What type of compressor do you use to power your engines?

[CeteriParticipant @ceteri]

I am completely new to model engineering, i'm interested in it as it was a hobby of my late fathers. I have a few of his old engines and would like to get them going running. I know the best way to run these is steam, but can anyone suggest a small air compressor that is suitable to run these engines (they are mostly Stuart models).

what do people use?

Also what do people use to attach the air hose to the engine?

[CeteriParticipant @ceteri]

[mechman48Participant @mechman48]

I use a small spray compressor ( off eBay ) for my oscillators & Stuart models plus a Clarke Ranger with a 24 litre tank for general use, noisy ( uses the volume up at a steady rate ) but does the job. I would like a 'silent compressor' 'Clarke or Bambi' but too expensive for me. I know of members who have built their own silent ones from refrigerator compressors but it's the purging & & safe disposal of the refrigerant gas ( CFC's ). Usual disclaimer applies.

George.

[CeteriParticipant @ceteri]

Thanks George, I was wondering if an air brush compressor would be enough to power them (perhaps something like this would be suitable? Also do you use anything to attach the air hose or can it just be pushed on?

[MikelkieParticipant @mikelkie]

the refrigerant is already exhausted when it's removed from fridges so the compressors is ok to use, new ones has not been gassed yet.I run four of them into a common receiver very quiet can hardly hear them

[JasonBModerator @jasonb]

Single fridge and the silent type compressors seldom deliver enough volume of air to run much so you are better off with a small but noisy spray compressor as George suggests with a displacement of around 8CFM and a FAD of nearer 4cfm. Even then on something like a No1 you may find it wanting. Lidl and Aldi often have cheap ones.

[mechman48Participant @mechman48]

I use pneumatic push in fittings from eBay ; Just type in pneumatic push in fittings in the address box & it brings up pages full of fittings. I can't seem to link it at the mo' ?. I use the 6mm OD x 4mm ID nylon tubing size from the compressor regulators via the tubing to the model inlet branch, usually just pushed on a brass tube at the inlet manifold.

George.

[JasonBModerator @jasonb]

Same as George, if the engine has not got a thread that the fittings come in then I just make up an adaptor. I have a mix of 4mm, 6mm and 8mm OD tube to suit the various size engines that I make.

[CeteriParticipant @ceteri]

Thanks George, that's really helpful. I did wonder if you could just push a tightly fitting tube over the air/steam inlet, i didn't know if it would make a good enough seal. JasonB that setup looks great! i like how you can power multiple engines at once.

[mechman48Participant @mechman48]

Protected browser stopped my link…

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2323847.m570.l1311.R11.TR12.TRC2.A0.H0.Xpneumatic.TRS0&_nkw=pneumatic+push+fittings&_sacat=0

George.

Edited By mechman48 on 25/01/2019 17:14:43

[I.M. OUTAHEREParticipant @i-m-outahere]

Has anyone made a unit from a automotive aircon compressor and an electric motor ? I know here in Australia you could buy a compressor unit to pump up the tyres of a 4WD. It consisted of a small two stroke motor and a modified aircon pump off a car – the modifications were mainly for lubrication of the pump . If run from an electric motor it would be almost silent .

Just a thought .

Ian.

[Paul LousickParticipant @paullousick59116]

You do not need much pressure (10-30 psi) but need a lot of volume. The little tyre inflating compressors, etc are the opposite. High pressure and low volume of air.

We sometimes move full size traction engines with air but need large diesel compressors like the ones that power jack hammers. Even then we have to charge the air receiver to full capacity and only move slowly or keep stopping to build up pressure again.

I have run my model traction engine that I am building on air. A bit bigger than a Stuart and has a 10" dia boiler using an 8cfm compressor. With the compressor air tank charged to 90psi, it will run for 20 seconds before it runs out of air. Steam contains much more energy than compressed air and expands differently, because of the latent heat.

Paul.

[Mick B1Participant @mickb1]

I've posted this before, but it shows an engine with a moderate swept volume (7/8" bore x 3" stroke) running from a 12V tyre inflator. The battery has since given up the ghost, but Lidl's handheld cordless compressor gives the same result.

**LINK**

I put a 5/16" thread on the inlet pipes for all my models so that tyre pumps will fit. The noise is enough to make the grandchildren jump.

 

Edited By Mick B1 on 26/01/2019 09:23:30

[HowiParticipant @howi]

there are two types of airbrush compressors, piston type and diaphram type, you need the diaphram tytpe as they have a larger air volume (but lower max pressure – about 40lb). get the one with the largest air volume.

just bear in mind though that they will only run fairly small engines – Stuart No. 10 or double 10 max.

bigger air compressors are more costly and VERY noisy unless you are prepared to pay megabucks.

have a look on ebay to get an idea of whats available and at what price.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Paul Lousick on 26/01/2019 07:29:38:

You do not need much pressure (10-30 psi) but need a lot of volume. The little tyre inflating compressors, etc are the opposite. High pressure and low volume of air.

…

 

That's right, but you can shift the output towards high-volume low-pressure by adding a reservoir between the pump and the model engine.

With a foot-pump, an ordinary 2L fizzy drinks bottle will do – there's no danger of anything nasty happening because the human is in control. OK for a quick check, but working a foot-pump soon gets tired.

A motorised pump with a reservoir is more convenient and less safe; it needs to turn off automatically when the reservoir is at max operating pressure, and back on again when the pressure drops. Additionally, there needs to be a regulator between the reservoir and engine, and a couple of pressure gauges and a throttle would be nice too. The reservoir has to be suitably strong with a drain-cock and reliable safety valve,

A quiet affordable pump well suited for supplying air to model engines doesn't seem to be on the market. It may be because most domestic requirements for low-pressure high-volume air are met by fans. For this purpose fans aren't much use because they churn inefficiently at engine pressures.

Instead people adapt things like air-brushes and a variety of less suitable pumps. Given the need and the fact we all have machine tools, it's odd that no-one has designed an engine compressor yet – or have they? It would make an interesting project!

Dave

 

Edited By SillyOldDuffer on 26/01/2019 09:57:27

[CeteriParticipant @ceteri]

Thanks everyone great info, having a look on ebay, does this look suitable? It’s a diaphragm type, I guess it will need a regulator buying for it too:

**LINK**

[Ian S CParticipant @iansc]

A pump type available here in NZ quite cheap is for inflating air beds, this would probably be ok on very small motors. For small motors I have a small medical type diaphram compressor capable of 30 psi, but to just test the motor to see if it works I just connect it to a 5L garden spray pump(armstrong power).

Ian S C

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