Author Topic: Atom Minor Mk III  (Read 18875 times)

Offline Jo

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Re: Atom Minor Mk III
« Reply #60 on: December 31, 2017, 03:42:04 PM »
 ::) The bottom of the piston has been milled out with a square hole to give the end of the connecting rod some space and the piston put bck into the cylinder so that it is not lost while I make the connecting rod.

A piece of plate has been put on the bed of the BCA and two 6BA holes drilled to take either end of the connecting rod. Using the flat edge of the Dural the rod was rotated to give the correct angle for the side of the rod and first one side milled. the rod was then flipped over and the second side milled. By flipping the rod over we know that both sides are as the same angle /position relative to the centre line of the rod.

Jo
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Offline Jo

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Re: Atom Minor Mk III
« Reply #61 on: January 01, 2018, 04:28:37 PM »
The ends of the rod have been rounded and the profile finished by hand, leaving the slot down either side of the rod. These slots are cut with a 2.4mm cutter 1.2mm deep  :paranoia: I chose to first mill the slot down the centre with a standard slot drill, then go over to a ball nose cutter and swing the rod either way on the BCA's table to form the curved sides to the slot. A tickle and a polish and the rod was done  :)

Of course when the rod was fitted first the skirt of the piston was a bit too close for comfort :o to the crank web so I skimmed an extra 0.5mm off of that. Then found that I still have to grind a bit of a groove round the inside of the crankcase so the rod does not catch  :-\

W**k tomorrow  :toilet_claw:

Jo
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Offline Admiral_dk

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Re: Atom Minor Mk III
« Reply #62 on: January 01, 2018, 08:08:55 PM »
That is truly unwanted interference  >:( - been there, done that :censored:

All the rest - nicely done Jo  :ThumbsUp:

Offline Jo

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Re: Atom Minor Mk III
« Reply #63 on: January 05, 2018, 04:10:14 PM »
Thanks Per  :),

Further investigations showed that something was a miss  not with the engine but the drawing.  Having got the calculator out all is obvious: The crank throw is 23.82mm, the outside of the bottom of the connecting rod is 9.92mm = 33.74mm which is going in a 32.54mm hole in the crankcase  :rant:

I decided that was miles too much to grind out and make it look pretty  :disappointed: so opted for the mount it on a three jaw and take some out. Remembering that the case is only 1.5mm thick  I took the diameter out by 1.4mm. I thought what remained was a bit thin  :o so phoned a friend who told me " who yes had I not mentioned you needed to do that, no the drawings don't show that do they".

The other bit to be aware of while moving towards round and round testing is that slot in the cylinder: the centre line of the bore is off set from the centre line of the crankshaft in the casing, the result is that it needs that slot to clear the connecting rod and it is a bit tight on the rod but the good news is that it can be opened up a bit more. The connecting rod sides can also be reduced a little more if required  ;)

A little bit of fettling later and the cranks in, and the piston is going up and down when you twirl the crank and if you put your finger of the spark plug hole while you make it go round and round it sounds like a very passionate little engine  :embarassed:

Jo
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Offline b.lindsey

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Re: Atom Minor Mk III
« Reply #64 on: January 05, 2018, 05:32:19 PM »
Glad you have all the little kinks sorted out Jo. It's a fine looking little engine and you have made rapid progress on it. Just mind your fingers when it comes running time :)

Bill

Offline Roger B

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Re: Atom Minor Mk III
« Reply #65 on: January 05, 2018, 05:41:50 PM »
The joys of engine building  :) So parts of the crankcase are now less than 1mm thick? I was concerned about going that thin on my vertical engine Mk2  ::)
Best regards

Roger

Offline Jo

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Re: Atom Minor Mk III
« Reply #66 on: January 05, 2018, 06:47:48 PM »
Thanks for following along Guys  :) I do love making these old aero engines but it would be nice if they updated the drawings  ::)

So parts of the crankcase are now less than 1mm thick? I was concerned about going that thin on my vertical engine Mk2  ::)

Yes Roger they are less than 1mm thick  :paranoia: but I was reminded that this is an engine for a model aircraft so the builders would be looking to make things as light as possible.

