Ohrndorf V12, new challange

[fumopuc]

The rear bearing plate was prepared at the conventional lathe and the computer has done the hole pattern.

[petertha]

Next to make was the rear bearing plate at the crankcase.
This will host the gear train also.
There are no real dimension for the position of the idler gears at the drawing.
The designer has given an recommendation only, to mark them when all other related things are finished.
That means crankshaft gear and camshaft gears in final position.
Always a good idea to do it like this.
I have done it virtually in my CAD to get an general idea about it.
The original drawing does show the gears in one horizontal line.

Just catching up on your post, nice work! Can you elaborate on this gear position issue. Are you saying the idler gear center dimension were not provided in drawing package because he assumes/recommends they be hand fitted once the other major component gears are established & axles drilled from that? So you laid them out in CAD on your own & approximated position using pitch diameters? So ultimately, how did you fit the gears & how close were they to theoretical position? Reason I ask is I had a similar issue on my Ohrndorf 5-cyl radial with the planetary idler. I couldn't think of a good way to simulate fit with very thin foil between the teeth or however its done, so i just obeyed the pitch diameter circle & hoped I could locate it accurately & trust Maedler made correct gears. Anyway I have this same issue coming up so your comment was timely.

[petertha]

Achim, please correct my understanding if wrong. I assume the crankshaft alignment is dictated by the series of bearing blocks which are mated by their OD's mated to the partial ID bore within the crankcase (red arrows)? And the blocks are notched on top for screws which then secure the bearing blocks into position? Maybe I misunderstood your procedure but sounds like you started out with end blocks, then added each inboard block, one by one, feeling for any resistance to the dummy crankshaft rod. Is that the general fitting procedure? It worked & you are home free. But for example if the crankcase bore happened to deviate a bit, say it was a bit smaller ID mid case & you did experience slight rod bending & resistance, what then? Would you custom fit the OD of that particular bearing block position & it would be forever indexed to that position?

I'm getting ahead of myself, but when this crankcase bearing block sub-assembly is complete (aligned), does that become the alignment basis for the segmented built-up crankshaft itself? Or does crankshaft sub-assembly alignment occur external to the crankcase? I tried to interpret the German instructions but I became kind of lost. Seems like some crankpins are pressed into web elements permanently with retainer, but maybe the alignment relaxation points are the web/bearing areas? If you are getting to all this later just say so & I will try to tone down my anticipation excitement haha

[fumopuc]

Next to make was the rear bearing plate at the crankcase.
This will host the gear train also.
There are no real dimension for the position of the idler gears at the drawing.
The designer has given an recommendation only, to mark them when all other related things are finished.
That means crankshaft gear and camshaft gears in final position.
Always a good idea to do it like this.
I have done it virtually in my CAD to get an general idea about it.
The original drawing does show the gears in one horizontal line.

Just catching up on your post, nice work! Can you elaborate on this gear position issue. Are you saying the idler gear center dimension were not provided in drawing package because he assumes/recommends they be hand fitted once the other major component gears are established & axles drilled from that? So you laid them out in CAD on your own & approximated position using pitch diameters? So ultimately, how did you fit the gears & how close were they to theoretical position? Reason I ask is I had a similar issue on my Ohrndorf 5-cyl radial with the planetary idler. I couldn't think of a good way to simulate fit with very thin foil between the teeth or however its done, so i just obeyed the pitch diameter circle & hoped I could locate it accurately & trust Maedler made correct gears. Anyway I have this same issue coming up so your comment was timely.

Hi Peter, first I have been unsure if I should follow the CAD or the good old fashion way and mark the idler gear position by some stripes of paper and in relation to the other gears in their final positions.
My conclusion was, that due to some other obscurities with the dimensioning in the original drawings of the crankcase, to go the recommended way and not to follow the theoretical position of the CAD model.
I am very sure that the Mädler gears are in accordance with their drawings, in the pitch diameter also, which was used for the CAD model, but I am not sure for the other variables.
My virtual positioning has shown, that the original drawing of the gear housing base plate and cover would not fit for my build.
There has been a collision between the idler gears, the cover and the position of the lower fixation bolts.
So this was my main finding from the simulation in my CAD model and I have been able to adjust it. 
All these is modified now in a suitable way for my build.

[fumopuc]

Achim, please correct my understanding if wrong. I assume the crankshaft alignment is dictated by the series of bearing blocks which are mated by their OD's mated to the partial ID bore within the crankcase (red arrows)? And the blocks are notched on top for screws which then secure the bearing blocks into position? Maybe I misunderstood your procedure but sounds like you started out with end blocks, then added each inboard block, one by one, feeling for any resistance to the dummy crankshaft rod. Is that the general fitting procedure? It worked & you are home free. But for example if the crankcase bore happened to deviate a bit, say it was a bit smaller ID mid case & you did experience slight rod bending & resistance, what then? Would you custom fit the OD of that particular bearing block position & it would be forever indexed to that position?

