Mercedes-Benz W165 Grand Prix engine in 1:3 scale

[Roger B]

Looking good    Take it easy, things will get better 

[Admiral_dk]

Great to hear that you are enjoying yourself again Mike

That it has to be 'smaller doses' is still a lot better than No Joy 

The rest of us will also enjoy your post - no matter the size 

Per           

[Brendon M]

You hack-sawed the crank counterbalance weights!?

By golly, that would have been good exercise

The crankshaft looks amazing

[Vixen]

Machining the Crankshaft Counterweights

Thank you everyone for calling in and those of you who just looked in. It's nice to know you are there.

Brendon, A brand new 32TPI Eclipse bi-metalic blade helped. However, I only had the energy to do two or three each day.

Kim, actually I did show the fixture plate and the setting device way back in Reply #729: 29 August 2022. I think that was the day before the Covid paid me a visit. There's been a bit of brain fog since then and I still have that damned cough, eight weeks later.

Here is a brief picture summary of the fixture plate how I located each crankshaft part prior to machining the outside profile and the three scallops on both sides.










Here is a nearly completed crankweb. There will eventually be 16 of these, for the two crankshafts.






I have a new helper in the workshop, He says 'Hi' to the two Elfs and also to 'Slim'.



His friends call him 'Crash'; most others just call him 'The Dummy'. He says he is going to help out in the shop by getting me organised and giving his advice as often as he can. I guess we will see how long that lasts.

Mike

[crueby]

Great use of the fixtures, well thought out!

And the shop elves here say Hi! to Crash, they are (trying to) save him a beer...

[Kim]

Thanks for the pictures of your fixture and how you use it!  Very clever   

Kim

[Vixen]

Initial Assembly of the Crankshaft

It's taken a long time, what with the unwanted interruption and everything; but finally, I have enough part completed components available to do a loose assembly of the full crankshaft. As I say, it's a loose assembly, everything is in it's approximate position but nothing is yet correctly aligned. The crankshaft needs to go into the assembly jig for that.

Oh!, to get a sense of scale, 'Crash' is about 6" (150mm) tall.







The next two images clearly show how the Mercedes Benz balanced the W165 crankshaft. A classic example of a cross-plane crankshaft with counterweights.
The outer rows 1 and 4 are 180* opposed, as are the inner rows 2 and 3. The middle two rows are also set at 90* to the two outer rows.






Now it's all got to fit into the crankcase somehow and there is not much room to spare, especially when you start adding the con-rods as well.







I feel I am getting somewhere at last.

Mike   

[crueby]

Awesome work! Hopefully when its done Crash wont get it in a chassis and live up to his name...

[steamer]

I'm in the middle of some generator repair but I'll be poking in later my friend  Nicely done sir!!!

Dave

[Roger B]

Splendid     

[Admiral_dk]

Looks Amazing      Mike

Is there a reason for the single 'Bearing' on each Throw ?

Per           

[Vixen]

Thank you all for taking the time to call in and for stopping by to see the progress.

Per, when fully assembled, there will be a full compliment of eight bearings for the eight con-rods.  Actually I broke one of the jaw fingers of my bearing puller, so until that is fixed, I do not want to press the additional bearings onto the big end journals. I only needed four bearings to align the big ends for this trial assembly.

Cheers

Mike

[steamer]

That looks magnificent Mike.    I can't wait to see it in place.   I'm sure its wonderful!!!

Let us know when the bearing puller is fixed!!!

Dave

[Admiral_dk]

Alignment - yes of course .... I should have figured that one out myself 

I really hope that the leg on the Bearing Puller, will be that last time you encounter Sods Law on this build ....

Per

[Vixen]

Assembling the Crankshaft and Con Rods into the Crankcase

There is rather a lot of steam engine stuff on the forum at the moment, so I thought something for the 'petrol heads' would make a welcome change.

The Mercedes W165 build seems to be moving at a glacial pace. It has always been a slow build and the forced eight week stoppage , due to post Covid complications, has not helped.

In this installment from Vixen's Den, I will concentrate on the final assembly of the first of the two built up crankshafts. You will recall the original W165 had a one piece crankshaft with split mains and big end bearings. All bearings had the rollers bearing directly on the hardened crankshaft and bearing shells. I felt that a hardened and ground crankshaft, all those con rods and bearing shells was beyond my machinery capabilities and elected to use commercial ball races with one piece con rods and a built up crankshaft. I also chose to use the Shillings alignment approach rather than Hirth couplings. The illustrations below show the principal I intended to use.







You will notice that the crankshaft must be assembled from front to rear, one component at a time, because each clamping bolt is covered and hidden by the next item to be assembled. When fully assembled; none of the clamping bolt heads will be visible.

The whole assembly process needed careful alignment to ensure the assembly was both straight and concentric. I chose to use the crankcase as the alignment jig and build up the crankshaft in situ.

Here, you can see the component parts required for each pair of con rods. The main bearings are aligned by the 20mm ID, main roller bearings. The con rod journals are aligned by the 12mm ID, big end bearings. None of the journal ends actually touch each other. Instead, they butt up against the precision ground bearing inner. The big end bearings also require a shim washer between the roller bearings to control their distance apart. The shim washers were between 30 and 35 thou thick and were selected to fit, as required.









Here you can see how the first pair of con rods are assembled to the crankshaft. This repeats as more sections are added to the crankshaft







Here you can see the crankshaft growing in length from the front to the rear.










You can see just how tightly the crankshaft fits into the crankcase. The gap between the counterweights and the bearing caps is typically 10 thou. That is why the shim washers need to be carefully selected. That involved no end of assembly/ test/measure /dis-assembly/ repeat; to find the correct shim thickness.





All that careful work paid dividends. The fully assembled built-up crankshaft spins straight and true with minimum effort require to rotate it. This clearly shows that all the main bearings achieved near perfect alignment; much to my relief.

Crash decided to add his own version of quality control, he says he can get in much closer than me.




Now all I have to do is repeat the whole exercise for the other crankshaft. At least I have been up the learning curve once, so it should not take as long.

Cheers

Mike