Member postings for mick H

Hallo Martin. I take your point but a gas leak from any fitting will be equally not detectable. It will still go bang (under the right conditions) whichever (faulty) fitting I use.

Photo of the flow control on way.

Mick

I have used 4mm pneumatic push fittings for loco plumbing for a while now and find them to be cheap, reliable, unobtrusive and easy to connect/disconnect. Typical specs are up to 60 deg.C use and 10 Bar pressure and for use with water, oil and air. There is a really neat little flow controller in the range that I would like to use as a butane gas controller but I cannot find out whether it is suitable for LPG. The suppliers are very cagey about recommending them for this use and I don't blame them for not committing themselves to something not specifically mentioned by the manufacturers. But, I am also aware that things can be used quite safely for purposes not specifically recommended eg if water is OK, what about beer?

My experiments so far have been quite satisfactory but are there any experts out there with a point of view?

Mick

I am refurbishing a twin cylinder marine engine with 5/8" pistons fitted with O rings. One of the pistons glides down the bore in an smooth and easy manner. The other piston requires more pressure to push it down. I assume that it is most desirable to have equal resistance in both cylinders for best performance. I thought that I might "measure" the force required to send the "easy" piston down the bore by applying weights. Then I could possibly adjust the O ring groove depth on the second piston until the same amount of weight sends it on its way.

As a master of indecision, I then thought....."perhaps the "easy" piston is too easy and the stiffer piston is correct ?" In other words tighten up the "easy" piston ring.

Just how much force is optimal. Any ideas please.

Mick

I always used Eclipse blades because of their superiority but found that my supplier had sold out and could only offer me another make.....Bahco, made in Germany. It is sad to say and with great regret that I have to admit that the Bahco blades are imho better than the Eclipse by a good margin.

Mick

Thanks Brian. I shall try one out on a vertical boiler I am building.

Mick

That O ring check valve looks interesting. Is the O ring mounted on a spring loaded plunger?

Mick

Thanks Phil. Thanks also for the Searchable Index- very good.

Mick

Was there a previous series on a vertical boiler published in ME some time ago? I seem to remember seeing it in one of my bound volumes. I have started to plough through them but there is so much material I have given up.

Mick

I had an NSU in the late fifties and hated it. It was so "uncool" but it was needs must at the time. I would love to get my hands on one now though and I think it would now classify as "supercool". So well made and reliable although as I recall I was very prone to punctures as I couldn't afford decent inner tubes. The spark plug needed regular dewhiskering and having dewhiskered on one occasion I loosely screwed the plug into the cylinder head and forgot to tighten it up. Believe it or not the engine started with only about two of the threads engaged....a bit rough, but it started. Amazing. Saw one in the ring at the Carrington Steam Rally this year, going like the clappers with the blue smoke coming out of the exhaust.

Mick (Boston)

At the risk of boring the forum to death on this subject, I have had some further thoughts overnight (dangerous territory). I intend to make a boiler feed pump which will be actuated by a drop link from the rotary valve at the flywheel end of things. The pump will obviously be a load on the engine especially at the beginning of the delivery stroke. If the links were adjusted appropriately would this provide the necessary "brake" to stop the engine at the required place? Is there a method of calculating this or is it a trial and error exercise? As ever, your thoughts are valued.

Mick

What are you intending the engine for Ed?

Mick

Thanks Jason / Bazyle, That sounds good. Gauging the depth of the recess will obviously be the subject of trial and error. I was wondering about the inevitable "click, click, click...." as the plunger engages the recess but a plunger with a teflon tip might solve that problem. You never know, this could become an essential add-on for non-selfstarting engines. Thanks for the assistance everybody but any other suggestions still welcome.

Mick

I have been playing with it this morning and I have found that I can get 100% self starting on very little air (5-10psi) if I position No.1 cylinder at approximately 45 deg. after tdc. I can find no other position which will give me repeatable results. Perhaps a small cam....such as a round headed rivet....on the flywheel circumference with a light spring loaded plunger playing on the flywheel circumference might encourage it to stop in the required position. Would this be the basis of the idea that Bazyle refers to? Experiments continue.

Mick

This is the engine. How would your cam/spring idea work Bazyle?

Mick

Duncan and Bazyle......would you kindly expand on what you have said above. I will post a picture of the engine in the morning which might assist on the cam/spring and sprag clutch ideas.

Mick

Edit:- I was tinkering with the idea of a solenoid operated spring mounted rod which would "flick" the flywheel if necessary. Unnecessary complication agai I suppose.

Edited By mick H on 26/07/2018 21:37:40

Is there any angle other than 90 or 180 which although not guaranteed, might provide most likelihood of self starting?

The engine has a rotary valve by the way.

Mick

I recently purchased a small marine engine with 2 x 5/8" single acting pistons with 11/16" stroke. The cranks are at 180 degrees so that when one piston is at tdc the other is at bdc. The motor turns over quite sweetly with low pressure air. If the air is turned off then on again it will sometimes self start......probably about 25% of the time, but as the engine is destined for a boat it will be mighty inconvenient if the engine stalls midstream in the river.

Other than remaking the crankshaft and setting the cranks at say 90 degrees are there any other simple wheezes to promote self starting.

Mick

Thanks Jason. I did mention those woods and trees. Just interested in whether the chappie got it fixed.

Mick

No more than a couple of days ago there was a thread about a leak on a water tube on a vertical boiler. Has the thread been removed because I now cannot find it? Mind you, I am well known for not seeing the wood for the trees.

Mick