Lurked for long enough. couple of ?s on new build

[StlS_Ron]

ok I just bought two of these

<NEW!> Electric Oven Bake Element (GE WB44X200) - eBay (item 400057919989 end time Jul-24-09 13:22:21 PDT)

and have my pid on the way as well.

Anyone have any advice on a 40a ssr with heatsink? maybe a link?

[ed_denu]

A quick search found that this elements is rated 3100 watts at 240 volts, or 12.9 amps each.

Check Auber Instruments for an ssr and heatsink, or consider using a computer cpu heatsink and fan. The later will require a 12V transformer to drive the fan.

[iosovens]

Hi,

Just read your ideas and after being in the oven aand furnace trade here in England for 25+ years it is all about the air movement.Uniformity is best acheived with the fan a higher running rpm at lower temperature ranges of up to 550 deg c typically 1425rpm.

Fans in alot of respect will only move what air they can find, so the return duct area/volume will have alot to do with the fan size and rpm, not just the working space.The fan position through a cowl can change the whole charateristics of uniformity. We work to NACAP specs of +/- 3 deg c over here and by movng the fan position by 6mm/ or 1/4 inch changes the whole concept.

I had a quick look at your pictures and must say it looks good. If you do get a chance and if they sell it over the pond, line the hot face with 25mm/1 inch ceramic fibre before then put the mineral wool its thermal properties are amazing it stops heat transfer which cuts down on your running costs.

Hope this helps a bit.

[TDCRacing]

Hello, First post here. Just getting into the powdercoating thing and this looks like the perfect size oven for me to start building.


Was wondering mainly how much wool insulation is needed for something this size. And is this all I would need to do the build?

1 PID
PID Temperature Controller Fah/Celsius + 40A SSR - eBay (item 350032448608 end time May-27-09 07:12:47 PDT) This auction is for a pid and 40 amp ssr.

1 SSR
New in Box Solid State Relay SSR 24-480V AC, 25A - eBay (item 370186672607 end time May-11-09 19:50:10 PDT)I would go with a 40A ssr for a little more capacity. Driving a 25A ssr at 21 amps is pushing the limit. But, you don't need this as the pid you are referencing comes with a 40A ssr. Just don't forget the heatsink!

1 Fan
Still Looking

2 Elements
NONE - CH776-456091 - RANGE OVEN ELEME - Neobits Inc.

Control box to house components
Still Building

High Heat Wire
Still Looking Look at McMaster(search hi tmep wire) or ebay on occasion.



Also, Does anyone have any simple wiring diagrams so I could better understand how everything is hooked up?

[iosovens]

Hi all,

Read through the thread on ovens and just incase anyone wants to know the basics here they are.

P.I.D control = Prop, integral,derivative also known as three term control. These are values which are either manually programmed into the controller or via auto/self tune method. These enable the controler to slow the rate in which it inputs power to the elements as it approaches the selected set point temperature, the temperature which you require. The idea is that the controller does not overshoot the setpoint or slow down the amount of power that is applied to the elements to quickly.


The oven should go up towards the setpoint temperature then cut back the power just before allowing the final few minutes to settle down and run at the setpoint with no under or overshoot. See website for more of an understanding.

PID THREE-TERM CONTROL

Thermocouples (tc) and their cable should always be in the working space and compatiable with the instrument i.e if its a j type tc then use j type tc setting on instrument along with same compensating cable if K type then use the same matching cable. If you mix the types your contoller will indicate alls well but the true temp will be well out. Always connect the +/- to the correct contacts or the tc can read backwards so the controller works but counts the temperature down as the heat goes in.

The best type of elements are sheathed or shell type (kettle type) which are better to use a few in smaller rated (watts) capacities as to spread the heat over a larger area where they are to be fitted and allow more air flow to pass over them.

SSR( solid state relays) should always be used with the largest heat sinks possible as they tend to get rather hot, if possible fit a cooling fan into the panel along with a filter.

Fans are always the most critical part of the oven we at I.O.S manufacture our own versions which work well. These are direct mounted onto either 1.1kw motors or 2.2kw motors, dynamically balanced and running at typically 1420rpm flowing approx 612cuft per minute. Make sure you use a cowl type of system to make a fan work correctly and not not hunt for air.

