A Mills At Last.

[thomas oliver 1]

I think it was at ED that all the lapping was done by one man - a well known West Essex club member called Len, using a Delapena honing machine. I have a friend who has made around 40 small engines - petrol and diesel, and he used such a machine. He is was elected as one of the "Motor Boys" on the MEW site. I made a copy of the female lap using slices cut off a Rolls razor hone and it worked quite well, but the male laps and the machine are complex. Making a one off engine means that maybe two or three pistons might have to be made, whereas the manufacturers could match up pairs from long production runs. I have several spare Mills l.3cc pistons and it is surprising the difference in the individual sizes of them.

Edited By thomas oliver 1 on 24/12/2014 23:48:28

[PC.Vere]

Whatever I don't know, I'll no doubt find out about with the trial & error or "suck it and see" method, while reading it all up as much as possible, (which I am in favour of doing), but ..... there does come a time when reading dire warnings etc.over and over will just "freak me out". I am prepared to give it a go with a bit of machining knowledge from way back, also a great interest (although no actual casting experience) in the whole foundry process, this did include some patternmaking and corebox making experience acquired during my engineering years, this should help to back me up.

Having said that of course, I am happy to hear from any of you people, but I feel that I shouldn't spout on too long about it all until I have actually made some practical progress on the project, which is still in it's infancy - it's still only words as yet and I'm more worried about it remaining as only words, than in any mistakes which might be made during the learning process!

Thanks again and happy 2015.

Edited By PC.Vere on 25/12/2014 11:23:54

[PC.Vere]

It's been a while since I started this thread and to get this project up and running, but I've at last managed to get my little foundry in action!

Last Saturday, I did my third pour and have been experimenting with pattern making and moulding, so this was the first pour into an actual mould (it was just a basic wooden "thing" I put together to prove to myself that I could do it!) it was reasonably successful and made me feel good, if nothing else.

I think I'm now proficient enough to at least try to make a pattern and mould for a Mills.75 and pour it, that will probably be the next stage.

To date I have constructed a furnace and a burner to use with it, all the design work has been done by educated guesswork and has all worked well so far. I made all the tools, (like tongs etc which was a bit of a challenge but they now work perfectly) - I'm now working with the mark 1d version of my tongs)

I hope to keep you posted with my progress, (I have also had to do a lot of grandchild minding).so this progress will be slow!

[PC.Vere]

BTW, I meant that the pattern was made of wood, (not the mould).

The Mills.75 crankcase is not a particularly complex casting, ie the outer form, but the inside cavity shape will have to be captured in some sort of pourable,(and easily removed )rubber type material in order to be able to make a mould for producing the sand core (which I still have to learn to make.) Possibly I will use a core produced by the sodium silicate (waterglass) process. This is sand mixed with a little sodium silicate and which is quickly hardened by passing Co2 gas through it.

Looking forward to trying that in the next week or so.

[Foxfan]

Percy,

my son decided to build a furnace having looked at youtubes. He did so with nothing but cheap hand tools and battery powered power tools. I then found him a local supplier of sand (a small local foundry) and off we went. I made him some mould boxes in wood and a sand tamper tool (which he later replicated in aluminium).

Considering he had only derived ally from drinks cans, poured into cake tins as ingots, we got surprisingly good results. Draught angle on your patterns is essential with sand casting.

I'd already made a simple pattern to produce 2" diameter "top hats" to hold the mudguards onto my Triumph based Special and after a session in his back garden I have 8 excellent casts which just need boring out and facing on my little Peatol lathe.

What stopped proceedings was a gust of wind throwing charcoal ash into the mix and spoiling it. He is now working on a gas powered burner version of his furnace and alloy supplied from quality car parts from a breaker's yard.

It is perfectly doable. BTW, he degassed using pills of some sort and fluxed the mixture which helps it pour. These things are all on youtube with a bit of searching.

Very best of luck to you. I have always wanted to make a working IC engine but never had a big enough lathe for the kind of engine I want (Westbury Sealion).

Cheers,

MrTin

[PC.Vere]

It's getting close to bedtime here in New Zealand, but I just had to reply

That is the spirit that makes people successful. Sure, we should listen to those who know and even those who are extremely cautious of course! but never give up on trying to have a go, just always use commonsense when dealing with the safety aspect.

It would be easy to be deterred by listening to too much about what could go wrong and not being game to try anyway, however I see that you guys have given it a go.

Of course, I am not exactly an expert but I was surprised at how easy it actually was!.

Myford Boy's video series is very good, I didn't follow it to a tee but I liked his no nonsense style of getting it across,(no real need to say anything)! I used common salt for degassing as per his instructions.

