Several people have expressed an interest in the oven I use. But first a story and the rationale. My wife bought a book n The Art of the Trout Fly" by Judith Dunham published in 1988. In the flytyer's Library section on page 124, the book lists one of the tyers Preben Thorp Jacobsen of Denmark who wrote Stangbyging, Bygning af splitcane-fluestaenger Rodbuilding, Building of split cane-flyrod Hobro, Denmark:Flyleaves, 1982 in Danish. His address was also listed. I wrote and asked if it were possible to get a copy of the book. He not only wrote back, but sent the book c/w pencil translations of some of the things within it. The book prompted the acquisition of a Danish/English dictionary and I attempted to translate. Finally gave it up. Never forgot my youth & Playboy and I can still read the pictures. On page 56, there were 2 drawings of tempering ovens. One appeared to be like Garrison's and the other a recirculating design. I certainly had had enough of pipe and torch or heat gun ovens by this time. I know and have seen some fabulous work come out of these ovens, but I seemed to screwup about 1 out of 5 attempts. Three years ago, I'd had enough. Previously, I had built a recirculating oven in 1985 using a design similar to Mr. Jacobsen's and used it for the testing I mentioned in my previous posting. It was lousy construction and finally fell apart. Within the inspiration of Mr. Jacobsen's oven, the previous efforts of my own and an incredible desire not to have another rod show uneven tempering, I got at it!
Enough of why.
Design criteria: - must be able to temper a number of rods at one time - must have a large enough heat sink within the oven that the temperature of the oven will not drop when door is opened to introduce the rods. - must have no cold spots - must be able to be operated safely indoors - must be temperature controlled - parts must be readily available - must be able to be temperature monitored - must be moveable - must have removable top for servicing and installation of components - cane must not be subjected to radiant heat. - constant air flow from side to side of the center baffle to distribute the heat Parts list: - 1 1/4 hp furnace motor got a spare - in Alberta you just can't be too careful - 1 1/2" rubber V belt - length to be determined by motor location - 2 Vee pulleys - 2" on 1/2" fan shaft and a 3 1/2 on motor shaft - 3 ground fault detectors and trip devices - 2 1500 w 120 volt straight oven range elements - 8 steel standoffs designed to hold the oven elements - to be 1 1/2>2" long - 1 oven thermostat c/w indicator light thermostat electrical box to hold thermostat - 1 Tel Tru bimetalic 50 > 500 degree thermometer c/w 8 probe - 2 pillow blocks for 1/2" shaft - 2 pillow block stands - some shims - 2 feet of 1/2" steel shaft - 3 120v electrical light switches - 3 extension cords - 15 ft. of high temperature wiring for 120 v 20 amp c/w asbestos covering - 4 electrical grounding lugs - a number of murats for electrical connections - a number of electrical connectors - 1 sheet of 4'x8' 3/4" plywood - 4 legs c/w caster wheels - 1 4" aluminum 4 blade fan c/w center hub and locking screws - 1 fan shroud - 10 #10-3" screws - 15' of 2" high temperature pipe insulating tape - One oven box - 4>8 2" high metal standoffs to support the oven box above the plywood - this prevents heat build up between the oven box and plywood as it allows air circulation between the box and the plywood. Oven box design: - External dimension: 17"x17"x67" long - Internal dimension" 14''x14"x64" long - Difference between dimensions external to internal is 20 gauge galvanized tin and pink the oven fiberglass insulation ( note: all surfaces of the box are metal, both internally and externally) - Cane access door to be approx. 6" square to reduce oven buns to hands - The box was constructed 2 baffles - a center baffle to separate the heating elements from the tempering side and a baffle in the tempering side 6" from the bottom. This baffle to be of expanded metal. - Center baffle to have 2 openings to the electrical element side of the box. 1] an opening cut 4" from the bottom at the opposite end from the door. The opening is round to accommodate the 4" an and fan shroud. The shroud is 6" long and is required to increase fan efficiency 2] slots cut with the metal let in place to direct the air flow towards the door opening at the door end. Installation of Parts: - mount the oven box c/w standoffs to one side and one end of the piece of plywood - mount the pillow blocks c/w stands, 1/2" shaft and fan c/w shroud. Shim the pillow blocks as necessary to center the fan within the opening previously cut in the center baffle. Of course, drill a hole to get the fan shaft through. - mount pillow blocks in a over hung position about 1' apart with the fan at the extreme end and the pillow blocks located outside the box. Leave about 1>2" from inboard pillow block for shaft cooling. Install the 2" Vee pulley prior to installing the outboard pillow block. - install the motor the required distance depending on the Vee belt diameter - install the oven elements about 46" off bottom of box on metal standoffs 1 1/2">2 long making sure the standoffs only contact the oven element where the metal cladding/insulation is installed. Other-wise you'll get a tremendous flash before the current interrupters shut the current off - install the high temperature wiring to the elements with the electrical grounding lugs and run the wiring through the box wall. The electrical supply for each of the elements is as follows: = element one: requires a switch only from the extension cord to element. = element two: requires a switch, thermostat and extension cord.
