Author Topic: Four cylinder scale engine  (Read 22200 times)

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Connecting rods finished
« Reply #30 on: February 19, 2017, 03:36:31 PM »
Hello,

It needed a little more time than i expected but now i have the conrods.

This conrods are standard ones. There will be bronze bushings pressed in on the small end and two pieced bronze bearing cups on the big end.

I add a few pictures again. I hope i dont post to much pictures. Please let me know if i waste to much webspace.

 - 1. Drawing with measurements
 - 2. After milling the blanks to size i drilled and threaded the big ends.
 - 3. Cover for the big end.
 - 4. Drilling and reaming of the holes with the cover already bolted on.
 - 5. A simple holder for clamping the conrod for cnc machining.
 - 6. Milling
 - 7. Finished conrods.

Best regards,
Thomas

Offline Flyboy Jim

  • Full Member
  • ****
  • Posts: 1556
  • Independence, Oregon
Re: Four cylinder scale engine
« Reply #31 on: February 19, 2017, 03:43:17 PM »
Great documentation of the machining of the conrods.  :ThumbsUp:

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Re: Four cylinder scale engine
« Reply #32 on: February 19, 2017, 04:17:32 PM »
Thank you Jim. By the way : Is the Rans in your avatar yours ? 912 powered ?  Flying and model engine building seems to be a common combination...

Thomas

Offline Flyboy Jim

  • Full Member
  • ****
  • Posts: 1556
  • Independence, Oregon
Re: Four cylinder scale engine
« Reply #33 on: February 19, 2017, 04:32:38 PM »
Thank you Jim. By the way : Is the Rans in your avatar yours ? 912 powered ?  Flying and model engine building seems to be a common combination...

Thomas

Your correct on all 3, Thomas.  :)  Here's a link to a thread I did with some info and pictures (go to post #12): http://www.modelenginemaker.com/index.php/topic,5886.0.html

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Oil pan
« Reply #34 on: March 04, 2017, 03:49:36 PM »
Hello,

I want to make a little update.

Things are going a little slow because i have to make the castings, moulds and patterns on demand when i need the part.
The next part i did was the oil pan.

Here is the description of the attached pictures :

 1. The mould of the oil pan. In the background you can see the red pattern. It forms the outer shape and also the core so i donīt have to
     make an extra core box.
 2. The casted part turns out to be usable. The surface finish could be as always better but i use sodium silicate as a sand binder for the
      complete mould. I like the advantages over the disadvantages. I believe oil bonded sand would give much better surface results but i dont
      know where to buy at a reasonable price. I experimented with greensand ( bentonite clay binder ) also but i dont like the effort of mulling the
      sand after use and not being able to store the moulds for a few days before pouring them.
      Other people know much more about casting than i do. I am always very lucky when a casting is a success but i am getting better.
 3. After roughing the sealing surface on the belt grinder i clamped the oil pan to the mill table and drilled the holes for fixing the pan to the
     crankcase ( 3 mm ). I also i milled four flat 16 mm spots to the bottom to have a reference when i turn it around for milling the sealing surface
      to size.
 4/5. I used four 8 mm nuts between the milling table and the reference spots for machining the other side.
6 . After bolting the pan to the crankcase it was possible to machine the surfaces of the complete crankcase together with the oil pan to finished
     size.
 7. Drilling of the water inlet into the crankcase.

Now i want to complete the crankcase with the cylinder liners, valve guides and so fourth. I also have to make the bearings for the connecting rods and the middle crankshaft bearing.

Best regards,
Thomas


Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 4013
  • Switzerland
Re: Four cylinder scale engine
« Reply #35 on: March 04, 2017, 07:41:05 PM »
Very nice  :ThumbsUp:  :ThumbsUp: Home casting is something I have never tried but your results look good  :praise2:
Best regards

Roger

Offline Myrickman

  • Full Member
  • ****
  • Posts: 261
Re: Four cylinder scale engine
« Reply #36 on: March 17, 2017, 10:22:42 PM »
Just stumbled in Thomas...impressive build. I'll have to keep the sodium silicate trick for one-off parts for later use. The crank fabrication was fascinating. Will be checking in on future visits to the site. Paul

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Update
« Reply #37 on: April 02, 2017, 01:31:02 PM »
Hello everybody,

I want to keep you informed on my Model A engine project. It has been a while since the last update but i have much work to do at my house and also at work.

The engine block of this engine is the part that needs most of the time to machine compared with all my previous builds but now it is finished and ready to be painted. I think i will use the same dark green color with mate finish on it that i have used on my hit & miss engines.

Here are the pictures :

 1. Machining of the conrod big end bearings. The bearing where split after machined to size.
 2. Assembled big end bearing.
 3. The cylinder liners are made prom precision steel tubing. All i have to do is tuning it to length and chamfer the inner corners. The outher 
     diameter is already close to the engine block bores and has only to be grind with emery paper to become a nice press fit. When i pressed the
     liners in i also used loctide to ensure they are not leaking between the water passages and head gasket.
 4. The crankshaft with all the bearings mounted for testing. Everything moves without to much friction.
 5. I do not know the correct word in English for the pieces with are valve stem guides and valve seats in one piece. This did not stop me from
     machining eight of them and pressing it into the block.
 6. The setup for machining the inlet and exhaust ports and also the sealing surface with the holding threads for the valve gallery cover. The red
     marked ports are exhaust ports and the black marked ones are for inlet ports. The inlet ports are machined at a 40 degree angle because two
     cylinders use one common inlet where exhaust ports are separate for each cylinder. This is the same in the original engine.
 7. Finished ports. The ports are 6 mm diameter.
 8. The finished engine block with the STM-2 hit & miss engine painted in the dark green color i eventually use on this engine too.
     The cylinder liners are also already honed with a shop made honing tool to remove any possible deformation while pressing them in.

