Ovens and kilns maintenance and specifications

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Shop Area: Metal Shop

Tool: Ovens and Kilns

Requires in-person training: Yes 

Procedure Number

MT 130-08, Rev. 1




KH 418 Evenheat Kiln

Chamber Dimensions: 18" Deep x 6.5" Wide x 4.25" High Max Temperature: 2200°F

Heat Treat Oven – Kiln (Evenheat) for the heat treating of metals for knife making, gunsmithing, automotive and general machine shop work.

Evenheat Knife/Heat Treat Ovens are a controlled heat source designed for the sole purpose of heat treating metals

Heat Treat Oven.png




  • The thermocouple is a temperature sensor.
  • Located in the ceiling of the oven.
  • Standard thermocouple is known as a Type K. The term “Type K” refers to the type of alloys used to manufacture the thermocouple.
  • Thermocouple needs no maintenance other than replacement if it fails. Failure of the thermocouple is seen as an error message on the controls.
  • The thermocouple must be replaced with another Type K thermocouple.
  • To replace the thermocouple first unplug the oven and allow it to return to room temperature.
  • The thermocouple is part of an assembly is located in the ceiling of the oven.
  • Remove the 2 screws that fasten the assembly to the oven and pull it from the oven.
  • Loosen the 2 screws that fasten the thermocouple to the oval shaped block and remove the thermocouple.
  • Attach the replacement thermocouple to the oval shaped block with the red thermocouple lead to the red thermocouple lead wire.
  • Tighten the screws.

Control Relay Replacement via the Relay Access Port:

  • The oven uses a device called a relay (a.k.a. contactor) to control power to the heating element.
  • During use the relay continually turns on and off to maintain the proper kiln temperature.
  • The relay is a service part and is likely to need replacing at some point.
  • To replace the relay use the external, relay access port.
  • The relay access port allows relay replacement by removing the access plate located on the outside of the kiln control enclosure

Heat Treat Oven Replace Relay.png

Fire Brick:

  • The insulating fire brick while strong, can be damaged with rough handling.
  • Damage that is small or minor may be ignored.
  • Any brick damage that affects performance should be repaired or replaced, such as brick that holds the heating elements in place.

Control Fuse:

  • The electronic controls are protected with a control fuse located in a fuseholder on the backside of the oven control panel.
  • The fuse is rated at 250V/250mA, slo-blo.
  • If replacement is necessary, replace only with a fuse of the same rating.


  • Period vacuuming of the oven chamber removes debris that may damage the heating elements.
  • A gentle vacuuming with a soft brush is perfect.
  • Pay particular attention to the element grooves.
  • Unplug the oven before vacuuming.
  • The oven jacket is Stainless Steel and requires no real maintenance or cleaning.
  • The oven control panel requires no cleaning.


Heat Treat Electrical Table.png

                                              END OF THE PROCEDURE