Introduction: Prepping a Bike Frame for Powder Coating With Logos
I was given a nice Specialized Allez frame that just happened to be the right size for a girl that I am somewhat fond of (in the spirit of understatement). The frame was damaged and I did not really care for the stock Specialized aesthetic, so I stripped the paint off, added some logos and had the frame powder coated anew. The process is toxic but straightforward, and the results are not bad....
Step 1: Strip the Paint
There is not much finesse in this step, but there are a couple of tips. The first tip is that most places that powder coat things will also strip them for you. I was quoted $65 for the job of stripping the paint off of my frame. Naturally, I am far too stubborn (stupid) to recognize the value of this and opted to do the stripping myself.
Ok, so for the actual tips:
1) Get the Red Jasco - the really nasty stuff
2) Use _Neoprene_ gloves - Jasco will eat through everything else
3) Have a lot of scotch-brite on hand to aid in the stripping
4) A set of jewelers' files also help get to the bits stuck in the welds ... but will do bad things to the files.
The process of stripping the paint took me about 10 applications in various places. You wipe the Jasco on, let it sit and then rub the paint off. It is gnarly - do this outside.
Step 2: Cut Out the Logos
Instead of using stickers, I wanted a more textural and permanent look, so I cut the logos out of 0.0625" aluminum plate (6061-T6). I did this with our water-jet cutter. I know that this is cheating, but it is also rather inexpensive to hire a shop to do this.
If you are even more stubborn and would like to cut the logos out by hand:
1) Print out the logos
2) Laminate the paper to the aluminum plate with spray adhesive
3) Rough cut the logo with a jig-saw
4) Finish with jewelers' files (the same ones we wrecked whilst removing the paint)
A couple of suggestions for drawing curvey things that can be cut with waterjet software:
1) Simplify the curves as much as possible (get rid of extra knot points)
2) Omax has a curve simplification tool that is quite good
3) Omax also has a minimum radius tool that can fix tight corners
Step 3: Form the Logos
The logos need to be formed to the shape of the frame. I did this using a piece of stainless round stock and an aluminum form. I used a hydraulic press to create the force needed, but a shop vice would likely be sufficient.
Step 4: Adhere the Logos
Once formed, the logos need to be bonded to the frame. The difficulty with this part is the choice of the adhesive given that the powder coater will cure the frame at above 400 degrees F. Most epoxies burn at these temperatures, but standard JB weld does just fine up to 500 F. So, despite a wonderful selection of aluminum adhesives - Hysol, 3M Aluminum Series....etc - I choose JB weld.
The best way to affix the logos would likely have been to vacuum bag them to the frame. I was too lazy for this, so I used a clamp and clear packing tape. The nice thing about clear packing tape is that it will not bond to anything (that I have found yet). This makes the clean up easy.
Try to put a small amount of epoxy on the logos as you adhere them to minimize the finish work after they cure. I found that the finish work (getting rid of excess resin) was best done with a dremel.
Step 5: Finishing
Once the adhesive has cured, come back in and sand out the edges of the logo with sandpaper. Be careful to not use too rough a grit - it is easy to put deep scratches in aluminum. The most coarse I used was 320.
Step 6: Powder Coat
This is the easy part: take the frame to the powder coaters. I had great luck with West Coast Powder Coating in South San Francisco. AJ at West Coast was able to simply wipe the paint off of the surface of the logos before curing.