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powder coating oven

ch2co

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#31
What? Not using carbon fiber tubing for your trusses? Shame shame, that thing is going to weigh a ton.
Unfortunately I have a great powder coater just 4 blocks (easy walking distance) from my house and they work with me so well.
My Surrier Truss plans for my little 10" are probably going to be alum tube, but carbon fiber is sooo tempting.
 

savarin

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#34
What? Not using carbon fiber tubing for your trusses? Shame shame, that thing is going to weigh a ton.
I've worked with carbon fibre before and didnt like it much (building windsurfers) but it sure looks cool.
I dont mind heavy as it dont vibrate in the wind but then inertia starts rearing its ugly head.
 

savarin

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#35
Found a fan at last, I hope its strong enough to take the heat, its from an electric oven and used to circulate air to cool the outside of the oven. It obviously gets hot in use but can it stand the temps I want.
I guess I will find out.
Made the holder to fit it to the oven wall
oven-24.jpg

In place and a quick test shows it produces plenty of puff.
oven-23.jpg
Now on to the ducting but I have a full calendar this week so not much more will get done.
 

savarin

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#36
Got the ducting done
oven-25.jpg

Now working on the outer insulated cover
oven-26.jpg
The top section needs a box for the wiring and also be easily removable in case I have to replace the motor.
I'm still in two minds as to whether I should insulate the motor of leave it exposed.
It would be the only place where heat could leak away but its not a large area. Hmmmmm.
 

mark_f

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#38
Randy is correct. Tbe motor needs to be exposed as the heat will ruin it. You could insulate the squirrel cage fan housing and leave the motor exposed as it is on the end of the fan housing. ( That's the way it looks in the photos ).
 

FOMOGO

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#39
Coming along great. Oil-lite bushings, or bearings on the fan? If oil might want to make up some oiler tubes and give a drop or two every once and a while to help it live. Not too much too often, or it may cause issues with your finish. Cheers, Mike
 

savarin

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#41
Bad grammer, I actually meant just insulate the housing.
I will block all the side holes and gaps in the housing so no hot air will suck or blow.
I am thinking that unless the motor is rated for that kind of heat, I'd leave it exposed.
The blower has a weird silicone type bearing opposite the motor so I have a doubt it is although the fan rotor is metal bladed.
Looking at some oven parts diagrams they appear to be for blowing air over the outside of the oven towards the door, possibly to actually cool the door???
So maybe it wont stand up to the heat. The major problem as I see it is the silicone bearing plate will deform or the motor windings will get too hot.
If that happens its relatively easy to make a new end plate for the rotor and extend the motor shaft getting it well away from the heat but I dont want to do that unless its necessary.
 

savarin

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#42
Finished the rear of the oven
oven-27.jpg
Now started on the door.
I stripped the glass out of the old oven and cleaned it but in the end I decided to rebuild the original door and set in in to my door.
oven-28.jpg
All so I can watch paint dry.
 

savarin

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#43
Got both sides of the door sheeted and in the process it twisted.
Closed at the top but wide open by 5" at the bottom so I placed a wedge at the top and clamped the bottom to twist it the other way
oven-29.jpg

It worked spot on
oven-30.jpg

Finishing off the wiring and door lock. Cant wait to fire her up.
 

savarin

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#44
Finished. (Well almost)
The door shuts and holds tight,
The door gasket has to harden fully then I can trim the excess off, I used a high temp silicone as the gasket and greased the door frame so I could clamp them lightly together without them sticking.
oven-31.jpg

All the wiring is done and it works.
Each item has its own warning light.
oven-32.jpg
A splash of bolognaise and it almost looks edible!
The thermostat actually turns off the power at its lowest setting, turn it up and the power light comes on, flick the switch for the second element and that light comes on, turn the fan on and that light comes on.
The thermostat controls both heating elements so both lights turn off when the thermostat trips.
Both heating elements get hot.
I have to install the thermometer so I can read it outside the oven.
First job is to calibrate the thermostat, then I can fully cure the exhaust white paint inside and then its flat out powder coating the bits for the telescope to finish that.
Only another 6973 projects in the pipeline:bang head:
 

savarin

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#45
first test is a possible let down.
According to the new oven thermometer it only gets to 185'C, I need 200.
But, when I opened the door and tested a metal bracket inside it read 204'C with my infra red thermometer which I would believe more than the cheap dial one.
However, the door warps at temp so heat leaks out there and the fan also pumps a bit of heat out its sides.
So, still work to do.
Think I should also add another element.
 

mark_f

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#46
With a door that long, you need a latch near the top and another near the bottom. ( Connect them with a common rod so they work together).
 

savarin

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#47
And a more pronounced gasket.
I will re make the door latch with 4 in total hooks to close it all the way down and add another hinge in the middle.
Cant do anything for the next two days, hosp appointments.
 

savarin

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#50
The oven is finished and works. No more leaks and gets up to temperature.
Built a spray booth from wood and plastic sheeting.
spray-booth.jpg
and test sprayed a can
tin-test.jpg
That looks a nice shiny black to me.
Now to strip the spray paint off the scope pier and sand blast a few parts and get them coated.
 

savarin

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#51
No photos for the next bit but I decided to make a dedicated earth post.
I silver soldered two x 1meter lengths of hard drawn copper tube to make a 2 meter length, connected it to the hose pipe, turned it up full and started pushing it into the crap stuff we call soil here.
The top 500mm is dry sand/soil/gravel, next came a 800mm layer of dry clay finishing in fine sand.
Total time was approx 20 mins. Going through the clay was hard and was a sort of punch out a plug, lift to clear and re do.
I have never done this before and was totally surprised at how easy it was.
 

sanddan

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#52
I had to pound in ground rods for my shop back in the day. Code at the time required them to be 6' down and at least 3' apart. We have clay soil so it was a bear to get that deep.
 

ch2co

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#53
I'm impressed! What a project.
I don't remember, do you use electrostatic attraction in your spray booth? If so what do you use to power it, two balloons rubbed together or maybe a neon sign transformer? ;-}
 

savarin

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#55
I have a cheap gun from Eastwood with no choice of Kv.
The major test of large parts will be this week hopefully.
 

ch2co

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#56
Keepin' the fingers crossed.
You've gotta show us the results right away no matter how bad they are.;)
 

savarin

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#57
The very first powder coated project.
All the black parts of the telescope stand and I must say I was extremely pleased with the finish and not difficult to do although its a bit messy with excess powder to clean up after spraying even in the booth.
stand-1.jpg
Being gloss black it doesnt show in the photo but everyone who has seen it remarks on the glossy finish.
 

ch2co

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#58
Wow! beautiful job, and yes I can see reflections i.e. gloss finish. A major accomplishment albeit maybe a bit messy?
Very cool. Congratulations. The first time even!

Charles, AKA the grumpy one
 

savarin

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#60
Thanks Chuck. I am most impressed with the ease of use.
One lesson learnt is to make sure the hooks holding the items in the oven are strong enough to hold up.
The long section of the stand was held up with brass hook that straightened in the oven allowing the item to fall.
No damage to the oven but it did mar the paint at the top of the tube but it cant be seen as its covered up by the top aluminium casting. Phew!
 
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