailed me twice today and I sent him photos. Skutt has really good customer service. I believe you get what you pay for. I had no idea what they cost so 16.00 didn't phase me.








This kiln was a gift in dec 2009 - before i even bought any glass- very basic little kiln.( 15" firing chamber) I did write kromur last night
.
Thank you

Hope you all have a good weekend and we get ahold of these wild fires.

S