Cheddar Kompact – help please

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Cheddar Kompact – help please

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13 April 2009 at 02:32 #20176
Tony Couch
Participant
@tonycouch45334
Hello

I recently purchased a second hand Cheddar Kompact plant. It looked to be in very good condition but when I ran it on steam, one cylinder stiffened up. It frees up to an extent if I clean it out with solvent (I used methanol) and lubricate it but, after a few minutes running on air, it stiffens up again. I fear the piston seal on that cylinder has been damaged.

The piston and cylinder assemblies appear to be sealed units and the instructions say they were supplied that way from the factory.

Can anyone suggest what I might try to either verify the problem or solve it? Alternatively, does anyone know how the cylinder assemblies are fastened together?

I suppose a third option would be that, if anyone has a spare cylinder assembly for this engine or even a complete engine, I would be very interested in buying it.

I am very keen to get the plant operational and the rest of it is in excellant order.

Thanks.

Tony.
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13 April 2009 at 02:32 #7274
Tony Couch
Participant
@tonycouch45334
13 April 2009 at 16:34 #20197
Richard Simpson
Participant
@richardsimpson88330
Hi Tony,

I don’t know this model specifically, but I know a man who does so I’ll point him in this direction as well, but a few generic thoughts may be of use to you.

First thoughts are that is is tightening up when it gets up to temperature, which is not unheard of in a new engine, so you need to assume that it has not been run in and that would be your first step. Why it should tighten up when running on air I’m not so sure but I would suggest that you start of the process very slowly, using low air pressures.

Ideally an engine should be run in by either mechanically rotating the shaft by means of an external driver such as a lathe or a pistol drill or by compresed air. Either method allows you to free up the parts gently before running the engine on steam. If you have a compressor I would use that to slowly run the engine on air for anything up to four hours or so. During this time you will have to administer oil into the inlet, which I do by using a hyperdermic syringe into the rubber supply line. Don’t do this with the air on as it will blow the plunger out of the syringe and make a hell of a mess! Oil the engine every ten minutes or so to start with, going down to every 15 minutes for the second and third hours then every 20 minutes for the last hour. You can slowly increase the pressure and therefore the revs as well over this time and avoid high revs for the first couple of hours.

I use a light engine oil or general purpose lubricating oil because I actually want the parts to wear at this point. Using the highest grade synthetic lubricants will never allow the bedding in process to take place. Car engine oil is too heavy so something lighter such as hydraulic oil is a possibility.

After all this has been done you should find that the engine spins just that little bit easier and will rotate nice and slowly on a very low air pressure. Now you can have a go at running it on steam again. Now you will have to rotate the engine manually to get some steam oil circulated, then fil up the lubricator with steam oil and run it on steam at a low pressure.

I am hoping that your carefull running in will have freed it up sufficiently to now allow it to operate smoothly on steam.

As for dismantling I strongly suspect that the cylinder covers are pressed in as they are on my Hemmens oscillator so you would have to prise them out with a knife. I would avoid this for now though as I really believe that running the engine in will cure your problems and once you have removed the covers they are never quite as tight again.

If this doesn’t work and it continues to tighten up no matter how careful you are then you will have no option other than to dismantle it for a thorough cleaning and checking of all parts.

Just another thought, if this engine has a gland seal on the piston shaft that is adjustable then slacken it off during the running in period. It could be over tightened and causing it to bind.

Let us know how you get on and don’t be afraid to ask more questions.
13 April 2009 at 16:35 #20198
Colin Bishop
Moderator
@colinbishop34627
Can’t give you any direct help on this Tony, but there has been a series on steam engines by Richard Simpson running in the magazine, a couple of articles are on this website, and there are two articles on steam in the forthcoming issue of Model Boats due out this coming Thursday 16th April, both of which deal with maintenance and running problems.

Colin
14 April 2009 at 00:47 #20205
Tony Couch
Participant
@tonycouch45334
Richard,

Thank you very much for your prompt and very detailed reply.

It had not occurred to me that the problem may be due to lack of running in. When I bought the plant, it appeared to have been used but not for some time. There was congealed oil in the bearings and the o-rings on the boiler were perished. My first step was to dismantle the engine and soak all parts in methanol. This softened the dirt and old oil and enabled me to clean it up very nicely. After reassembly, I ran the engine on air for about an hour, stopping every 10 minutes to oil it and change direction. I used refrigerator compressor oil with a little molyslip in it so this may have prevented any wear taking place. After this process, the engine ran freely, turning over happily on 5 psi or so.

