Opposed twin Onan engine in half scale

[teeleevs]

Hi Ignator, I was given parts from a wrecked Chinese bike or quad, I have no idea why it was wrecked but guess the ignition failed. In my tries I only had the wires to the CDI and coil connected, tried several coils. Power wires to the rectifier only put out 2.5 volts AC, perhaps I should connect the rectifier and a battery, but it should spark without those. No kill switch connected. As for the Onan, I have been working on the ring gear and had trouble getting my head around cutting 85 teeth with a 120 tooth rotary table, watched some Youtube videos on the subject and found that both figures can be divided by 5 ie 5 x 24 = 120 and 5 x 17 = 85 I have some indexing plates somewhere put away safe? Searched for a gear and found one 17 tooth gear, just need now to build up a gear train at 24/1.
As for the up-side-down parting tool we have been using a small Bransby lathe with no back gear and the tungsten saw blade just cuts Alloy and steel like butter, must keep the lube up to it though.

 

[teeleevs]

These pictures have been posted elsewhere excep #6, don't know why they are not here, #1 lightening the rod with piston attached, #2 oil groove #3 finished job with roller bearings fitted, #4 setting up the magnito #5 flywheel in place, fan fits over this, #6 cutting teeth in the ringgear, this gave me a headache producing 85 teeth with 120 tooth rotary table.
Ted

 

[teeleevs]

Another day on the Onan, finally got my head around the 85 tooth ringgear setup picture 1 cutting teeth, the fan needs a little more finishing and balancing, #2 the 24/17 geartrain, #3 the 17 tooth gear which goes 5 times into 85 while the 24 goes 5 times into the 120 tooth rotary table, #4 making stub shafts for the geartrain, the Bransby parting off in reverse with the upsiddown parting tool.
Happy New year to you all from Ted from down under

 

[ignator]

Another day on the Onan, finally got my head around the 85 tooth ringgear setup picture 1 cutting teeth, the fan needs a little more finishing and balancing, #2 the 24/17 geartrain, #3 the 17 tooth gear which goes 5 times into 85 while the 24 goes 5 times into the 120 tooth rotary table, #4 making stub shafts for the geartrain, the Bransby parting off in reverse with the upsiddown parting tool.
Happy New year to you all from Ted from down under

That flywheel fan casting looks like it came from a complicated pattern. And your gear train for a home built dividing head, very ingenious.

 

[teeleevs]

Lost foam casting, thanks Ignator.

That flywheel fan casting looks like it came from a complicated pattern. And your gear train for a home built dividing head, very ingenious.

Today I finished and balanced the fan, part of the ringgear is still rough cast making it look uneven, pictures #1 the foam pattern, 2 days work, #2 successful casting #3&4 finished ringgear, that took 5 days to a successful conclusion, happy with that.
Thanks for watching
Ted

 

[ignator]

That flywheel turned out well balanced. Lots of carving of foam.
You must have a full size engine your using as the model for all your parts.
I would have never thought of using a flycutter arbor for a gear tooth cutter. I'll have to keep that in mind if I ever do any gears. Oddly I have the universal dividing head in a box that I've never used. That was always a future project.
My current project is fixing the light duty surface grinder I purchased back in 1991. Always has had spindle hop from cheap bearings and poor quality machining (which I just learned). It looks like it was originally designed for a match pair of angular contact ball bearings, but to cheapen it, they used deep groove bearings of non precision quality. The machine would make flat surfaces, but the finish had ripples. Kind of looked like a scraped surface. I could not find a pair of angular contact bearings that had seals. So that's part of the project to modify it to keep dirt out of these expensive bearings. I found ABEC7/Class4 matched pair on eBay, same dimensions as the deep groove. I need to figure out a way to balance the motor shaft/spindle, it was balanced, but I bet to a motor only standard, and that is part of the surface finish problem.

 

[teeleevs]

Ouch! oddly you get what you pay for when buying cheap machines. No, I do not have an engine to copy, I owned one back in 1974/5 but now with Google and eBay there are plenty of parts listed for sale to Save Image As, into my computer.

 

[ignator]

Ouch! oddly you get what you pay for when buying cheap machines.

