My electronic end caps were also loose. I figured the same thing that the 150 watt laser cutter that I used, cut a larger Kerf, making the dia. a little less. I had not potted the wires in the one end cap, yet, as I was making sure everything would gotogether. I also had used 1/8 inch pipe plug in one end and 1/8 inch vented pipe plug in the other end. I remove the pipe plugs and inserted a 3/8 bolt with fender washers on both sides of the end cap and a nut to tighten everything down on the end cap. I then put the end cap in my lathe using the 3/8 bolt in a 3 jaw chuck. I made the o-ring grooves bigger ( 0.135 inches wide and a little deeper). I also order new o-rings from McMaster-Carr (9396K227 OD 3.75in, ID 3.5in. ). These are a little wider .125 inch in dia. I kept cutting and testing for a good fit. I lightly beveled the ends of the clear plastic electronics tube with sandpaper for easier assembly and applied Vaseline on the o-rings. I realize this solution is only possible if you have a lathe in your shop.1979-endcapwiredsidelargerendview.jpg (112 KB) 1980-endcapwiredsidelargersideview.jpg (108 KB)
For those of you who have access to one, 3D-printing the whole end caps eliminates the cutting and lining up of all the acrylic disks. Additionally, many printers should be able to do the whole electronics internal chassis in on unit, eliminating all the gluing of connections and allowing for customization at the CAD stage.
Thats a good idea! I have a cheap 3D printer that prints ABS plastic but didn't think to try it.
Man, I'd love to see how that turns out. The lining up of the acrylic disks isn't really that difficult, though, if you use the syringe as a dowell pin. Also, I'd be concerned about the ABS from a cheap 3D printer being the main point of structural integrity for the e-housing. If that fails... yikes!!
If you decide to do it, post pictures!