Rain forest part 4 - all cylinders

Today on the bidoowee channel: we are making cylinders!

I was holding back from tackling the handles for the steam and h.w. in the hopes that I could find something off the shelf. I've been looking for months and I have a number of candidates, but there are problems or complexities with them all so I am admitting defeat and making them out of tree. I wasn't particularly happy about having both wood and plastic in the design in any case, so there is an upside.

All that to say, we are not out of the woods yet ;-)

I cut another section out of leftover lumber and ripped it into two squares profiles.

Then I knocked the corners off to get closer to the final shape. 

Then I put the dreaded four jaw chuck on the lathe. I hate these things - what a pita: use a dial gauge to measure one side of the stock. Rotate the workpiece 180 degrees without upsetting the gauge, measure again. Move the stock by adjusting the jaws by half of the offset between the opposite sides. Repeat until it is correct or you get bored. Then do it again for the other two opposing sides. Tighten everything down, then readjust because the stock is soft. Requires the patience of saints.

I did some fairly careful planning for cutting these parts because they are reasonably complicated. I figured that I can get all the pieces out of two 29 1/4" lengths. The octagons just fit between the chuck and the tailstock of the lathe and, with about 1/8" to spare between the thread chasing dial (which I thankfully no longer have to use 'cause CNC is the just the bees' knees for threading thank you very much) and the pillow block, there is enough travel to machine the entire length. 

The setup for the machining requires good dust extraction to keep all the crap from getting onto the ways and into the screws. A metal lathe is really not the correct tool for this job, but I don't have an alternative. So, I found a high tech solution: elastic bands and bailing wire to hold the vacuum nozzle in place and scrap of plexi held with a magnet.

A number of passes were required, but the carbide bit is fairly sharp and leaves a reasonable finish on the wood. 

I also made a blank out of foam so that I have an expendable test piece that wont break any tooling during the next phase of machining.

Result? Two wooden dowels and a foam blank. Total excitement.

Rain forest part 3 - rail corners

Next episode in the on-going subdivision of my piece of exotic ligneous plant: the rail corners.

First job is to put shoulders on the exterior of the round over.

Then the same thing on the inside, finally cutting out a left-over square of stock.

Then, using exactly the same setup as before on the chop saw they get cut to length.

Then, it was time for the biggest head scratcher of the day: how to chamfer all eight interior corners without it taking all day. I'm sure there is a more efficient way to do this, but I don't know what it is.

A quick trip trip on the round-over plus a bit of sanding and they are off to the finishing department.

Done!

Rain forest part 2

More clues...

I chopped up that fabulous piece of lumber and sent it out to be dressed at Atelier Clark, the cooperative shop wing of the Clark artist run centre and general benevolent force in the universe.

Back from the planer, jointer and shaper:

A close-up of the profiles.

Two squares, one with a round over, two different rectangles and one length of left-over.
Of course, I changed my mind on the design and had to laminate a some extra material to one of the profiles. After which I added shoulders to both sides.

Then I made a simple jig to hold the shouldered profile at an angle to the (ripping) blade.

And then I cut off a little tiny wedge that I know is useless, but wont be able to throw away.

On to the chop saw with a block plus a piece of round rod to set the length.
The rod is removed before the cut is made to allow space for the part to move away from the blade safely. The circular form of the rod means that dust/chips can't get between the end of the stock and the block thus guaranteeing a consistent length.

... et voila, the rough part. 

Rinse and repeat 21 more times.

And now I also have a lovely collection of wedgy off cuts that will never ever leave the shop.

Adding a matching shoulder to the top and bottom.

By now, I sure you have all figured out what this is for... but if not, here is a test fit.

A little head-scratching was required to come up with a quick way to chamfer all four corners so that they don't interfere with the inside radius of the sheet metal.

... finally, 22 cup warmer rail stops...

... which all have to be finished with a tiny round-over bit and some old-fashioned sand paper.

Home stretch! The tung-oil finish. I love this stuff. Non-toxic and easy to work with. Just brush it on, let it soak in and wipe off the excess.

And here, after about a day spent more in figuring out how to make them than actually making them, they are.

Rain forest part 1

Teaser for the next installment of the build: 16' of former rainforest.

Sheeeeeeet metal part 4 - powder coat

End of September update: progress has been made on a number of fronts! 

I discussed the auto-fill circuit with a friend who is an electrical engineer. He agrees that in theory at least, an AC circuit is better than DC for this application: "The only potential drawback over an 'AC' based capacitance system is that the probe is always positive and the pot is always negative". In practice however, a DC circuit can be made to work with little or no compromise by limiting the current that passes through it. His suggestion is to use a bipolar transistor which, depending on the components, should limit the current to 1 or 2 uA. Lowering the duty cycle to 1ms per second by strobing the power to the probe may or may not be necessary. In any case, once a layer of scale builds up on the inside of the boiler, all electrolysis bets are off. To be continued when I get around to buying the required parts!

Something much more exciting: after a long delay because of things getting lost in the post, the POWDER COAT PAINT ARRIVED! 

Time to build a paint stand! Two cross bars with pins to fit the holes on the top of the cover: 

...and a pair of U-shaped legs formed with the bender.

Some quick welds...

...and the stand is done.

Unfortunately, I don't have much documentation of the actual powder coat process. I did it at a friend's shop and it was a bit of a mad rush. Also, because he is set up to paint smaller things, applying the powder took four hands, leaving none for the camera. As with most painting, the hard part is the preparation - you know, Saturday afternoon you decide to paint the living room. First you move out all the stuff: the couch, the tv, 10 years of magazines you never read etc., then it's cleaning and putting masking tape on all the trim and every last switch and electrical outlet, then Sunday just after Home Depot closes you realize you forgot to wash the  &*^*%$ing roller and brushes last time so now your whole house is upside down until you have another free weekend... Can you tell I love painting?

Prepping for powder coat is still arduous, but the end result is so much more satifying. First, I sanded the entire inside and outside of the cover to remove every last trace of rust. Then, the part has to be completely de-greased. I started with a commercial water-based de-greaser and then finished with 99% isopropyl alcohol. Then it's into the oven so that the metal can off-gas. As this is mild steel, it turned a pretty color after what is essentially also an annealing process.

Applying the powder itself relies on creating opposing electrostatic charges between the paint particles and the part itself.




After application the part goes back into the oven to melt the polyester resin so that it forms a permanent bond with the substrate.

The date on the first drawing for the cover is the 4th of February 2017. So after eight months and twenty more minutes in the oven, this part is DONE! I think that we might just be starting to see some light at the end of this tunnel.