If it scares off cats I’ll take two.

That is awesome.

Loved the build thread on the mig welding forum, especially for the ingenuity of how you built things with what tools you have or could rig up.

Thank you!

How did you make the outer case and stand?

The outer case is a sheet of 0.5mm stainless steel bent into a tube with an end cap of the same material spun over a plywood former.

The stand is welded up from some aluminium sheet, ground to be pretty & then anodised.

It’s easy to come out with statements like the above, and give the impression that the outcome was assured. However, the truth is that I had no idea whether / if the result would be OK, but I’m chuffed to hell that it came out how it did.

If you want to make stuff, then start making stuff. You will learn.

You are way to talented for my liking op!

Superb stuff mate.👍

Wow.
.
.
Nothing further to add

I don’t know what the fuss is all about, it’s not exactly rocket science is it Dr Von Braun?

Very very cool!

That. Is. Amazing.

as the home made compressor wheel is limited to ~95k RPM.

Huh?

as the home made compressor wheel is limited to ~95k RPM.

Huh?

The limiting factor is the stress in the turbine disc which is operating at 5-600°C. The stresses due to centrifugal force peak at the hole in the centre of the disc, and are approaching the yield strength of the material – go too fast, and the disc bursts!

I believe that decent stainless steel (310,321, etc.) is usable up to ~80,000 RPM, but suffers from creep in the blades. The turbine discs for commercial model engines are vacuum cast from temperature resistant nickel alloy (Inconel 718, I think) which is both very strong and very resistant to creep. Turbines the size of mine seem to be very reliable up to ~130,000 RPM.

The best material I could lay my hands on was a nickel alloy called ‘Hastelloy X’ – it’s better than stainless, but not as good as (say) Inconel 718. I came up with my own RPM limit based on comparing the various material properties.

Chapeau

Meanwhile i’ve checked instagram about 1000 times. I wonder if my generation will get anything done ever? Chapeau.

If you want to make stuff, then start making stuff. You will learn.

Love this mentality! Just jump in the deep end and learn to swim.

you want to make stuff, then start making stuff. You will learn.

Takes on an ominous tone when you are talking about melting metal. You end up with your workpiece welded to your clamps and the worktop on fire.
Or in the case of a homemade spot welder, blacking out the entire county. Which is okay cos the neighbours could keep warm from the embers of my house.

It’s not pointless, discovering how things work for yourself is important learning. Noisy…. Yes but a cop noise!. Polluting, not fuelled on butane but….well yeah.
. Completely awesome though! I’d never have thought it possible to make in a shed. Hope balanced does it need to be?!! To run at 85k rpm!

Amazing. Scary, but amazing 😂👌

Just thinking about Rolls Royce firing a load of chicken (I think to simulate a bird strike), into the engine for an A380, just to break all the fan blades off and to make sure that the outer casing did not rupture and contained all of the energy and thousands of loose bits of metal.

Thanks for the interest and nice words 🙂

Ho[w] balanced does it need to be?!! To run at 85k rpm!

As good as you can get it! 😀

It’s only been statically balanced – the compressor wheel is a commercial turbo part and should be very well balanced already; it is a shrink fit on the shaft so it should be concentric; and I did my best to make sure that the shaft was true (machining between centres, etc.), so if everything is assembled carefully (and all the spacers, etc. are dead parallel), the only thing that *should* be out of balance is the turbine wheel.

The turbine wheel, shaft and rear bearing are balanced as an assembly – you can rock it in its bearings to find where it settles, then grind a bit more off the blades in the heavy spot.

The balancing method that worked best for me was one described in Kurt Shreckling’s original book: You hold the bearing at the back of the assembled shaft / turbine between finger and thumb, gently spin the turbine up using compressed air and feel for vibration as it slows down. You then repeat the test with a small piece of tape stuck to the turbine, moving the tape around until you find the spot where the vibration is least. If this is better than the bare disk, then you grind a little bit off at the opposite side to the tape, then go again. When you get close, the lack of vibration is really noticeable.

