Craig,
? Thanks for the info on your splash tank. I read all the posts and take mental notes so in the future I may refer back to them. For now my needs will be very limited. I was going to make a so called splash tank with a plastic container on a "see-saw" platform with a cam driven by a slow barbecue spit motor. I may still attempt that as a simple project.
Thanks,
Dave
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On 3/23/2019 9:47 PM, designer_craig wrote:
If you want to be quick and efficient doing your own boards build a splash tank.? I built one years ago and it did may boards before I quit doing them myself.? My tank could etch two 10" x 10" boards at once but I would not build that large a tank today.?? The advantage to a splash tank is the speed of etching due to the aggressive agitation of the etchant and the minimal quantity needed.? Bubble tanks usually take a lot of etchang and the bubbles tend to ad hear to board shielding the copper from the etchant.
I built my 12" x12" x 12"? tank from 1/2" plywood but any material would work.? The plywood was coated with fiber glass and epoxy resin to resist the etchant.? But one could make a tank out of almost any plastic just as well.??? The top was built from a piece of acrylic and removable by lifting off.? The edge where the top intersected the sides was formed with a jog step in the sides so splashing etchant in the tank would not splash out the joint, no seal was used just the jog step.? The bottom of the tank was slightly sloped from the left and right sides towards the center ( Ie there was a low spot in the center of the tank).??? You should not be thinking how a kitchen dish washer? or food? blender works)? Above the acrylic top I mounted a small fractional junk box AC motor coupled to 1/4" shaft that extended to the bottom of the tank.? There was a small acrylic block used as a lower bearing block epoxied to the bottom center of the tank.? A small strip of stainless steel was fitted to the bottom of the shaft (saw a slit in the shaft) possibly 1" x .5" in size to be the dasher.??? It only took enough etchant to cover about half of the dasher strip to sling etchant on all sides of the box.?? To hold the boards I used? a piece of acrylic that would slip down into the chamber, held by some guides against the left and right wall.??? I only had a board holder (two of them) on each end of the chamber.?? The boards were mounted to the acrylic pieces wedged by some small rubber suction cups.? The suction cups were easy to move around for different size boards and held the boards by their edges. Note: only one side of a board at a time could be etched, once the first side was etched the acrylic piece was lifted up and the boards flipped over to do the back side.??? With fresh (ammonium persulfate) etchant a board would etch in less than a minute and never tool longer than 5 minutes. ? Quick etching gives less undercutting of the traces.
I don't think stainless steel would work with copper chloride based etchants so one would need to use another material for the rod and dasher.
Now I just use JLC pcb? -- just can't justify the time, effort and mess against their quality, deliver and price.
Craig
