ffkiwi

Yes and that little VA Bambi was an absolute honey to start and run-it was the actual engine used for the VA Bambi review published in 'Model Engine World' Dec 98 issue (issue #56). There were no swear words strong enough when I realised what had happened..................

ChrisM

AMB

well a little off topic I like running engines well not IC external combustion but I can run it at night on my kitchen counter top just a little wiff of hot oil in the steam
and yes they are still made from the UK and Germany martin

I know steam is dead

ffkiwi

I remember those when I was a kid-I never had one-but 'Mamod' was a popular UK brand-and they did a whole range of steam engines including a self propelled working steam miniature traction engine about 6 or 8" long. Always seemed to be painted in green and red enamel. Some ran on meths, others on solid 'meta' tablets (also used in Scouts camping stoves).....

ChrisM
'ffkiwi'

AMB

Mine runs on the pellets . It had a broken sight glass in storage got it from a place called toys and books of yesteryear had it (German engine) got a catalog from them this week
everything you can think of in steam even trains boats and yes the mamod stuff , not cheap some of this stuff $600-$700 martin

got mine decades ago $35-$ 40? now $150 and thats the cheapest one amazing all this stuff still there and yes the traction engines

ffkiwi

Martin-did you know OS are also big in the steam engine world? And I mean serious stuff-to the tune of many thousands of dollars a unit. Have a look at www.oslivesteam.com
I believe the late Shigeo Ogawa, the founder of OS, was very fond of model steam locomotives......

ChrisM
'ffkiwi'

earlwb

Saito made or still makes some very sophisticated steam engines too.

AMB

OK guys will have to settle for my little oil burners(aircraft) unless I hit the lottery incredible Saito and OS in the steam biz martin

aeroland

Chris,
Many thanks for that. I had no idea of its existence.

Yes, having spent a lifetime in product design, development and manufacture I can happily say there is a lot more to making a good Mills replica than those not skilled in the art would think. Whenever I make replica parts I go to some lengths to get into the mind of the original Designer and if I make any design changes they are made with great caution. Others like Aurora Mills did not and got themselves a very bad name.

Jon

ffkiwi

Jon as you'd know-Mills were by no means perfect-the 75 prop driver set up was silly-and burred the flats on the shaft with use (making shaft withdrawal a real problem if you snapped a shaft)-the two flats were a stress raiser-and if they break a shaft, that's usually where it breaks. The tank retention system was a bad joke, and there was nothing to stop liner movement within the case-leading to conrod damage.

The perfect Mills replica would have a replaceable prop stud (the Russian Doonside replica), a taper fit prop driver (the Irvine), a pinned liner (the original Doonside), and a screw in tank (Irvine) while keeping all the other design aspects of the original.......and I like the large tank option for the Irvine for R/C use.

I think the genius of the Mills was their choice of such high quality (and expensive) piston liner materials, coupled with their very fine fits (0.000075" P/L clearance) and mild porting. Put that together and you get a very nice handling engine that will last forever (they quoted life in excess of 400 hours running)

But we should also remember that while we revere them now, in their day they were quite expensive compared to DC's, Frogs and EDs and many modellers could not afford them, when a 5 shilling or 10 shilling price difference meant being able to afford a model kit to put your engine in as well, or not. Like the Olivers, although filling a totally different market niche, they were built up to a standard, not down to a price-which was the approach of most of the big UK manufacturers.....

ChrisM
'ffkiw'

PS Nice that we're now back on topic-and I was one of the offenders who dragged it away.....

gossie

Just for fun and to hear it run, I fired up one of my old Mills.75s yesterday.
It had not been run since June last year and had been oiled up with motor oil later on on after using it then to preserve it.
I filled the tank yesterday, choked it, dribbled a little on the piston that was at TDC, and flicked the 8 x 4 twice and it fired...........2 more flicks and away it went running the tank out at slow revs.

What great little engines these were and still are. I have four of them that I treasure and don't really need a modern ones.

AMB

Very nice combo, aircraft outstanding, nice job, I would imagine lots of open room needed, looks like it stay airborne forever martin;;

have never seen one like it

aeroland

Chris,

I'd know better than anyone about the design shortcomings within a Mills engine. After the developments in the early 1950's good development work stopped which is a pity.