I made a gas burner (my own design) which at the start wasn't too good but with a bit of trial and error tweaking, it's now fantastic.

As much draught angle as can be accomodated in the design would be my approach. - can never be too much really.

I bought a Boxford lathe about one and a half years ago, not too bad, but I consider myself lucky to have one at all! (understanding wife).

I'm supposing that you are talking motorcycles when you mention Triumph - I used to be a motorcycle and aircraft fanatic - still am I guess!

[Foxfan]

Percy,

you're in NZ? That explains everything. Huge respect for what the Kiwis get up to at home (Aussies too). MyfordBoy was the guy I couldn't remember. His videos are what my son and I used for info, as my casting at school was just too long ago to recall much of!

I have a chum there who is building a couple of Specials with whatever he has to hand and is now supercharging a Coventry Climax FWM 750 with a tiny blower from a Daihatsu! Good on him. I was able to help him with a Mk1 Imp clutch when he was visiting UK last year.

My Triumph Special is a home built vintage style sports car, built from Triumph Spitfire bits on a dedicated chassis. Based on the Burlington Arrow. The separate mudguards are held on 15mm tubes, so what we cast will strengthen the mounts to the bodywork and look very neat.

My other Special is an Austin 7 Cambridge Special Sports, but there's little A7 left as I, too, am using a CC FWM engine, ex RAF Genset, which I got for £65! I also have an earlier one which I was actually given! 40 bhp from an Austin 7 engine would cost about £10,000!

With Cambridge suspension and a genuine Cambridge Sports body and 1958 Speedex ally wheels it's all period.

Basically a pair for the pension pot later!

My son and I used leather gauntlets and eye protection for the casting. The local foundry also were very helpful and sold us a bag of sand for £25. I have an old Calor blowlamp for the new furnace which I will send my son back home with when he comes down later this month.

BTW, 3/4" ply mould boxes were absolutely fine.  Didn't even char.  We made open dovetails either end for accurate registration.

Cheers,

M

 

Edited By Foxfan on 15/07/2015 12:33:25

[PC.Vere]

I remember an old neighbour when I was a kid had an Austin 7, he couldn't drive it anymore but he used to wheel it out and rev it for hours every now and then - helluva noise.because the muffler was rusted out.

I'm told that those models had only two bearing cranks so I guess 40 BHP would have produced heaps of flex!

Also I used to be a fan of the Hillman Imp engine, unfortunately they died out and Fiat (seems to me anyway) carried the design a lot further.

Interested in all engines from model aircraft to trucks, another design I sort of liked was the Commer TS3, very smooth and economical two stroke, pity they needed that large noisy blower though!

Meanwhile the humble Mills.75 is my main priority, that's enough for me at the moment!

[Colin Leighfield]

I've got an original Mills .75, the best known mark 2 with cast magnesium crankcase, it's the absolute dream engine that these always are, just like the first well worn example I bought for 5/- in about 1959. I've also got the 0.5cc replica, which runs just like the 0.75. I've got an Irvine 1.3 brand new which I haven't run yet and an Indian 1.3 which also hasn't run, but I've got some reservations about. Additionally I bought the Boddo in-line twin which proved a disappointment, it's in bits at the moment until I get round to replacing the bent rear con-rod, if a contra piston is a bit tight and doesn't immediately back off immediately if you inadvertently over-compress when getting ready to start, a bent rod is guaranteed. Original .75s were bullet proof in my experience. CS built versions not necessarily so. I've got the replacement con-rod, just other priorities at present. I have a bit of a collection of small diesels, plus Cox .049s, a Pee-Wee and a Tee-Dee .010, an absolute jewel.

I don't have the engineering craft skills or the kit to make my own engine, I wish I could because there are all kinds of ideas I'd like to try out, it's a bit late now though. I absolutely love these things, I suppose it's the same kind of fascination that I have with motorbikes.

[Foxfan]

Percy,

quickie.

The Imp engine was a revamp of the FWM in my A7. Another Coventry Climax masterpiece!

MrTin

[PC.Vere]

Posted by Foxfan on 15/07/2015 23:15:30:

The Imp engine was a revamp of the FWM in my A7. Another Coventry Climax masterpiece!

Mr Tin

I was going to say that but not being 100% certain, could have been developed more I reckon. Pity how things turned out in British industry, but I guess that's what happens when you win a war! (as opposed to the two "losers" who were helped to recovery!).- Big time!

Colin

Yes they have a certain charm, mainly because a lot of kids had one in those days. I'm not at all certain that I can make one but I'll keep trying and probably declare all my mistakes,which I'll no doubt make. ("warts & all".