CRITICAL INFO - GROUNDING OF ELECTRICAL EQUIPMENT - THE EXTENSION CORDS GROUNDS MUST BE USED TO GROUND THE OVEN BOX, THERMOSTAT, THERMOSTAT ELECTRICAL BOX, MOTOR GROUND, SWITCHES AND ANY OTHER ELECTRICAL EQUIPMENT. I WOULD SUGGEST THAT YOU CONSULT WITH A CERTIFIED ELECTRICIAN TO WIRE THE TEMPERING OVEN. FURTHER - - INSTALLATION OF GROUND FAULT DETECTOR STRIP DEVICES IN THE WIRING CIRCUITS MAY/WILL PREVENT ELECTRICAL BURNS OR DEATH.
- test electrical system
Make sure that you don't plug all the extension cords into the same house circuit. This will cause the breaker to open as each element is drawing 15 amp. I split the tempering oven electrical use over 3 circuits by the use of longer extension cords.
- install the oven box lid c/w 2" pipe insulating material as a gasket. Use the # 10 screws. The elements, oven box and its internals will give off a disturbing odor the first times you use it. At the elevated temperature, the oil used to protect the metals is flashing off.
- install the oven box lid. I find that the box requires about 25 minutes to come up to temperature with the two elements due to the mass of the box. After it comes up to temperature, you can shut off the one element that is not controlled by the thermostat. Use the circulating fan from the first time you start heating it up. This will prevent hot/cold spots from existing within the oven. The above only applies if you are tempering in a building where the temperature is 65>70 degrees. Tempering outside at lower temperatures may/will require either larger or more elements, greater oven wall thickness or other adjustments.
BE AWARE - THE EXTERNAL SURFACES OF THE OVEN STILL GETS HOT ! ! ! ! IF I WAS TO BUILD THE OVEN BOX TODAY, I WOULD INCREASE THE WALL, LID, BOTTOM INSULATION LAYER TO 3" TO PREVENT HEAT LOSS or POSSIBLE BURNS
I know I sound like a lawyer towards the end - - I ain't!!! Its just that this stuff is important and I for sure don't want anyone hurt. I'm not computer literate enough to create image files yet. If you are unsure from the above description just how things are built, please contact me off list with your postal address and I will send a sketch.
Best of luck,
These elements should be available at any one of your local appliance repair shops or they can order them for you. I got my first one about 5 years ago in Edmonton with no effort and my second one I got through the local repair shop (they had to order it from Edmonton) again with no effort. The elements are built straight so they can be bent when installed into the range. They cannot be bent after they are heated. I cannot imagine that you cannot get them in the States. We have much the same appliances as you folks GE, Maytag etc.
- eight steel standoffs for the elements:
These I built of 1/8"*1" strap iron with a smile in them to accomodate the element. A couple of holes in the strap will allow you to wire them to the standoffs. I bent a foot about 1"*1" c/w a hole in the standoff so it could be pop riveted it to the oven case
- hold down straps for the oven to the plywood case: >These were built of light 20 guage steel to anchor the oven to the plywood. The reason is so the oven will not move. The fan assembly must stay put otherwise it will contact the sides of the fan shroud.
- oven thermostat:
any repair shop should have an oven thermostat for an electric range. I cannot remember how I wired it but any compentent electrician should be able to figure it out
- thermostat indicator light
This light I picked up @ a local electrician. Just a common 120 volt indicator light with 2 pig tails.
- thermostat box
Any electrical shop will have a series of boxes that things electrical are mounted in. I used one about 6"*8" c/w lid for mounting indicator light on and thermostat in.
- Tel Tru thermometer 50-500F c/w 8" stem 1/2" NTP thread
This is an industrial grade of thermometer available at most any supply stores that sell to the industrial operations. Pricey though. Suggest you look @ a candy thermometer or equivalent.
- 15 feet of pipe insulating tape
This stuff is used by insulators in industrial operations for insulating of high temperature piping and odd shaped pieces. I would suggest that you contact one of the insulating firms in your area about the tape. It looks like lamp wicking and is 1/8>1/4" thick and of braided material.
- 15' feet of high temperature wiring
This one I picked up at the same shop where I got the electrical box. They had a lot of it and I would expect that any well stocked electrical shop would have some. Tell them its for electrical services in excess of 400 degrees F and you will get the right thing. Most of the applicance repair shops would likley carry this product.
- 4>8 metal standoffs to support the oven above the plywood. I would use 1" steel square tubing c/w some of the insulating tape above between the box and the tubing.
I hoped I've helped. If I can help further, please send me a note.