Another one of those Bob Hope/Bing Crosby Road movies? The two of them singing "We're off on the road to Powder Coat"... ? I used to love those movies when I was a kid. Of course it's not one of those.
My last post about my shop shenanigans ended with me saying that since some of the parts I'd been working on were going to be visible in use, I thought I'd powder coat them. The next day, I dutifully got everything spread out to work on, read everything I had in my instruction manual, and everything I could find online. (There's an excellent summary of how to powder coat parts online from the Houston Home Machine Shop Club (pdf), if you're interested). The first thing I did was prep the parts mechanically; made sure the edges were all broken (not sharp) if possible, then wet sanded with 220, followed by 400 grit. Then I started working at trying to get ready to spray and hang parts.
This is something that needs to be done with the least amount of handling possible. The biggest way powder coating gets good coverage is that the paint is charged with static electricity by the gun. While you can get some paint adhesion without it, coating works best if the gun is grounded to the work; the paint literally jumps on to the piece. If the colors stand out well, you can see the powder cloud moving toward the work. Still, while the powder is clinging to the metal, it's just a powder that can be knocked off the part if you bang it around or (especially) touch it. The easiest way to make sure you don't mess them up is to spray and bake on the same metal rack with the parts grounded to the rack by bare wire. This is where I discovered my first problem. My bake-out oven is a plain old toaster oven, and it has a limited selection of positions for the rack. The oven maker envisioned food on top of the rack; I'm hanging metal pieces below it! (If I put parts on top of the rack, they'll have bare stripes).
So now I had a problem. How do I raise that rack, which is recessed into the sides of the toaster oven? Thankfully, as I like to say, I know someone with a machine shop.
I first thought of simply making some standoffs and mounting the rack on them, but that rack is too wide. You can see the grooves it slides in: about an eighth inch deep on both sides. I thought about cutting the rack narrower, and that might have been an acceptable idea, but I eventually thought I'd just get a piece of perforated sheet metal with lots of holes in it and mount that. My local Borg store had this stuff in stock - and it's almost exactly what I was thinking of. All I had to do was cut it to size, and my jig saw cut it like a hot knife through butter.
I made some 5" tall standoffs from some 1/2" diameter round aluminum bar I had, threaded them 8-32 down the axis, and then found that they were too tall to clear the burner on the bottom. So I swapped the back two 5" standoffs for some 3" ones I had made for the CNC project. Voila. Here's one of my big parts in a fit test. Tons of room - that motor mount above fits on this one over the big hole - the mount is actually a bit shorter than this end cap.
Rarely do I run into someone more obsessive than myself....!ReplyDelete
Seriously, congratulations on your fine work. I make a few specialized woodworking machines, but since they are to make money with, the aluminum normally ends up raw. Guitar work, on the other hand, gets really detail oriented. Hard to figure why, they get played hard and dinged up anyway.
Thanks - I think. Seriously, I have a friend I used to work with who retired with her husband to the family farm. Way ahead of me and younger than me. We were talking about something once, might have been jewelry, and I said, "I'm not anal-retentive enough for that". She said, "Don't sell yourself short". I still get a laugh out of that 15 years later.Delete
You do guitars, though? Acoustic? Electric? You may have seen I have some interests down those roads, too.
Mostly electric, and repair work. Years ago I was really into it, and after a career in woodworking have recently slowly stated getting my feet wet again. Just finished a complete neck replacement on an acoustic which came out well.Delete
Keep us posted. I'm curious as to how well a "Home Brew" powder coat job can come out. You're the only guy I know that will RTFM, and follow it!ReplyDelete
I would amend that to say most guys will RTFM only after messing up. (and that is a little close to home)
Can you just sit the oven up on its back end, turn it on, then hang your work down into it without ever having to take it off the charged wire?ReplyDelete
I'm not sure I see the advantage, but I could stand it up (or make something to hold it up). But I wouldn't take the ground wire off the parts the way I'm doing it. I just disconnect it from the paint gun.Delete
I guess I'm thinking that by sitting the oven up on its tail, you would not only be able to hang your work in the heat without removing the ground, but would significantly lessen any chance of marring the finish with lines from sitting on a rack.Delete
Dang. If you're going to create a run-on sentence, go big or go home.
Nevermind. I see what you did. Probably would have helped to read the front page first...Delete
I was putting a new thermometer on the gas grill, and I noticed the grill goes way past 400 degrees F.ReplyDelete
Yes, you would lose the accuracy of the electric toaster oven, and I will have the read the reference you quoted, but the grill is outside and has a very large inside area.
I will look at my eight dollar, thrift store toaster oven and begin the modifications.
DON'T DO IT!!Delete
The fumes from the paint are flammable, and an open ignition source is that last thing you need.
Oh come on, man! Here we were about to get a brand new "Hey, y'all, watch this!", and you decide to be a killjoy???Delete
I have learned to take good advice, the propane fired powder coating oven is now off the list.Delete