Oven Troubles!

[JWFilips]

Fired up my trusty convection oven this morning to powder coat the bullets I cast yesterday and Troubles!
I had found that the 450 deg setting always gave me a stable 400 deg on my casting thermometer Nothing different today ( actually it is in the mid 70's) however I have not been able to get the temps up beyond 350 deg!!! Of course if I turn it up a bit more the fan shuts off and only the top elements work because that is the Broil feature! I even went so far as to put a large 1/2" thick 10" x 10" plate of steel on the top of the oven and after 1hour of pre-heating still 350 deg
My first batch of bullets have been in for almost 1 1/2 hours they look nice but I 'm not sure then can cure in that low of temps.
Anybody have any thoughts?
Jim

 

[popper]

Digital controls? Mine is directly wired to PID, fan always on. If the fan is 115AC you can jumper across the relay to keep it on. If a 12vdc, might be able to do the same but there probably isn't a relay. Gave up trying to fix the digital oven. No replacement parts. Solution may be get a used manual oven.

 

[JWFilips]

No it is a manual oven! The fan switched off at the broil setting ( I melted-saged some of my first batches of bullets with that setting! ) took me awhile to fid that sweet cut off spot on the dial at about 475 deg

So the first bach of today is out and they never got above 350 deg with smokes clear but were in for a bit more than an hour!
Hammer test went fine ....flattened a bullet out with no cracking or pealing! So that good.
I wonder if more time at the lower temp actually works the same as 400 deg for 20 min!

 

[CWLONGSHOT]

It likely may for some powders. But I’ll about guaranty it will not across the board.

IIRC of the powders I have none has recommended cure temp under 375...

I’ll guess your shortly due to be shopping a new oven.

Good luck!

CW

 

[fiver]

when it kicks off like that try unplugging it and plugging it back in.
airc they have a thermal switch, and sometimes they just act up.

you might just have the little thermocouple probe thingy covered in powder coat causing it to not read quite right, it's insulated now and thinks it's at max.

 

[popper]

Broil uses the top elements only, probably like toast setting, no fan. I use bake only, upper & lower elements run. Most just have the bi-metal switch on the temp control -no temp probe. You may have bad element on the bottom. Bake/toast/broil knob switches the elements. Power goes through the timer switch. I scrap the old ones as she breaks the timer switch knob - that is non-fixable and other knobs don't work.

 

[JWFilips]

All 4 elements kick on work fine! it is a Black and Decker convection countertop...it is just not heating up like it used toat the top most setting ( with convection fan) Fiver ....I think you have the same oven because I bought mine when you showed a picture of your oven ( I believe ) about 2 years ago! Would you have any idea where I can find ( & try and clean) the thermocouple? On the inside of the oven all I have is 4 elements ...2 top 2 bottom and the hole for the fan. There has to be a work around but I'm stumped.
All in all I had a miserable day baking only 4 loads of .270 bullets for the Arisaka! I'm sure they were all in for about 1 hr at 350 deg ( sometimes I got to 375 deg) however every batch passes the hammer test so I'm going to load them
Jim

 

[Rick H]

My B&D convection oven works best plugged directly into a socket, or with a heavy extension cord. Did you move it's location and get voltage drop?
That said my oven cycles between 350 and about 410* and my PC has always cured just fine. I preheat and then let it cure for 20 min. once the powder gets glossy.

 

[JWFilips]

My B&D convection oven works best plugged directly into a socket, or with a heavy extension cord. Did you move it's location and get voltage drop?
That said my oven cycles between 350 and about 410* and my PC has always cured just fine. I preheat and then let it cure for 20 min. once the powder gets glossy.

Rick H,
That sounds exactly how mine always worked until today! No I did not change its postion however it has spent a few summer months between the metal bilco doors and my cellar door! not being used! wonder if the humidity mucked up the contacts or something! It used to work flawless!

 

[popper]

Take outside cover off and look at temp control. Should just be a bimetallic contact. If bad, cleen with point file or sand paper. Weird fan cuts out. Is it free to spin? Went through a couple euro, taken over by shark and junk. She has oster now.

 

[JWFilips]

Popper,
fan is supposed to cut out when it is on broil.....Everything works as usual but it dosen't come up to proper temps anymore

 

[fiver]

going from memory since I haven't coated anything since like this winter.
but I seem to recall something on/in the back wall.
the contact strip Popper talks about is where I would look first though, mine has been kind of a pain since I got it and it acts just like my first LEE pot did until I cleaned and slightly adjusted the contact strip.
I over done the contact thing the first time and the pot went from barely making 600-625 to going straight over 800 as soon as the alloy melted, when set at about half dial.

 

[popper]

2 or 3 knob version? Still must have it on bake, I think they combined the mode and temp control but it should still have the same thermostat. Got a pic I can send but visit mom tomorrow so late afternoon.

 

[popper]

Temp knob has a cam on it to operate the thermostat, with steps to operate the fan and element switches. May be an adjustment screw there for temp also. Probably a stack of leaf switches o the control. Find th wires from the elements to decide which is the temp switch. They use a plastic peg to actually opererate the thermostant and switches. Peg could be worn or cam out of sync. You can slightly bend the bimetal leaf to adjust temp. Hope that helps.

 

[JWFilips]

I'm going to try to work on it tonight or tomorrow but you gave me a lot of good information!
Thanks

 

[JWFilips]

OK took it apart Not simple had to disassemble the front and over cover ( about 16 screws!)
Here are the knobs and the inside of the temperature control. You can see on the knob photo the black mark just past 450 deg this has always been the sweet spot but not anymore. Not sure where the contacts would be not a thermocouple and adjustment screw

If these are the "points" Just above the pink things ?

 

[JWFilips]

FIXED IT! I'm not really sure what I was doing but I closed the points on a small piece of folded over Carborundum 340 grit paper and cleaned the points and I even pushed the whole points mechanism toward the dial a tiny amount until I heard the points click on just before the Warm setting!
Before that they clicked on at the middle of the warm setting. Put it all back together and tried it out ! I now get 445 deg at the 450 setting which is great! just have to back it off until i find the sweet 400 deg spot!
Thanks for all the great tips and suggestions!

 

[Rick H]

That is a good thing to put in my memory bank....since I have the same oven. Thank you.
Do you think pushing the points closer to the dial made you temp's more realistic? My oven needs to be set higher than 400* to reach the desired temp.
Good Information and great pictures. Thank You again. I think I will leave mine alone until it starts acting up.

 

[popper]

The second leaf in the first pic appears to be the temp sensor while the white pin in the second is the temp adjuster. Increasing temp setting moves the pin out (away from the panel) for increase temp. The temp sensor has to bend more to break the contact. Bending the goldish bar (first pic) in does the same thing, permanently. Don't bend the leaf contacts. Yea, they get pitted and need cleaning.

 

[JWFilips]

OK I watched that little white pin with head magnifiers come out slowly as the dial temperature setting increased but I notice it seemed not to move much once I got to the 400 setting! that is why I lightly bent the mechanism toward the white pin ( I backed the pin off the contact point before doing this!) Now i did not see it bend ( otherwise It probably would have been too far!) I guess you can say "I coaxed it back very slightly" not really bending it.
(Rick H) I knew i had changed things slightly since I saw the points close just before the W in Warm. Before this They clicked closed between the R & M! so now it brings me close to the dial temperature marks!