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Economy Hit & Miss Engine Build.

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Andrew Johnston01/03/2017 10:44:59
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When I made my Economy it wasn't possible to machine the base casting to the drawings. For the crankshaft bearing supports I made the inner dimension to the drawings, but had to make the width of the bearing surfaces narrower. When I made the crankshaft bearings I made them full width as per the drawings. But I made the groove narrower, and biased, so that the inner and outer dimensions across the bearings coincided with the drawings.

Andrew

Nick_G01/03/2017 16:55:07
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Cheers Andrew, Your knowledge having made one will be valuable. smiley

Am I right in thinking that Colemans is basically a more refined / purified petrol with a lower octane level.?

Nick

JasonB01/03/2017 18:37:21
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I think it is naptha based and does have a lower octane

Nick_G03/03/2017 03:30:48
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.

Not a lot of progress in the last couple of days. But I have made the split bearing for the big end.

Soft soldered the splits together and centered the divide up in a 4 jaw. Bored out the center to 20mm and then cut the groove on the outside as can be seen.

This was a nerve wracking process as the wall thickness ends up at only 1.5mm on this. I had visions of the solder giving way or it collapsing like like clay on a potters wheel. laugh

So towards the end I sharpened the tool and took light cuts of 0.1mm - Got there eventually and the solder joint held. I will split it later down the road with a blip of heat from a blow torch.

The steel has arrived for the conrod so it seems logical to make that next. - This may take some time.! frown

Nick

Andrew Johnston03/03/2017 11:33:18
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Posted by Nick_G on 03/03/2017 03:30:48:
The steel has arrived for the conrod so it seems logical to make that next.

In the early kits the conrod was supplied as a flame (laser?) cut blank. I didn't get one in my kit, and it took a lot of argy-bargy to extract it from the supplier. Having received the blank it was thinner than the finished size on the drawing. sad So I binned it and hogged it out of hot rolled steel.

Andrew

Ian S C03/03/2017 12:00:17
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Coleman fuel contains a mixture of Cyclohexane, Nonane, Octane, Heptane and Pentane. Octane rating is 50% / 55%, there is no Naptha in it

Ian S C

JasonB03/03/2017 12:11:38
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Probably bad spelling on my part its a Petrolium Naphtha product eg a mixture of hydro carbons.

see wiki and the wiki for "white Gas" as it is often known (option 1)

Edited By JasonB on 03/03/2017 12:12:23

Neil Wyatt03/03/2017 15:55:21
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Posted by Ian S C on 03/03/2017 12:00:17:

Coleman fuel contains a mixture of Cyclohexane, Nonane, Octane, Heptane and Pentane. Octane rating is 50% / 55%, there is no Naptha in it

Ian S C

Ah a mixture of flammable hydrocarbons! Sounds like naptha

The trouble with 'naptha' is it is just a vague word for readily burnable oil l. I've always thought of it as an all-inclusive word for more volatile oils like petrol, diesel, paraffin and maybe white spirit in contrast to vegetable and lubricating oils.

Neil

Martin Cottrell03/03/2017 21:14:26
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Nice progress Nick! How did you produce those lovely smooth curved corners on the crank webs?

Martin.

Nick_G03/03/2017 22:11:42
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Posted by Martin Cottrell on 03/03/2017 21:14:26:

How did you produce those lovely smooth curved corners on the crank webs?

Martin.

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I would 'like' to say I am a demi-god with a file. angel But I would be lying .!

The truth is they are courtesy of an ARC product in the form of :- **LINK**

If I had done them freehand they would have looked like a well chewed wine gum. blush

Nick

Martin Cottrell04/03/2017 22:21:35
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Posted by Nick_G on 03/03/2017 22:11:42:
Posted by Martin Cottrell on 03/03/2017 21:14:26:

How did you produce those lovely smooth curved corners on the crank webs?

Martin.

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I would 'like' to say I am a demi-god with a file. angel But I would be lying .!

The truth is they are courtesy of an ARC product in the form of :- **LINK**

If I had done them freehand they would have looked like a well chewed wine gum. blush

Nick

Ah yes, hadn't thought of using one of those! I thought maybe you had rounded them off on a belt sander but they looked too uniform to have been done like that freehand. All looking fabulous so far, will be an impressive engine when finished!

Martin.

Nick_G07/03/2017 17:35:29
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I am on with making the conrod. yes ............ It's taking ages as there is a lot of metal to carve away. indecision Getting close to the shape now but getting the 'jitters' at each new machining section as I have a lot of time invested in this part and to make a bad cut now would be ................ Bad.! frown

Anyway. The cast iron casting for the cylinder / water hopper turned up today. Postman remarked that everything I seem to have delivered is heavy. laugh

Nick

Michael Gilligan07/03/2017 19:30:26
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That 'looks the business' Nick yes

MichaelG.

Nick_G07/03/2017 19:57:10
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Posted by Michael Gilligan on 07/03/2017 19:30:26:

That 'looks the business' Nick yes

MichaelG.

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I just wish they would not have letters or numbers on the castings as I have to grind them off.!

Nick

JasonB07/03/2017 19:59:42
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I hate that too, often done with a Dymo lable, suppose it helps the foundry keep track of patterns and castings. Could so easily have put that number on the push rod pad where it would get machined off.

Ian S C08/03/2017 08:40:13
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Why take the numbers off, full size motors have casting numbers on them?

Ian S C

JasonB08/03/2017 09:09:43
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If the number is not a scale representation of the originals then I take them off, some do replicate the original number so in my case they stay. I have even been known to add lettering/numbers but i try to do it to scale not stick a dymo lable oncrying 2

Ian S C09/03/2017 09:57:42
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I see what you mean with the number on the hopper opening, it looks likely to be a Dymo stick on, I was initially looking at the letters ECH on the side.

Ian S C

Nick_G10/03/2017 10:40:38
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The conrod.

I eventually got 2 pieces down to the major size required and drilled and tapped. The big end cap is a little longer as I want to turn a section in the lathe and then shorten it to remove where the live centre recess has been. - This rounding is not on the original drawing as it's shown as just a block. I thought it would look a bit better.

Decided to get the holes in each end while it was all a uniform shape and simple to grip. This is the first time I have used a boring head in a mill but there was no drama.

Checked the size of the split bearing (made previously) that is still soldered at the joint.

Then split it and checked it against the big end it's self. - Mmmmmm, twas a little tight. sad Not much, so had to lap the 2. A conversation with Jason gave me advice on the best way to do this.

Over to the lathe for that rounding shaping I mentioned.

Milled the sides down to the required width.

Then milled in the roundings for the taper of the rod. - By now I was getting concerned of doing something stupid and ruining a part that by now I had invested considerable time into. frown

This concern reared it's head when it came time to cutting the recess groove along the side of the rod. It should be following the line of the rods taper. But I ran out of balls.! I admit it would look better so I really should have grown an extra pair and gone for it. blush

Milled into the edges to form the taper and round off the little end.

Made some proper studs from 6mm silver steel and shortened the bearing cap to length.

I still have to make the PB bearing for the little and and drill in some oil holes etc. 

I will remove all the tooling marks and give it a polishing when it come time for final, final, final assembly. That way I will hopefully not do my normal trick of bashing, dinging and dropping totally finished parts during the rest of the build. crying

Nick

 

Edited By Nick_G on 10/03/2017 10:46:12

JasonB10/03/2017 11:00:48
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Looking good (and big) Nick. When you do the next one remind me to tell you the easy way to get that tapered recess to follow the outside of the rod.

J

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