Compressed air source for testing models.

[Richard BParticipant @richardb44403]

I’m interested to know how others test smaller engines – I’m currently testing my Stuart Compound which I’m just finishing (and had quite a bit of trouble with setting up the timing etc).

I don’t have a garage type compressor with receiver etc which I really don’t have space or ongoing need for and making do with a 12volt car tyre compressor running off a spare car battery.

This has worked fine in the past for 10v’s and my Double Ten but the compound’s cylinders (low pressure 1 1/4″) are rather too much for the poor thing ! I’m initially testing both cylinders seperately to ensure correct timing etc.

I’ve seen larger versions on E bay with twin cylinders aimed at larger tyred SUV’s etc and considered obtaining one but not sure its the best solution.

What do others use – is a 240volt option available but still fairly small ?

Richard B.

[Mick B1Participant @mickb1]

I use a handheld Parkside thing from Lidl, sold in a set with a larger-volume lower-pressure type suitable for lilos, beachballs and the like. Battery capacity seems quite adequate for what I wanna do. But…

It’s noisy – it frightened the grandkids till they got used to it… 🙂

The quiet compressors are pretty expensive and take up garage space.

[duncan webster 1Participant @duncanwebster1]

You could use the spare tyre from a car as an air receiver. That is unless you don’t have a spare, just one of those cans of gloop. Worst idea ever.

[JourneymanParticipant @journeyman]

I use a small airbrush compressor. OK for small engines but has no reservoir so runs all the time. Not quite as noisy as the car tyre pump. Pressure from these small compressors isn’t a problem but the volume is. definitely needs a reservoir / tank / receiver of some sort.

John

[Howard LewisParticipant @howardlewis46836]

Depending upon the size of the model, the need may well be for volume rather than pressure.

A small compressor can produce upwards of 100 psi (6+ bar) but be unable to deliver a large enough volume of air to keep the model running, even at 15 psi (1 bar)

A hole 1.5 mm daimeter, fed through a pressure regulator, at only 0.3 bar, will pass enough air to keep my 1.5 hp compressor cycling between 8 bar and 5 bar for 50% of the time.

Howard

[Ady1Participant @ady1]

Compressed air is one of these things where we can get along without it most of the time but once you get it you use it more and more

I got a “silent” version for under 100 quid and amazon got me one of those connector and hose sets for ~15

There’s other bits I could get but I haven’t bothered yet

I think it uses a diaphragm pump system and it’s pleasantly quiet compared to normal compressors, up to 90psi without tweaking anything yet

Any regrets? None at all, I’d much rather have it around than not.

[Paul LousickParticipant @paullousick59116]

A steam engine requires a large volume of air/steam at a lower pressure to operate but most small air compressors supply a high pressure at a very low volume. Therefore you need one with a large reservoir tank.

An option tor run small model steam engines is to use a hand steam cleaner.  Shown running this engine with steam instead of air.  Inexpensive and sold at lots of home appliance stores.

[Thor 🇳🇴Participant @thor]

I use a silent compressor similar to the one Ady linked to. It works well for testing my small steam engines.

Thor

[Clive Brown 1Participant @clivebrown1]

Perhaps shouldn’t relate this but when, long ago, I completed my Simplex 5″g chassis, I had absolutely no means of running on compressed air. Solution was to connect to my propane cylinder. Ran beautifully. Outside of course!

Not recommending this by the way.

[JasonBModerator @jasonb]

As Said Volume is what you need so if your car tyre inflator has a piston smaller than your engine you are onto a looser. Even using a tyre or other form of tank will only last a while before the pump can’t replenish it fast enough. Plumbing the Compound as a double high may help as compounds never run as well on air as they do steam.

If all else fails

[martin haysomParticipant @martinhaysom48469]

compressor with maybe an extra tank. it need not use up space in your workshop, put it outside under a cover run the pipe and cable into your workshop with extra pressure regulator inside if required, reduces the noise too. mine is in a shed

[Jim Young 2Participant @jimyoung2]

Sorry for ‘blank post’ trying to turn off notifications.

[Neil WyattModerator @neilwyatt]

Bear in mind that compressed air will only give you approximate settings. Compressed air works very differently from steam, as steam is capable of giving up much more energy by cooling through expansive working.

While setting up a simple engine on compressed air will give workable results, the working principle of a compound very much relies on expansive working so you can’t properly tune a compound on compressed air.

Neil

[Richard BParticipant @richardb44403]

Thank for replies,

Yes I realise volume not pressure is my issue !

Have now run it initially as seperate engines – re-worked the low pressure double eccentrics as per Keith Appletons video – Mainsteam Models – don’t thnk I’ll ever bother with solid or pinned double eccentrics again – keep them seperate for adjusting !

Finally put the connecting pipe back on and it runs as a compound ! all the more amazing as I have not fitted the piston rings or packing glands and only a few gaskets !

I’m sure with the extra drag I’ll need to get a compressor – Ady, I had been looking at the Hyundai one you linked to – have you fitted a reducing valve as i don’t think it comes with one ?

Jason – although I do quite a bit of singing i think my lungs would not keep up with a compound !

Neil – my intentions are to run on air to set up and eventually steam and then with a fair bit of superheat to see what it does !

 

Richard B.

[JasonBModerator @jasonb]

I also have a Hyundai, the 50lts one. It has a pressure regulator and for just display 5psi is more than enough.

To regulate the speed an engine runs at I use reasonably cheap push fit pneumatic flow regulator fittings which control the volume of air. I made a simple manifold that can run several engines but a single inline one would do.

In all my videos after this that is how I’m adjusting the speed.

[Martin ConnellyParticipant @martinconnelly55370]

I’ve got an argon flow meter with flow control from a welding regulator set and a small water separator on my compressor. I know the compressor is not running on argon at 4 bar but the flow to run a Stuart Twin Launch at a low RPM is in the region of 12 litres per minute to give some idea of the volume of air needed.

Martin C

[peak4Participant @peak4]

@richardb44403 Where in the country are you?
I’ve not seen it since I moved house and tidied up, but I suspect I have a small belt driven compressor which could be adapted.
I’m in Buxton Derbyshire.

If you’re anywhere near, I could dig it out and take a photo

Bill

[Richard BParticipant @richardb44403]

Bill – thanks for the kind offer but i’m way down in North Zumerset.

I’ve bitten the bullet and ordered the small Hyundai compressor with tools – they had a 10% reduction so it helped  bit.

See how i get on – thanks all for help and comments.

 

Richard.

 

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