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A Mills At Last.

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PC.Vere11/12/2014 07:33:26
98 forum posts
14 photos

After looking around for some time and always missing out in auctions I have acquired a genuine Mills .75 diesel at last!

I did pay top dollar for it though, as I was always trying to fluke a cheap one in the past, being outbid each time. So I decided I would fork out on the next good one that came along and I did!

I have also downloaded a plan for a Veron Cardinal (free flight model). This takes me right back to the first successful model aircraft I ever built, while in my teenage years!

Being a practical and reasonably good engineer/machinist, my plan initially was to try to make a replica of one of these popular little engines - that has still to happen of course! but, I have almost finished setting up a small home foundry which should help me make the dream a reality.

My question is :- has anyone here ever attempted a build such as this? - if so, I would be happy to hear from you, re techniques used in the various operations and also any pitfalls which I am likely to encounter (i'm sure there will be a few!).

smiley

Thanks....

Peter Miller11/12/2014 08:34:45
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11093 forum posts
1309 photos
10 articles

AH! The MIlls .75 and the Cardinal. Takes me back to 1953 and my first successful power model.

I still remember buying a couple of balls of string and making a bow and arrow from the hedge to get it down from a tree. Also walking back through the village. The vicar stopped me and wanted to talk. I was more interested in getting home and applying first aid to my chopped finger. (First of many engine bites.)

bert baker11/12/2014 08:40:28
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1609 forum posts
331 photos

The Veron Cardinal has been to date my most susesfull free flight plane.

Use the right metals for the engine B&Q alluminium is not a good idea.( Been there bent it chucked it)

Bicylce alluminium pedal cranks are worth a go.

Best place would be a metal scrap yard, you will probably find some old truck pistons that can be melted down.

There's loads of plans for engines all over the internet, and plenty of books to.p4280005.jpg

Good luck

Simon Chaddock11/12/2014 09:32:37
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5715 forum posts
3034 photos

PC.Vere

Home building such as a Mills is possible but you would need access to quite a bit of engineering equipment. The Mills used remarkably sophisticated materials for the time. Link

A cast magnesium crankcase is not really a DIY proposition and would have to be substituted for a machined all over aluminium alloy version.

You would also need access to both heat treatment & grinding facilities for the piston, cylinder liner and crankshaft if you wanted to achieve the long life of the original.

I certainly don't have the skills to make a model plane engine but my Dad did and as a young lad I watched him do so.wink 2

Paul Jefferies11/12/2014 10:56:15
254 forum posts
39 photos

I would agree with what Simon has said but since you now have a Mills .75, why not build a replica of the original Mk1 Mills 1.3........ That used a solid block of Ali (or possibly dural) for the crankcase and is the granddaddy of them all! smiley

David Davis11/12/2014 11:44:22
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3757 forum posts
718 photos
Posted by Peter Miller on 11/12/2014 08:34:45:

AH! The MIlls .75 and the Cardinal. Takes me back to 1953 and my first successful power model.

My first successful model too! it followed a Keil Kraft Ajax and a Keil Kraft Invader IIRC neither of which flew well. If it hadn't been for the Cardinal i wouldn't be typing this now. Being a faddy sort of twelve year-old I wanted a purple fuselage to set off the yellow tissue covered wings and tail. You couldn't buy purple dope then so I mixed red and blue. It came out brown!

I don't suppose anybody else had a brown Cardinal!

PC.Vere11/12/2014 12:08:26
98 forum posts
14 photos

Thanks for those replies, they all make sense to me.

However, since having to retire about 5 years ago and after a period of hospitalisation, I have gradually managed to built up a fairly modest little home machine shop and now a small foundry in my garage ( nothing very sophisticated), I would like to use up what's left of my ability to make use of it all and this is the sort of stuff I would like to do. - (especially the foundry part), which I have wanted to try, for a lot of years.

I do have some good cast aluminium bits and pieces available for melting (probably heavier than the original magnesium of course). I'm told that a lot of older chainsaws have cast aluminium/magnesium crankcases as do many of the more expensive alloy car wheels but I may not be able to cast it easily, I dunno.