For best results we have found to always allow the air to blow through the working space so you can fit a fan louvre box and direct air to where it is required.

Insulation is always a major factor, always buy good quality ceramic fibre or mineral wool the better the thermal density the more heat you can retain. The insulation will out last the other oven ancillaries and will not be upated as easily or as often.

My final bit is when you fabricate please do not forget about linear movement i.e expansion and contraction. When the oven gets hot things expand. On average the rule of thumb 1/10th of an inch per 100 inches per 100 degrees centigade. So if your oven has a peice of steel in it at 100 inches long at 200 deg cent then it should roughly expand 2/10ths of an inch if it was bolted down either end then it would break the bolts or simply bend.

[StlS_Ron]

Ok got the sheeting done.










I think I'm going to skip the air circulation fan. Alot of people on here dont have them. Let me know if this is a bad idea. now is the time to put it in.


Does'nt look too bad so far. I get kinda OCD about stuff like this.

[baz]

The recirculating fan is in the plans as well. possibly 2 pending on how this goes.


This oven is purpose build for wheels. I'm sure I'll find other things here and there, But 99% of my needs are wheels. That the only problem with a household oven is the depth 18" deep. too small.

I'm just going to make it easier and scrub the whole separator idea and just build it and be done. that would prob be best.

do you know what gauge wire is nec for 40 or 50 amp breaker?

So parts list as of now:

1 PID
PID Temperature Controller Fah/Celsius + 40A SSR - eBay (item 350032448608 end time May-27-09 07:12:47 PDT)

1 SSR
New in Box Solid State Relay SSR 24-480V AC, 25A - eBay (item 370186672607 end time May-11-09 19:50:10 PDT)

1 Fan
Still Looking

2 Elements
NONE - CH776-456091 - RANGE OVEN ELEME - Neobits Inc.

Control box to house components
Still Building

High Heat Wire
Still Looking

Oven
Sill Building

missing anything? Feel free to tell me if the parts i have listed here are **** and I buy nicer parts

Ed thanks for all the help

your oven being 48 wide 38 tall and 24 deep
and your main work will be wheels .
how are you going to fit and support 4 x18 inch wheels in there ?

[StlS_Ron]

today after the inner skin was screwed into place, My roommate and myself stood and hopped on the top center stud of the oven. With a combined weight prob approaching 400 lbs, it barely moved.

Either way I have two 1.5 inch 3/8 square tubing that is going to be added across the top to be tied into the wall supports and center top support. One on both sides of the main support. should be able to park a car on top of it with no problems.

as far as fitting the inner top of the oven will have 3 channels to hang from. I have some Eye bolts that work well with wheels. Test fitting 4 is no problem. Actually got 6 in it but it was a bit tight. Too tight to maneuver with loose powder on them.

Any Suggestions on the air circulater? I've almost completely convinced myself to skip it

[ed_denu]

I'm not sure how you intend to mount the elements but here are a couple of thoughts. Since your oven isn't huge, the wheels will be in close proximity to the elements. Electric ovens heat 2 ways, both ir and convection. Wheels closest to the elements will heat faster, primarily due to the ir of the elements. Without a fan this will be compounded. Lighter color often are more susceptible to over temperatures than darker colors.

I've experimented with putting ir shields(common aluminum foil) in front of the elements. This absolutely helps in evening out temperatures throughout the oven. I am using a fan also however.

[StlS_Ron]

I'm not sure how you intend to mount the elements but here are a couple of thoughts. Since your oven isn't huge, the wheels will be in close proximity to the elements. Electric ovens heat 2 ways, both ir and convection. Wheels closest to the elements will heat faster, primarily due to the ir of the elements. Without a fan this will be compounded. Lighter color often are more susceptible to over temperatures than darker colors.

I've experimented with putting ir shields(common aluminum foil) in front of the elements. This absolutely helps in evening out temperatures throughout the oven. I am using a fan also however.

I've been thinking about different ways of doing that. I think I have one that will work perfectly. As of right now I'm going to skip the fan. The entire skin is removable so that will allow me to add it later.



I need yet another question for you guys. thermocouple that i have is about 2 foot too short. Can this be extended or will it interfere with the readings?