oddball thread size

[anchorman]

I have a set of kid's toys that is basically a wooden erector set with some injection molded ABS screws and nuts that hold it all together. I'm trying to make a few replacement pieces before I pass them on to someone, and was wondering if there is a "standard" thread size that matches these parts to be close enough for the job.

As near as I can tell, the threads are 10 TPI, and the outer diameter of the bolts/screws measures .400 inches +/-, with a minor diameter of 0.315 or so. The inside diameter of the nuts are .343 .345 depending on the part sampled.

I'm primarily looking for a tap to make holes, as threading the outsides is easy enough using a couple of different method. The closest I could find for sale is a 7/16 - 10 acme threaded tap (a size I haven't actually come across in any thread charts), but I was wondering if there is some other standard size that would be close enough for a kid's toy.

I know the easiest things to do would be to find some of the parts for sale online, or to just use standard fasteners, but that wouldn't be any fun, and I want all of the nuts and bolts to be interchangeable.

 

[Limy Sami]

Make your own tap from a piece of drill rod, .you have the male to get the correct profile, and a nut for a gauge.