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COOL, your getting me excited . i'll have to wait until the rains start before I can get going on mine. right now I'm derusting some 31 Chevy parts with electrolysis.
Jay D.
More more wiring for the control box. All seems to work as planned, TC plugs in the bottom, solid state relays and heat syncs on the right side. Couple more switches and ldiot lights to go
Wiring is pretty simple, front of the box is hinged and the front drops down for access.
This is probably way over built, but works for me. A smaller over would be fine with a single control PID and SSR. But gives mr the ability to monitor the air temp in the oven, and with a ring thermocouple (TC) and a magnet I can monitor the p art getting coated at the same time. And use the part temp to control the oven. This will insure wheels have a good powder to metal bond
Quick oven project up date. Finished up the instrumentation and heater element wiring. Got the rock wool insulation installed . I also covered it with a layer of Orcon film like the satellites just incase it gets away from me and goes into orbit. I added a Volt/ ampmeter to each heater leg to monitor the load on each heating leg along with the square total power ans voltage meter. There is a total of 10 thermocouples inside and they can be plugged in to any of the PIDs by the TC plugs in the bottom of the control box. I don't know if it will work yet but I have a ring terminal TypeK T/C to attach to the item being coated, I can hold it to the part with a magnet to a screw. This will allow monitoring of the part it's leg and the air temp inside
I read on the Caswell site that they sometimes install a small fan to help even the heat out. do you think this is going to be a problem.
great job !
Jay D.
Another update, with a design change. It progresses and is close to relight and calibration. I decided to use a DIN Rail and terminal blocks to distribute the power to the heater elements. My first use of these outside of putting fire systems in CnC machines. There allow me to use 8AWG wire and power all the elements in any configuration I want in just a few minutes. The use a jumper between terminals like a blade fuse. So I can tie the heater elements in series or parallel and group them is any configuration I want. They are Color coded for location of the heaters inside. These are pretty cheap and very reliable and configurable.
I started the calibration today, Goes to 350 F in 6 minutes, with 2000W of power consumed. The meter in the lower left corner is power meter (volts/ amps/ current watts/ total watts) with a Pearson Coil (CT) monitoring one leg of the 240V in. Each of the SSRs also has a coil to monitor the current on each leg, displayed on the square row on the bottom. These all add up and equal the big power meter. I also used a clamp on multi meter and they all agree. The four lights at the top come on as the SSRs outputs to the heaters. They blink on and off at when you reach the set temp. . Most current draw seen was 18-19 amps. Once it gets close to the set temperature, the SSR start to pulse and the current drops to about 3-8 amps to hold 350 Deg F.
384 F @ floor and 220 C @ ceiling temp readings
Jay D.. Badsix I did not use fans in this design. I think there are enough heating elements and different levels to get the thermal circulation needed. I have a couple wall ovens with convection fans. I believe a fan is needed in single element ovens, based on my experience.
Also so modified the Bead roller with a drive wheel replacing the crank. A 5/8" "ground rod" from the electrical section of HD makes a good 24" ring. Add 6 spokes and presto it's easy to bind a wire edge by your self
We inset the wheel to make it easier to reach with out decreasing the capacity. 6" cast iron pressure wheel on the left
The pressure application wheel is much superior to the standard bolt supplied with the stock unit.
Justin the wheel works well and I did not have time for a motor right now. But it made from a grounding rod from Home Depot. $ 8.00 and some scrap rebar, I also put a L bracket on the pressure wheel so it lifts the upper bar with no spring, Just a 25MM hole in a flat strap, the drive rod goes through the hole and a nut under the hand wheel.
The oven is done.. it was a long journey but it works well. I for the inside temp up to 225C in 20 minutes and only used 2930 Watts. Then I opened the doors for 30 seconds and internal dropped to 175C but went right back to 225 in about 5 minutes. It draws about 25 amps to start but when its get close to temp it drops down ro 3-5 amps. each SSR comes on for a few seconds and cycles. Having four separate selectable controllers is the trick for controlling the total electrical load. I wired them in pairs on opposite walls.
The exposed DIN rails also make it easy to reconfigure the heating elements. They all terminate on one side (RED WIRE) of the 240 V, the other side (BLACK WIRE) power the elements via the SSR. Since the SSRs has a toggle switch between the PID and SSR they can be easily selected on and off. Each PIDs monitor a thermocouples inside at different height. So I can see the heat column inside. The thermocouples come in via a plug at the bottom so I can switch them around also to feed different PIDs is required, I also put a female plug low on the inside so I can put a thermocouole on the part being coated on on the carriage to insure I get the part up to temp for the ceramic powders.
Broke it down and painted it International Harvester Red, with enamel. Now off to do a couple sets of tin and 3 sets of wheels this winter.
Last edited by Jbrooks; 10-11-2019, 06:49 PM.
Reason: added photos
I bring the oven up to temperature by activating 1 or 2 SSRs at a time via the toggle switches. I monitor the upper center ceiling temperature in Deg F on the upper left PID. I monitor the current flow because until it gets within 25 degrees of set value it will try to run full bore. This beast can draw 80 Amps starting cold. As it gets close to temp the SSRs will reduce the current to only what is needed. AT 240C I was drawing 4 amps holding the temp within 2 deg C.
I have 8 Type K thermocouples inside the oven in a tree at different heights and sides. I have both 100mm and 25mm probes and a circuit for a ring type to put on the component being coated. I can change the PID they feed via the yellow TC plugs in the bottom of the box. This makes reconfiguration pretty easy. If a part is in the center of the oven, I can use a center height thermocouple to monitor. All the PIDs read the TC value all the time, but only output when I select them with the toggle.
The PIDS are very complicated if you want to use all 40 parameters available. The have 20 different input types, TC, volts, amps and they have high and low alarms, temp bandwidth variances of the temp spread, varying monitoring timing . I am only using a couple parameters now until I get better at Chinglish and play with them some more. But for 20-25 bucks for a PID. SSR and TC kit it was pretty cheap. I plan to build a heat treating oven next using my spare one.
John, there are not so many around that could follow your instructions and obtain all the parts and build one let alone, think about designing it from scratch.
Very professional indeed.
Roy
Roy, Its really not that hard and the parts are all on eBay .
The power coating oven now has a rail road system to move the parts in and out. it as car that sits on the floor and a car has rails to move the carriage with parts into the oven.
Four swivel casters on the bottom car frame, easy to spin with applying the powder Garage door cable pulleys for wheels and a old piece of fence post " T " for railroad rails. Carriage is made with some angle with an removable EMT frames . The frame used EMT panel terminals with the threads cut off welded to the carriage. So you just undo the screws and it comes off the carriage, and another shape frame can be installed. It holds an entire set of engine shrouds at once, or a set of wheels.
Works well. Now I can move a couple hundred pounds into the oven with out picking it up.
Hole located using a drill guide. Below are some photos of a drill guide I forgot I had. I needed to locate a 10/32 hole in a bracket. I could measure it, or use dividers then I remembered this tool. They come is #40, #30,#21,1/4. They are super for replicating holes in skins like matching a rib or bracket through skin.
I use them to locate the guide holes for Clecos when replacing or fabrication of air plane skin. Got 200 rivets to locate this is the way.
Looking for some photos of indicator holders to measure valve guide clearance on 356 heads. I'm planning to make one tomorrow, so will post photos when I am done.
Retired software engineer
'59 Convertible D
'64 SC
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