Member postings for SillyOldDuffer

I not sure anyone who calls Atomic Number 13 "Aluminum" can be trusted on this important question. In the US a tube is a valve and they don't know what an earth is. Vive la différence!

Cheers,

Dave

Tidying up is fatal. As far as I'm concerned it renders things invisible. And it's so annoying when stuff I lost by tidying turns up out to be in plain sight - a month or two later! Scanning with a torch CSI style whilst constantly repeating the name of the missing item helps but I'm pretty hopeless. Forgetful bloke with machine tools might make a good sitcom.

Great minds think alike. I fiddled with the displacer just as you suggest this afternoon. It didn't make much difference but that may be because a bigger problem is masking the effect.

Nonetheless I was pleased with today's improvements. Although the engine still won't go faster than 80 rpm I increased the run time per boil from 6 minutes to 26 minutes with more careful sealing, balancing of the flywheel and "running in". The next big thing is the flywheel. It wobbles because the axle hole is oval at one end. Not sure how that happened but I admit to being the only suspect. It's a workshop job to fix and I'm not up to it until recovered from an exceptionally severe case of man-flu.

Dave

Is this just the English language playing games with us again?

English has upwards of 250,000 words happily stolen from just about everywhere in the world. So I can say "I pulled a full-on schadenfreude haka outside the bungalow's gazebo when I saw the naff old-school henna tattoo on that hooker's derriere. " English is a complete mongrel and all the stronger for it, but it's not always consistent or logical.

Pipe is Old English and Tube is Latin. They have similar root meanings. Over the years english speakers have used both to to add subtle meanings to their blatherings. That's why we need ducts and conduits as well

Nope pgk pgk. The elusive polystyrene must have transferred to an alternative dimension to join an Axe, Travelling Steady, Stopwatch, Camera Charger, yesterday's new bottle of Meths and my only copy of Machinery's Handbook. Not all is lost however: I know exactly where to find the Haynes manuals for all the old bangers owned by my family since 1970. I shall never need any of them again.

Edited By SillyOldDuffer on 04/03/2016 14:16:53

It does! I would never have admitted to doing such a terrible thing without Rod's brave example. Perhaps we should start a "True Confessions" thread.

Cheers,

Dave

Edited By SillyOldDuffer on 04/03/2016 12:09:24

Thanks for the congratulations: your encouragement puts the icing on my cake! I get a real buzz when something I made myself works. Much preferred to the slough of despond I fall into each time a mistake adds to my scrap bin.

Today slow progress because I have a stinking cold and getting chilled in my 6C workshop doesn't feel like a good idea.

Experimentation after small tweaks reveals that the engine still only runs slowly for just over 9 minutes from a boiling start . There may be a problem with my seals because modelling clay softens with heat. Methinks a small leak may be developing as the top plate warms up. Consequently I've ordered some silicone tubing as suggested by AJohnW. The top plate warms up more than I like so I may blacken it and replace the steel pillars with something less conductive.

I found an article on the engine by Jan Ridders in the ME archive this morning. It's in #4329, July 4 2008. Unfortunately the free plan isn't in the digital magazine - must have been a pull-out.

Many thanks for the hint that Jan can be emailed and that he has a website. (My earlier research didn't find it for some reason.)

Cheers,

Dave (atchoo)

I've just finished the evening with a smirk on my face. The engine runs! It looks a right mess but it's going. Special thanks to Trevor, Ian SC, Howi and Gordon with apologies to anyone I forgot : there was overlapping good advice.

Problems fixed were:

1. Displacer replaced with 4mm balsa and carefully fitted to the cylinder with a gap of 1 or 2mm. Adjusted to nearly hit the lower plate on the downstroke.
2. Plasticine type modelling clay works as a sealant, at least as a temporary expedient. Wallace & Grommit taught me everything I know about making gadgets. Slight leakage was fixed by smearing extra clay into the outside gap between upper & lower plates and the acrylic tube cylinder.
3. The flywheel was more carefully re-balanced with blobs of modelling clay in lieu of blu-tac. The engine went without doing this but the improvement was obvious. More needs to be done to the flywheel.

