The latest laser cutting order arrived last week: boiler and frame parts.
This can only mean one thing: welding day!



The laser company has a 3D tube cutter which I thought would take the sting out of preparing the boiler tube.
Definitely more efficient than cutting all those holes on the mill although the inside of the tube is slightly contaminated with splatter.
Glad I found that out before cutting a bunch...
Swiss cheese anyone?



A test fit of the diagonal tube.



I want the hole tolerance for the brazed-in-place inserts to be tighter than the laser cutting process allows, so they are specified under-size by 10 thousandths of an inch and drilled to the correct size. They should probably be reamed, but I didn't get around to ordering that size of reamer.



Then I put a chamfer on the edge of the boiler tube using a grinder on the lathe.



The cap for the diagonal tube gets a countersink, some edge chamfers and is threaded 1/4" BSPT.



The cap weld-up :



... and then the hard part: welding around joints between the diagonal and main tubes.
This is particularly tricky as there are actually three separate volumes that must be purged with the argon gas.
I might try brazing these joints as well at some point when I have plenty of material on hand.



Welding is hard and requires lots and lots of practice that I don't get But all in all, the result isn't too bad.



After a generous application of flux, I can fire up the acetylene torch to set the inserts with silver braze from WeldingSupply.com - recommended by OldNuc - thanks Rich! After a clean up, I will put the ends on.

I would certainly not be embarrassed if I'd made those welds!

Ira

Nope, nothing at all wrong with that job. Welding Supply is a great source of all of those hard to find items at a decent price.

The process is fascinating. Raw elements panned by nomadic tribes from the stream beds of the Mongolian watershed are brought on horseback across the vast plains to a Tibetan village high in the foothills of the Himalayas. Offerings are made and, once the necessary purifying rites and rituals have been performed, the monks of the temple begin their work; their techniques unchanged for millennia. Young novices at the monastery use pestle and mortar to reduce the constituent ingredients to the consistency of sugar or very fine sand. Boys become men and the novices, following initiation, become monks and move on to simple tasks in the forming room. There, blocks of quartz, hewn with the traditional mallet, stone drill and wooden pegs from the living rock are painstakingly ground into hollow flasks: receptacles for the carefully measured, dull-grey blend of powdered metals. Once a year, at the culmination of the autumn festival, the lama, spiritual head of the monastery, leads the entire village in a procession, chanting and drumming, up the valley to place the finished forms in certain cavities in the rock at the foot of the glacier. As winter deepens the glacier advances, imperceptibly but inexorably, covering the flasks with a sheet of ice a mile thick. Crushed between the glacial hammer and the anvil of Himalayan bedrock, the ingenious geometry of the flasks focuses the already tremendous pressure, fusing the elements inside. In early summer, when the glacier retreats, the monks retrieve the forms, smashing them open to reveal the gleaming finished parts - a golden yolk inside each precious egg. Prized for the regularity of the bronze crystal lattice it yields, the three thousand year old Tibetan 'cold' fusion-pressure process achieves a purity and precision surpassing that of even contemporary German and Swiss heat-centric foundry methods.



While it may be a little slow, it is said that the best things come to those who wait. A new batch of castings arrives next week when I get back from holiday.

Thomas, here's a photo here of my antique, traditional Tibetan bell and dorje. The bell has a wonderful sound. When I first touched it, it felt charged with the blessings of the prayer rituals in which it had been used.

An extremely dry and amusing anecdote/metaphor update ...thanks for sharing, Thomas..

I still reckon that the customary wearing of a cilice belt wouldn't hurt....whilst nature/industry takes its course.

Gees...in Australia they even come in fashion colours..

Just looked at the manufacturing label on one....says "Made in Canada"

June and July were like molasses from the fridge as far as tangible progress is concerned.
I finally received what I fervently hope will be the last round of prototype castings.

The relatively straightforward cam casting is dimensionally correct and looks good to go.



The new group is out for material testing. Preliminary results look promising.



The mold was the right way around this time!
Fingers (and toes) crossed.