I'm getting ahead of myself, but when this crankcase bearing block sub-assembly is complete (aligned), does that become the alignment basis for the segmented built-up crankshaft itself? Or does crankshaft sub-assembly alignment occur external to the crankcase? I tried to interpret the German instructions but I became kind of lost. Seems like some crankpins are pressed into web elements permanently with retainer, but maybe the alignment relaxation points are the web/bearing areas? If you are getting to all this later just say so & I will try to tone down my anticipation excitement haha

Hi Peter, the purpose of my action with the dummy shaft was to get some safety only.
The main bore in the crankcase should be 42,00 +0,05 mm.
My one is 42,19 to 41,21 mm.
The round bearing blocks should be 0,01 to 0,03 mm less in diameter, followed the dimensioning at the original drawings.
I started to make the bearing blocks and learned very quick, that heat from machining does have an influence in the dimensions and the press fit of the bearing also.
So first the inner diameter for the bearing press fit was machined.
Than the bearing was pressed into its position.
Than the outer diameter 42,19 minus 0,03 to minus 0,04 was my target dimension.
Not every attempt hit my target, specially after parting of, the heat has increased the diameter a bit, so final measurement had to wait a bit until cooling down.
At the end I have had 6 bearing blocks in the range of nearly 42,15 to 42,18 mm.
These blocks I haven swapped several times in different positions until I have had 5 blocks of 6 I have made, in situ and the dummy shaft still turns by hand.
So theoretical I have been sure a straight shaft will be movable, the only finding of these action.
The later situ will be totally different.
The concept of these cranks shaft is, if I understood it right:

• two con-rods with shims, a con-rod bearing pin and two webs will be assembled by a press fit to a single unit. 6 of these pre-assembled units will be needed.
• the main bearing blocks will be pre-assembled with the crankshaft pins, 5 of them. The middle one with some additional shims for axial adjustment.
• outside the crankcase these above mentioned components will be assembled to the crank shaft without the front and read shaft extension.
• than this part of the crank shaft will be fit into the crankcase.

Sound all like a logical theory, but I am very curious what will be the reality later.

[Roger B]

Nice work on the gear design/positioning   

With the shallow angle between the gears a small change in the clearances and PCD will make quite a large change in the position.

[fumopuc]

Last picture of the build has shown an assembled dummy cam shaft with bearings.
I the meantime #2 cam shaft dummy is sample assembled also.
These cam shaft bearing block was a trainee program for me I have made in spring 2022.
The target was to see if I am be able  to machine these 6 bearing blocks in one row in a way, that a shaft turns still.
Most of the pictures should be self explaining.
tbc ...

[fumopuc]

The overall machining was a combination of CNC use and conventional milling.
A good opportunity to make a new  arbor for the circular saw blade.
tbc ...

[fumopuc]

The strategy for getting proper and round holes was, to make a hole and than to use a reamer.
Idea was to make the hole by the CNC mill with the operation drill milling.
Here I had to learn first, that there is a special feature with must be strictly followed.
This video does explain the details very well.
<a href="https://www.youtube.com/watch?v=6wLU97gVo5k" target="_blank">http://www.youtube.com/watch?v=6wLU97gVo5k</a>
I had to pay the learning curve by one VHM cutter.
tbc ...

[fumopuc]

Next, I had to pay with another VHM cutter, the mishap to forget to remove the spacer for parallel clamping.
First I didn´t realize, that the cutter was damaged by this action.
So the next part was not drill milled, it was more drill pressured.
Five good ones one ugly one not finished.
I have had no set up part in my work flow, so I decided for the moment to go ahead and give it a try by finishing the drill and ream operations.
tbc ...

[fumopuc]

Next challenge to get a flat surface for all bearing block of each batch in an equal level.

This was archived as shown in the pictures.
Here is an unknown factor for the earlier mentioned story, positioning of the idler gears.
Than the point of truth, will it really work with a dummy shaft.
A rectangle aluminium stock was drilled and tapped.
tbc ...

[fumopuc]

Inspecting the mishap bearing block again,  my decision was not to make a new one.
There is still a lot of remaining surface for guiding of the shaft.
All matched pairs are marked and the thread in the lower parts had to be removed now.
First a sample assembly with half of the blocks and than all of one side.
Everything was movable still and the unit was hidden in a box under the bench until some days ago.

[Roger B]

That's coming together nicely    Shame about the cutter mistake 

[fumopuc]

Hi Roger thanks.
I would say that is the same problem as well known by the IT people already.
The reason for all problems is always located between keyboard and the surface of the chair in front of it.

[Roger B]

Indeed  Most road accidents are caused by the nut behind the steering wheel.