started building my oven

[JTW37]

I first used the stuff that came in the tub. Boy what a mess that was. The stuff I just put in the seams is black and in the caulk type tube. Not the continued expanding type, but the regular hi-temp type. It also say to wet the surface and that to completely set it, that it takes 3 to 4 hours with different ranges of temps to set it up.

[defed]

here's a pic of the control box in operation. currently, the oven has 2 sets of 2 elements, 2 in the back and 2 in the front. each pair is controlled by its own thermocouple and controller. i did it this way to facilitate dividing the oven in half.

i auto tuned them at the same time, and they both completed their tuning at the same time. not 100% sure how well they will work together, as i haven't run it at temp for a long period of time yet, but when this pic was taken, they both fluctuated +/- 2 ...that should be good enough i'd think.



should be the last picture until i get the parts hanging/loading caddy built.

i also added an air space between the plywood and the insulation that the control box is mounted too. even after adding 1.5" foam between the box and plywood, the box still seemed to be heating up. the bottom of the box, which isn't fastened and was actually pushed out from the plywood was cooler, so hopefully the air space is the last mod for that part.

[corecoatings]

Good work, I remember buiding my oven, I went with 3 inch insulation basically fire barrier from Rugg Lumber

[defed]

i made a trolley for the oven, but may need to modify it.

1st, i tack welded 2 pieces of angle to the bottom of the oven base. these are the tracks for the cart.

i had some 3" diameter by 3/4" inch thick steel discs. i drilled a hole in the center of each to use as a wheel. i made the base frame out of unistrut and these discs fit into the channel. i just put a bolt thru them, and the complete base frame rolled quite easily. after i added a couple uprights and a cross piece to tie them together (hanging bar), it started to roll harder. i may need to add a brass bushing on the wheels to reduce friction.

i also have an old power supply that has some large heat sinks. i still need to cut these down to fit on my SSR's before i really run it.

but now that it is cold here in WNY, it will probably sit until spring.

[defed]

added some heatsinks to my SSR's. i had this heatsink off of some electronic device...



i cut in 1/2 width wise to give me 2 finned heatsinks w/ a solid back to bolt inside the control box.



i filed and polished the surface which contacts the SSR and then used some thermal paste.

one small problem...i need a bigger box or reconfigure the one i have, as it won't close! i forgot that the PIDS stick WAAAAY into the box. i'm thinking a bigger box would be better as to not get the PIDS too close to anything that might get warm. but, i've run the oven w/o the heatsinks, so i doubt they will get too warm.

the SSR's are rated at about 2x the load they see, but figured better safe than sorry and add the heatsinks.

[defed]

one more pic of the entire mess in the control box.

[defed]

also began re-working my parts hanging trolley. i didn't like the way my 'steel wheels' came out.

i found some all metal swivel casters at home depot. i welded them fixed straight. then welded them onto my current frame (flipped over w/ the steel wheel still attached). it seems to roll a whole lot better than on my homemade wheels. hopefully the casters don't 'lock up' at 400 degress. i don't think they would expand much at that temp. i did forget to wash the grease out of the swivels before i welded them on the frame tho.

not sure how i want to implement this whole rack yet tho. not crazy about wheeling it up ramps to get it inside.

[defed]

i was about to run my oven for the 1st time for actual coating (no more testing!), but my compressor died!

in the meantime, i have built a new rack for hanging parts. will post pics, but i keep forgetting to take some.

[defed]

used the big oven for the first REAL bake today. it worked very well. got to 400F in about 10-15 mins, held the temp there w/in 2 degrees +/-, and when i opened the huge door to load a part, regained the temp pretty well.

when we opened the door the 1st time to load and noticed it WOULDN'T load due to the part hanging too low and it would hit my thermocouples, it regained temp in about 5 mins. when we finally got the part in, about 150lbs of 1/4 steel, it took a bit longer, 15 mins at least.

it's a good thing i added those heatsinks to the relays. the heatsinks got to about 110F while on full blast getting to temp, and the relay itself got to about that.

here is a cpl pics of the rack system i made. i made a rack to roll into the oven for actually hanging parts, and a secondary cart to elevate the hanging cart to oven height. it is unistrut w/ black pipe in an A frame. i used all metal casters for its wheel. i have a cpl extension arms that will bolt on for putting another piece of unistrut on both sides of the center strut.

the part hanging is the massive hunk of steel previously mentioned.

[defed]

five full bake cycles and the oven is working great.

just a few issues w/ the side panels warping due to their large size. each 'section' is about 3'x3'. that appears to be too large an area w/ no extra support. the roof sagged a bit in the center of each 3'x3' and the door, which is actually a little bigger, bulges out.

i will be adding some additional steel studs to reinforce it. otherwise, good results.