Injected Diesel 56cc 2 Stroke, Will it ever work?"

[Lloyd-ss]

@Steamchick , I have read enough of your well thought out posts to know that your head and heart are always in the same place, the right place. So, no upset or offense to either of us I hope.
But I do understand your point about conciseness of our descriptions. Sometimes the attempts at humor blur the lines a bit. Write, and machine, with accuracy.

 

[minh-thanh]

Personal opinion...a little grinding..., a little adjustment ..no problem.
A little error in the design and machining of parts of a home-made engine is normal.
I'm not a design or manufacturing expert, although errors are limited... but it's still there.
Sometimes fixing mistakes is fun,...

 

[Steamchick]

For the benefit of readers who are learning, and do not know better, I try to avoid giving the fixes and fiddles we do when things go wrong, or make it clear that it is damage recovery, not the standard process.
While I am a student here, I am also a bit of a teacher, but prone to being misleading with my advice, so I need all you experts to correct me when I make a gaff.
Thanks,
K2

 

[minh-thanh]

standard process.

Standard process: difficult, because everyone has different approach, different machines, different tools, different technical background... moreover most of us only build one or two engines

so I need all you experts to correct me when I make a gaff.

We come here to have fun, learn....

 

[Steamchick]

I do have fun and learn. But as we all should do, I "filter" what I need to know, and "reject" what I don't need to know. A part of the human Psyche? - Isn't that called learning? It means I am sometimes right and sometimes wrong, and sometimes it is simply neither, just "opinion"?
Thanks for taking a interest in what I write.
K2

 

[Lloyd-ss]

I do have fun and learn. But as we all should do, I "filter" what I need to know, and "reject" what I don't need to know. A part of the human Psyche? - Isn't that called learning? It means I am sometimes right and sometimes wrong, and sometimes it is simply neither, just "opinion"?
Thanks for taking a interest in what I write.
K2

I agree about the necessity (EXTREME NECESSITY) of filtering the youtube videos , but I have saved so much money over the years with repairs that "almost" knew how to do. The first videos that I reject are the ones that start, "Uhhhh, I've never done this before, but let's see what happens." As the camera accidentally scans around the room. OMG!

 

[Steamchick]

I think mistakes, then a need for repair, is simply a part of being human. Although some of us come very close, we are not perfect. But if we consider ourselves to be "model" engineers, then we should at least be telling others the "proper way" first, and the "recovery method" second. I think part of being an expert is knowing, and having experienced, both.
My Dad told me, "If you can't fix it, don't break it". I still try to do that....
K2

 

[Lloyd-ss]

I like to take the approach to testing, that its main purpose is to prove that all the design work and calculations are correct.

Let's get back to the clearance of the rod to the piston skirt and cylinder liner. Both the calculations and the drawing layout showed that the clearance was going to be tight. That is why I had to keep dropping the wrist pin hole down, and lengthening the rod. Almost to the point of considering a cross-head style crank and rods. But I cam back to my senses.

To do a check on the rod clearance before getting a big chunk of steel, I mocked up a Delrin and Corian crank with bearing blocks along with some Jo Bloks on my surface plate. Poor man's version.

The real rod and piston are installed. The aluminum "Jo Blok" under the piston is the same length as the cylinder liner and also set to the bore radius from the crank centerline. I rotated the crank by hand in 2 setups to check both sides of the conn rod. As I said previously it will need a bit of polishing and a little clearance for the inside radius of the cylinder liner. But if you look at the "minimum clearance" photo at 71.5 degrees ATDC you can see daylight between the conn rod of the piston and the Jo Blok. Passed! But if it hadn't a few thou removal would have been ok and still had buckets of strength.


TDC



71.5 degrees after TDC (or BTDC)
Minimum clearance conn rod to cylinder liner.




