Thursday, May 19, 2011

A Stake for a Miniature Bird Bath

My wife found this miniature bird bath somewhere or other. It's quite an elegant little garden ornament, but it has no stake to stand it up by. So, unsurprisingly, it's on my workbench waiting to be attended to.

At the centre of its underside there's a round boss with a poorly threaded 10-32 hole in it. I applied a plug tap and a bottoming tap to it, and now it's properly threaded for the full 9/16" depth of the hole.

A three foot length of 5/16" diameter plated steel rod that I have on hand will make a stake for it. I just have to make one end pointy for going into the ground, and fit the top end with a 10-32 stud. It'll make for a pleasant little machine shop project.

- - -

And no sooner had I started the machining of the pointy end of the stake than I ran into a little complication. When you have a long piece of slender rod chucked in the lathe, the end of the rod that's hanging out the back of the lathe's spindle is free to flail about quite wildly. That action needed taming, so I came up with this -- the rag bearing. Details are at the link just provided, but here's how it looks.

I was pleasantly surprised by how well it worked and how easy it was to set up. It let me peacefully get on with machining the pointy end, and I soon had this.

Now it's time for the 10-32 threaded end. There are a number of ways such a thing can be done. An obvious one would be to turn down the rod end's diameter and thread that directly, but that struck me as bearing too close a resemblance to work. There's an easier way that will give an excellent result.

I'm quite partial to interference fits and the use of pins in permanent mechanical assemblies, so I'll use those methods here.

First, I cut the head off a 10-32 screw to obtain a 1 1/8" long 10-32 stud. Miking the screw threads' major diameter showed me 0.182". A No. 15 drill is 0.180" diameter -- there's my interference fit. I squared off the top end of the rod and bored a N0. 15 size hole in it to a depth of 9/16". Here are the rod end and the stud ready for assembly.

I chamfered one end of the stud a bit to make it easier to get it started into the hole. The two nuts are jammed together there so I can hammer the stud without damaging its end. Just prior to assembly, I coated the stud's threads with CA adhesive, and then hammered it in. And just for good measure, I added a 1/16" diameter roll pin to secure the stud for good. Here it is assembled and with the roll pin in place.

The roll pin was a cheap one from an assortment from Princess Auto. I haven't been too impressed with the dimension tolerances of their small diameter roll pins, and this one went in a little more easily than I would have liked. I flooded it CA adhesive to secure it.

There's a little embellishment you can do on a roll pin installation to make the pin ends all but disappear, and I went ahead and did it to this one. Here's how it looks.

That's a length of 0.040" wire inserted and glued with CA adhesive. Once I've painted this, there'll be no way that water can get into the pin's centre.

So, the thing is ready for its flat black paint job. As luck would have it, I recently built a spray-painting lathe for painting just this sort of thing. I just have to make up suitable adapters for this rod to go onto the lathe.

- - -

And here we are. Following are two shots of the rod in the spray-painting lathe.

This will be a breeze to paint. I'll just have to touch up the very tip of the pointy end where it will have been masked by the tailstock cup centre that I made by centre-drilling the head of a 1/4" carriage bolt.

- - -

Here's a shot of the finished interface.

I'll do a final assembly of this and the decorative elements on top with blue threadlocker, and it'll be ready for installation.

- - -

And here it is in its new home.

I took this shot after it had already been outside for a week or two, and the thing has rusted a bit. I think I'll just call that 'rustic charm', and leave it at that. I had a picture of it when I had just installed it, but I was embarrassed by it because the bowl wasn't level, so I deleted the picture. In the meantime, I rigged this little bubble level to help me install it properly. I just got that done today, so that's why you see a photograph of a 'new' birdbath with a level, but rusty, bowl.

- - -


Addendum -- A Paint Job

By the end of the summer, my 'rustic charm' attitude had worn a bit thin. The factory's black finish really was worthless -- the birdbath acquired many splotches of orange surface rust that looked awful. A proper paint job was in order.

Spray painting small items is often a breeze; each coat takes about as long as it takes to get the can of paint well shaken. The challenge, though, can be to contrive a way to hold and manipulate an item while you paint it.

This birdbath lends itself to being rigged for painting relatively easily, because each of its three components has a threaded hole in it. The two flat head screws can be supported by a small block of wood with shallow holes drilled in it. Here's a view of the screws, and the two ornamental bits after painting, still mounted as they were for painting.

Those support 'stalks' are 3/8" diameter dowel, with lengths of M5 screw fixed in holes drilled in the ends of the dowels. The items pictured have received a coat of grey primer, and two coats of flat black enamel. They can go hide out in a safe place now for the paint to harden.

The birdbath's bowl has a 10-32 threaded hole in its bottom for a similar rig, but I'll have to come up with a stronger stalk construction. The bowl is much heavier than the ornamental pieces. I'll make something similar to the steel stake I made earlier.

- - -

And here we are.

That's a 6 1/2" length of 12mm diameter steel rod that I had on hand, with a length of 10-32 screw force-fitted into its end. Now I have a way to handle the bowl for painting.

I need to stock up on little Dremel wire brush wheels before I can proceed with this. What I'd like to have is a sand blast cabinet and an air compressor the size of a Jeep, but I don't have those things, so wire brushing will have to do. Here's a view of the inside of the bowl. You can see where I went at it a bit with a Dremel wire wheel.

That 'orange' rust is very light and comes away easily, it's just that there are countless little crevices to attend to. I'll photograph this again when it's ready for painting.

- - -



The rusty bowl got me thinking about acquiring a sandblaster. I wasn't all that keen on the idea, because my air compressor is barely adequate to power one. Then Princess Auto came up with a little 'spot' sandblaster for $12.99, and I figured that might be worth a gamble. It worked out reasonably well; the story of it is here.

- - -

And here's the cleaned up bowl just freshly primed.

I'll have it fully painted today, and it can harden for a week or two. Then all the components will be ready for reassembly and installation.

- - -

SUNDAY, MAY 13, 2012

All Done and Back in the Garden

Much better. It no longer has that 'post-apocalyptic' look about it.

# # #

# # #