Stirling Engine : Laura

I tried to buy Alum in Cairns today but no luck : two chemical supply companies, three pharmacies, one hardware store and one health food shop. Nobody even knew what I was talking about even though I did give the full name and the abbreviation. So when I got home I found that a M2 nut would just fit over the broken tap that was sticking out. I screwed it down and then attempted to hard solder the nut to the tap. Disaster : not only did the solder not take (no idea why) but where I had soft soldered to make a repair earlier (see above), this ate its way into the brass completely destroying the whole thing. No need for a photo, I am sure you get the picture !

Anyway, I still have two more work cylinders that can be used. I was looking forward to using the Alum ; I will have to buy some online in preparation for next time.

I am still waiting on my M2 X 16mm socket cap screws. These things take a long time to arrive from China now. I may be better buying from the UK in future.

I have also decided to paint the inside of the flywheel red as per usual so I have given it two coats of etch primer. The first coat of Killrust red will go on tomorrow. I could have left it unpainted as it looked quite nice with the machined and polished outer surfaces contrasting nicely with the rougher inner surfaces.

I also took apart the cylinder holders (parts 3 and 4). I suspected that the Hylomar I used had got into the groove which connects both cylinders ; it oozes everywhere when you tighten things up. Sure enough, the hole was blocked so I spent one hour cleaning all the Hylomar from both pieces and all the screws. Even with the recommended methylated spirits this stuff is messy and sticky. I do not think I will be using it again. As I am not soldering these two pieces to the base plate as per the instructions, I can try it without any sealer and see if it works. If there is a problem then I can easily take it apart and try something...gasket goo perhaps ?

Andrew : what did you use to seal parts 3 and 4 ? Are you sure the connecting groove on part 3 is clear ?

Edited By Brian John on 02/02/2016 07:02:55

Ya Didn't try the garden shop did ya, they should have it there.

Ian S C

Kung Hei Fat Choi. (or maybe Gong Xi Fa Cai on the mainland.).

Officially the New Year starts Feb 8 but there are already 100,000 people trapped at Guangzhou railway station trying to get home for the season. Things will move very slowly now for about three weeks or so. Hopefully your bolts got dispatched before the madness started.

Peter : Yes, they were sent on the 16th January. I am hoping that they are out of China by now. Where do you buy Alum in Cairns ?

Gong Xi Fa Cai is correct

Ian : why would they have Alum in garden supplies ?

Edited By Brian John on 02/02/2016 11:44:46

Edited By Brian John on 02/02/2016 11:45:18

Brian it's use to lower the PH of the soil, so garden shop or agricultural supplies. Health food shop may have it, or the super market among the preserving stuff, it is used when drying fruit. It is also used in a perfumed form as Bath Salts, so you can go and soak in it.

Ian S C

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

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

I wonder how long it takes without boiling the solution ? Nice to know that it works but I still can't buy any Alum in Cairns. I called five gardening supply places today and nobody knew what I was talking about so I will have to buy it on ebay.

Edited By Brian John on 03/02/2016 17:09:38

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!

Andrew, you can grow the cryslals in the same way as copper sulphate(blue stone).

Ian S C

Brian, you could ask at the botanical gardens, if they haven't got enough to give you a few grams, they may be able to tell you where you might get some, it might be E Bay, but it is handy to have.

Ian S C

Moving into the final stages of assembly now that the M2 X 16mm socket heads have arrived. They were a bit long so I cut them down with the Dremel tool to make things a bit neater. I have order some M2 X 14mm and M2 X 12mm but I am not going to wait 3 to 4 weeks for them to arrive.  I know I will be using a lot of M2 socket heads in the future so I have ordered many sizes to have on hand. I have also ordered two more replacement sets of M2 X 0.4 HSS taps in the event of future breakages...and still looking for Alum !

I think this is a much better idea than soldering it all together :

Edited By Brian John on 05/02/2016 06:02:39

Edited By Brian John on 05/02/2016 06:03:59

Looks good with the screws holding it together. I agree better than solder.

No idea where you would get alum in Cairns. I do know that it is used in boiler water treatment to settle out soilds, or used to be, so not sure if a pool shop might have some for clearing murky pools??

If you wish to buy decent quality screws and stuff in Cairns, have you tried this place? **LINK**

(Go to the store locator on the home page)

I buy heaps of fasteners from the my local branch, they are very inexpensive by the box and much better quality (ISO traceable) than some of the cheesy imports.

* Danny M *

Danny : Thanks for the link but they charge ten times what I buy them for from China (and that includes the nuts). I will call next week to see if they have small sizes in stock though.

Hopper : I wonder if this is Aluminium Potassium Sulphate : it could just be sloppy labelling (Aluminium Sulphate) ?

**LINK**

Edited By Brian John on 05/02/2016 08:06:31

You have it Brian, Aluminium Sulfate is how it seems to be labled. I didn't think of swimming pools, I can only think of one private swimming pool about 5k down the road, there is a public pool in town. Your local council will also use it in the town water supply. Sorry for leading you up the garden path in the hunt for Alum.

That's going to be a very nice looking motor.

Ian S C

Yes that looks like the stuff. The MSDS sheet says it is otherwise known as Alum.

What a lovely word - flocculant! Got to try and use that today!

I'm not see if that's exactly the same as the stuff I used. Mine was labelled as aluminium potassium sulphate, and from the formula on the data sheet the flocculant is only aluminium sulphate. Not sure if it makes a difference or not, I'm no chemist!

You could look through what these people have for screws Brian. The only problem is that they will usually come in packs of 100 so choose sizes you are likely to need. In my case I have a couple of sizes in nickel plated brass as they usually get used on electronics bits and pieces - BA too but those tend to be a bit expensive now.

You'll find all types of screws kicking around on there.

**LINK**

I just picked out M2 plain brass. Often it's best to search a general term and then use the filters to home in.

There will also be model, say aircraft etc suppliers around at your end that sell screws. There was a good one in the uk, Initially Giant Shark, then Giant Cod and now rcliffe.co.uk but no longer selling screws.

For shortening I usually use the lathe. Unwanted bit in the chuck, part part off, chamfer with a file and then finish off or lock 2 nuts on the thread and grip those, saw off and finish off the end with a file. There are various ways. If I was doing this a lot 1 would make a holder with a split to grip in the lathe. There are all sorts of options but I like neat ends that screw in without any problems.

John

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I have fixed the main engine assembly to the wooden base. The initial design called for the aluminium columns to be drill and tapped for M2 socket heads and then M2's screwed in from top and bottom but aluminium is messy stuff to drill and tap so I drilled right through the columns and used M3 socket head caps passing straight through. The wooden base is counter bored underneath for the M3 nut and washer. This is my usual method of attaching things to a wooden base.

You can also see six nuts and washers resting on the wooden base. If this engine works (big ''if'' !) then I will sit the whole thing on a larger wooden base having two handles and a copper plate on which to rest the burner. I will drill through this smaller wooden base to take M4 X 40mm socket head caps ; these will be inserted from underneath (counter bored) and the nuts on top. This is not quite as neat as having the socket heads inserted from the top but it allows me to join the two bases easily without disassembling any of the engine parts ie. the cylinders get in the way when trying to insert the socket heads from the top. Placing the holes elsewhere did not look right.

I have finished painting the inner flywheel red (two coats of etch primer and three coats of Killrust) so now I have to wait a few days to let it dry thoroughly. I should have painted it earlier but it was a last minute decision to paint it. The unpainted cast iron did look quite nice and I am still not sure I made the correct choice there.

Edited By Brian John on 06/02/2016 06:15:03

Edited By Brian John on 06/02/2016 06:15:49