What's cool about plating is, only your imagination is the limitation, and fixturing. On the right is a backplate I chromed for an engine, where the rod likes to ride off the crankpin and rub. I wanted to see what I could get away with by doing some simple taping and fixturing. As you can see the results are great but, there is some build up on the edges.
  Once the basic principals of plating is understood, problems like these can be avoided. Picture this, pull your car up about 10 feet away from the front of your garage at night, and turn on the headlights. Now pretend your headlight is the part being plated and the headlight pattern on the door as your cathode. The rays at the bright part of the door or, the same area as the part come straight however the the weaker rays outside of the bright center, still deposit chrome but only at the closest point which, in this case is the edges. The way to prevent this is to focus the rays or "lines of action" straight or, funnel them by making a plastic/something tube, with small holes to allow the solution to flow through and the gassing bubbles to flow out, and the anode capping the open end of the plastic tube or, it could be even larger becasue the rays will be deflected by the tube.  
  
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Results from the trials
  Well, the first liner was a bust! After running I noticed some scratches on the piston through the exhaust port. Upon inspection, I noticed the the chrome had peeled away from the ports, right at the edges. I made another liner and again plated like I have a steel or, ABC liner with about .001" of chrome per side but, this time I deburred a bit more and chafered the ports a bit more before I chromed. After I inspected and took a hard look at the edges of the ports and saw, that I had broken through and signs of flaking in a couple of areas, no need to try that liner.
  It would seem that with  the aluminum liners, adhesion seems to be a problem, even with proper preperation, compared to a steel or brass liner, just doesn't like a thin plating probably because, it's not as conductive as brass or steel.  I guess I should treat it like and M&M candy, build up that nice hard thick coating to protect the soft and delicate inside. So, with the next liner, I'll build up about .003" per side figuring, I'm taking off between .0005"-.001 per side when I hone.
  The results were perfect, it allowed enough buildup around the ports after honing to prevent the flaking,
  
  Next is my attempt to flash chrome a crank. The reason I wanted to do this crank was because of the rear bearing fit, it was spinning in the inner race.
  I wanted to build a fixture to accept many different types of cranks so, I come up with the lower unit which the crank bolts to and and plenty of vents for circulation. Next is the anode which is a tube of lead that snugly fits around the lower unit and is long enough to adjust to the length, of different cranks. And last, is the upper unit which is designed to block off the " lines of action " from the excess anode material on top. Note there's a little tongue built in to rest upon the crank pin and hopefully prevent any excess buildup on the edges.
  I'm trying to build up about .0003 on each side for the bearing fit and about the same for the crank pin.
  The results were somewhat mixed. On the area along the main body of the crank, the plating was some what tapered. The crank web attracted the chrome that was meant for the bearing areas so it only received about .0001. The crank pin received chrome on the outer part but was void on the inside where, the web attracted the chrome deposit.
  I t would seem that there's no easy way to do the task. It seems that I would have to isolate the areas that I need to plate and block off those areas closest to the anode and I don't want to plate. I could use tape or " stop off " paints to accomplish the end but, I worry about the contamination after the electro cleaning and sulfruic acid dips which would probably eat away the paints. If I paint after the cleaning, rust would develope before it has a chance to dry.
  So I believe that " hard " tooling is needed to accomplish the task. I'll make up some caps to cover the web area, with a hole in one to let the crank pin peek through, and a seperate anode washer to chrome the pin placed closer.
  Something else I've always wanted to do is, chrome the OD of a bearing. I think it's beats buying a new case for that engine that has a loose fit on the rear bearing also, I wanted a better fit on the rear bearing for the K&B .40 that I use for Quickie Rat. For those who know the engine, it's a slip fit into the case and tends to move around a bit. Photo to the lwer left shows the seperate pieces to the fixture, note the bearing closed up by the brass pieces. Photo to the lower right shows the assembly, notice the open areas for the free flow of chromic solution while plating.