Of course, the precision steel parts will be challenge, ie crank, liner and pistons and at the moment I don't have access to grinding equipment. I can easily have the liner and piston hardened (maybe nitrided) depending on the steel used - I don't think that there was any cast iron used in this engine.

The 1.3 is quite 'doable' in a machine shop like mine of course, but I already have a good British .75 example on hand for copying and also a brand new .75 conrod, stowed away somewhere.

A nice replica of my first model as a whole, ie the Cardinal fitted with a .75, complete with its cast crankcase, would be my objective.

Any more suggestions are welcome, they will all be a help.

Edited By PC.Vere on 11/12/2014 12:15:13

BobW11/12/2014 12:29:02
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42 forum posts
23 photos

Hi

If you haven't already looked at it I would suggest having a look at **LINK**

Although Ron is no longer with us his website is still up and running with a massive amount of information within it and might prove useful solving any problem you come across smiley

Woops just realised the link has already been added  .... you can't have too much of a good thing smiley

Edited By BobW on 11/12/2014 12:36:22

Steve T11/12/2014 13:16:26
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488 forum posts
74 photos

Mr. PC Vere you rotten sod, I have been looking for a 'useable' .75 for what seems like forever. First engine I ever got to perform and I've had that good old soft spot for em ever since (1970 16yrs old). An early Vic Smeed free flight just bimbling around the sky on a dead calm afternoon. Sigh!

Enjoy and well done for finding one.

Steve T11/12/2014 13:42:11
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488 forum posts
74 photos

Has anyone any experience of the CS Engines Navo VTE series, 0.375, 0.5, 0.75 and 1.3. Very familiar aren't they. They look just like Mills as well. Steve Webb do them, and I have had nothing but good service from SWM. If I get good feedback I shall be back to 2ch with a nice little diesel up front next year. Lovely!

Erfolg11/12/2014 21:16:34
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11749 forum posts
1337 photos

The engines that Alex Whittaker builds use small quantities of materials. So he and his cohorts would be a good group for entering into discussions on material saucing and techniques appropriate to the small workshop, with its limited equipment.

Also being an ex engineer, I would look to machine the crankcase from the solid, as it is a one off. Crankshafts, really need to made using a jig, for the easist results, to hold the crankshaft, whilst machining the crank pin. Although this is a one off, is it worth while? But that is me. Alex and friends are far more knowledgeable and experienced with respect small volume, small sized engine building. They could well have very different approaches and ideas.

With respect to the old engines, although many materials were sauced from scrapyards, there was a pretty good idea, what different bits of war surplus scrap were made of, and hence what to look for, at that time. These days, engineering and knowledge who are doing what, with what, is less well known. Many items being made all over the world in even the humble motor car. With producers who treat their specifications like gold dust, so others do not know.

I personally would not try and cast anything in my garage, not that it can not be done. For me it is the risk, effort, and probable failure (at least on the first attempts) would not make it worthwhile. I am not well known for my love of health and safety.

On reflection, I would just buy a Bodo Mills, a lot easier.

I guess the difference though, is you love metal working, for me I loved getting others to make what I had designed/specified or I just managed. On reflection, I love engineering from a safe distance, even more now that I have retired.embarrassed

Alex is the way of the future, Alex knows.

PC.Vere12/12/2014 00:49:25
98 forum posts
14 photos
Posted by Erfolg on 11/12/2014 21:16:34:

[The engines that Alex Whittaker builds use small quantities of materials. So he and his cohorts would be a good group for entering into discussions on material ..............

Also being an ex engineer, I would look to machine the crankcase from the solid, as it is a one off............. Crankshafts, really need to made using a jig.......... Although this is a one off, is it worth while?

I personally would not try and cast anything in my garage, not that it can not be done............ I am not well known for my love of health and safety.

On reflection, I would just buy a Bodo Mills, a lot easier.