Jo

P.S. Did I mention spring is in the air? Having found sorting out that crank problem had not helped me recover from having to go back to w**k   :toilet_claw: I decided to get the first batch of onion (seed) in. Having seen what monster onions Dave can grow  :o from seed in one year it seems silly to buy onion sets
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Offline Bluechip

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Re: Atom Minor Mk III
« Reply #67 on: January 05, 2018, 08:41:28 PM »
Spring is in the air is it ???     :headscratch:   I'll be happier when it gets down to soddin' ground level    :cussing:   

Went for a blood test this AM, then got sopping wet and abandoned my shopping trip .....  :Mad:

My onion seed arrived a couple of days ago ....  :D

PS If you land up with a bumper crop, what shall I do with mine ????  ( Apart from the obvious )

Dave


Offline Jo

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Re: Atom Minor Mk III
« Reply #68 on: January 06, 2018, 05:05:31 PM »
My onion seed arrived a couple of days ago ....  :D

If you land up with a bumper crop, what shall I do with mine ????  ( Apart from the obvious )

hi Dave, it looks like we both have the same standard onions seeds to try growing  8) (I also have two types of red ones) all are now residing in my little conservatory. One can never have too many onions  ::)


Sorry nothing significant worth reporting on the Atom progress hope to feel better tomorrow, going back to w**k has made me feel  :toilet_claw: about to resort to some  :wine1: to help me forget how horrible it was and I will have to keep off the morphine this evening as it does not mix well with alcohol  :disappointed:

Jo
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Offline Jo

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Re: Atom Minor Mk III
« Reply #69 on: January 31, 2018, 01:32:49 PM »
Dave: I have green paper clip sign  :cartwheel: how are yours doing?


A bit of 1.6mm gauge plate drilled to match the screw in the inlet plate and screwed onto a mandrel with some superglue to keep it there. This was then turned to 32mm outside diameter to match the inside diameter of the crank case.

On to the BCA (whose DRO is working again  :embarassed: )  drill for the pin at zero degrees and then (remembering to offset in the correct direction) drill the two root holes for the open part of the valve. Using the rotary table mill the two sides (again getting the offset in the right direction) and the bottom curve. Finish with a needle file and rub both sides on some wet and dry before riveting in the drive pin.

Another rub on the wet and dry to make sure the riveting is flush and in the rotary valve goes  :)

Jo
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Offline Bluechip

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Re: Atom Minor Mk III
« Reply #70 on: January 31, 2018, 02:57:58 PM »

Dave: I have green paper clip sign  :cartwheel: how are yours doing?

Jo

Onion seeds in the packet, resting.    :embarassed:

Greenhouse still infested with wood.  :rant:
Just painting the last bits of rustic rubbishy shelving I'm making. Or would be, I've run out of red paint. Getting some tomorrow.
Then that's it. Finished with wood butchering. The end is in sight ( or nigh,   :headscratch:  depending on one's outlook ).
Between snow showers the paint is drying fairly well, gets quite warm in there when the sun comes out.
Should be able to liberate the g/house for it's intended use Sat / Sunday-ish ....  :whoohoo:

Cracking on with this engine   :ThumbsUp:  when's the 'First Bang' scheduled ????

Dave  :old:


Offline Jo

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Re: Atom Minor Mk III
« Reply #71 on: January 31, 2018, 03:28:51 PM »
You can keep your cold weather up North  ;) My Daffs, Irises and yet more snowdrops are smiling at the sun down here  8)

Cracking on with this engine   :ThumbsUp:  when's the 'First Bang' scheduled ????

Engine running is dependent on availability of the necessary safety support team: Currently they are all a bunch of wimps and the numbers of engines that need testing is building up :( enabling certain people to be very rude about it  :ShakeHead:

Jo
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Offline Bluechip

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Re: Atom Minor Mk III
« Reply #72 on: January 31, 2018, 10:26:17 PM »

" certain people to be very rude about it "     :ShakeHead:

Jo

Absolute Cads and Bounders !!!  ....  Name and Shame  !!  ... Should be tied up and horse-whipped !!

...... unless, of course, they enjoy that sort of thing in which case I'm  pretty much stuffed for ideas ...  :headscratch:

Dave



Offline Roger B

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Re: Atom Minor Mk III
« Reply #73 on: February 01, 2018, 08:04:15 PM »
Sounds like you need to go down to Hampshire and help Dave  :stir: I do have to admit that propellers scare me   :paranoia:  They seem to be capable of chopping bits off  :(
Best regards

Roger

Offline Bluechip

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Re: Atom Minor Mk III
« Reply #74 on: February 01, 2018, 09:21:54 PM »
Sounds like you need to go down to Hampshire and help Dave  :stir: I do have to admit that propellers scare me   :paranoia:  They seem to be capable of chopping bits off  :(

I will be going down there in the next couple of weeks or so, but propellers are definitely off the itinerary after some lurid tales I have heard ...  :insane:
As I mentioned to Jo, I only had one very brief involvement with model planes and that ended in catastrophe. ( For the plane, not me ).

Like you I am very wary of sharp whizzy-roundy bits. In fact I have adopted rank cowardice as a lifetime philosophy.
I'm probably entitled to medals for it ....  :D

Dave

 

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