Aluminium for LTD Stirling

Despite two previous Stirling failures (made 'by eye' without any plans) and one moderate success I'm going to attempt a simple LTD/Ringbom type engine. It calls for two circles of aluminium plate, one 8mm thick, the other 5mm thick and both about 4.5" diameter.

These sizes seem too thick for plate and too large a diameter for bar - can anyone suggest a source (preferably one that won't break the bank (I've never machined aluminium before and expect to make one of two mistakes :D )

Cheers

Paul

Talk nicely to someone at Richard Austin Alloys:

**LINK**

http://www.raaltd.com/aluminium-plate-products.html

... They sell offcuts.

MichaelG.

5mm and 8mm plate are readily available on the likes of e-bay in offcuts or cut to size

This is one such piece of 8mm that came my way via e-bay, I usually use this seller for ali

Noggin End also do a range of sheet/plate in small sizes

Edited By JasonB on 07/04/2017 20:05:20

Another interesting link Michael. It's given me a new word: apparently "Shate" is defined as the "overlap between sheet and plate."

Excellent word - it will come in handy whenever I have an 'expletive deleted' moment in front of mother.

Cheers,

Dave

Sounds like the Geordie pronunciation for you know what!

@Michael Thanks for the link - added to my stash

@Jason Doh, why didn't I think of eBay?! Plenty of suitable bits on there, cheers.

Just need to figure how I'm going to turn/groove the bottom plate that has no central hole - super-glue and cross everything I suppose...

Fix it to a faceplate by the corners to do the groove before you cut them off.

Good idea! At the risk of going way off topic... Any tips for turning the outside diameter? I've used super-glue and/or a wood pad and a live centre in the past. I'm sure I once saw someone turning a disk held with wax somewhere on the net...

I've not tried wax but the watch makers tend to use that or shelac. Another alternative is thin double sided tape and a pad to aply pressure from the tailstock.

Paul,

In this context the term 'wax' refers to something like sealing wax [or the stone-cutter's 'dop wax'], which is based on Shellac.

Pure Shellac is fine for small pieces.

MichaelG.

.

Good video [with bad music] here: 

https://m.youtube.com/watch?v=C70qBYtvEyA

Excellent article [and larger scale] here:

http://www.snclocks.com/TechnicalInformation/Tid-Bits/Tid-Bit-2-Using-a-wax-chuck/i-m84DvXF

Edited By Michael Gilligan on 08/04/2017 08:11:37

I rounded the aluminium square plate by facing a short length of 32mm aluminium rod and supergluing it to the centre of the plate. Although I was nervous that this wouldn't be strong enough (and took gentle cuts only) at the end I had to warm the work on an electric cooker ring to break the bond. Warming with a blowlamp works too.

Isopropyl Alcohol is fairly good at cleaning up the residue.

The secret of using superglue successfully for this is new glue, absolute cleanliness and not moving the joint while the glue takes effect. The slightest trace of oil or grease seems to seriously weaken the bond as does fussing with the alignment during the setting period.

Dave

My 8" diameter LTD Stirling Engine started life as two frying pans found in a skip, top 3 mm, bottom 5 mm thick, there was enough left of the 5 mm pan to make the rim of the flywheel.

Ian S C

Edited By Ian S C on 08/04/2017 11:05:51

Thanks to all for the tips. The shellac idea looks neat, I suppose I could make a little stubby 'faceplate' to stick it to rather than play a flame over the real one. Looks like a really nice finish on that bit of brass in the video.

Ian, that's monstrous (in a good way)! I don't hold out much hope of randomly finding a frying pan in a skip although I think we have some Trangias and mess tins lying around from when the kids did their DofEs but I bet they are nowhere near thick enough.

Yes Paul it is quite large, but I had the fry pans, and a bit of plastic tube, and some 5 mm nylon bolts (to join the two aluminium plates.

Ian S C