I guess the difference though, is you love metal working, for me I loved getting others to make what I had designed/specified or I just managed. On reflection, I love engineering from a safe distance, even more now that I have retired.embarrassed

Alex is the way of the future, Alex knows.]

.................................................................................................................................................................................

ERFOLG,

Thanks for your comments, I'll do my best to answer.

I'll try to find Alex (don't come here enough to know anyone) and get an opinion.

I am doing this for love of engineering really,as opposed to flying, (which I like too). Despite doing engineering work for a large part of my life, I still love doing it and casting is the next challenge for me, well, hopefully, (I'm now 70 and time is of the essence!).

I would never melt or cast anything in my garage (which is attached to my house) that would be madness! I intend to do it outdoors at a friend's place out of town or - at my son's holiday home, which is in a little seaside country town far removed from where I'm now living. - I do want to keep on side with my neighbours here!

So as you will no doubt understand, whether it is worthwhile ( from the point of view of economic sense) or not doesn't really enter into the equation!

the Bordo Mills I'm sure is very good, from what I have seen, but my comments above should explain why I just don't go and buy one.

 

Edited By PC.Vere on 12/12/2014 00:52:07

PC.Vere12/12/2014 01:02:58
98 forum posts
14 photos
Posted by Steve T on 11/12/2014 13:16:26:

Mr. PC Vere you rotten sod, I have been looking for a 'useable' .75 for what seems like forever. First engine I ever got to perform and I've had that good old soft spot for em ever since (1970 16yrs old). An early Vic Smeed free flight just bimbling around the sky on a dead calm afternoon. Sigh!

Enjoy and well done for finding one.

.................................................................................

STEVE

Yeah, I've been called a 'rotten sod' many times before! - doesn't bother me much though! smiley

I might be prepared to sell on this (more or less perfect) example, sometime next year, ie. when I've got all the measurements and drawings done and a copy actually made. - not wanting to make a huge profit - just enough to recover costs really.

bert baker12/12/2014 08:32:55
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1609 forum posts
331 photos
Posted by PC.Vere on 11/12/2014 07:33:26:

My question is :- has anyone here ever attempted a build such as this? - if so, I would be happy to hear from you, re techniques used in the various operations and also any pitfalls which I am likely to encounter (i'm sure there will be a few!).

Well I would say yes a few have made their own,

I get the impression you will be fine, and able to work through any problems.

The trick will be working out the sequence of machining without the need to make many jigs etc.

It's nice to be able to make your own for fun, I have spent loads on mills drills and lathes, if i totaled up the cost of it all, it sure would have worked out cheaper to have stuff made for me.

One day I will get round to making the David Parker Vega twin four stroke and perhaps the Maltese Falcon too

Erfolg12/12/2014 10:48:47
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11749 forum posts
1337 photos

The theme of this thread, has been praying on my mind, all night. There are so many issues.

My first port of call, was making an engine involves a lot of work for a home worker, with limited equipment. It also struck me that when in industry, many machining processes that would be undertaken on optimal machine tools, would either be series of had-hoc processes on a lathe or hand worked. I also thought that many of the design decisions would be based on minimising operations, based on batch production processes, be it the use of extruded sections, castings and bar stock, treatment processes etc.

Again I reflected as a young man, it was initial workshop training that made me resolve, to get off the tools. As my dad said, anybody can do what tradesman do, what is difficult is making things to a size, to time, day after day, just to feed yourself. It also became rapidly apparent whilst doing foreigners, that my knowledge of materials and material processing, characteristics was poor. As to designing, I personally did not have a clue, not understanding, that everything has a cost and minimum duty to be achieved. Anything greater comes at some cost, and possibly no tangible benefit.

Which took me onto casting, and thinking of the most obvious issues, of where to get the sand, at what cost, for such a small amount. Issues of coping boxes. Then safety, what could go wrong, consequences. Access to leather aprons face guards and so on.

I did think you really have to be dedicated to produce a replica engine, who will invest so much time, money? You really have to enjoy manufacturing things in metal.

