temp all over the shop

[Lee - Kilncare]

Prototype fabrication finished mid next week. Chamber build and electrification the following 5 days. Doors final design and fitting the following week. Testing, then out to a few "top" beaders the following 2 weeks then into production providing the darn thing is deemed fit for purpose .

I prey we can, both build the "right" kiln and also meet the tight re-sale price critior, if so we will be go before the biennale where we shall be exhibiting and hopefully more.

Fingers crossed, the bead sector is the one remaining section of British glass that we do not have a kiln specific to.

[turnedlight]

Wow cool! That would be great, a Brit annealing kiln

[Lee - Kilncare]

I had to take the mandrel rest right off my kiln as I couldn't get the bloomin door closed enough with the mandrels sticking out at the angle that the shelf forced them to be at (even with lots of "manipulation" of the shelf angle.)
Now when I open the door all the mandrels try and fall out, but at least the door closes.
The open-ness of the bead door makes a HUGE difference to the temperature stability and the annealling.
I have a Paragon Bluebird which was designed for bead annealling but to look at and to use it you wouldn't think the designer have ever annealled anything on a stick before. It's a truly rubbish design. Hope you're reading this Paragon!!

What are your primary complaints about the Bluebird mate?

[Robin]

hi

the bluebird is a low-cost kiln for batch annealing. the door design is much like the door on the sc2b, but bigger. it can use a regular socket. however, some people use internal bead mandrel supports and never use the bead door. it's described on www.electrickilns.co.uk.

paragon have made more kilns than anyone else - approaching 400 000. they draw on worldwide user experience. we've not had one complaint re the 50 or so we've sold, or those we've sold through resellers.

to say it's a rubbish design is unfair. it's basically a ceramic hot box with a door and a comprehensive programmer. they're easy to use and easy to repair. we've never sold ANY spares for a bluebird so i'm assuming they've never gone wrong.

thx

rob

[glassworks]

likewise we have had not one single complaint or failure in any of the paragon's we've shipped throughout europe - from russia (siberia) to dubai... they are simple and robust tools and easy to programme once you've cracked the peculiarities of the system..

it would be great to have a locally produced bead specific kiln, i always have a twinge about airfreighting kilns on pallets as being "not sensible"..

but we digress from the thread a little here - i have been running one of ours to check and the temp does move around a little but nothing as much as you are showing... i suspect the probe is sitting a little deep and hence "over reacting" allowing the controller to under and overshoot.. although, it may also just be playing up although i am told that they are very VERY simple devices and usually don't misbehave, they just fail...

[Robin]

hi

just a quote from www.electrickilns.co.uk about temperature wobble:

All programmable kilns work in the same way: the thermocouple checks the internal temperature regularly and tells the programmer to switch the elements on or off to control the heating or cooling rate.
When the target temperature is reached, the elements are switched off. However, residual heat in the firing chamber allows the internal temperature to overshoot the target temperature briefly before starting to fall back.
This is more noticeable at low temperatures than at high temperatures. For example: 300°C will probably overshoot to 320°C whereas 800°C will probably only overshoot to 810°C before starting to fall back. Take this into account if you're working with temperature-critical materials or processes.
During the hold-time, with the elements still off, the internal temperature falls. Although the programmer will soon switch the elements back on, the firing chamber will initially absorb some of the new heat before the temperature recovers. The continual switching of the elements on and off causes the internal temperature to cycle around the target temperature.
The actual temperature of your work will be affected, slightly, by its position on the kiln shelf, the vertical spacing of any stacked shelves, and its nearness to the elements, a lid, a door, a bead door, a window, or a peephole.

If temperature is REALLY REALLY critical, buy a digital pyrometer and experiment a bit.

Remember that glass needs radiant heat and will fuse, sag, or slump better on one shelf than between stacked shelves.

Kiln doors and lids are not meant to be a perfect fit otherwise, at high temperatures, there'd be no room for expansion and the door could stick and the ceramic-fibre or firebricks could crack.
Eventually, with normal use, kilns discolour slightly, inside and outside, and some firebricks might develop hairline cracks. Remember, your kiln is a robust, versatile, red-hot tool: not an ornament.


thx

rob

re glassworks comment about shipping: yes it would be handy if kilns were made next door, but they'd probably be a lot more expensive. we have kilns arrive on big palettes from the US via a specialist shipper. there's NEVER any damage.

