Author Topic: Mercedes-Benz W165 Grand Prix engine in 1:3 scale  (Read 151400 times)

Offline nj111

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #285 on: March 30, 2020, 10:29:14 AM »
That's great! Thank you for the update
Nick

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #286 on: March 30, 2020, 11:46:04 AM »
Hello Simon, Art, Nick and everyone else

Thanks for calling in and for looking in.

I had not intended to return to the Mercedes W165 until mid summer at the earliest. I had hoped to meet up with the Mercedes historic car people at the Goodwood Festival of Speed in July, or during the week after, before they returned to Stuttgart. I had hoped to talk them into releasing some more photos of the rear of the engine, particularly the cam drive train.

But the world changed overnight and all plans for 2020 have evaporated.

I have made a best guess at the design of the camshaft gear train based on what little information I have collected together over the years. Some things are know. The camshafts have 64 teeth gears, therefore the crankshaft and magneto drive must therefore have 32 teeth pinions. The idler gears between, can have any number of teeth, that does not affect the 2:1 reduction. However the idler gear wheel size is dictated by internal clearances and the need to pass through the ring of bolts holding the clutch housing in place. I modeled my 'best guess' gear layout in perspex on the back of the model and it appears to be a logical design. I cannot confirm it's correctness. Even so, I will proceed with what I have. The next step is detail design drawings, which should keep me indoors and busy for a while.

How far can I get? That all depends on the supply of raw materials. I had not planned to start so soon, so I have not bought in the required stock to complete the job, I will try to make do with what is available, but I don't have a large materials collection.

Stay in, stay safe

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Johnmcc69

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #287 on: March 30, 2020, 02:29:25 PM »
Beautiful work Mike!

 John

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #288 on: March 30, 2020, 02:51:25 PM »
Stunning Work.   :praise2: :praise2: :praise2:

Colin

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #289 on: April 01, 2020, 03:55:58 PM »
The design of the cam drive train for the Mercedes W165 will be challenging as I do not have any detail drawings or photos of the rear of the engine. Mercedes Benz corporate policy is not to give such information away as it could assist unauthorised counterfeit reproductions of their products to be built.

So be it.

Fortunately, I did find this photo of the back face of a V12 W154 in the Louwman Museum, Holland.  It provides a good indication of how the Mercedes engineers designed these parts back in 1938. You can clearly see the camshaft drive train was enclosed in a narrow cast alloy box with external bosses to support the bearings for the individual gears in the gear train. Although the gear layout is different to the W165, I believe it gives a good idea what it should look like.




I believe it is asking a lot to get the centres of all 10 gear centres in the correct position to give perfect meshing. Instead I decided to mount the two pairs of intermediate idler gears on two separate bridge pieces. This is in some ways similar to the bridges used on watches and precision time pieces. The positions of the  intermediate idler gear pairs can be adjusted until a perfect mesh is achieved then bolted firmly in position. The bridge pieces will be bolted to bosses protruding from the engine side, half of the gear case. The intermediate gears and bridge pieces only attach to the front half casing, there will be no connection to the rear casing The rear half of the gear casing will bolt to the front half and will carry cosmetic, non functioning external bearing bosses over the individual gear positions.




Well that's the plan. I have steel bar for the idler gears on mail order. So if it ever arrives, I will start my making the idler gears and bridge pieces, which can be tested against my perspex mock up.

Stay in, stay safe

Mike
« Last Edit: July 26, 2021, 11:54:46 PM by Vixen »
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline fumopuc

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #290 on: April 01, 2020, 04:10:17 PM »
Hi Mike,
that seems to be a brilliant idea to get it proper and a bit flexible done.

Kind Regards
Achim

Offline Roger B

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #291 on: April 01, 2020, 05:29:58 PM »
That's a complicated gear train  :headscratch:  :headscratch: and a good solution  :wine1:

I guess that the shaft in the middle of the picture is the steering column?
Best regards

Roger

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #292 on: April 01, 2020, 05:34:27 PM »
I guess that the shaft in the middle of the picture is the steering column?

That's correct. Perfectly designed to impale the driver's rib cage in the event of a collision.

Mike
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Offline cnr6400

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #293 on: April 01, 2020, 08:21:45 PM »
Ah, the old sternum-werfer, eh?
"I've cut that stock three times, and it's still too short!"

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #294 on: April 05, 2021, 09:10:24 PM »
I have found the time to return to my two Mercedes Benz W165 engines and hopefully I will be able to make some more progress towards their eventual completion.