It was only when I steamed the engine that the problem occurred. Initially, it ran cleanly but started to stiffen up after a minute or two. After that, I had the problems described in my original post. It now requires 20 psi or more to even turn over.

In case it may be relevant, I used Saito steam oil (the green stuff) when I ran the engine on steam.

What I may not have made clear in my original post is that this is a twin and that the stiffness problem has affacted one cylinder only. The other one remains free and smooth.

In case it may help you or other readers to recognise the engine, here is a picture:

As you will see from this picture, the gland seals on the cylinders are not adjustable. It also appears that, as you suggest, the end covers of the cylinders are pressed in. I would still appeciate it if anyone familiar with this specific engine could confirm that they are pressed in rather than being screwed.

Any further suggestions anyone may have will be gratefully accepted.

Regards.

Tony
14 April 2009 at 07:40 #20207
Paul T
Participant
@pault84577
Hello Tony

You say that the engine is second hand, do you know the original owner and why they decided to sell it?
From your description it sounds as though something is slightly out of line and causing the engine to seize when it comes to working temperature.

Could the manufacturer throw some light on this problem and, as I am of the suspicious frame of mind, it is perfectly feasible that the original owner contacted them and discovered that the problem could only be rectified by fitting a new engine.

Paul
14 April 2009 at 10:17 #20211
Bob Abell 2
Participant
@bobabell2
Hello Tony

What a miserable little steam engine!………………..and it looks as though you can`t strip it down too!………………………LOL

I recommend you fill it with oil…in every joint and opening……………and run it in with an electric drill for about an hour…………….if it`s any better…………..do it again………….if not………….whizz it!

Bob
14 April 2009 at 10:39 #20212
Colin Bishop
Moderator
@colinbishop34627
Bob, I reckon that would totally ruin it! If it went together then it will come apart and it should be possible to rectify the problem once identified. It seems from what Tony has said that the problem is associated with expansion associated with the heat of the steam which should provides a clue. It’s a relatively simple engine so there will only be a limited number of possible causes. People with practical experience of steam plants like Richard should be able to help Tony to pin down the problem and suggest a remedy.

Colin
14 April 2009 at 10:42 #20213
HS93
Participant
@hs9317166
Have you got any way of getting steam oil in to the system ?as the compact would normaly have a displacment lubricator attached to it . and has anybody used WD40 on it to lay it up or to free it off if so it has distroyed the seal , give Gerry Watson a email him he assembled them at one stage at Cheddar he also sells new seale and undertackes repairs but is a very helpful Chap

[email protected]

Peter
14 April 2009 at 10:47 #20215
HS93
Participant
@hs9317166
After re reading the post I think you have distroyed the o rings with the methanol and the compresor oil may have adatives in that effect nitrit seals I think the bottom glands where glued using a locktite adhesive.

Peter

Edited By HS 93 on 14/04/2009 10:48:50
14 April 2009 at 13:31 #20224
Richard Simpson
Participant
@richardsimpson88330
I’ve just read the second post from Tony and I think it could be a possibility that the methanol or the compressor oil could have damaged the seals. Refrigerator compressor oil is actually very hygroscopic and unless kept in meticulously clean sealed containers it will absorb water moisture over time. It also has a lot of quite volatile additives so there is a very real possibility it has not agreed with either the gland seal or the piston seals. It is not actually recommended to play around with this stuff with bare hands so I would strongly recommend that you don’t do this again.

My initial suggestion would be to go through a process of running in as I have explained above as you have nothing to loose by trying it. If this doesn’t work then it looks like a strrip down and a new set of seals but I now thing that something has been damaged by your lubricants and probably will not fix itself.

I would be very careful about what type of oil to use in such engines as many industrial based lubricats are simply not compatable with this type of application.
14 April 2009 at 18:44 #20225
Bob Abell 2
Participant
@bobabell2
Hello Tony…………………..BE CAREFUL!

If you strip this engine down………………..How can you be sure that the end caps won`t blow off after you have reassembled it!

Bob
14 April 2009 at 18:55 #20226
Colin Bishop
Moderator
@colinbishop34627
Bob,

Check your personal messages, you may have received one from Richard Simpson. Unless you have personal experience of this engine it might be better to leave the advice to those people who who have or who are expert in these matters. I’m not so I would not want to muddy the waters by offering specific advice to Tony on a subject that I only have a generalised knowledge of.