In the interim, I've been spinning a few other plates.

The new-and-improved second generation laser-cut frame parts are coming together.
For the production run I will likely order the base components pre-bent, but it isn't worth it for the prototype so marking and bending has to be done by hand. Bend radius compensation in real life has to be squared with the values from CAD.



Once, that little puzzle has been dealt with, the 1/8" thick base parts go into the 16 gauge V press brake!



Tool abuse . But the result is good.



I decided to add a new part to the frame design for mounting the SSR and the AC distribution terminal block.



Initially, I had intended to weld it to the frame uprights, but I didn't really think it all the way through. The SSR I'm using comes with a slip of flimsy paper in the box and one of those thousand page pdf choose-your-own-adventure design manuals online. Depending on a number of factors including the load, duty cycle and ambient operating temperature, it may or may not require a heat-sink mounted with thermal grease. At 1300W and how-am-I-supposed-to-know-the-duty-cycle-and-ambient-temperature-without-a-complete-thermodynamic-model-and-or-functional-prototype, I thought that it would probably be OK to stick it on the painted metal frame. That plus the added hassle of paint not being electrically conductive for the ground means would be better if the flange were made of aluminum - which of course cannot be welded to steel. Anyhow. It has clever little tabs for locating it on the frame prior to welding.



I also decided to add an mounting flange for an IEC connector inside the perimeter of the frame. I could have added a hole in the frame itself, but this way, the cable can be completely hidden if you have through-counter electricity and plumbing. The cutout relief at the bend-line makes the part both easy to fold and repeatable.



Laser cutting is my friend.



And lastly but definitely not leastly, the beta PCB-driven controller is coming along.
The PT100 probe is connected with screw terminals inside the box because of the risk of crimp terminals slipping off the very fine wires inside the cable. Everything else (power, SSR, solenoid, switches and lights) can be connected to the box without disassembly.



I added a real time clock with battery backup for timed startup and shutdown.
The home screen (the diagonal purple stripes are interference with the phone camera, you can't see them unless your eyes also have a refresh rate) now displays a verbose debug version of date and time.



Righto.

Thanks for the update! You're inching your way closer to the final prototype. Can't wait to see it!

bidoowee wrote: Laser cutting is my friend.

Indeed, this is a friend I wish I had. It all seems to be coming along so nicely; thanks for keeping us informed!

A few more inches gained towards the finish line of Zeno's race this week.
I can see the Tortoise now. He has a bumper sticker on his shell: "Only half as much left as last time."

Testing of the cam casting went well. The press really takes the sting out of this formerly arduous job. I just need to add so guides to keep the dies from rotating when you turn the handle.



100% compression of the spring.



The part survives the installation of the knurled pin and will now be tested in daily use in the studio machine. I'm gonna call this good; essentially no changes need to be made and the rest of the parts can go to finishing.

Another longish, but ultimately time-saving task is to build a jig for the frame weld-up.
I'm starting with some scraps of 3/8" 6061 aluminum which will suck the heat away from the welds as well as conduct electricity.
Using plywood isn't ideal (being combustible and all) but it is so much faster than metal.



To make room for the TIG welding cup and to avoid accidentally welding the aluminum instead of the steel, I cut out some notches in the aluminum bars with a 1/2" corn-cob hogger. I love this thing. It takes such an agressive and efficient cut that you almost don't notice when the it engages the material - but the dense cloud of chips that it throws on the floor kind of give it away.





The aluminum bars are installed with button head screws after careful alignment and then locked in place with plywood and countersink head screws for strength.



Welding the cross bars to the uprights is a little tricky as the bars are solid 3/8" steel and the tube is 1/16" wall.
Guide tabs for the back splash are also welded to the tube uprights while the frame is in the jig.
There was a little bit of burning of the plywood base close to the welds, but I'll just cut out those parts later.



I'm also welding all the mounting studs to the base this time to get a completely clean, fastener free exterior finish on the part of the frame that is exposed.

Stay tuned!