At the time, it was all that I could afford, and it predated the online used stuff for sale sites that exist now. But I guess that's my hobby, buy cheap import tools, as pre-assembled kits, and then make them work as expected. Old-iron was not available in my region back then, or was beyond my income to purchase. The two milling machines I have are old iron. One was from the 30s, and originally powered from an overhead line shaft. The previous shop that used it, put a common conversion kit available back in the 40s that powered it with a 3HP 3 phase motor (Lima). It's a horizontal mill, that sits collecting dust, as the newer vertical mill does all the real work. But I bought that in my ignorance back then. The shop owner wanted to get rid of it as it was treat for his employees to use. But the spindle speed was very slow. He said his dad purchased it new. Modern for its day, as it had power feed in all 3 axis. #2 Rockford Miller, made in Rockford Illinois. That company morphed into heavy duty automatic truck transmissions for Lorries in the 1950s. This morphed into automatic transmissions for aircraft alternators powered by turbojet engines, the idea to keep the 400Hz constant over engine idle to take off power. That has now died. But that company then got into aircraft power systems, and makes automatic circuit breaker distribution black boxes. Gone is the machine tool production it all started from. Back in their day they also made large lathes and planers.
I don't do much repairs that require working in ten thousands of an inch, so I'm learning some things along the way. We shall see if I can make the machine better. I don't figure I can make it worse.

 

[teeleevs]

Hi guys, I haven't been on for a while, had some work to do on my tractor, fitted an electric lift for the mower. Fixed some other niggling problems. Done more on the Onan, no joy with the ignition purchased a new stater but still no joy so the new CDI box must be bad, have ordered another so we'll soon know for sure.
5 pictures cutting a 28 tooth idler gear for the oil pump drive from bronze bushing material, I began making a steel 30 tooth but it moved and ruined then I discovered it wouldn't have worked anyway. Then amongst my "good" junk I had a 28 tooth gear but it was too narrow.

 

[teeleevs]

I don't know why but my story has fragmented and some bits don't show up at all. I purchased another CDI box and now I have spark

 

[gadabout]

Lost foam casting, thanks Ignator.

Today I finished and balanced the fan, part of the ringgear is still rough cast making it look uneven, pictures #1 the foam pattern, 2 days work, #2 successful casting #3&4 finished ringgear, that took 5 days to a successful conclusion, happy with that.
Thanks for watching
Ted

Very nice work ! Can you please tell me what the sand is you are using in your casting and where you get it from.
Thanks
Mark

 

[teeleevs]

Hi Mark, the sand was given to me by a fellow alloy casting experimenter because it was too course for his purpose. It is just ordinary river sand with the appropriate quantity of bentonite added. Bentonite can be purchased from a casting supplier in Australia, can't speak for the rest of the world. I have screened out a lot of the coarse stones which makes for a more workable mix. The sand mix can be used over and over but may need some Bentonite added from time to time.
Hope this is helpful
Timothy from down under

 

[ignator]

Bentonite clay, I think that is the same material that is in clumping cat litter.
Or is this some other compound of bentonite?

 

[gadabout]

Thanks for the reply! I am from Hobart and am using a fine sand with Bentonite added but I got the Bentonite from a farm supply house and am not happy with the results I am getting with it , mine is very light in colour , not the nice brown that yours looks! I believe there may be two types. Am currently on the Sunshine Coast and would like to pickup some before I head home in March, really would like to get some Petrobond to try !
Regards
Mark

 

[teeleevs]

Hi Mark, I have found a web site greensand.com.au the foundry is in Coburg North, Vic they also have Petrobond. Bunnings sell Play Sand which works. Bentonite Resources mine it right here in Ipswich Qld 0754673345 bentoenviro.com.au but it is white in colour. and yes Clumping Cat Litter will do but you might have to wash it out of the paper or whatever it is compounded with.

 

[teeleevs]

Today I repositioned the idler gear for the oil pump so that now works fine. Timing gear at the top with grooves for the governor balls, crankshaft below, idler gear next and oil pump at the bottom.

 

[moose4621]

Bunnings also sell "Brickies sand" which I have found to be a much finer sand than play sand giving better surface finish.

 

[gadabout]

Teeleevs, I intend to visit greensand foundry supplies on my return trip but wondered if you had a source for foundry supplies up here that had eluded my searching!

Moose4621, I have tried all of bunners sand supply and various grades from a landscape supply but not ever having foundry sand in my hand before I am not really sure if I am getting my mixes correct and using the right bentonite!
I need to spend some time with an experienced caster to see what works!
Regards
Mark

 

[teeleevs]

More work on the Onan opposed twin yesterday, fixed a tight spot in the timing gear train. Picture 1 Made a part for the governor pivot, 2 a spring to keep the governor balls in place when engine is stationary, 3 cleaned up the timing cover 4 fitted the fan to the flywheel, it blows a lot of wind at 400 RPM so I reckon cooling won't be a problem.
Ted from down under

 

[teeleevs]

More work on the Onan opposed twin half scale engine. I have reached the point where I can start on the cylinder sleeves but need to be sure I can fit a friends steam engine pistons and rings into the available cast iron bar and still have enough for my two sleeves. Made up a tool to get the cylinder directly under the mill head. Picture 1 & 2 measuring tool, accuracy questionable, 3 upsiddown parting a steam engine piston, 4 turning off the rings with a tungsten carbide saw tooth.