[Soo]

My Paragon SC2 maintains temperature within 3 degrees even with the door open.

It did overshoot in the early days when I was getting used to it but now I ramp at the fastest rate up to 400C and then have a second much slower step to take it to 515C. It takes about half an hour to get up to full temperature. I know others who get theirs to full temperature in 10 minutes, I'm sure I could do that with some tinkering with the programme, but I like having some time to pull stringers before I start beading without the pressure of feeling like I'm wasting the fully hot kiln time!

[julieHB]

Hi,

This seems to be a good place to ask, as a lot of our kiln-experts are joining in 

I have just been over to a lady who has been sitting stroking her sc2 kiln for 6 weeks without daring to fire it up  Anyway, we went over how to program the sentry 4.0 controller, which she got the hang of immediately, once she was shown. Whilst I was there we let the anneal-as-you-go program start up and run:

ramp1: full
temp1: 510 deg C
hold1: 5hrs

etc.

As I sat there I noticed the temperature went all the way up to 580 deg C before starting to turn.  Now, to me, in the limited experience I have with kilns, that is way beyond overshooting (in my experience should not have exceeded 10-15 deg C).  I showed her how to ramp up more slowly, but still feel there might be a problem there.  I did check that the thermocouple was sticking a good way out from the wall of the kiln. I think I have read somewhere that a relay might be stuck, and that can cause this type of problem.  If so, is there an easy fix?  The kiln was standing on a flat slate on top of a workbench with good distance to any walls. Any thoughts anyone?

I couldn't stay there long enough to see how it reacted when we skipped to the next segment, but it would be nice to be equipped with some expert advice before going over to see her again.  Thanks! 

[Robin]

hi

it may be the thermocouple projection or is it partly obscured by a shelf or work? i've never had such a deviation, so can't reliably comment. we did do tests with a pyrometer and the data in my previous mail is more or less ok. a slower ramp speed?

the sc2/3 now have two side elements, not both sides and back, to even out the internal temp, esp with a bead door.

or maybe email laura@paragonweb.com in the US to see whether she has anything like that on her database.

rob

[julieHB]

Thanks Rob,

I will speak to my friend later to see how the kiln behaved after I left her.  The kiln was totally empty and the door closed when I observed.   

[turquoise]

Hi again, I was just wondering if anyone had any thoughts here, As soon as my paragon sc2 kiln goes into the annealing stage which is set at 520 for 60 mins the temp go nuts it has just been at 550!!!!! never seems to stay close to the temp I have set it at??

[julieHB]

Hi turquoise,

I am not an expert on kilns at all - it seems you have a similar problem as my friend.  Do you get any error messages at all?  Have you checked that the thermocouple is protruding sufficiently into the kiln? As I said above I think I have read somewhere that a huge deviation from set temperature can be caused by a defective/stuck relay, but I don't know much about it.  I told my friend to fire it a few times to see how it behaves over the weekend, and if the problem is still there we need to call the supplier etc.(she has a totally new kiln). Sorry I can't help much 

[turquoise]

never had the error message, kiln warms up great and stays around 510 when I am making the beads than when I go to the annealing part the temp goes nuts!!!!

[Robin]

hi

although i'm happy to help, if you feel that the kiln is faulty, and under guarantee, you can call/email paragon in the US. calls only cost 20p and they open about 14:00 our time. email is on www.paragonweb.com.

it's the first time i've heard of such a deviation, but sometimes they've had a similar thing happen in the US so have experience of it. we do have relays and thermocouples in stock if the US suggests that's the cause of the problem.

it's worth saying that the SC series kilns that we, and our resellers, sell have a 'new style' sheathed thermocouple. other suppliers may still be using the bead type thermocouple which, in my experience, was more prone to corrosion and subsequent failure.

if you look inside, the new type is a short stainless steel tube and the old type is two wires with a dot-weld joining them together.

if you turn your kiln on (make sure it's not hot) and hold the thermocouple with you fingertips the programmer should register about 37C.

replacing a thermocouple is easy. watch one of the videos on www.electrickilns.co.uk.

rob

[turquoise]

thanks for that info, I need to have a closer  look and find out more. thanks