BDC

 

[Steamchick]

Beautiful work. And thorough! That's what you do that sets the example to which we aspire.
Frankly, the addition of clearance at the bottom of the bore by adding some planned grooves for the rod to clear is something I did with a file as an apprentice - to the drawing! First I popped out the old liners, cleaned up the job and fitted new liners, filed the rod clearance grooves then bored the block and honed to size for the new pistons. Thinking now, I wonder if that was an original design gaff, or more likely a change to larger bore and / or stroke that necessitated the grooves for rod clearance? 55 years ago I just did the job the boss told me to do. Too young to wonder "why?".
The loss of cylinder wall for the piston skirt to bear upon is inconsequential, as the dynamic side thrust of skirt on cylinder ceases at BDC . In fact it is going from thrust on one side of the skirt to the other.
All I should avoid is removing material from the con-rod. These are highly stressed and balanced dynamic components so should not be fettled away from design.
Great to see your work, and thorough test set-up.
K2

 

[minh-thanh]

Hi K2 .
Anyway, your opinion is correct !
Precise design, precision machining are always the first choice !

 

[Lloyd-ss]

STARTING THE CRANK

Now getting started on the crank. Roughed out on the mill, now doing the first lathe roughing operation. The fixturing foot at either end of the crank has the centers for the crank and crankpin, one inch apart to give the 2" stroke. The counterweights will be bolted on to make constructing the crank easier, and also to make it easier to work with the balancing. Calculations show the balance will be wonky and will require balance countershafts. The actual Detroit diesels had balance weights on the cam shaft and also had a dummy balance shaft mirror imaged to the camshaft. Slick.

 

[Roger B]

Crankshafts are fun I fix a bridge over the crankpin gap using the counterweight fixings to keep everything straight when finishing off the shafts. All single cylinder engines are intrinsically unbalanced (probably like me )
This is a 25mm throw crankshaft.

 

[minh-thanh]

STARTING THE CRANK

. Calculations show the balance will be wonky and will require balance countershafts. The actual Detroit diesels had balance weights on the cam shaft and also had a dummy balance shaft mirror imaged to the camshaft. Slick.

Hi
A seemingly stupid opinion of mine
I usually ignore those considerations when designing and building my first diesel engine - the counterweight for the crankshaft is just an estimate, I just focus on making the engine run.

 

[Lloyd-ss]

FINISHED CRANK

25mm mains
20mm crank pin
24mm outboard of mains
50.8mm stroke
Counterweights bolt on as separate pieces

 

[Nerd1000]

FINISHED CRANK

25mm mains
20mm crank pin
24mm outboard of mains
50.8mm stroke
Counterweights bolt on as separate pieces

View attachment 156560

Looks good!

 

[Lloyd-ss]

Looks good!

Thank you. It was a little iffy as I approached the final diameters, because I was having problems with vibration and chatter marks. After the cutoff blade was ground and honed to a full nose radius with a few degrees of positive relief on the front, sides, and top, all with sharp, crisp edges, I was able to get nice finish, maybe as good as a 16 (imperial, not sure of the metric equivalent). Some polishing is needed, but I am very happy that the vibration finally stopped.
It feels good getting to the point where the number of major tasks remaining can be counted on one hand!

 

[Lloyd-ss]

Fly Wheel Bearing A-Frame Support

This should work. Still need to make the cap and bore it for the bearings (after I get them).
Milling the cut-outs on a manual mill is time consuming and gets boring pretty fast.

 

[Lloyd-ss]

This video is an overview of the current progress of this ongoing project.
A lot has been done, but there is still a lot left to do.
The current goal is to finish just enough to see if it will fire, and maybe even run! That means no governor, no working water jacket, etc, etc.
The progress is accelerating, but I don't want to get greedy. That always gets me in trouble.
Lloyd


===EDIT
This first video is just a short 2 minute overview. The full video is below.
Lloyd ====

++++++++++++++++++++++++++++++++++++++++++++++++++
====
EDIT
Longer video added.
Here is the full video if you have 12 minutes to spare, LOL.=========


Full 12 minute version of the update.

 

[minh-thanh]

Great project !!
Please update .....

 

[Lloyd-ss]

Great project !!
Please update .....

Thanks, Minh-thanh!
I added a second link (in blue letters) at the bottom of post #238 for the full 12 minute update on youtube.