fitting decorative plastic metric cap onto imperial hex nut

We have some railings for our deck that are white metal. They are secured to the deck with stainless nuts that measure 9/16" (or 14.288 mm) across the flats of the nut. I have found some white plastic decorative caps made of nylon to fit onto the nuts, but I can only find metric. They are M8. under the cap, there is a recess that is hexagonally shaped. The caps just push down onto the metal nuts. The dimension across the flats in the cap is 13mm. Essentially, the stainless nuts are .05 inches (or 1.288 mm) larger than the nylon recesses in the caps. Will I be able to fit these onto the metal nuts with a little persuasion or some heat applied to the caps? Thank you. Dave

 

These what you're looking for? 9/16" White Hex-Caps - bolt caps for 9/16” hex heads | Pro-Dec

As to your actual questions... I think you'd have to try it; perhaps you can request a sample. As a class, Nylon is fairly dimensionally stable and also has a fairly high working temperature range (although there are varieties of nylon with varying properties). So I suspect it will be hard to get those items to "stretch" enough to fit.

Another option would be to go a little bigger and affix with a touch of construction adhesive...enough to keep them on but still allow them to be pried off if necessary.

 

Thanks. I ordered the M10 size which has 17 mm across flats dimension. The nuts are .562 inches across flats or 14.29mm. They are 16.51 mm from point to point. The M10 are 17.77. I thought this would allow the caps to be very slightly loose and amenable to a dab of sealant to hold them on. I then went down my basement and found a 9/16 nut and tried to put it in a 17 mm socket. It was extremely loose and spun around. Am I missing something?

 

In theory you have a little over a mm clearance, but the socket will be a little oversize so actual will be a little more. If it was a 12 point socket I would think that would be enough to let it spin easily. The actual decorative nuts may be a little tighter; in any case, a dab of adhesive will hold them well enough.

 

Thanks, Paul. Now that you mention it, it was a 12 pt socket. I will update when I get the caps and try them.