[Simon Chaddock]

Nothing to do with a Mills (although I have both an original 75 and 1.3) but in 1964 I went on holiday with 2 mates driving right through Europe to Yugoslavia in a Hillman Imp. It never missed a beat.

At this time Yugoslavia was still a strict communist dictatorship under President Tito but they had just opened up a part of the Adriatic coast to tourism although there was little English spoken.

When you booked into any camp site the first thing was they took your passports away as you had to be registered with the local police.

We thus had no option but to return to our tent & cook an evening meal and wait for our passports to be returned the following morning.

Our meal was interrupted by 3 gentlemen in dark suits driving a Fiat 124 (classic secret police) who pointed at the Imp and said something. We obviously looked blank so " Sprechen Sie Deutsch?" All we could reply was "English". One of the guys then indicated for the bonnet and then the boot to be opened. Wondering if we were about to be locked up for drug smuggling we duly obliged.

Satisfied they jumped back in their 124 and roared off.

We immediately went to the camp site manager and we explained what had happened. Fortunately his daughter spoke reasonable English. Her dad immediately had a very heated conversation over the phone!

Her daughter explained there was nothing to worry about. It was indeed the secrete police and her dad was incensed that they had harassed one of his campers but it was simply they were car enthusiast who knew about but had never seen a Hillman Imp and wanted to see inside!

[Colin Leighfield]

Simon, you were lucky! I thought the Imp was fascinating, as I understand and recall it was an all aluminium single overhead cam 4 cylinder engine, sloped 30/45 degrees. It was in effect half of the Coventry Climax "Fire Engine" V8 that was so successful in Formula 1 and was derived from an engine designed for use in aircraft as an APU. A friend bought an early one from new and had trouble with exhaust valves burning out, apparently a common problem originally but once sorted out it was fine.

Later on in the Rootes Group/Chrysler/Simca/Peugeot catalogue of events they produced the Talbot Sunbeam, which was a very neat front wheel drive car using the 1.0 litre Imp engine. Although never a big seller, it was actually very good. My wife had one in about 1980 and it went well, the engine was excellent. For its' time, a very advanced design.

Percy, you'll do it. I look forward to seeing the results.

Edited By Colin Leighfield on 16/07/2015 14:32:26

[Foxfan]

The Imp engine was actually originally developed for an outboard motor, hence FWM...Feather Weight marine. It was later spotted by Rootes and redeveloped by Mike Spence, the racing driver for the Imp, which has originally been intended for a small flat four. The Imp engine became known as the FWMA, Featherweight Marine Automobile. Elements of the little 750 were in the racing V8 which was not a Fire pump V8 but the 1.5L FWMV8. The Fire pump V8 was known as the FPE for obvious reasons, following on from the FPF, Fire Pump Four, so called to confuse the bean counters, but designed purely as a racing engine, starting as a 1.5 Litre and ending up at Indy as a 2.7! One of the most successful racing engines ever.

The FPE has recently been re-united with the Kieft racing car built to take the original. I saw it in the paddock at Goodwood a few years ago.

Cheers,

MrTin

[Colin Leighfield]

There are some facts that I didn't know before, thank you. I remember Kieft, didn't they start with Firmula 500, using Manx Norton engines etc?

[Mike Etheridge 1]

Anyone remember the Sugden Special, a home-build engine you could buy the ready cast crankcase for ?

[Colin Leighfield]

Yes, I do a nice looking engine although I can't remember if I ever saw one in real life.

[PC.Vere]

Well, the info here is mind boggling! - Its a little off topic of course but it would have become a very dull thread had it not been for all this stuff! I for one, am very happy to hear all this discussion, so long as it keeps the original topic in sight and doesn't offend anyone.

So my ultimate goal has now changed to attempting to make a replica Hillman Imp engine to power a 25 foot wingspan RC plane! - but perhaps it would be better to build the Mills.75 first, in order to get a feel for it! - I really don't want to end up just being a "Gunna" type.

Yes I have heard of the Sugden special but I haven't seen one here (NZ) - seems to me that although castings have been produced for several engines over the years,the market for that sort of thing isn't really big, so they just disappear.(unfortunately).

The RTF market (great as it is for some) is really the death knell for the genuine engineer/modeller who wants to actually be able to make things!

[PC.Vere]

A few photos to bring things up to date and show where I've got to so far.

The casting looks rough really but it's not nearly as bad as it looks ( the camera flash makes it look worse!). What is it? I dunno, it's just a 'thing' I guess.

The tongs have been modified since (the 4th amendment ) - they now work very well and I'm ready to make a tidier version incorporating all the lessons learnt.

