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

[jcge]

Thanks for the filing tips Mike - much appreciated.
I sit here dumbstruck looking at the pics of your work.
John

[petertha]

Mike, I'm glad you are feeling better & back in the shop. Nice to see these stunning pictures again.

Re your supercharger manifold, I am pondering a similar but less complex assembly for next project - individual manifold components joined with JB or similar aluminized epoxy. I've made a few test coupons with minimal but present external fillets & they have a nice appearance. The epoxy color blends well if the entire part has kind of satin finish & I'm confident it would take indirect (non-exhaust) heat. The only thing that gives me pause is I made certain repairs to RC engine components in my past life. The epoxy never let go but it took on a different color over time, like a few flying seasons. Not sure if it presence of fuel/oils, UV or even just mild heat cycles? It wasn't horrible but also not as pretty as new. Have you had good luck with JB in running conditions?

I looked into some aluminum brazing options but the melting point is so close to the stock. With practice I might get lucky with a single joint, but multiple joints & different relative mass between parts, I suspect the odds are in favor of a molten puddle. I've seen a video where a somewhat complex assembly was pre-fluxed & pre-wired with braze on all the joints, the whole thing put into a controlled (heat treat) oven, slowly crept to temp until it flowed & then door opened. The part looked great but one never sees the prior sacrifices. Any comments in this regard?

https://canadaweldingsupply.ca/products/harris-al-braze-1070-kit

[Vixen]

Hello Petertha,

Good to hear from you again.

In truth, an epoxy bonded fabrication is the last resort. Far better to use a casting or machine the component from solid but sometimes that is just not practical. A metal/ epoxy fabrication is best suited to a static or low stress environment.

Cheers

Mike

[Admiral_dk]

Unfortunately only in German :  <a href="https://www.youtube.com/watch?v=NNTm5Vz8iRI" target="_blank">http://www.youtube.com/watch?v=NNTm5Vz8iRI</a>

.... and homepage https://www.tav3.de/

Disclaimer – I haven’t tried this myself – but the product has been tested by Technical Institutes in Germany.

This is Alloy Soldering @ 308C (melting temp for the 'Solder'). He uses the 'Solder' to indicate the Temperature and the Screwdriver to penetrate the Aluminium-Oxide.
This Alloy made up from eight different materials – like Al, Zn, Cu, Mg, Mn, Ag (he does not mention them all).
So, you can solder a number of different materials together – like a Galvanized steel nut, to Aluminium as in the Video. He does mention that this is as solid as the Zn is fixed to the Steel (not Alu to Steel).

He also states that it is very important that the parts can't move relative to each other during the Procces and until cooled down (like normal Soft-Solder).

Sorry if I have mentioned this before .... + I agree that it will still be difficult to hold it all in possition and not removing the heat while doing so ....

Per

[RReid]

Hello Mike. It's great to hear that you're feeling better and getting back into the shop.

I'm curious as to why you chose to round over that central tube with files rather than by CNC, and why it was done after rather than before adding the inlet stubs? In any case, the end result is beautiful!

[Vixen]

Hello Ron,

Back in the shop, yes, but not for more than an hour in any day.

We have a saying, "there's more than one way to skin a cat" and that is also true for complicated fabrications.

Here is my rational.

I wanted the stub tubes to form a concentric spigot in the central tube i.e. with a well defined square shoulder; for the strongest bonded joint.
I needed to precisely control the -17* down facing angle of the stub tubes and also to ensure they were square to the axis.
I reasoned, a precisely machined angled, flat face on either side of the central tube was a good way of achieving the required angular accuracy on all eight stub tubes.
The central tube does not have a perfectly circular cross section, it's egg shaped.  So lathe CNC was out. It could maybe be done in short sections using the 4th axis but I don't have adequate 4 axis software.
Besides, there is an interesting intersection where the smaller diameter stub tubes intersect with the larger central tube. This was not amenable to machining on my simple 4 axis CNC mill (may have been possible on my 'dream' 5 axis machine: I wish) . So some hand filling would always be needed. So I decided to cement in the stub tubes first, to achieve the accuracy I needed, then file all the centre tube, by hand.



There may have been other or better ways to do this manifold, everyone's mileage will differ

Cheers   

Mike

[RReid]

Thanks for the explanation, Mike. That makes perfect sense.

[Admiral_dk]

Very very nice Filing (handwork) 

.... but inquiring minds like to know what the small hole in the last picture is used for 

(may have been possible on my 'dream' 5 axis machine: I wish)

You + quite a good number of the rest of us   

Per         

[Vixen]

Very very nice Filing (handwork) 

.... but inquiring minds like to know what the small hole in the last picture is used for 


Per         

As far as I can tell, the small hole is a pressure gauge tapping for the second supercharger stage and was used only during bench testing. On the racing car, the hole is blanked off (no supercharger, or should I say Kompressor, pressure gauge on the car)



More interesting, may be the second tapping (see photo) on the side of the pop-off valve housing. A thin rubber tube ran from the pop-off valve tapping into the drivers cockpit. The driver tucked the end of the rubber pipe inside of his cotton crash?? helmet. He could hear when the pop off valve blew off..... that was his signal to pull the next gear.
No ECUs or AI in those far off days.

The driver only had three instruments, so as not to distract him. Tacho, oil pressure and water temperature.

Cheers 

Mike

[crueby]

Absolutely  stunning  model!  About how much does it weigh so far?   

[RReid]

The driver tucked the end of the rubber pipe inside of his cotton crash?? helmet. He could hear when the pop off valve blew off..... that was his signal to pull the next gear.

That is interesting. A kind of audible HUD. At least those "helmets" were good for something!

[cnr6400]

Hope a backfire never went up that tube from the pop-off valve! That would be distracting, to say the least!   

[Vixen]

Hope a backfire never went up that tube from the pop-off valve! That would be distracting, to say the least!   

Ha ha!!  I would have thought a sudden blast of nitrobenzine doped fuel inside your hat, would have been stimulating enough.   

Chris, the engine currently turns the scales at a little over 6 Kg.(13.25 lbs); mostly aluminium alloy and steel. You seem to have cornered the market for shiny brass. I guess the weight of all the swarf and chips (and scrap) must weight 5 to 10 times more than the engine itself.

Cheers 

Mike

[Art K]

Mike,
Glad to see you're healthy & in the shop again. I had gotten a few pages behind and used a long weekend to get cought up. Impressive work as usual, and it's fun to hear the story behind things. Keep up the great work!
Art

[Vixen]

Thank you Art,

It's a slow news day, so I thought I'd better post some progress on the pop-off relief valve cover and vent pipe which adorns the W165's inlet manifold.

Although I only need two, I set about making three valve covers, as a sort of insurance policy. Making was straightforward turning and milling. Here are the outside and inside views and one with the cutout for the vent pipe. The wall thickness is about 1mm





The vent pipe is inclined at an angle of 20 degrees, so I screwed each cover to a jig plate held in the machine vice and tilted over to the required angle. A 10mm diameter hole was bored to depth, which produced this interesting blend line.





A family shot showing two assemblies bonded together and the component parts for the third.





Here you can see the pop-off relief valve cover and vent pipe bolted in place on the inlet manifold. You can also see the pipe union and rubber pipe used for the pop-off detection. Everything seems to fit well. Next is to clean up inside the valve cover followed by a visit to meet Mr. Sandblaster.





Another small part almost ticked of the never ending 'to do' list.

Cheers   

Mike