Post Caps For The New Entry Stairs

Hello everyone. Hope this finds you warm and safe. Sorry for the long hiatus but I’m just emerging from my hideyhole. Saw my shadow the last two times and went back in.

I’ve got the process down for the post caps I’m making for the entry stairs here at the condos.

First I had to make the RTV silicone molds. The model is a 2×10 cut down to 7-5/8″ square pyramid with a 3/4″ skirt around the bottom to insure that no moisture gets to the top end of the post. The skirt slopes outward at 10 degrees to make it easier to remove the cap from the mold after the hand layup and finished coat is formed.

Next I build a box to house the silicone that will be the outside (female) portion of the mold. Here’s the male plug and the matching female mold. At this point I should point out that the RTV silicone pretty much sticks to nothing except itself. This makes it easy to pour the molds in steps but the surface of the mold has to have enough texture for the RTV to encapsulate and stay attached to the mold. I used small screws with a countersink head that I left standing about 1/8″ high for the RTV to grab onto.

Then I cut down the male plug by 1/4″ on all eight sides and coat it with RTV silicone. It is subtle but you can still see the wood grain.

The backside of the mold.

Now we are ready to actually make a cap.

I do a hand layup with epoxy on the male RTV silicon mold. After it sets up enough to stop flowing I mix up 300ml of epoxy, add some black and white pigment and pour it into the outside mold. Then I brush some of the epoxy onto all surfaces of both molds and insert the inside mold into the pool of epoxy in the outside mold. It wants to float so I have a set of 1″x2″s that I use to hold the inside mold in the right position.

Alt first it was a two day process but after a few, I got it down to the process described above and that takes about two hours plus curing time.

Here’s the finished cap blank. All that is left is to trim the vertical sides and drill two mounting holes. I wanted the wood grain and a few flaws to make it look like painted wood.

Currently have five of the nine made. After I have all the blanks made it will be on to building the jig for trimming the sides.

OK, it’s Thanksgiving and I’ve finished all the blanks and began trimming the sides. Of course, first I must build a quick jig to speed up the process and “simplify” things.

Then, after some final mods, I moved the process outside.

Any of you that have worked with fiberglass know how dangerously annoying that dust is. I use a painters mask, overshirt  and gloves and that worked well to prevent the “itch”.

All caps now need a hand cut at the corners and final sanding. I’m taking a break here to clean up my tiny shop.

After some final filing, a light sanding on the skirt, a light coat of wax all over and drilling holes to attach the cap, I pronounced them done. It took less than an hour to put them on. Here’s the view from the deck outside my door.

There’s ten caps in total with a half cap where the railing that I’m leaning on here runs into the wall. They are held on by two screws with decorative caps that are small plastic buttons with a torx nipple on the inside to hold them on. I’d seen them before but couldn’t find them online. Finally, I found some in the UK. 50 Each of grey and black cost $20 plus $20 shipping; but they got here in 5 days.

One final note. The best way to make these would be with a vacuum bag; unfortunately, my vacuum pump is down for repair.

It was lots of fun but I don’t think I’ll be going into production any time soon.

Snow is all gone down here from sea level to over 1000 ft; but that won’t last.

Stay warm all y’all.