newby new engine

[nfk]

Hi folks
I`ve been building this engine the last 3 months, before knowing HMEM wisdom (YOUR wisdom!) was at the reach of my hands.
The engine is my own design, i have a few notes and draws of it with a few bugs discovered during construction (i hate that!) but, after all, it is going fine. (unless you find more bugs!, please, find more bugs before i continue!)

Ok, now the pictures..
This build started before i join this forum, so no pictures where taken before this stage.

The next pictures show:
Crankcase
Cranckshaft (hiden inside, more details will follow)
Pistons (ringed pistons! what a challenge!)
Con-rods *
Cilynders and liners *2

Some words about the *
The con-rods where (are!) a frankenstein.
The big ends end up smaller than the small ends!
I`m not sure if it is a problem or not, but they are like this to save a piston rebuild.
While drilling one of the piston pin holes, i accidentally moved my cross table X axis about 1mm. I end up drilling 5mm instead of 3.5mm to save the piece.

Cylinders: The liners where about 8mm short due to a miss calculation on my drawings.
The liners where so square and polished that it was more than a waste to remake them (i had no more steel to do it!).
So, i made a nice hack... i enlarged by 8mm using the sleeve. The piston travel is ok anyway.

More in the next post.

One more thing... besides learning machining, i`m learning English. Please, let me know if i anything could not be understood!

Cheers,
Norberto

 

[nfk]

This is the continuation....

The next pictures show the cranckshaft and the front of the engine (i have no idea how to call it properly in english!), two bearings are in there.
Amazingly, the crankshaft is not wobling! it was made using interference fits for the pins.
I`m not sure if i will need bearing support for the last crankpin... all the assembly looks rigid. Please let me know if you think it`s better, and why!

Next is the heads being turned, the fins exactly.
The fins are 0.75mm wide! I used a broken saw blade with a home made holder. Properly sharped, they cut beautiful fins!

The last picture is similar to the first one but with the heads assembled.

More to come!

Cheers!

 

[nfk]

As promised, more pictures....

The next job was to start working on the cylinders bolt holes (i hope someone understood what i meant with bolt holes!).
I had almost no clearance to drill the holes and actually been able to put some screws in there, so i made some pockets on the sides of the cylinder to accommodate the screws.
I used the 'poor man mill' technique (i have no mill!).
A broken carbide was used to build a holder for the cylinder, and using a 6mm end mill, i milled a pocket using the lathe Y axis. Now i`m thinking it could be better if i`ve used a ball nose mill instead of an end mill, but i had no one in the shop.

After the pockets, i drilled the holes on the cylinder and the crankcase.
It was a success!
Amazingly all the holes lined perfectly

Notice the red tint i`m using to mark the hole`s locations... i`ve learn that by reading this forum.. :bow:
Thanks!

 

[dsquire]

Norberto

Hi Norberto

You have made an excellent start on your engine. The learning curve can be steep at times but it looks like you are finding ways to overcome the obstacles and I am sure that you will end up with a fine first engine. I am sure that there will be others following along with your build that are more knowledgeable about engines that will offer advise or answer any questions that you might have. As far as your English goes Norberto, there is nothing lacking in your descriptions. :bow:
Keep up the good work and we will be watching.

Cheers

 

[Stan]

Some of your problems are the reason that using an existing plan is recommended for first engines. It is too easy to overlook things like having enough metal left for screw holes. I am sure you will not make the same mistake again, but I am also sure you will find some new mistakes to make.

Don't feel bad about design errors on your model. Just look at all the recalls on cars, airplanes and consumer products.

 

[nfk]

Hi
I made a bit of progress the last few days.
I`ve faced and cut to size the crankcase and i`ve made the gaskets.

So far so good!

The next things to do are the reel valve, exhaust pipes and carburetor....
Any of you have plans for a carburetor? I where unable to find any suitable one. The engine is 14cc.

Here are a few pictures.

Cheers,
Norberto

 

[b.lindsey]

Looks like you are off to a great start Norberto, even with a few challenges along the way. By the way, your English is fine !! Looking forward to more progress.

Bill

 

[nfk]

Hi
I`m almost there

Folks, thanks for your words and the patience for my silly Q&A, that encourage me to keep going Thm:

The following pictures are the final assembly of all mayor parts.
The engine was sanded and polished before assembly, but sadly the pictures made no justice of the overall look.

The carburetor is not shown on the pictures, i will post them in the next update.
I`ve used cfellows design and it seems promising as it is.

I fitted a 10X6 prop on the engine (sorry for the rusty bolt, it was the only one available in that size!) just to try to start it with not much luck, a few pops and then it stalled.
After another priming, i got a few more pops and a stall..
I`m not sure if is because of the carburetor, the fuel tank level or simply the prop is too small to maintain momentum...
And my wife is not allowing me to figure it out right now :
I will try again tomorrow and send another update.

Norberto

 

[BlakeMcKee]

(Off-topic): Really surprised to someone else here from North Carolina! (b.lindsey)

Nfk: Very nice job hopefull everything is going good I see its been a few days since last post, keep up the good work!

 

[nfk]

Hi Blake,
I made no progress the last couple of days, i`m having plumbing problems at home and it is consuming all my shop time and budget
I have a few more pics from the carburetor and the reed valve assembly, i promise i will post them soon.
I think i will be done with the engine as soon as i have at least one day of shop time (and maybe a couple more to polish and tune the thing)

Norberto

 

[nfk]

Hi
I got it running!.....but my happiness last the same as a can of beer..
I realized that i had almost no compression on the cylinders after about 5 minutes running (one of the cylinders died after about 40 seconds), and i believe the usual suspects had not the guilt (cylinder head, gaskets, rings, etc), i`ve test for leaks .
I think i made a barrel when honing the cylinders and when the rings went hot they stop sealing with the liners...
I`m about so disassemble everything to check it out.

I`m adding a few pictures anyway.
Below you`ll find the reed valve, the first carburetor attempt (i end up using an OS on the first run, i could not make it to start with my attempt) and the completed engine fitted with a 14x6 prop.

Let me know about any hint if you have any!

Cheers,
Norberto

 

[nfk]

I know what went bad...
The rings broke
I`m not sure if they get trapped on the exhaust port or if i leave too little clearance in the gap and thermal expansion made his magic.
I will re-hone the cylinders and make a new rings set.

 

[nfk]

Hi all,
I finally got this thing working
I had to remake the rings and pistons, this time i`ve enlarged the rings thickness from 0.7mm to 2mm and used just one ring.
I`ve also made a retention pin to avoid rigs to rotate and getting caught on the ports.
I have no pictures of the new parts, only a few of the old ones. You`ll see them attached on this post.
I finally decided to avoid using my forgiveness attempt on carburetor building, it end up bad i think, and the engine won`t to start with it. I`ve installed a nice OS carb which work perfect.

Video after the brake

The last one is where all the magic happens...
I need to clean up a bit, it`s rather chaotic whit my wife storing everything she don`t want anymore.

Norberto

 

[RManley]

Very nice norberto ;D , I have a special liking of boxer twins and to make one from no drawings is quite an achievement. It looks a very well proportioned engine and I hope to see this video soon. P.s. your english is very good too