My coffee-cup is a vacuum type that holds heat much longer than an porcelain mug. At the moment the engine only runs on near boiling water. It goes for about 10 minutes. Don't ask how I know that it is still unpleasantly hot when spilled onto one's gentleman parts. I suffer for my art.

Before steps 2 and 3 it was obvious from the feel of the engine that it was in a better state. With heat applied It span much more freely in one direction than the other. In the forward direction a flick would result in up to 20 seconds of rotation, a significant improvement. Although the engine slowed down quickly I noticed that it was rolling gently past tdc rather more than could be explained by energy stored in the flywheel.

After fixing the minor leaks I spun the engine several times each time re-flicking it impatiently before allowing it to stop. After a fortuitous distraction I returned to find the engine still ticking over gently. It runs much more slowly than I expected - a stately 80 rpm dropping to about 45 rpm before stalling. Is this normal? I seem to remember seeing similar engines at exhibitions turning a lot faster. There will be no danger of it taking off when I add a propeller, ho, ho.

I shall have another go at it tomorrow. The flywheel isn't properly true and I think the balance can be improved. After more "running in" it needs serious cosmetic attention.

Thanks again,

Dave

Wow guys, thanks very much. I repeated the leak test using water with a drop of washing-up liquid to make it wetter and some red food dye to make it easier to see. The engine's lower plate was immersed for 5 minutes.

The result may explain why the engine wouldn't run yesterday.  (Water Hammer!)

The cardboard displacer was ruined.

Stripping down the engine revealed more problems due to acetic acid corrosion. See what it did to the polish of the power cylinder bore!

It looks worse than it is, fortunately Duraglit made a huge improvement. The end of the piston was rusted again but the damage isn't serious.

I went out and bought Balsa and a Flat `At. Wearing a traditional cap in the workshop will multiply my meagre skills. Sadly I found that my traditional local ironmonger has stopped trading and I was unable to easily buy more silicone sealant.(I've gone off RTV Instant Gasket because of the fumes.) I've decided temporarily to use modelling clay as a sealant. It 's like plasticene but rather softer. I use it very successfully it to weather protect the nuts and bolts of an antenna system: it's clean, lasts outside for years and is easy to remove.

Noting advice above. I'm off to make a balsa displacer. Now I've spent money because of it I fully expect to fall over the missing polystyrene in the next 5 minute. I have the wherewithal to make a hot-wire cutter and may well end up trying it. Some of the other ideas are now in a queue because I don't want to change too many things at once.

Very many thanks for the intel that the engine works but is difficult possibly due to a design issue. I'm starting to feel that everything has to be "just so" before it will run. Watch this space!

Cheers,

Dave

Edited By SillyOldDuffer on 03/03/2016 16:50:44

Edited By SillyOldDuffer on 03/03/2016 16:53:38

Progress Report

I've fitted a double thickness (4mm) cardboard displacer with edges sealed with a smear of latex glue. Still not running in either direction. (Until Howi's advice I'd only tried spinning it clockwise.)

Some more facts:

I followed Jan's design fairly closely. My acrylic tube is 96mm inside diameter. The other components are to spec except that the upper and lower plates are 1/4" (6.25mm) thick rather than 5mm. The flywheel is 1/4" thick rather than 7mm and I increased the diameter to 106mm to compensate. (Design says 100mm diameter.) The piston is mild steel rather than graphite but that's allowed. I used RTV silicone instant gasket rather than cut rubber hose to make the seals. The plate fixing spacers are drilled through and secured with 2mm stainless nuts and bolts rather than being tapped M2 at the ends with an air gap between.

The various bearing points have been de-burred. The engine was spun by hand and then given about 30 minutes drive with an electric meccano motor for "Running In - Please Pass"

Mistakes:

Due to a measuring boob the lower plate groove is 7mm wide rather than 4mm. The extra width is inside the cylinder and the dead space is partly filled with RTV.