The crankshaft burr is a real problem as pushing the shaft back through the bronze bearing causes two axial grooves that degrade the crankshaft sealing. For shafts still in one piece I get around this by gripping the threaded end in a Lathe collet and then skimming off the burrs with a carbide tipped tool. For broken off shafts which I haven't encountered yet I would probably make something like a threaded mandrel to screw the crankcase onto with a slot milled in the end face to slide over and drive the crankpin. May well have to hold that mandrel in a 4 jaw chuck to get the shaft running true enough to skim.

I have made replica tank tops with fold down tabs and cracked newly made acrylic tanks folding them over. Note that the original Mills acrylic tanks had two angled flats for the tabs to fold into to avoid this. The Mills .75 Mk I had a screw in tank which only Irvine chose to copy. As Irvine Owners will know problem with that system is castor oil degrades over time and glues the tank bowl to the tank top. Bowl then gets destroyed trying to unscrew it to clean it. Can't use agressive solvents on the castor either as it attacks the acrylic. If the bowl was made from HD polythene it should survive the paint stripper treatment. So owners of Irvine Mills and Mk I Mills .75 should clean the male and female threads with a tooth pick then wash in kerosene and keep the threads clean and that avoids the problem. I made a simple tool to unscrew the Irvine tanks out of a piece of 1 1/2" wooden dowel taper bored to fit the tank OD. Wood grips the acrylic well and the 1 1/2" dia. is easy to grip in the hand.

Later Mills .75's with tabbed tank top bowl retention I have improved with replacing the top with an internally threaded top derived from the Mk I design and a threaded acrylic tank bowl.

Crankshafts I can repair for people by drilling out the shaft with a carbide tipped tool and then silver soldering in a 0.2% carbon steel extension. Colleting off the shaft's OD I then skim the insert down to dia. and length and recut the 4BA thread. Bonus is should you ever hit anything the new extension will bend rather than break off.

Jon

ffkiwi

I know all about the shaft flats issue the hard way Jon-30 odd years ago (about 1982 IIRC) at a South Island Champs in Invercargill I broke a Doonside Mills shaft flying Aggregate (under ridiculous weather conditions! Most of us were willing to postpone-but one competitor insisted on sticking to the program so we all had to fly!) when the model clipped the top of a car windscreen-in the days when windscreens had chrome surrounds, not rubber (I might have got away with it if it had been rubber)-not only did I break the shaft in the usual place, but also lost the prop driver, prop washer and spinner nut in the long grass!......and that was only the beginning of my troubles....

On returning home and trying to remove the shaft, I discovered the 'burred flats' effect-fortunately before doing any damage to the bearing! Several hours of filing with Swiss files on the driver flats eventually removed the burrs to a level where the broken shaft could be removed without damaging the bearing. Lord but that Taipan made shaft was hard!

In an even bigger irony-that engine (Doonside Mk2 #122) has been running on an Indian Mills crankshaft ever since-you know-the ones that break if you even glance at them sideways.......

ChrisM
'ffkiwi'

fiery

My Feedback: (2)

My example of the AURORA K MILLS 100 (1 cc) engine shown in GCB's post (No. 9 of this thread). Obtained used from another occasional contributer to this forum.

It is the best Aurora engine I have handled. No obvious evidence of poor materials or execution. All working parts are well made and fitted. Alloy parts are nicely finished. The cooling jacket on this variant is anodised light gold. Anodising is even. Case is cleanly cast and fine bead blast finished. No slumping or pin holes. There is castor and factory preserving oil staining on the case. If removed the engine would present better.

A slight disappointment is the drilled and tapped case boss for the screw in intake. The thread is good. However the hole as drilled is not perfectly perpendicular. The facing on the boss which mates with the securing nut is also slightly pitted. It not as bad as it looks in the images below and could be easily lightly skimmed out. Minor matters which do not affect operation, but are nonetheless annoying. Most owners would not notice.

I will post running shots in due course.

fiery

My Feedback: (2)

Howard,

Name and details of that twin-fin trike ship in your post above please.

Very elegant.

AMB

IN one word 'elegant' airframe martin

gossie

The model is a replica of the winning Scramble model from the 1956/7 & 1957/8 Australian Nationals, designed and built by Cyril Marsdon in Melbourne. Original Mills.75 power in original and mine.