[John Olsen 1]

Hi Percy

Whereabouts in NZ are you? I could put you in touch with a guy here in Cambridge (NZ) who has built a number of model aero engines and is currently working on a 12 cylinder blown two stroke...I forget the capacity but it is about 8 or so inches long...there is a thread on the Model Engineer website with photos. Anything that he can't tell you about lapping probably doesn't matter. I also know some guys in Auckland who could help out with small quantities of casting sand.

Another possibility these days is to draw it up as a 3D model and 3D print the wax...which can be done for you...then have a lost wax casting made. One of the members of the Auckland Model Engineers has been doing this. This gives very high quality castings.

John

[PC.Vere]

Thank you John,

I live in south east Auckland (Howick), I'm just doing this mainly because I always wanted to, but couldn't find the time when working and bringing up a family. I will be working slowly through it (as I find the time) so I want to learn all the old basic stuff first and then perhaps I'll progress to more hi-tech stuff later, lapping I will probably need to learn. Any advice on lapping would certainly be welcome, but I would tend to think that it can't be learnt completely from a book or advice, it needs to have the 'touchy feely input!

I do prefer to do all my own stuff as a rule (just because I think I can and that makes me feel as though I'm achieving something) and I usually do things as the spirit moves me. Perfection is not the ultimate goal for me, as perfection is never enough and takes up too much of the precious time I have left .

However, in saying that, I don't want a heap of junk either, just a smooth running piece of machinery which goes well and is finished in a reasonable time, then I can move on to something else ( knowing me, the reality is that I'll probably be running two or three projects concurrently!)

Casting sand I can make myself (greensand, because it doesn't smoke, - I still want to stay friendly with my neighbours and a gas fired furnace for the same reason!

If I set myself a goal (which I have done) to do this and share the ups and downs with you people then I will have to keep going in order to save face! - that certainly will give me an incentive to finish it!

We'll see.......

[Foxfan]

A 3D printed pattern doesn't make for any higher quality results than a hand made pattern!

A shape's a shape. If you can't do it by hand, you're unlikely to see a whole project through. On the other hand if you want a casting covered in parallel lines and steps, by all means trot off to the dreaded Shapeways!

Percy's talking model engineering here, not push button.

 

MrTin

Edited By Foxfan on 17/07/2015 10:22:37

[Foxfan]

Colin, yes Kieft were a successful 500 cc producer.

The Sugden Special is still in the Model Engineering Plans list (I cannot bring myself to mention what the once great company has sunken to calling itself).

Since the demise of a few casters, it seems that Hemmingway are the current producers of casting kits for these IC engines.

I wonder what size prop the Westbury Sealion engine would swing. It has a Hillman Imp look about it. 30 cc overhead cam 4<G>

Percy, your casting progress is rapid and impressive! We'll be seeing a crankcase shortly I feel.

MrTin

[PC.Vere]

Posted by Foxfan on 17/07/2015 10:22:02:

[Percy, your casting progress is rapid and impressive! We'll be seeing a crankcase shortly I feel.]

Definitely not rapid, it.s just a catch up from late 2014 when I started the thread, although the casting bit is current. Impressive? well I hope so, but my intention is to let any Joe Blow know that it can be done, and who better to find out by mistakes than ....me! Well I have a few skills in metal machining of course but in pattern making and woodwork you could say I'm not quite up with the play. Next I'll try to make a wooden pattern, then a core, that should be fun.

[PC.Vere]

I did say that I'd describe what I have done "warts and all" and so I'll show the casting with all it's voids as well. T he holes ( I;m told) were caused by not using big enough runners and risers, not adequate to feed the shrinking mass in the middle, while

I've included a better picture of the machined casting showing the voids caused by inadequate runners and risers (not being large enough to feed the central mass when cooling), - so I need to address that.

The other pics show the general construction of the furnace back in January - I made the collapsible inner from 0.4mm steel sheet and attached two wooden battens flush with the edges of the metal and held them together with bolts for easy removal when the castable refractory had set, the outer part of the mould I made with the same sheetmetal and kept it in place with a rough wooden framework glued together.

When formed and set I wrapped this inner hotface with two layers of ceramic fibre and put it in the sheetmetal outer casing with tubular legs etc. The castable refractory at the top to cover the ceramic fibre is very thin and prone to cracking but it's not really important (just looks bad) but it works very well 'as is', so i'll leave it in the meantime.The bottom is a loose fitting round refractory slab (as was the lid, but i smashed it unfortunately. However, I managed fine with a flowerpot ceramic saucer after cutting a suitable size hole in it! (amazing how you can adapt things to suit!).

But.... It all works perfectly which is what I want it to do, it's not meant to be a showpiece - it's purely for melting metal and it does that admirably well!