JohnB. wrote:Powdercoat quality control is complicated alright. I've lost track of how many failures I've seen over the years. Rust creeping under the powdercoat can start with a single chip so I'm surprised you aren't using a decent grade of stainless for the cases if you are going with powdercoat considering the environment. It would also eliminate the rust issue while the cases are stored awaiting the coating.

Good point!
I was thinking this too.

JohnB. wrote:?..I'm surprised you aren't using a decent grade of stainless for the cases if you are going with powdercoat considering the environment. It would also eliminate the rust issue while the cases are stored awaiting the coating.

That is an excellent suggestion. Even a quarter of an hour prep time to remove the rust in a bead blaster is probably enough to offset the material cost. Also, the case on my 'European import' Aurora has chips and dings aplenty but the exposed base metal shows no sign of rust - leading me to suspect that it has some corrosion resistance.

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!

Beautiful!

Thomas, when's the next episode? This thread is one of my current favourites. Keep them coming!

@barny - thank you!
@arcus - lol - see below.


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.

Those cylinders were a lot of work but a nice result. You're getting closer to a completed machine. Can't wait for the next episode.

The smart way to fabricate the valve handles is to make them out of plastic using an injection-molding machine (actually, the smart way is just to buy them, but anyhow). However, as we don't necessarily do things the "smart" way around here and wood is rather difficult to melt, that method has been ruled out. Consequently, there are quite a few machining steps that have to gone through in order to make these individually. Getting the order of operations right is important because we might find ourselves 'machined into a corner' and unable to hold the parts before they are completed.

Starting with the foam blank cut to finished length in the lathe, I bored out the front and back interior profiles.



The front:



and the back:



Now, I want to put an outside taper on the back while the stock is still in the lathe. This is problematic as I will no longer be able to hold the back of the part in a chuck after I cut the taper. This calls for a stub or jig that fits the interior profile of the stock.

Drill and tap a hole in some aluminum round bar:





and then machine the tapped end to the correct diameter.



Check to see that it fits! In the background, you can see the work-holding setup for the mill: the stub will be held in a three-jaw lathe chuck which in turn is held in the milling vice bolted to the bed. A little recursive, but it has the advantage of being repeatable - the part can be taken out of the chuck and replaced without having to re-located the center point.



Now I can cut the taper.



All the operations on the lathe are done and I can move the part, securely fastened to the stub, over to the mill.





The milling program roughs out a perimeter to a certain depth and then refines the shape moving back upwards before stepping down to the next roughing level. The white rubber keeps the dust (mostly) within the range of the vacuum.



...down to the fourth roughing level.



... a few levels more and then I can take the part off the mill.



The threaded brass insert from the valve fits snugly in the foam version and will be glued in place for the finished parts.



I (heart) foam.

So, I have a question about seals.



Ok, not that kind. I've been thinking about the seal setup for the aurora and comparing it with some other solutions. The aurora uses two different W and V seals that are currently made by Faema.



Cafelat make a nice silicon version of the V seal, but I guess there isn't enough demand for the W. I am not worried about being able to find parts (there are plenty, plenty machines out there that need the W seal). But I was fooling around with a Flair, a completely manual lever, and it set me wondering: why this seal setup in the first place? What advantage, if any, is there of this type of seal over the much more common o-ring? After all, o-rings are completely ubiquitous in hydraulic and pneumatic cylinders with pressures a least a couple of orders of magnitude greater than the ten bar range.

This is a setup from a smaller-bored lever, I don't remember which.



Anyone have any thoughts?

Nope, fully agree with you. O-rings are plentiful and available in any size you want (as long as it's in AS568a). I've replaced the V seals in my Caravel with O-rings as well and they work perfectly fine.

Sure, X-rings are technically a bit nicer. But O-rings are available and plentiful. Maybe, maybe that x-rings will last longer, but that's only really useful in a commercial setting, where a bar can be down for an hour or two to let the machine cool down, exchange the seal and let the machine come back up to temperature.
https://o-ring.info/en/downloads/materi ... vs-o-ring/