Colin
14 April 2009 at 19:14 #20227
Bob Abell 2
Participant
@bobabell2
Thank you Colin

My only advice to Tony was…………..Be careful

Bob
14 April 2009 at 19:20 #20228
Colin Bishop
Moderator
@colinbishop34627
Bob,

Actually you told him to put the thing in an electric drill and bin it if that didn’t do the job!

Careful?!

Colin
14 April 2009 at 19:52 #20229
Bob Abell 2
Participant
@bobabell2
Colin

When I said be careful………….I was referring to the danger of end caps not being securely retained…………….ie………….a dangerous situation!

Bob
14 April 2009 at 21:19 #20230
Richard Simpson
Participant
@richardsimpson88330
Gents, to help out here a bit, there are a number of engines such as this one and Hemmens oscillators with cylinder covers held on by a tight fit only. The trouble is that if you remove them and then clean up all the parts you will inevitably loosen the fit which is far from ideal.

Consequently your only options if you have to remove them is to thoroughly clean up the mating surfaces without removing any metal, i.e. don’t use abrasives, and then completely degrease the joint with a strong solvent such as Methyl Ethyl Ketone (MEK), probably spelt wrong before every one writes in, which is a solvent used in plastic pipework from plumbers suppliers. Then use a thick bearing lock Loctite liquid, which will ensure that it doesn’t come adrift again in service. Of course it will be quite a challenge to remove them again in the future, which is why you want to do this as infrequently as possible. Be very careful with the Loctite, one spot in the cylinder and life will get very difficult.

To be honest I have always been cautious about press fit covers but they have been used on a number of engines and I haven’t heard of anything horrible happening with them. If the worse comes to the worse the engine will simply stop and worse case scenario would be if the inlet port was open on the opened cylinder. If the control valve was simply shut off there would be no further escape anyway so I don’t think it is going to be a horrible scenario such as a glass breaking.

Keep us informed with progress Tony and don’t be afraid to ask further questions.
15 April 2009 at 04:29 #20234
Tony Couch
Participant
@tonycouch45334
Hello All

I am overwhelmed by the many responses I have now had to my call for help. Thank you all.

I accept that the oil I have used may have caused the problem but, if that is so, I am surprised. Many years ago, I was a projector mechanic by trade and we sucessfully used this oil for numerous different types of projector where it came into contact with all sorts of plastics and other synthetic materials. I cannot now remember the exact name of the oil but it was made by Shell and I think it had a name like “rotax”. It occurs to me that if it was the oil, the same problem would have occurred in both cylinders yet only one is affected.

It would help to know what sort of material Cheddar used for the seals in these engines. If anyone knows what it was and, even better, whether that material may be affected by methanol or synthetic oils, I would be very pleased to know.

Someone suggested that the stiffness may be due to mecahnical misalignment. That does not seem to be the case as, when I remove the cylinder assembly, it is clear that the stiffness is in pushing the piston back and forth.

Someone else asked about the origins of the engine. The complete plant was purchased new from Cheddar by a collector some years ago (not sure how long). He died last year and I purchased it from his widow.

One possible explanation which has just occured to me is that the original owner may have tried to lap the vavle face on the cylinder in question. The assemply instructions specifically warn against this for the very obvious reason that it will inevitably result in abrasive getting into the cylinder. If this is what happened, it would explain why the problem is occurring in only one cylinder. Would this be consistent, however, with the problem only coming to light when the engine got hot?

The conclusion I am coming to is that I will have to dismantle the offending cylinder. If this reveals that the seals are damaged, does anyone know where I can obtain replacements, either original or suitable substitutes?

I appreciate the warnings about the need for care in reassembling the cylinder if I do dismantle it. A technique we used to use in similar situations on projectors was to lightly pop with a centre punch one of the surfaces which have to be pressed back together. This effectively creates a mild interference fit which, in conjunction with a little loctite, makes a sound joint.

If anyone has any further suggestions, they would be greatly appreciated. In particular, if there is anyone who has had actual experience in dismantling or servicing this particular engine, I would be very interested to hear their views.

Regards.

Tony
15 April 2009 at 08:03 #20242
Paul T
Participant
@pault84577
Colin

Was it really necessary to publicly vilify Bob for his comments when a simple “read your PMs” would have sufficed.