As previously confessed the hole in the upper plate for the glide bearing is not centred exactly. The new displacer runs closer to the cylinder wall but it must be a tad unbalanced as a result.

The flywheel wobbles slightly and needs to be shimmed. I'm not entirely happy that it's balanced properly.

Tests

From a flick the engine spins 9 to 11 times with the power piston disconnected. It spins 6 - 7 times when connected. Providing heat doesn't give more revolutions.

The upper and lower plate seals where tested by immersing the engine body in water. The upper plate brass work was tested by spinning with soapy water smeared around the bolts and seams. The displacer piston rod and piston where tested with sewing machine oil, now removed. As I've had the engine apart I will have to repeat the leak tests.

Visual check. The displacer doesn't seem to be fouling the side, top or bottom of the cylinder.

Feel check. Rotating the engine doesn't reveal any stickiness in the motion.

Next step will be to fix the flywheel wobble and recheck the balance. Unless I get more good advice that is!

Thanks again,

Dave

Many thanks Gordon.

My effective displacer gap is much bigger than 1mm in 100mm so that definitely needs fixing.

You are right that my displacer is thin: the cat food carton cardboard I used is only 1.8mm thick. I didn't realise that the depth mattered which may have been unwise given that the design calls for 4mm.

As it's easy to do I'll double the thickness and cut the displacer for a much closer fit. While I'm at it I'll seal the corrugations as well - airflow through them may be reducing the effective thickness of the displacer even more. Oh dear.

Fingers crossed!

Ta,

Dave

I agree. I don't use mine much and in my home workshop at least the money would have been better spent on almost anything else. Inexperience led me to expect that I was going to do much more heavy milling than is actually the case. DRO was a far better investment.

Regards,

Dave

Cast Iron is the only metal I've heard of that should be machined 'dry'.

The main purpose of cutting lubricants is to keep tools sharp by removing heat, to improve finish and to discourage metal from sticking to the tool and blunting it. Flood cooling also flushes swarf away from the cutting edge which is a very good thing. I don't think slipping on a light cut would be a problem in the way that a scrape would be.

Water based coolants are recommended for steel, and light oils for everything else.

My needs are usually far less demanding than an industrial process. For light cuts I rarely bother with coolant at all. For medium work, parting and threading I splash bottled or aerosol CT90 about, perhaps paraffin on aluminium because it's cheaper. I flood cool heavy milling with neat cutting oil rather than an emulsion. This is because flood cooling is extremely messy and neat oil won't cause rust when it ends up somewhere precious!

One thing I learned the hard way is not to splash coolant on to carbide cutters. Thermal shock cracks them. Carbide is all or nothing: either run dry or flood generously.

I agree with HowardT about old recipes. Some of them grow bacteria and can badly infect cuts,. And they stink when they go off. His point about experimenting to find out what suits you and your equipment is also very well made.

Cheers,

Dave

Thanks Peter,

I used "Pro Seal Blue RTV Silicone Instant Gasket".

It might be past it's best as I've had the tube in my garage for several years. Took a few days to set as well as smelling strongly of vinegar. The seal is good though so I'm not too unhappy.

As the blue colour of the sealant doesn't improve the look of the engine I may visit the fish section of my nearby garden centre for a replacement.

Dave

Having built Jan Ridders Coffee Pot engine I am, surprise surprise, unable to get it to run.

There are no leaks and the engine spins freely. The piston passes the 'pop' and vacuum tests. That's the good news and I'm now focussing on the various defects. Of these I'm particularly suspicious of my displacer for two reasons but lack the experience to know if I'm right to worry or not.

Firstly the sheet of polystyrene carefully put aside to make the displacer has gone AWOL and I temporarily used cardboard instead. Is cardboard suitable for this purpose? (Cardboard doesn't feature as displacer material in any of the designs I've seen.)

