Ghosty's "V" Twin

[Ghosty]

Hi All,
Thanks guys, will keep moving on. Got the timing gears and cams done.

Cheers
Andrew

 

[Ghosty]

Hi All,
Got the crankshaft done this arvo. not happy with the bearing boss, did not put the spacer width in.
May make up another shaft.

Cheers
Andrew

 

[Ghosty]

Hi All,
Not a lot done today, messing around with the brother in laws band saw, got a bi metal band for it, had to repair the drive wheel, rubber band had come off. Cut the 1" alloy bar stock for the engine frame with Oldhams lub on the band it worked good. Better that using a hacksaw.
Brother in law used it to build model trawlers, and gave up after the band came of and went back to cutting the wood by hand.

Cheers
Andrew

 

[Ghosty]

Hi All,
Made a start on the engine frame, after pining and bolting two 25mm thick plates together, I started the machining of the engine frame. I trial fitted the crank and cams, I will be making a new crank, just not happy with it.

Cheers
Andrew

 

[Ghosty]

Hi All,
New shaft and crank web made this morning. Now off to race some boats.

Cheers
Andrew

 

[Ghosty]

Hi All,
Got the cyl mounts done, and a first assy of the engine parts.
Will make a start on the pushrod assy today, it is going to be a hot day today, so don't how much I will get done.

Cheers
Andrew

 

[Ghosty]

Hi All,
Got the push rods done and intake done except for the O ring seal collars.

Cheers
Andrew

 

[Ghosty]

Hi All,
Got the rocker gear and the intake O ring keepers done.

Cheers
Andrew

 

[Ghosty]

Hi All,
Only got the timber base done today. Waiting on some Oilite bearings so I can do the con-rods.

Cheers
Andrew

 

[Blogwitch]

I do hope you are not using oilite bearings in your con rods.

There is a reason for it.

Oilite bearings are not solid, but sintered, made up of tiny balls compressed together, great for rotary bushes but I doubt if they will stand up to explosive forces pushing down onto them mounted into the con rods in your engine, they are liable to just shatter into tiny pieces.
I had enough trouble carefully parting them off to make thrust washers for rotary tables, they just disintegrate before your eyes.

John

 

[Barnbikes]

Beginners question here.
Seeing that it is a 2 cylinder will you need twice as big flywheel to carry the momentum? or how do you calculate that?

Jon

 

[Brian Rupnow]

I do hope you are not using oilite bearings in your con rods.

There is a reason for it.

Oilite bearings are not solid, but sintered, made up of tiny balls compressed together, great for rotary bushes but I doubt if they will stand up to explosive forces pushing down onto them mounted into the con rods in your engine, they are liable to just shatter into tiny pieces.
I had enough trouble carefully parting them off to make thrust washers for rotary tables, they just disintegrate before your eyes.

John

John--are you speaking from personal experience, or just posting what you "think" you know? I have used oilite sintered bronze bushings in con rods on engines that I have built. I do have personal experience with them. They work fine. I wouldn't want to run the engines at 18000 rpm with sintered bushings, but for low speed engines they work very well, and their ability to retain oil seems to give them an advantage over solid bushings.---Brian

 

[Blogwitch]

Brian,

No experience using them like you are doing, just many years experience of using many types of bearings and materials for bearings, including Oilite in a vast array of circumstances. In other words, the right ones for the job.

They are not designed to be used with shock loads because of their build structure, they are very fragile when used in shock compression, which is the state you are using them in. Maybe you are just lucky.
I know this isn't definitive, but it does show that solid bronze is preferable to Oilite due to their relevant strengths

http://www.getyourbearings.co.uk/oilitephosphorbronze.html

Take note of the shock loads and maximum load.

If it was me in that situation I would use something like these polymer bearings or their steel or bronze counterpart. In fact, I would most probably make my own out of something like ali bronze.

http://uk.rs-online.com/web/p/linear-plain-bearings/6671434/

One of these bagged sets would last a lifetime in the smaller sizes.

John

 

[Ghosty]

Hi All,
Made a start on the con rods.

John,
Like Brian, I have had no problems with the Oilite bearings in the big end, as long as they are not machined. They fall apart if you machine the ends(brake The seal so to speak) if they are too long. I order to size. With the con rods for the twin, I have will have to make them out of some bronze that I have as my supplier can not supply the width of bearing that I need.

Barnbikes, Jon, the fly wheel does not need to be twice as big, could use the same as for the single, could even use a lighter one. How do you calculate is a lot of maths that I don't have handy.

Cheers
Andrew

 

[Ghosty]

Hi All
Got the con rods done, started the assembly.

Cheers
Andrew

 

[Ghosty]

Hi All,
Getting close now, have to work out a fuel tank, and a flywheel. May have a contact with someone who has there own forge, may be able to make my own flywheel blank.

Cheers
Andrew

 

[Longboy]

Really aced Andrew on your design of offset (to block) cylinders and overhang crankshaft. I have a couple engines using that concept I'm happy with. :thumbup:

 

[Ghosty]

Hi All,
Sneaky little fuel tank made and fitted. Just waiting on some more magnets for the ign system.

Cheers
Andrew

 

[Brian Rupnow]

I'm interested in seeing this run. Everything I have read about twin cylinder engines indicates that if the cylinders are not diametrically opposed, or side by side, that the engine will "lope" because of the angled configuration. I don't know if this is a concern for model engines or not. I have seen videos of the Hoglet engine that seemed to work alright. I have no doubt that it will run. It is an interesting adaptation of the original design.---Brian

 

[Ghosty]

I'm interested in seeing this run. Everything I have read about twin cylinder engines indicates that if the cylinders are not diametrically opposed, or side by side, that the engine will "lope" because of the angled configuration. I don't know if this is a concern for model engines or not. I have seen videos of the Hoglet engine that seemed to work alright. I have no doubt that it will run. It is an interesting adaptation of the original design.---Brian

Thank Brian, I am looking forward to running it as well.
Got the magnets today. Fitted the twin pickups, and then set the timing(5 deg BTDC) very easy with the ign test module.
[ame]https://www.youtube.com/watch?v=N023IU-GztA[/ame]
Got a reply on a price of 6" dia brass today, will be in next week I hope, will make a very nice flywheel.

Cheers
Andrew