This is after all an open forum and therefore any advice given must be treated as objective and, as such taken with a “large pinch of salt”

You might be surprised to learn that Bobs proposal to “fill the engine with oil” does actually have historical precedent as when steam engines were first being developed some engineers bedded them in by opening all the ports and valves then filling the cylinders with a light oil and turning the engine (although not with a drill) for a hundred revolutions.

Bobs only error was in trying to apply this principal to a model steam engine with sealed cylinder heads.

Paul
15 April 2009 at 08:32 #20244
Richard Simpson
Participant
@richardsimpson88330
Paul,

I can assure you that was not his only error as I explained in a PM to him. If he is going to come out with posts such as the one above he will have to expect some suitable guidance and unfortunately Bob decided to make his comments publically. No one is questioning his advice to fill the engine with oil but I had issues in the way it was presented to a newcomer to the hobby who has come to us with a problem and is looking for help.

Tony,

I would suggest before you take it apart that you go through a complete running in program as I have suggested above. If this engine has not been properly run in from new this could still be a possible cause of the problem, which is supported by the fact that you say it runs OK on air but siezes up after a time when running on steam. You have nothing to loose by doing this and a lot to gain so I would have no hesitation in conducting a thorough and prolonged running in process, prefferably on air, for at least four hours with regular oiling and see how it goes.

I would also very strongly recommend that you do not ‘pop’ the surfaces to tighten up the fit. You might get away with this on larger bearing housings but the problems are that you end up with point contact and a greatly reduced interference fit and with small brass components there is a real danger that you could deform the parts in the process. I have seen it done in the past with bearing housings and it is really only a botch to avoid having to either replace or sleeve the housing. I wouldn’t call it good engineering practise and I wouldn’t recommend it to any one who works for me on larger items but on small brass parts you may well end up with something that you cannot sort out.

I’ve sent you a PM regarding the engine.
15 April 2009 at 16:54 #20261
Paul T
Participant
@pault84577
Hello Richard

I fully understand the extent of Bob’s comments and the errors contained within and I also sent a pm to correct him however I would never have considered making my observations in such a public way as Colin did, which I considered to be a tad heavy handed.
My feelings are that this is an open forum and as such every member is entitled to their own opinion and if an error is made then a tactful and private enlightenment is in order and not a public disparagement.

But as I have said these are my own views and perhaps other members might have a different opinion.

Paul
16 April 2009 at 00:28 #20266
Richard Simpson
Participant
@richardsimpson88330
Hi Paul,

We seem to be confusing opinions here with attitudes. I fully agree that every one is entitled to have thier opinion and I actively encourage all to share them with everyone else. Unfortunately here referring to a newcomers recent foray into the steam world as a “Miserable Little Engine” and suggesting that if filling it with oil does not work then he should “Wizz it” is not an opinion. It was an attitude that was neither helpful nor supportive.

My communication with Bob would indicate that he agrees and we have moved on so continuing to discus it further is now only drawing more attention to it, which of course for the very reasons you state above, your own comment to Colin may have been better sent via a PM.

I think we would be more gainfully employed trying to help Tony get his engine up and running!!
16 April 2009 at 16:20 #20281
Paul T
Participant
@pault84577
Hello Richard

Yes I was just making a point at poor Colin’s expense by not sending a pm………water under another bridge.

On a more productive note I have been looking at Tony’s engine and it’s pressed cylinder heads, if removed I believe it should be feasible to silver solder or braze them back into position but I would value your expert opinion.

Paul
16 April 2009 at 18:15 #20283
Bob Abell 2
Participant
@bobabell2
Hello Paul

No chance of using any heat…….spoil the seals!

This in my suggestion……………….A plate at each end, held together with 6BA tie rods

Bob
16 April 2009 at 18:54 #20285
Richard Simpson
Participant
@richardsimpson88330
Paul,

The only time I have dismantled one of these I went through the process I described above and used Loctite. Bearing Lock is actually a very strong compound and, if prepared properly I’m sure will do the job. The trouble with any heat treatment is that you stand a chance of deforming the item or, more likely, damaging the seals.

If you are unfortunate enough to have a cylinder cover that has become slack then your only options are either an arrangement as Bob has suggested above, make a new cover or come up with some arrangement that can introduce a screwed fastening. All a bit messy and fiddly but I’m sure that with the right care and attention Loctite will do the job safely enough.
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