- Joined
- Oct 29, 2006
- Messages
- 2,912
I have had a Paragon KM36D for about 2 1/2 years. I use it mostly for thermocycling and tempering. I don't use it for heat treating because the design is such that the thermocouple is near the door and the rear of the kiln gets much hotter than where the thermocouple is. I figure it's a design flaw of the 36" model. Still, I prefer using my Don Fogg style HT forge as I can see what's going on.
So.. After just accepting things the way they are, I decided to write Paragon and ask if they had suggestions or were aware of the issues I've been having. The worst issue is when trying to temper anything. I usually set the temperature on full ramp speed to about 15 degrees or so below target then drop the ramp speed to about 50degree/hr for the final 15. The problem is that it overshoots the mark and still keeps firing until it hits about 25-30 over the mark then shuts off and lets it drop sometimes as much as 10 degrees under, then fires until about 30 over... etc..etc... It sucks! I've taken to standing there and opening the door to balance the temperature from shooting way over the mark.
I keep a large jackhammer bit in the oven at all times so even if I do that, the temperature evens out quickly once I close the door...
For the high temp issues, I've heard a good fix is to stretch the coils at the back so there's less heat output back there. I'm going to do that soon.
Anyway.. it's been a couple years of stupid solutions so I wrote them..
Regarding the high temp problems, this is what I wrote and what they said..:
subject/topic: problems with my KM36D Hello.
"I have had a KM36D for a couple years and I wondered if you had
some tips on how to get it to heat more evenly. I find that having
the thermocouple so close to the door leads to the rear of the
chamber heating a fair bit hotter than the rest. I find this difficult
to use for thermocycling sword blades in preparation for heat treat.
Further, because of this I find it not particularly reliable to use for
heat treating. I have tried placing the oven on an incline to try to
get the heat to flow forward as well as putting a large steel rod in
the chamber to attempt to even out the heat, particularly if the door
needs to be opened.
So you have any ideas short of me disassembling the unit and trying
to stretch the coils at the back to reduce the heat produced at the
rear of the kiln.
Thanks,
Stuart"
the reply:
"We do believe the temp could be more accurate from front to back, Engineering is going to look into it, In the mean time, To help, you might relocate the TC farther towards the back.
To do this, you would need to:
1) remove the Switchbox
2) unscrew the TC mount
3) drill a new hole
4) reattach the TC
5) relocate the wires as needed
You might need a new TC with mount and longer wires. And some flex conduit wouldn't hurt, to run the wires in."
New TC with mount?!?!... I hope not
Regarding tempering... (I had just come from doing the door duty and hence my last quip about regret)
subject/topic: problems with my KM36D I wrote earlier today but forgot to mention that my KM36D does
not work well for tempering. I try to set it for 400F by letting it
heat quickly to about 385 then lower the ramp speed to about
50 to finish the last 15 degrees but it seems to climb up to 430.
Then it slowly drops to about 393'ish then starts up again, even
turning on after it reaches 400 and climbs up to 425-430'ish...
It's very difficult to be accurate with such a wild temperature
range.
I'm really thinking the 36 is too large for the current single
thermocouple set up.. I'm really regretting buying this kiln.
Stuart
Their reply:
Hello
Our controllers do not hold temp very tight until you get all the brick heat soaked above 1000F
Does Evenheat work for tempering? Perhaps the strength of the Paragon is at high temperatures.
Anyway, I'm seriously contemplating ditching this one and getting an Evenheat if I hear that they work better. Like I mentioned, thermocycling and tempering are my main uses.
Otherwise, I write this as a warning to others about the KM36D model. I believe the 45" has a second thermocouple but I'm not sure.
So.. After just accepting things the way they are, I decided to write Paragon and ask if they had suggestions or were aware of the issues I've been having. The worst issue is when trying to temper anything. I usually set the temperature on full ramp speed to about 15 degrees or so below target then drop the ramp speed to about 50degree/hr for the final 15. The problem is that it overshoots the mark and still keeps firing until it hits about 25-30 over the mark then shuts off and lets it drop sometimes as much as 10 degrees under, then fires until about 30 over... etc..etc... It sucks! I've taken to standing there and opening the door to balance the temperature from shooting way over the mark.
I keep a large jackhammer bit in the oven at all times so even if I do that, the temperature evens out quickly once I close the door...
For the high temp issues, I've heard a good fix is to stretch the coils at the back so there's less heat output back there. I'm going to do that soon.
Anyway.. it's been a couple years of stupid solutions so I wrote them..
Regarding the high temp problems, this is what I wrote and what they said..:
subject/topic: problems with my KM36D Hello.
"I have had a KM36D for a couple years and I wondered if you had
some tips on how to get it to heat more evenly. I find that having
the thermocouple so close to the door leads to the rear of the
chamber heating a fair bit hotter than the rest. I find this difficult
to use for thermocycling sword blades in preparation for heat treat.
Further, because of this I find it not particularly reliable to use for
heat treating. I have tried placing the oven on an incline to try to
get the heat to flow forward as well as putting a large steel rod in
the chamber to attempt to even out the heat, particularly if the door
needs to be opened.
So you have any ideas short of me disassembling the unit and trying
to stretch the coils at the back to reduce the heat produced at the
rear of the kiln.
Thanks,
Stuart"
the reply:
"We do believe the temp could be more accurate from front to back, Engineering is going to look into it, In the mean time, To help, you might relocate the TC farther towards the back.
To do this, you would need to:
1) remove the Switchbox
2) unscrew the TC mount
3) drill a new hole
4) reattach the TC
5) relocate the wires as needed
You might need a new TC with mount and longer wires. And some flex conduit wouldn't hurt, to run the wires in."
New TC with mount?!?!... I hope not
Regarding tempering... (I had just come from doing the door duty and hence my last quip about regret)
subject/topic: problems with my KM36D I wrote earlier today but forgot to mention that my KM36D does
not work well for tempering. I try to set it for 400F by letting it
heat quickly to about 385 then lower the ramp speed to about
50 to finish the last 15 degrees but it seems to climb up to 430.
Then it slowly drops to about 393'ish then starts up again, even
turning on after it reaches 400 and climbs up to 425-430'ish...
It's very difficult to be accurate with such a wild temperature
range.
I'm really thinking the 36 is too large for the current single
thermocouple set up.. I'm really regretting buying this kiln.
Stuart
Their reply:
Hello
Our controllers do not hold temp very tight until you get all the brick heat soaked above 1000F
Does Evenheat work for tempering? Perhaps the strength of the Paragon is at high temperatures.
Anyway, I'm seriously contemplating ditching this one and getting an Evenheat if I hear that they work better. Like I mentioned, thermocycling and tempering are my main uses.
Otherwise, I write this as a warning to others about the KM36D model. I believe the 45" has a second thermocouple but I'm not sure.
Last edited:
The insulation should not be an issue at all though more is usually better. Thermocouple placement is a matter of where the piece that is being heated is located. If you have any questions feel free to message me, happy to help if I can.