The first job I needed to complete, was to line bore the five main bearing journals which hold the ball race bearings for the crankshaft. It is essential to get all five bearings perfectly in line, so I needed to make a long, between centers, boring bar and to fit it with a 'microbore' precision adjustable cutter. I was lucky enough to find and buy two small  'microbore' tool holders from WWW. jurasictools.com in the UK. One, the larger of the two, has a replaceable ceramic insert tip and the smaller one has a brazed on tip. The smaller tip could be made to fit a 25mm diameter bar. However, I could get a larger diameter 28mm bar inside the un-machined big end bearing journals. The slightly larger diameter 28 mm bar would have nearly twice the stiffness of the 25mm bar.






The height of the cutting tip is raised by rotating the adjuster nut with the conical base. Two small keyway pegs prevent the tool rotating. The small countersink screw in the base  then locks the 'microbore' cutter at the desired setting. The boring bar was machined with the necessary cone seating and keyway slots




The adjuster nut is engraved to indicate the depth setting, but these were very difficult to see, hidden deep within the boring bar and also down inside the engines crankcase. I knew I needed to make a special 8mm square socket to adjust the depth nut, so I added a large diameter timing disc to the top of the 8mm socket; which makes the depth adjustment so much easier. The disc has 50 sub divisions. Each division gives a 1 thou"  (0.0254 mm) change of depth. I cheated slightly and used a plastic laminated paper disc rather than an engraved scale.







The only lathe I have, big enough, is my old and very worn Chipmaster lathe. The cutter needs to traverse approx 200mm (8 inches) to bore all five journals. The normal way to do this work, is to bolt the crankcase to the saddle and move the saddle backwards and forwards over the rotating boring bar. Unfortunately, I know the Chipmaster's bed would be too worn to allow me to do it this way with any accuracy. Each journal would end up being a different diameter, as the saddle rode up and down over the worn out bedways. An alternative method is to fit bearings to either end of the crankcase and use these bearings to position of the boring bar accurately within the crankcase. The crankcase would be loosely driven by the saddle, the precision being derived from the additional bearings rather than from the lathe itself.

Here you can see the two bearing plates spigotted and bolted to either end of the crankcase. I am hoping the plain aluminium bearings (with plenty of lubrication) will survive long enough to finish all of the bores.








The depth adjustments can be made easily and conveniently through the rectangular (supercharger dive) aperture on the top of the crankcase, while the locking screw is tightened from below






Finally, here we have everything set up ready for a trial run (on the spit roaster). Looks promising, now where did I put my beer glass.  :DrinkPint:




Stay safe, stay tuned.

Mike




It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Admiral_dk

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #295 on: April 05, 2021, 10:34:01 PM »
Very interesting alternative when the Lathe isn't precise enough - thank you very much for showing Mike  :ThumbsUp:

Will look forward to see the rest of this operation  :cheers:

Offline 90LX_Notch

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #296 on: April 05, 2021, 10:53:00 PM »
I’ll be watching the line boring with great interest Mike.  I have been kicking around making a bar to line bore my Britnell four cylinder.  I also need to make a table for my Rivett 608 in order to do this operation.  The scary part is that the bar will be .250 (6.35 mm). 

-Bob
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Offline john mills

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #297 on: April 05, 2021, 11:00:16 PM »
Hi
That set up should work well.  reminds  me of when i did line boring on full size engines the machine had adjustable movable arms  the boring bar run in removable starnded  drill bushes  the bar was only 1" dia .the
tools were just a plain carbide round tool held by a grub screw from the side or on a shot bar about15 inches long a knob on the end and a rod through the bar .the tool was just set in a direct reading micrometer set at a fixed bush size adjusted by tapping the tool and tightening the grub screw.it was surprising how precisely i could bore to
size the bushes had a surprising amount of clearance.   nice to see you use as large a bar as will fit.
          John

Online steamer

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #298 on: April 05, 2021, 11:49:28 PM »
Love that set up...can't imagine why..... 8)

Keep it coming bud!.....

Dave
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Offline fumopuc

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #299 on: April 06, 2021, 09:36:58 AM »
Hi Mike good luck.
I am sure it will work fine.
I have used such a Microbore tool also in the crank case of my Bruce Macbeth Engine some time ago.
https://www.modelenginemaker.com/index.php/topic,7527.msg196888.html#msg196888
It works like a treat, 0,02 mm adjustment was easy to archive.
My Microbore tool is equipped with a CCMT cutting insert.
The adjusting tool is not as elegant as yours.


« Last Edit: April 06, 2021, 10:21:21 AM by fumopuc »
Kind Regards
Achim

 

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