It sounds long-winded, and I wasn’t really looking forward to it, but in the event, it went quite quickly – a couple of short afternoons and I got to the point where I could tell the difference when a double layer of strapping tape (~120g/m^2) about 8mm square was added at the root of the blades (R=22mm). I’ve just worked out that this is ~0.03 gram.cm = 0.013 gram.inches which sounds surprisingly good – I suspect some luck was involved. It really surprised me how smoothly the turbine ran.

(There is a containment ring built into the rear of the engine, btw!)

Chuffing amazing! Somewhere I’ve got the plans and instructions for building a pulse-jet, but I’ve never had the means or facilities to make one. 😕

Disappointed at the lack of single-crystal fan blades… it’s like you’re not even trying!

When I opened the thread I assumed it was assembled from a kit and you were being a bit grandiose saying you had ‘built’ it, but no – amazing bit of work. All the chapeaux!

Thank you! 🙂

Somewhere I’ve got the plans and instructions for building a pulse-jet, but I’ve never had the means or facilities to make one.

I’ve been hoarding pulse jet plans too, and now I have a welder 😉

Now that really would annoy the neighbours!

Very, very well done.

Needs a:

Right, your next challenge, should you choose to accept it, is to build two more, and mount them on the back of a car. Like this bloke did with his Tesla!

https://uk.motor1.com/news/552659/tesla-models-jet-engine-acceleration/

🤣

This is amazing work!

Best thread on mig welding!

I’m glad it’s got containment!

That mig welding thread has turned into a right time sink with more than a few tangents.

That mig welding thread has turned into a right time sink with more than a few tangents.

Sorry about that ! 😀

Brilliant. I would be dead within seconds of attempting this!

I was ready to point out that assembling stuff isn’t the same as making stuff, but you made it – very impressed!

Sorry about that ! 😀

Don’t be, I’ve enjoyed it immensely.

After something of a hiatus, I got my act together and set the engine up for liquid fuel.

It works! 😀

Did you ever figure out how much thrust it generates? Assuming not a lot unless your Workmate is securely bolted down.

Mount it on a little truck held back with a spring, and calibrate it with weights and mark a scale on a piece of tape on the bench. Should be easy.

Did you ever figure out how much thrust it generates?

Not yet – I intend to mount it on drawer sliders (or similar) and use a luggage scale similar to what you suggest.

It’s supposed to generate about 40-50N thrust (the higher figure at 105,000 RPM which is probably higher than my turbine wheel will withstand – I reckon 98,000 revs – so I’ll be pleased if I get >4 kg).

One step at a time though – it needed liquid fuel to develop any power at all, now I’ve got to sort out a reliable tacho and more volts to the pump so I can take it closer to disintegration 😀

Amazing!

Certified awesome! Lovely work, that’s a piece of sculpture, even when it’s not running.
Somewhere I’ve got a book from back when I was at school with plans for a pulse jet, which I always wanted to build, but never had the means, nor skilz, to ever really carry it off.

😎👌🏻🎩

I do love the still frame that youtube has chosen for you.

Is it possible to run one of the commercial ECUs on this?

Did you ever figure out how much thrust it generates? Assuming not a lot unless your Workmate is securely bolted down.

From experience, about 3kg of thrust will start to make an unweighted workmate a bit wobbly. A few bricks on the base / bag of soil / sack of spuds / etc, will stop it going anywhere. Doesn’t need to be bolted to the floor.

I do love the still frame that youtube has chosen for you.

Is it possible to run one of the commercial ECUs on this?

Thanks 🙂

(Spoiler alert: It wasn’t youtube that chose the thumbnail 😉 )

I suppose that it could be used with one of the commercial ECUs, but it currently lacks all the bells-and-whistles that the ECU would expect. Off the top of my head, I’d need to add an electric starter; electronic RPM sensing; a glow plug or sparker for ignition; more permanent EGT probe; gas solenoid; and probably a pukka metering pump – it’s not a route that I’m intending to go down currently.

I’ll add a bit of weight to the Workmate next time… Just in case. 🙂

Fair enough, I did wonder how much additional widgetry they might need. Stick with analogue 😉

If I were you I’d also consider adding eye protection!