The Mills engine has now been completed but has it started? No not yet BUT it did fire today...blue smoke and all! However before we get to that I decided to try and start her again today. First I made a starter to run in my drill and after that I stripped the engine down and checked the contra piston, and piston in particular.
According to Ron Chernich's article the piston fit was spot on. i.e. the little end moving to the exhaust ports before stopping. It also showed the taper to be correct as well. Looking at the contra piston though, it was a pretty good fit but not as good as the piston so I made up another and made it fractionally bigger. It did not go into the cylinder liner quite as much as the other before becoming stiff. Indeed I would say this one was more on the very tight side, which is what I wanted.
Cleaned the engine parts again in the ultrasonic ring cleaner (stolen from under the nose of 'she who must be obeyed'!) and reassembled the engine. I must admit I was very surprised at the difference in compression for such a small adjustment. But then, I am new to this game........
Armed with renewed enthusiasm, I followed Ron's start up instructions and screwed the compression screw in, between trying to start her. Unfortunately it became a little discomforting so I decided to use the startering adaptor I made earlier. After three or four more adjustments to the compression screw, the thing fired! Whereas I 'hoped' I felt it fire before, I now know it didn't, because this was completely different. This time there was a puff of blue smoke from the exhausts and a definite smell......(no comments please).
I thought I would go back to the manual method again, as it may be near its setting, but it was too difficult. So I decided to retire before I broke something, and will try again tomorrow.
I may make another piston though, first thing, and see if this will make as much difference and the contra piston did. Its easy to dismantle the engine and change things.
I marvel when dissabling on how few parts there are, compared to how long it took me to make the thing! It is a simple job to disassemble and reassemble so hopefully I can report a more positive result soon..........
Main build covered on the website www.mikes-models.com
About Mike Freeman
Hello, my name is Mike Freeman and I am a retired Chief Fire Officer from the United Kingdom with a keen interest in model engineering, silver caddy spoons and sea fishing. I live in the pretty fishing port of Brixham, South Devon, in the United Kingdom.
I am a sufferer of degenerative osteoarthritis, which impacts on the amount of time I can spend in the workshop, and is the reason why you will see seats and a stool in some of the photo's. I have only recently added the above sentence after a discussion with one of my Doctor's from the excellent pain clinic, based in Torbay. This does affect concentration one of the reasons why I double then re-double my measurements and set ups.
Before completing nearly 30 years of public service I and my wife Sandy, owned and ran, a small restaurant in Okehampton Devon. Prior to marriage I worked for my father in his various businesses, in the early days these were garages, which he bought in a run down state, then built them up before moving on, to start again.
I took every opportunity in those early days, to work in his workshop's
learning 'on the job' rather than as an apprentice. This, I suspect, is the reason why my building various model's in the early days, turned into model engineering, when funds allowed the required equipment to be bought.
My workshop comprises one half of a detached double garage. It has a
stud wall separating the two halves and unusually perhaps, its own
shower/toilet/washbasin compartment! (the true reason for buying the
bungalow - don't tell the wife!!!)
It is fully insulated with a ceiling and fluorescent lighting supplementing the one window. Several double electrical sockets are dotted around in
relevant positions.
Equipment consists of 2 lathes (1 Myford ML 10 and 1 Chinese variable
speed motor with etched glass DRO's), 1 milling machine (RF25 far East) floor standing pillar drill, Proxxon bandsaw, Warco bandsaw, 6" wire brush and polishing mop motor, 6" coarse and fine grinder, Proxxon mini drill, various benches and an engineers vice. I have just acquired a third lathe, a Myford ML7 which I am at present evaluating so I can decide which of the Myford's I will keep.
I have only just bought the Chinese lathe and had it fitted with DRO's prior to delivery. And what a bonus they are! So good in fact that I decided to buy another set for the Milling machine. Whilst my engineering experience can only be described as limited, I find the use of DRO's has affected my accuracy levels which have improved tremendously (although that's not saying much!) and would recommend their fitting to any model engineer.
Prior to retirement I built for my son's 17th birthday a Locost car. This
was a tremendous project and a great feeling when it passed its test. The book it was based on suggests it can be built for £250. Ours was nothing special in the sense of all new parts but still cost about £900 to build!
After all that effort you still have not seen it working yet! I shall keep watching to see if tomorrow brings some btter news.