Pandora and Maxine?

Dickie · January 19, 2009, 10:03:54 AM

As Sarah (silverlemon) said I spent the best part of a whole evening ramping her new kiln up and down and holding it at various temperatures all the time watching and measuring the temperature at every point along the kiln's length. (yes I'm a geek)

From this information I have set the anneal temperature so that the majority of the kiln is within the anneal range for the glass Sarah is working with.

The kiln also exhibits quite an overshoot after you open the door if you are not careful with your anneal temp.

As Sarah said... we will need to dig out the "fag packet"/"Beer mat" that the results were scribbled on !!!

silverlemon · January 19, 2009, 10:24:22 AM

Quote from: Dickie on January 19, 2009, 10:03:54 AM
As Sarah (silverlemon) said I spent the best part of a whole evening ramping her new kiln up and down and holding it at various temperatures all the time watching and measuring the temperature at every point along the kiln's length. (yes I'm a geek)

ha ha ha, he didn't want to spend time doing this but I made him! who'se the bigger geek?

Quote from: Dickie on January 19, 2009, 10:03:54 AM
The kiln also exhibits quite an overshoot after you open the door if you are not careful with your anneal temp.

To be fair you only get this on the Maxi if you keep the door open too long, like I used to when rearranging mandrels in my old kiln, but I don't have that problem now with all the lovely space in my new Maxine

Sarah · January 19, 2009, 08:26:46 PM

I'm grateful for your geekery Dickie & Sarah

My run at 530 has resulted in the pinkie overstrike colour and is worse the further left the beads were.

So I'll knock it down to 490 next time, try that & work up frm there. I'll have to do some research before I put any TNT2 in there as that needs a lower temp too.

And Helen - that's very kind - but hopefully we'll suss this & you won't have me standing on your doorstep over the weekend

Thanks again - and I'll let you know how I get on

Sarah
xxx

Dickie · January 19, 2009, 10:57:57 PM

Hi All,

I can't believe that there will be much difference between one Maxine and another. So given that here is the schedule Sarah uses for most types of glass... hope it helps.

Full to 465 degC hold for 20 hour (Garaging)
Full to 483 degC hold for 1 hour (Annealing)
60 deg/hr to 320 degC hold 0 (Ramp down)
Off (Switch off)

Now... I'm sure you're all thinking... 483 degC... that's not hot enough to anneal... well yes you are right... but... (keep reading)

The thermocouple in the kiln is in the far right hand corner, and this is the coldest point in the kiln.
When the sensor reads 483 degC then the hottest point (center top) will be at 524 degC (and a gradient in between)

A point to note... we have anneal tested transparent beads (from this annealing schedule) from right hand end using polarising filters and they were fine... so I would suggest this schedule to anyone with a Maxine.

Hope this helps

Redhotsal · January 20, 2009, 09:56:23 AM

Dickie and Sarah,
Wow.....I'm so impressed with your thermocoupling skills!
It would make sense. Horrible salmony pink colours can be obtained from the left of the kiln and more purple (but not quite the right purple colours) are found at the cooler right hand end. But the right hand end is still too hot.
I'm going for fourth time lucky on Pandora today so I'm going to take the temp down a bit and see what transpires.
Really - thanks for all the helpful advice on here. We ought to start some kind of Maxine Owners Club!

Dickie · January 20, 2009, 10:31:16 AM

Thanks Sal...

Basically everyone should check their kiln temperature, all kilns are different, and will have temperature gradients (unless they are fanned, and even then there will be differences).

The chances are if you are setting your kiln temperatures directly from the datasheets for the glass you are using, then it will probably be wrong for many places in the kiln.

We have carefully set the anneal temp (to 483 degC) so that over the majority of the kiln's width the temperature is within the annealing range of 493-520 I think, for effetre (that's off the top of my head don't quote me on it) . If we had just set the kiln to anneal at 510 or 505 or whatever then MOST of the kiln would have been WAY too hot.