Thank you for your interest. I ll keep you informed.

Best regards,
Thomas


Offline 90LX_Notch

  • Full Member
  • ****
  • Posts: 1406
  • North Eastern Pennsylvania USA
    • YouTube Channel
Re: Four cylinder scale engine
« Reply #38 on: April 02, 2017, 03:32:37 PM »
Wow.  I don't know how I missed this thread until today.  Great stuff Thomas.  I have great respect for those with home foundries.   Being a Ford guy, I will be following along with great interest.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Camshaft finished
« Reply #39 on: April 14, 2017, 04:47:58 PM »
Hello everyone,

I just finished the camshaft and want to show it to you. The camshaft is build from pieces like in most of my other engines too. Normally i use setscrews to fix the lobes on the shaft but in this engine there is not enough space to extend the lobes in axial direction to have enough space for the setscrews. So i had to fix the lobes in a different way witch you can see in the attached pictures. I use 3 mm steel balls from a disassembled ball bearing as a key. This is no new method but it is the first time for me i use this this technique.

I also had a little headache how to make the angular gears for the distributor drive witch had to be assembled together with the lobes to the camshaft. I am not equipped properly to manufacture angled gears. The gears for the distributor need to have a drive ratio of 1:1 and a bore of 8 mm for the camshaft has to be possible. At he same time the outside diameter has to be 12 mm or smaller. I searched a lot and was not able to find the right gears for this purpose. Every time i found something that might be usable at least one requirement was not fulfilled.

So after a few tries and errors i ended up with the easiest method i can imagine. I just milled the the teeth in the corner of a round blank without turning an angle to it before. the depth is the same as it would be when milling a normal gear but measured from the corner. the rotary table is set at a 45 degree angle on the milling table. This gears dont have to transmit notable power and run good when the backlash is set a little larger.

Here is the description of the attached pictures :

1. milling the teeth of the angled gears. The gear on the camshaft is made from steel while the one one the distributor shaft is made from brass
2. Position of the lobes on the camshaft. " A " means " Auslass = exhaust " , " E " means " Einlass = inlet.
3. Making the lobes. The outside shape is cnc machined. The lobes have a relatively hard opening curve but valve clearance would be large
    ( 0,5 mm ? ) so the opening acceleration would however be smooth.
4. Drilling the bores for the 3 mm steel balls in the needed positions. The square aluminium piece on the left is for setting the 90 degree angles in
     the different directions. On a four cylinder engine you only have to deal with 90 degree angles in different directions so no setup with the
     rotary table is necessary.
5. The steel ball in its position just before forcing the shaft in. The shaft with the steel ball is 0.1 mm larger than the keyway in the lobe.
6. Finished camshaft.
7. Camshaft located in the engine. It is tricky to place the additional split brass bearing in the middle but it is possible.

Best regards,
Thomas


Offline mnay

  • Full Member
  • ****
  • Posts: 73
Re: Four cylinder scale engine
« Reply #40 on: April 14, 2017, 05:06:28 PM »
Thomas,
I just noticed this thread today and I had to go back to the first to see everything.  Wonderful build and very creative.  I gave me some ideas to use on my projects.
I will be following along.  Keep us posted
Mike

Offline gerritv

  • Full Member
  • ****
  • Posts: 551
  • St Catharines, ON
    • Gerrit's Hobbies
Re: Four cylinder scale engine
« Reply #41 on: April 15, 2017, 11:56:49 AM »
A creative way to locate the cam lobes, simpler than pinning which is what I would have tried.

Gerrit
Don't confuse activity with progress

Offline yogi

  • Full Member
  • ****
  • Posts: 410
  • Duncannon, PA USA
    • Yogi's Workshop
Re: Four cylinder scale engine
« Reply #42 on: April 15, 2017, 01:09:53 PM »
Nice work Thomas!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
I like how you assembled the camshaft. Are the lobes just pressed on, or did you also use Loctite?

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Re: Four cylinder scale engine
« Reply #43 on: April 15, 2017, 02:21:16 PM »
Gerrit, i also thought about pins to fix the lobes but the wall thickness is only one millimeter at the " valve closed circle " so i dont trust the pin hole in the lobe not to wear out and become loose.

Yogi, i also applied Loctide but i think it would work without it because it is a form-fitting connection.

Best regards,
Thomas

Offline ThomasM

  • Full Member
  • ****
  • Posts: 49
    • My modelengines
Distributor drive
« Reply #44 on: April 16, 2017, 10:09:42 AM »
Hello everyone,

There is nothing spectacular today but i want to keep this building thread complete and want to show the distributor drive and a picture of the engine with the unfinished cast model of the cylinder head. The temporary bolted on ugly aluminium plates at the front and the end are to keep the camshaft in its axial position to test the distributor drive. The distributor shaft runs in two roller bearings 10x6x5 mm and there will be an shaft seal ring on the top also.  It rotates free and smooth when the camshaft is rotated. One thing less to worry about...

I have to redo the cast model of the cylinder head you see in the picture  because this one dont turn out usable out of the 3d printer. I also want to leave away the extensions for the screws so it would be easier to grind the surface to a usable and smooth finish. After that i will glue the extensions for the screws on. But now i can see the appearance of the whole engine ( without the gearbox ).

I will work on this casting simultaneously beside of making the other parts to complete the valve train.

Best regards,
Thomas