Fan assisted oven - stealing parts for a powder oven - couple of points to clarify?

[julianf]

I dont have the donor oven here, otherwise id just use my eyeballs.


They have two elements, right? One at the top that does the grill, and a circular one at the back that is to do with the fan?


Does the fan one have ducting from the top or the bottom of the oven, or is it not that advanced, and it just blows stuff about a bit? They always seem to have them mid way up, at the rear. Kind of surprised they are not at the bottom or top, but i guess 100s of cooker designers probably know better than me, so ill just copy what they do!


I assume the fan wont be powerful enough to disrupt the powder.


Should i put the grill element at the top or the bottom of my oven? Im guessing at the bottom?

Thank you.

ps. this is only going to be a tiny oven. About double the height of a standard 600 under counter oven - small parts, not motorcycle frames or tractor wheels.

 

[Parm]

I’ve never seen a fan in a commercial powder coating oven

 

[voipio]

Some fan-assisted ovens only have the heating element around the fan, with the fan being a centrifugal type that takes air in through the grille behind which the fan is located, and sends it past the circular element and basically out in all directions, causing a sort of rectangular doughnut shaped plume inside the oven, that results in a fairly even temperature throughout the oven. Individual designs vary in the location and size of the output slots through which the air passes. The airflow rate is quite high; sufficient to cause a sheet of oven liner to flap around like a mad thing at the bottom of the oven. The highest airflow rate is right at the centre air "intake", where I measured just under 5m/s. Elsewhere in the oven, the airflow varies, mostly being around 1-1.5m/s at the oven sides, lower flow in the oven cenre, and with some relatively "dead" spots.

 

[Rrobson]

Just depends on the oven with regards to elements, ours has got four!!! Round fan, grill, and two inside the oven casing (top and bottom) for conventional oven cooking and pizzas. Only discovered this when replacing the fan element (was installed in the house when we bought, must have been a few quid!)

but as mentioned above, the fans do circulate quite a bit of air, can’t imagine they’re very well suited to powder coating ovens but it’s not something I know much about. The designs I’ve seen people knock up on here and other places just consist of a couple of elements mounted fairly low, a thermostat or two and temperature control. They don’t need to be much more complicated than that. If it’s lagged you’d expect a fairly even heat spread after a reasonably short time anyway.

 

[MattH]

The fan won’t disturb the powder but it can cause the part to move.

 

[julianf]

The fan won’t disturb the powder but it can cause the part to move.

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You reckon theyre the tool for the job then?

Ive looked at photos and they normally (when in domestic ovens) have a bit of a cowl over them to suck air from the side and then blow it through a mesh at the front. This sort of thing -

I guess that would help with heat distribution, but would probably make it even more "blowey"


edit: or maybe its more just to stop people knocking the fan blades with their turkey legs?

 

[wyn]

They pull air from the front and blow it out the sides. You could add ducting to direct it a bit.

 

[Ruffian]

Done powder coating in a normal kitchen oven, (non fan assisted)
Using a £120 cheapie ebay system with good results.

Look better than some stuff that we have paid for in the past.
Would just snoop on Facebook or gumtree for a free one and bolt it in the shed on a frame.

 

[julianf]

Done powder coating in a normal kitchen oven, (non fan assisted)
Using a £120 cheapie ebay system with good results.

Look better than some stuff that we have paid for in the past.
Would just snoop on Facebook or gumtree for a free one and bolt it in the shed on a frame.

The parts i need to do are a little too large for a normal oven. If i could get a 900 insert oven it would probably work one at a time, but i figure ill just build a bigger box and save myself doing them one by one.

Largest parts are about 28" x 7" x 3" so if i hang them on end, and build a box to suit, i can probably still use the space over or under the oven for something else.

 

[Ruffian]

Just get an oven then but make it longer?
Easier option in my eyes

 

[julianf]

This was my very rough plan -

Because im lazy, i was going to do the CAD, and then just get it lasered and folded.

Two hoops for the internal and external sides, top and base, and a folded flanged bit for the front and a couple of backs (one innner and one outer).

If i put the holes in all the right places, i wont even need to get the welder out - i can pretty much pop rivet the whole thing together. It will be square without me even trying.

Sure, it will cost me a bit more, but im more bothered about the space it takes up, and that way, i can get it just the right size and no bigger.

Ill do some stuff in cad, email off a file, and get my credit card and rivet gun out, and it will, pretty much, be done. I think (hope!).