Kaz · January 20, 2009, 10:51:44 AM

My brain has turned to porridge just reading this lot - I think I will just have to stick with the 3 programmes that Lee input into my Maxine as I don't seem to be having any problems (so far

) and am avoiding Pandora like the plague although it used to be my call sign when I was very young and into CB radio!!!
Kazx

Dee Dee · January 20, 2009, 10:49:37 PM

Quote from: Kaz on January 20, 2009, 10:51:44 AM
My brain has turned to porridge just reading this lot - I think I will just have to stick with the 3 programmes that Lee input into my Maxine as I don't seem to be having any problems (so far ) and am avoiding Pandora like the plaque although it used to be my call sign when I was very young and into CB radio!!!
Kazx

Hey Pandora, what's your twenty? 10-10, we'll do it again!!

Kaz · January 20, 2009, 10:58:02 PM

Quote from: Dee Dee on January 20, 2009, 10:49:37 PM
Quote from: Kaz on January 20, 2009, 10:51:44 AM
My brain has turned to porridge just reading this lot - I think I will just have to stick with the 3 programmes that Lee input into my Maxine as I don't seem to be having any problems (so far ) and am avoiding Pandora like the plaque although it used to be my call sign when I was very young and into CB radio!!!
Kazx

Hey Pandora, what's your twenty? 10-10, we'll do it again!!

Eyeball, eyeball - but not til later in the year Steph!

julieHB · January 20, 2009, 10:59:23 PM

Yup, and that's when I fell off - it all made sense up to now

Dee Dee · January 20, 2009, 11:01:10 PM

kerensky · January 21, 2009, 02:19:40 PM

Hi Dickie and Sarah - Thanks for posting this info, it is so nice of you to share this information and help others.

I love this forum

;-)

Lee - Kilncare · May 13, 2009, 12:26:52 PM

O.K. flamers!!!!!!! In true tradition we have been monitoring this temperature variation issue.

With a kiln of this design we would expect a hot middle section but there are some quite extreme readings on here.

We have tweaked, changed and messed around with many solutions. Believe it or not, the first one we tried and the most simple, gave the best results and it was as follows.
It is very technical, not, simply, bend the end of you thermocouple upwards until it is around 10mm below the element. That's it.

The results here on 3 different MAXIs have all been very similar and they are as follows.
With the sensors we used, placed in the second holes up in the rear grill they gave, with the controller holding at 520c:
Right side 500c
Left side 507c
Centre 530c

Now quite why the variation should have pulled in by this simple mod is a bit of a mystery, we were expecting the variation to remain and just the temperatures to alter. I must be the leveling effect of heat loss.

Anyway, Red Hot Sal has tried the MAXIs out again for us with a couple of types of glass and under the polarizer, as Dickie says, the results were just fine.
I have also just had a rattle with Claire and she too is so far happy with the results.

All new MAXIs will go out with this modification.
If it is that you want to alter yours it is so simple to do, then again, you may now be used to the characteristics of your MAXI as it is.

Don't hesitate to reply or pm me if you have any further issues regarding this.

Sulis (Hazel) · May 13, 2009, 12:36:10 PM

Thanks Lee

I'll be trying that mod tonight. I have got used to my Maxine, but I think I'd prefer her to be running as sweetly as possible.

So when you say bend the end of the thermocouple - do you mean just with a pair of pliers through the open door whilst the kiln is unplugged? Nothing more taxing than that? Just checking because I don't want to start something I can't finish and I'm no engineer

Any chance you or someone could post a pic of the modified bit to make sure we know what we are doing?

Sorry, I'm probably being a bit (?!!) thick, but I don't want to take any chances with my beloved Maxine!!

xx

Lee - Kilncare · May 13, 2009, 02:23:14 PM

Here you go, as for how to do it.
The thermocouple is actually easy to bend and not too stiff.
The one here was actually bent whilst the kiln was holding 520c and I used a long screwdriver to apply pressure upwards.

It may be better to let it cool and gently push the end of the thermocouple upwards with your finger, it is that easy.

Oh yes, this is only optional, but you may tie it in a degree or two further if you remove the side cover, slacken the thermocouple retaining screw and fully insert the thermocouple into the kiln before re-tightening the retaining screw. MAKE sure the kiln is unplugged first.
When the kiln was originally assembled the thermocouples were left about 10mm short of being fully inserted.
As I say, this step is not really needed and the job will be fine if you choose to just bend the thermocouple as described at the start of this post.