Secondly, due to a cock-up making the upper plate, the displacer is smaller than it should be. The glide-bearing hole in the upper plate is off-centre and the diameter of the displacer is reduced to stop it fouling the cylinder wall. The effect is highlighted in red in the photo. How critical is the size of the displacer relative to the size of the cylinder?

It's not the cause of my problems but other builders of this engine might be interested in the second picture. It shows corrosion of the steel piston caused by acetic acid from the RTV I used to seal the displacer-cylinder. The corrosion is worse than the picture implies and it also greened up the exposed brass-work.

As usual I will be very grateful for all help and comments.

Regards,
Dave

Good things out of France? Loads, not least Toast, Mustard, Kissing and Letters!

Pinole is German for barrel or quill. Probably indicates that the manual was translated into English from German.

As Neil points out with the Ronan Point example, British engineering doesn't have an entirely unblemished record when it comes to quality issues. I can recommend the book "Why Buildings Fall Down" by Levy and Salvadori. It says that the problems revealed by the Ronan Point collapse resulted in the demolition of "hundreds" of similarly unsafe tower blocks. Ronan Point itself was dismantled piecemeal because of concern that the building's structural integrity wouldn't support explosive demolition. "The joints between wall and slab, supposedly packed with mortar, were discovered to be full of voids and rubbish."

Returning to steel, this LINK gives production figures by country for 2014 - 2015. The annual total is 1,496,105,000 tonnes. This is a huge quantity of metal and I don't find it surprising that some of it isn't to specification. Does anyone have any figures showing the percentage of steel production that's faulty, rather than quoting individual examples of poor quality? Individual reports are unreliable because people are less likely to report good experiences. Failures are much more interesting than anything that "just works".

Regards,

Dave

Thanks guys, even more good ideas!

I shall look at the next MEW with interest and I like John Hinkley's travel stop solution.

After all this excellent advice my problem now is making a dent in the resulting "to do" list.

Cheers,

Dave

Thanks Neil. I didn't know about Alutite which will also be useful for fixing some problems I haven't asked about yet!

Thanks to Anna and Fishy-Steve for the arrow marking ideas : that's so obvious I might never have thought of it. Brain-fade due to tiredness must be a factor as I do blunder more at the end of workshop sessions.

I used the 'stop' slot on my mill to mount a DRO scale. Thanks to Emgee I will have another think about ways of fitting stops. In addition to protecting the piece they would also speed up work because I wouldn't have to watch the DRO carefully towards the end of each cut.

Chris, Anna and Speedy Builder have all confirmed my suspicion that I need more practice. In the past I've tended not to do practice pieces simply because metal is rather costly. I now think this is a false economy.

As to Anna's kind remark about the suitability of my pseudonym, all I can say is that I know my limitations! And I'm looking forward to the possibility that I might evolve into an Old S.O.D.

Cheers,

Dave

I'm building the Jan Ridders Coffee Pot Stirling at the moment. Although my self-taught skills have improved considerably I am still in the bottom 10% of the class when it comes to finish, and I'm trying to improve.

I generally manage to put holes in the right place, turn to wanted diameters, and mill to the correct depth, more or less. The things I make usually work but the finish is poor. (This is not false modesty!)

One of my mistakes is that when starting a cut, or changing direction, I have a strong tendency to turn milling table axis controls the wrong way. This drives the cutter into metal that has to be left untouched if the object is to look good. Quite small errors can spoil an otherwise acceptable bit of work.

This picture is a close-up of the flywheel. You can see that I have crashed no less than three times into this particular spoke. It is very annoying because the other 5 are quite good, at least by my standards!

I feel like a learner driver having trouble with parallel parking again. My confusion is something to do with reversals of right-left and forward-backward movements, and ditto with my rotary table. (I usually get up-down right thank goodness!)

Is there a trick to this like "lefty loosey, righty tighty" or is it just practice, practice, practice? All hints and advice gratefully received.

Thanks,

Dave

Edited By SillyOldDuffer on 15/02/2016 18:26:01