Ohrndorf V12, new challange

[fumopuc]

One more part done.
The front bearing cover, prop/fly wheel side.
Prepared on the lathe and then clamped at the CNC mill for the hole pattern.
The 3D Finder was responsible to find the center.
Next the 12 times 2,5 mm drilling of the M3 core drill holes followed by the tread milling.
tbc ...

[fumopuc]

Than 6 times a 3,2 mm hole for the fixation to the crank case, followed by a drill milling operation to get the space for the bolts heads.
Finally and temporary bolted to the crankcase.

[fumopuc]

Hi everybody, I have to catch up this build progress, done so far, again.
Next part to make, was the outer prop shaft bearing housing.
First, taking off the crankshaft bearing cover as a matching part to check the right diameter at the lathe during machining.
Parting off, was not complete possible with my tool as it was adjusted.
I have been to lazy to adjust it, so the hacksaw did it finally.
For next machining preparation an older available arbor could be modified.
tbc

[fumopuc]

Everything fits nicely an the run out was fine too.
Tapper was done next and the press fit seat for the bearing followed immediately, hopefully true to the rest now.
The pattern was a CNC job again.
First a trial, to check the tool length and collet for possible collision.
Seems to be fine and a go for the all the remaining holes was given.
tbc

[fumopuc]

Finally the clearance holes has been drilled through.
Than a sample assembling at the crankcase again.
If it will run really true, no idea so far, but hope it great.

[fumopuc]

Next, some other flat covers.
I have ordered some plate material, no sheet material and it seem be very flat.
From this first the camshaft housing covers were made.
To get an proper idea how find the the best set up fixation, a 3D printed dummy was made first.
My vacuum plate was a bit to small for it and the final shape maybe has not the right remaining necessary surface for a safe clamping.
So the tape and super glue was chosen.
A tape layer to the part and another layer to the sacrifice plate, super glue between both tape layers.
Both parts in one set up, but one first covered by tape also.
First the drilling and hole milling followed by contour milling and chamfering.
tbc
 

[fumopuc]

Sample assembly was fine.
The sacrifice plate does show several marks in the meantime, including some door shape from the Bruce Macbeth engine, some years ago.
But my actual decision was no surface cleaning now, give it another try.
So the bottom plate was prepared same way as the camshaft covers.
10 to 15 minutes are necessary for curing.
Than same procedure as with the cam covers, first hole pattern followed by contour milling and chamfering.
Always no big issue to get it off again.
tbc

[fumopuc]

The result shown at the crankcase.


Next plate machining, bottom of the valve gear housing.
As mentioned earlier already, I have modified  this are a bit, due to some clearance of the idler gear positions.
The 3D printed dummy was used again to check the best set up and fixation.
Here I have used clamps first to fix it for hole drilling and hole milling, followed by using the big holes for next clamming and contour milling.
tbc

[Admiral_dk]

Some fine parts you have made in the last 3 weeks 

Enjoying watching your progress with this Engine and how you tackle the setups.

Per   

[fumopuc]

With the MDF plate as an sacrifice material, clamping is not so smooth, could be seen at picture #08 and #09.
In the middle is a little lift of visible.
This occurs some minor chatter and noise during milling, but does have no further influence to the part.
So I can live with it.
And finally another part in sample assembly.

[fumopuc]

Some fine parts you have made in the last 3 weeks 

Enjoying watching your progress with this Engine and how you tackle the setups.

Per   

Hi Per, thanks.
I can confirm it is really a challenge, specially to the accuracy.
It will be seen by the following con-rod assembly also.
I have never used so much the micrometer gauges as with this build so far.

[fumopuc]

To get a better idea about the crankshaft design and assembly, I have sent the crankshaft cheek data twice to the 3D printer.
Some standard pins and a bearing added to the dummy assembly.
The con rods without bronze bearings so far.
To get better understanding of the overall fit, I started with the measuring of the "standard of the shelf pins", they are 6 mm with m6 tolerance class.
That means they should be between 6,004 to 6,012 mm in diameter.
Measurement was tried always with different equipment.
Next challenge, to find out the right overlapping, which can be machined with my tools reliable for all press fits between pin and the to made crankshaft cheeks.
tbc

[Michael S.]

Hello Achim, good progress on the engine.
I'm currently on the Baltic Sea and I just remember that the Marien had speedboats with Russian 42 cylinder engines. A model of it afterwards? 😁

Michael

[fumopuc]

Hi Michael,
good idea.
Maybe I should stop by a Napier Deltic before.
https://en.wikipedia.org/wiki/Napier_Deltic
https://craftsmanshipmuseum.com/artisan/clen-tomlinson/
18 cylinders only, opposed piston style, better for a learning build.
https://youtube.com/shorts/3BSgDuG9p1k?si=dh50o4BcMWTg2kOm

I think to attack a project like this, some more nails across my head will be needed.
First I will try to get some success with the V12 and than I have to think seriously about the next project in accordance to my retaining lifetime.

[Michael S.]

Wow, and I can't even get a flame eater to work.