Member postings for Andy Holdaway

I don't know how long it would take without heating, I'm impatient! Probably a few hours I would have thought.

As an aside, I definitely had a saturated solution as I let it cool so that I could put it in a jar for future use. The Pyrex jug had a clear liquid in it until I moved it, and the Alum suddenly re-crystalized back to a white powder. Took me back to chemistry lessons at school!

Well, being the eternal sceptic I didn't really believe the alum trick would work, but I dissolved a couple of tablespoons in about 1/4 litre of boiling water, sat it on an old camping stove and brought it up to a simmer.

Dropped the part with the broken drill bit in and poked the hole with a cocktail stick to make sure the solution had fully entered the hole (probably didn't need to do that) and watched it fizz for about 15 minutes. Lo and behold, no more broken drill bit!

The offending hole is the one at the bottom of the piece. You can hopefully just see the bubbles emerging.

I washed it thoroughly, and found there was a sort of grey coating on the aluminium, but it rubs straight off with a cloth. Slapped it on the pillar drill and tentatively drilled down the rest of the hole. Nothing but aluminium swarf and a nice neat hole. I shall save the solution in a jam jar for the next time!

Andy

Brian, I used a silicone adhesive/sealant that sticks like ......! It probably is worth checking that the slot is clear, but I was quite sparing with it.

Alum is also used as a deodorant (apparently) and is what styptic pencils are made from (old school wet shavers will know what they are!).

My tub of Alum has arrived but I'm currently a few hundred miles from home in a very cold and windy Scotland. I'll let you know if it's successful when I'm back tomorrow night.

Andy

I've just bought a Kg of Alum for this very purpose, should be delivered today. I broke a 2.5mm drill bit in a piece of aluminium about 20mm in. I managed to chip out the majority of it but the tip remains deeply embedded. As I don't want to have to remake the part (cylinder head for a hit & miss engine) I thought it was worth giving the Alum a try.

Youtube has a number of videos showing the technique, and it seems to work a lot faster if you can heat the solution to about 90°C. I'll let you know how it turns out.

And no, Brian, I still haven't got my Laura engine to run, although I found a tight spot the other day which may be the cause. I'll fettle it and have another go, although work has decided that I need to be in Scotland for the next couple of days so it won't be immediate!

Andy

Looking at your photo of the terminal box, Z2 appears to be not connected. This is the end of the start winding and should have a start capacitor connected between Z2 and neutral.

As Muzzer says, a gauge is useless to determine how much gas is left until there isn't any left. the only way is to weigh the bottle against the Tare weight stamped on the bottle.

The 19kg is the charged weight and is usually painted on, the Tare weight is stamped somewhere.

I work in refrigeration / air conditioning, and people are often confused that a system is showing a good standing pressure, which they equate to it having a good gas charge, until the compressor starts, and suddenly there's no pressure due to the system having lost most of its bulk gas charge. This is the same if it's a small system holding a couple of kg's of gas or an industrial system holding up to a tonne.

I had no problem making the displacer piston with the supplied material, although there wasn't much to hold in the chuck. It did seem like a fairly hard aluminium, but machined and tapped with no problems.

Brian, that's a good point about the pistons at TDC. The displacement cylinder is virtually touching the end of the glass cylinder (perhaps 0.5mm clearance). I haven't checked the work cylinder, but will have a look tonight. If the gap is too big I can always make a connecting rod to your suggestion.

I'll let you know what I find!

Andy

Brian, No, still not working, but in fairness I threw in the towel after a couple of hours. I will give it some more time at the weekend.

I did strip it back down, and have reasonable compression on the working cylinder, and all the linkages are free. If I give the flywheel a spin (with everything connected) it will rotate for about seven turns before stopping, so I don't think anything is binding. There are no leaks in the air path that I can tell, and the air from the displacement cylinder is reaching the working cylinder, so I haven't a clue why it wont sustain motion. Time may tell!

As for drilling the connecting rod, the end that has to be drilled has to be filed down on both sides to create two flats. Once this was done I centre dotted it and drilled it easily. If it was still round it wouldn't have gone quite so well.

Andy

I use a Rothenberger torch with MAPP gas - you will never have a problem soldering / brazing again!

The heat output of these things is phenomenal, and while they're not cheap they make the job so much easier.

There are other makes available, usually described as a Turbo Torch, but the MAPP gas makes all the difference.

Mike, The star point is on the bottom three terminals, so you can rewire it in delta and run it from a 240v single to 3 phase inverter.

I have no idea what size it is, but I'm sure someone will be along soon with an answer!

Andy

I upgraded to Win10 on my home laptop when it was first available, thinking that I could test-drive it without any real risk (nothing irretrievable other than car club accounts and membership, which I backup weekly anyway).

I was a little 'anti' at first, as I really dislike operating systems that take over and make suggestions/decisions for you, but I have to admit it found all of my devices first time, including my wifi router, and has worked seamlessly ever since.

Emboldened, I upgraded my work laptop a month or so later, after having done a full backup. I was a little nervous as some of the software I use has yet to catch up with later releases of Windows, but with a bit of fiddling everything works as it should, most of the time. I still get occasional crashes and hang-ups, but I put that down to the 3rd party software, as it has happened on previous versions of Windows as well.

Overall I'm happy with Win10, and once you spend a bit of time with it you can stifle the suggestions and Cortana based annoyances.

It's alleged that the wartime scrap metal collection was more about getting civilians involved in the war effort than for the value the metal provided. Aluminium pots and pans took more processing to yield useable alloy than refining fresh from bauxite.

It's also said that the mountain of railings from Edinburgh, London (and according to my mother) most of Birmingham ended up being dumped in the sea after the war as wrought iron wasn't required.

The gap in my displacer cylinder is tiny - I had to adjust the rod as the piston was hitting the end of the cylinder. I'll pull it apart later and see if I can see what's going on. I'll take the work cylinder cap off first and see if I can feel any wind coming up the hole from the displacer.

My next project is the Bengs Karl engine. It's an I.C. hit & miss engine - I'm much more confident with petrol and a spark!

Brian, that was my purpose too, but it would have been nice to have something that works - how hard can it be?!?!?

I've also found that I occasionally have to use a different com port so that the system will have to 're-find' the new device. It usually works fine afterwards. As long as you have the correct drivers in the first place, that is!

Brian, I think the gasket paper may be a good idea. I finally completed my engine last night, and after an hour of frustration and burnt fingers conceded defeat!

I used silicon to seal everything, and either didn't do a good enough job, or over did it and bunged up the air passage.

I will pull it apart tonight and see if I can see anything obvious. I've checked all the usual things like good piston seal, everything free etc. so it's a bit of a mystery at the moment.

pgk pgk, I know you shouldn't believe everything you read on the internet, but this from Wikipedia:

"Red brass used to produce pipes, valves, and plumbing fixtures, and is considered to offer a good mixture of corrosion resistance, strength, and ease of casting.^[6] It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc."

Red brass is a gunmetal. I presume from the inclusion of lead and tin it provides an amount of lubrication for the piston.

Brian, I also had two in the kit and they are indeed 20mm x 2mm. I confess I didn't measure the O ring, I just shoved it in the recess - it fits, and gives the seal a bit more bulk.

I've just checked the drawing, and the recess in the cylinder cap is 20mm, so the O ring sits nicely in the cap and I presume then distorts down into the cylinder recess to effect the seal. So I apologise for sending you off on the wrong track - the recess in the cylinder cap is to house the O ring, which makes the recess in the cylinder a lot less critical.

Andy