Inspired by Bryan I thought I ought to build an engine. Each to their own ..so don't shoot me down.. but apart from the skill and achievement in doing so (and I'm not knocking that) I can imagine an awful lot of beautiful engines sitting in cupboards corroding away and never being played with. So if I'm going to go to the bother of building one it has to either do some work or be dead easy to fire up on a shelf and show working without dragging air lines about or boiling water.

Jan's Stirling (if I ever complete it) should be simple to power, plans are 'free' plus a donation and might appeal to OH since his builds look shiney.

So we have a bunch of plans that involved some thinking about:

I'm not fully committed to this and the hardest part strikes me as getting the glass tubes cut. I duly ordered some borosilicate tubes from ebay.. five of each needed size. If I break them all then it may be game over.

This is where the domino effect comes it. Jan recommends cutting the tubes with a dremel and brown disc – so I need to mount a dremel to the toolpost.

Initially I was going for a straight clamp round the tool body on my 'Woomel' (that's a woolworths dremel type drill I've had for years – under a tenner with a nice case and lots of bits). The I discovered the grip bit unscrews:

Bizzarely as best i could measure that thread it's a dead on 2mm pitch but the minor diameter is around 15.55mm and the major about 16.75 – so what the heck thread it's really supposed to be I have no idea. A woolworth?

I'd never cut an internal thread so ground up a stub of HSS and dug out a never used small boring bar. If I'm honest the end result did work but I'd messed up on the major/minor diameters when it comes to internal threads and bored the hole a bit big before I twigged. It was a bit loose but proved I could cut an internal thread.

I'm not quick at this stuff so that was end of evening one. The next session I started off right

And dug out a bar end of hot rolled, cleaned it up and roughed it square. It's a 'gerrerdun' project to make this holder and doesn't have to be that pretty.

Note the dodgy setup to trim a bit off the edge

I could have held it in my 4-jaw but not with through clearance for boring or threading with my gear so out came the faceplate and more dodgy setups:

The bolts on this attempt were way too proud and would have needed even more overhang on the tooling than I ended up with:

This was better and quicker than making up countersunk bars or a backboard. There was some imbalance wobble but tolerable.

Drilled, bored and threaded… but the threading was a mare. I'd left everything set-up from the practice but the gear under the threading indicator loosened and I lost my mark (there's no index point for the thread dial gears on the crusader lathe so knowing if the right tooth/teeth are aligned with the indicator is a trial error and black art as I see it).

The other issue was the tool overhang and flex and way too little space in the bore for the bar i had. Ultimately I cut this thread with quite a deep set of bites and multiple spring passes each time.

Things were a bit too tense and I failed to take any threading pics. That session finished with a rough markout for fitting a toolholder.

I was too lazy to handsaw the waste, too lazy to swap the setup on the bandsaw to vertical so just wacked off the waste with the mill: 3x 2.5mm passes each edge with handsprayed coolant

Despite being a gerrerdun i did pretty it up a bit and showed it the beltsander and some scotchbrite.

My toolholders can take 16mm which should be strong enough to hold it.

sometimes you fluke how the thread ends up when tightened.

Of course the next problem was that the discs for the 'woomel' are smaller than the width of the tool and with a length to cut off it's a choice of doing it in sections or angling the tool. First set the height by that'll do..

Then work out the least angle

And a catcher

OK so Jan says he managed with a brown disc. I had the woomel running full bore and the lathe at 100rpm and only managed a shallow dent in the thing. I switched to one of those black cut-off discs..half an hour later i had a slightly deeper groove and that was despite ramming the disc up hard so the disc spindle was bowing and having a tiny hard white light at the contact point from heat. I upped the lathe to 280 rpm. half an hour later and not much progress. Darn this glass is tough!

I gambled on shocking it with some coolant hoping to get a stress facture at the weakened hot zone – It laughed at me. The cutting disc got smaller but the groove hardly deepened. Shed laptop and i ordered some diamond dremel discs from ebay but i bet i'll have to keep them cool or turn the diamonds to CO2…..

I tested the residual strength of the groove… it broke nicely….leaving me with a not too bad wrong half and a crack in the end I wanted…..Hmmm… 4 tubes that size left when the diamond discs arrive…..

George,

I don't think any variant of that idea would work on my chester superlux. I'd be happy to be wrong…

I got lucky last night and the tramming went within 1 thou over 10" first guess…

A slight diversion tonight.. playing with a cheapo chinese air mister mixing thingy. It looks pretty efficient and just need to find a way of fixing it to the quill. Not bad for £2.55 delivered. Hope my compressor is up to the task..

Just a valve on the air side (1/4 or 1/2 turn – can't remember which). Set it too low and the coolant flow (suction) stops but still a decent air blast. Not used in anger yet. It may well be a case of having to take breaks to allow my lidl compressor to catch up. the nozzle has some adjustment too.. haven't played with it but probably just the spray shape.

hopefully I'll load some pics of how I attached it

Today I went in search of a better finish. As stated before I have bags of hot-roll plate but I don't like the mill finish .. that corrugated look after several furrows to thickness and I'm not very good at sanding them out. Ues the belt sander gets rid of them or enough patience with a sheet of abrasive and a flat surface but however you hold or rotate there will always be more coming of the edges than the middle…unless someone has a better way??

I bolted a 6mm plate to the backplate of lathe. This gave a diagonal of some 8-9 inches. With a carbide insert I could get a mirror finish on the outer part but once surface speed dropped as it moved across the face the finish fell off too. Is it reasonable to stop the lathe mid cut and change speed? Does it work or leave a transition ridge?

Anyway I tried with a facing tool in HSS.. and then ground a new one to see if i could do better still. The best i can say after several hours messing about is that the finish is 'OK'. It's better than mill but not mirror. I'll chop the plate into needed bits and start on the stand tomorrow.

There's a chance I might actually get some building done.

Ian, I have no doubt you're right…I just need a heck of a lot more filing practice and likely some better files.

I've not got much done..simply because i got bogged down in calculations for the support frame arms. The drawing supplied wound me up some being determined to work things out from the figures given.. until I realised that the only important dimensions were the spacing between bearing centre and distance to pivot point and the rest was really just artistic. Nevertheless i was determined to solve the figures on making a duplicate and wasted ages doing so before I 'cracked', 'cheated' and displayed the original pdf at several hundred percent on screen and measured the angles of the arms off the screen. I've finally dimensioned it all and ready to start cutting.

It would have been a lot quicker just to draw the arms out on a piece of plate and roughed it with a decent bandsaw then filed the rest but i've been using the mill dro rather than marking (don't have good height gauges or surface plates yet) and I'd already cut 2 strips and glued them together.

This is a learning experience for me as well as brain excercise.

I challenge anyone to dimension that drawing without guessing at at least 2 figures or measuring them off the original plans

You can hardly feel a mark on them with fingers or fingernails but they still show tool marks. Since they're scheduled to be painted…..

On to the next part..

On my first set of stand arms I used mild steel filing buttons and didn't like the result.. just not neat enough. I then made up a set of hardened buttons of slightly smaller diameter to try and salvage the parts (my first at hardening silver steel) but my filing wasn't neat enough and i ended up with a sort of neck where the bearing rings met the arm length. I've just finished remaking them and this set are acceptable; a good press fit on the bearings but again the problem was with the handwork where the rings part meets the longitudinal; I found it hard to file that junction and it took ages.

The crank webs now need reworking or remaking – a similar problem with neatness at the internal angles before i move on.