Cyril passed away over three years ago now and as we had been friends for many years I was given his original model. I restored it, and did a plan of it that was sent to Mike Glaister in Melbourne for him to do a profesional plan.
The model was not flyable as was too heavy etc, and the engine was very worn.
I offered the model to David Owen as an Australian design to be the model of the meet at the Muswellbrook meet next month and it was accepted. Plan from Mike was sent to "Brownie" in the Blue Mountans NSW to have a kit made for those that do it that way.

Original model is 36in span but laser kit model has been increased to 42in for some reason...........I know not why??????????? Original model now resides with the Potter family in NSW for safe keeping.

If you would like an original plan please contact mike dot glaister at gmail dot com I should think $20.00 would cover the cost including postage.

My original hand drawn plan has gone to the UK and two are being built from it.

Chris.fr

My Feedback: (1)

Hello, I know near nothing about these great engines and just curious about this Mills 1.3, serial number is 157 stamped between lugs on one side and 92 on the other side. is it a "genuine"Mills? Any idea about the year of manufacturing?

Also, is the interesting and unusual RC throttle from factory? Thanks for your help, Chris

gossie

It's a MK1 from about '47 or '48? and the RC throttle was an extra you purchased and screwed it into it. It was an extra in the early '50s.

The later MK2 versions in '52 or '53 one could purchase the engine either with or without the throttle. I've had both versions over the years.

brokenenglish

Yeah, as gossie says, that's a nice original Mills and throttle.
Just a remark... At the time, these throttles weren't RC of course. RC gear was unreliable and weighed a ton, even for rudder only control.
These throttles were intended to be operated by a timer, in FF mode, and the advertising even came up with a scheme whereby you could leave the engine idling while you walked to the centre of the CL circle to pick up the handle, and then trigger full throttle to take off!
I actually have an advert that explains this!

Chris.fr

My Feedback: (1)

Gossie and Brokenenglish, Many thanks for the infos, I'm currently assembling an ARF SPARKY from Thunder Tiger for this MILLS, What do you think about the best size of the prop?

AMB

Chris my kind of airplane a couple of beams for the engine any .09 to .10 or an 1/8 inch piece of ply to the original fire wall, plastic mount a few screws to hold the mount with blind nuts on the back side and your are set maybe 8x48x5 prop very nice should be trsdy to go in no time maybe 2 oz tank?? you could get a 3oz in.. I really like ther Hayes tanks no changes needed for diesel fuel martin

Just noticed you are using the Mills so not owning one maybe one the Mills guys will come up with the prop size to use

brokenenglish

It depends on what you mean by "best"...
The "outright" best prop would undoubtedly be wood but, failing that, try and get an old soft plastic prop. I think Kavan yellow are still available, and there are plenty of good old plastic props available on eBay. A modern composite prop will just be a risk of breaking the engine in a heavy landing, for no advantage... You don't need a prop designed for a modern schnürle.
The best "sport" plastic prop for a Mills is the old Topflite 10x3 1/2, but these are getting a bit rare (they're all in my cupboard!).
Don't go smaller than 9x4.

AMB

Well I was close but no cigar a 9x4 about equal to an 8x5 but the larger diameter 9 or 10 inch makes sense it is a long stroke engine some where in the 8500-9000 range my guess to move the plane nicely. on some of my stuff, converted electrics increased wheel size to get ground clearance for the prop diameter martin

ffkiwi

...no they're not-there's at least 6 of em in my cupboard.....;-) Actually I'm in 100% agreement with brokenenglish on this one-the old Toplflite 10x3-1/2 is ideal-soft, flexible, plenty of blade area and a thin hub. And still readily found on Ebay-sometimes in packets of 6 (which ought to be a lifetime's supply if you're careful). A second choice would be a Tornado plasticote wood 10x3 (but these are pretty thin on the ground these days). Certainly under no circumstances would I go smaller than a 9x4-and that would run it flat out-which is neither needful nor desirable for such an old and fairly rare engine.

ChrisM
'ffkiwi'

PS and the aforementioned 10x3-1/2 also makes a great prop for 3.5 vintage diesels such as the Amco 3.5s, ED Hunter and DC350 for vintage FF and RC use.................