Again i did think, of David Boddington, who achieved a lot, in not only getting his replicas produced, generally to high standard, getting better as his experience of the whole process increased. I am assuming that he produced the specification, which will have included drawings of the components, dimensioned to suitable limits and fits, material specifications, material finishing processes, deciding on economic batch sizes relative to projected sales, tendering process, obtaining sales. He must have loved it all, to bother after his first experiences getting engines made.

To make a engine at home has to be a process of love and perseverance. I wish the very best. You will either learn a lot, or it will re-enforce a considerable collection of knowledge already held.

Edited By Erfolg on 12/12/2014 10:50:39

PC.Vere12/12/2014 12:44:21
98 forum posts
14 photos

Thanks for all these replies with your ideas.

Having been retired for 5 years now and having recovered quite well, I feel the need to prove that I can do more than just sit on the computer, watch TV and generally become even more geriatric before my time - I'm actually getting some things done, albeit slowly.

Whether or not I will actually manage this I don't know, but I need to do it soon,before my eyesight gets really bad as it's quite fine work! - It won't be a dawdle I know, but there is nothing about the casting or construction of the Mills which could be called really sophisticated or complicated!

I have already acquired or made most of the stuff needed, ie. foundry equipment/materials/ingredients(nothing really expensive here as the cost of material etc for these small castings will be negligable) and most of the tools, I have made.

Safety gear? - well, careful, sensible and not rushing into things is probably half the battle! - Other things like good boots, gloves glasses, etc? - that goes without saying and this sort of equipment I already have, (but I'm sure I will have forgotten something!).

It's a labour of love only, with no thought of marketing it profitably (as in Boddington's case). Any jigs etc. I have to make, will possibly only be used for one example. - unless it's easier to make than I thought, then I might have a second attempt and learn from my mistakes!

Looks like the grinding will be the biggest challenge, but I'll give it a go somehow! - again, any tips on grinding/lapping/fitting these small hardened steel piston and liner assemblies would be appreciated.

smiley

PC.Vere12/12/2014 23:01:37
98 forum posts
14 photos

I think that I've probably got enough info.now on this little engine. I have more or less read every link that I could find on the net.in the last 6 months ( amazing the amount of info there is on this seemingly insignificant little engine).T

The rest is now up to me and I will now just have to take the plunge and hope for the best.

Again, thanks to you all for your interest and hopefully I will be able to come up with something worthwhile reasonably soon.

PS sorry for earlier using the name "Bordo" instead of "Boddo"  (David Boddington's version)     smiley

Edited By PC.Vere on 12/12/2014 23:08:07

bert baker12/12/2014 23:58:55
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1609 forum posts
331 photos

Good for you just go for it and have fun, best of all if a bit wears out you can remake it.

The internet is full of how too's.

No doubt the new kids will 3D scan the engines and get a 3D printer to print the thing in wax and lost wax cast them

Best wishes and looking forward to seeing a build blog,

Bert

PC.Vere13/12/2014 01:08:13
98 forum posts
14 photos

Thanks Bert,

Yes, these things are truly wonderful of course and I do mean that,but........where's the challenge?

You just have to work harder and longer hours to buy the things and maintain them (read throw them away and buy the latest model with bright sparkling lights and pretty cowlings!). Still - that's progress I guess, who are we to halt "progress".!

A build log will only come after I've made some progress    .smiley

Talk later.

Edited By PC.Vere on 13/12/2014 01:11:21

Mark Lubbock14/12/2014 17:21:03
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313 forum posts
13 photos

Get yourself a copy of Ron Moulton's Model Aero Engine Encyclopaedia, it details designing, building, (including casting of crankcases) a model engine. It was my inspiration for building my own little engine, the ML Midge (one also fitted to a Cardinal). You can find details of my little engine on Ron's website it is a good beginners small engine.

I think everything you say is doable at home, once you have a crankcase the Mills is a very simple and forgiving engine, best of luck!!!

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