Author Topic: Mercedes-Benz W165 Grand Prix engine in 1:3 scale  (Read 151466 times)

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #375 on: May 16, 2021, 05:24:21 PM »
I thought I would take a short break from all the 2.5D and 3D tool paths and 3D machining. It can make your head spin.

I decided to have a go at some of the engines internal pipework by way of a change. To do that, I needed to make a small bend radius pipe bender specifically for 5.0 mm copper tube. I based my pipe bender on the design used by Steve "Old Bill" to bend the external pipes on his 1909 Mercedes aero engine.

It did not take long to make, using offcuts and scrap pieces from the 'come in handy one day' box. Some of you may recognise the rear bearing block from the crankshaft line boring exercise is being re-used as the bed plate. There are one or two changes to the "Old Bill" design; I use two bolts on the adjuster to stop the slide bar from rocking, Similarly I added a third roller for the same purpose. This bender is designed to bend 5.0 mm copper pipe around a tight 5.5 mm internal bend radius. However is can easily be adapted or modified for other sizes of pipe or bend radii.

The 5.0 mm diameter groove in the slide bar and the rotating bit were made with a 5.0 mm ball ended cutter. The 10 mm AF hex was quickly done by indexing on the 4 th axis unit. The three brass rollers spin on hardened steel shafts, but this is realy not necessary to harden the shafts as they do such little work.

The pipe bender can easily be adapted for other tube/pipe diameters by machining a different diameter grove in one of the other faces of the slider and making another rotator with an appropriately sized groove at whatever bend radius is required.






A few 90* test bends pointed out the need for an internal bullet to prevent the 5.0 mm copper tube from flattening on the outside. A piece of angle iron was used to anchor a length of 4.0 mm steel rod inside the copper tube. The steel bullet rod needs to be clamped sufficiently far away from the bender to allow for a long length of stock tube.




In the photo below; the bend on the left was made from, as delivered, hard copper pipe without the central bullet. You can clearly see the flat on the outside. The middle bend was made the same way after the copper had been annealed (heat to bright red then quench in cold water). The flat is much reduced but still there. The final bend on the right was made with annealed copper and with the internal steel bullet rod, as you can see the bend is perfectly formed without the dreaded flat on the outside. The internal bullet is positioned inside the copper tube just short of where the bend commences. Somehow it prevents the outside of the tube from collapsing inwards






The bending part was easy, once the bender was set up properly. Not so easy was getting the second or third bend in the correct place or at the correct angle to the previous one. Lots more copper pipe found it's way into the scrap bin until I eventually discovered the knack.



There was no excuse now but to try it for real on the model. So stay tuned for the next episode from Vixen's Den

Mike

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Online Kim

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #376 on: May 16, 2021, 05:48:27 PM »
... The final bend on the right was made with annealed copper and with the internal steel bullet rod, as you can see the bend is perfectly formed without the dreaded flat on the outside. The internal bullet is positioned inside the copper tube just short of where the bend commences. Somehow it prevents the outside of the tube from collapsing inwards

You really got a nice bend there!  I'll have to remember this technique.

So, is the bullet rod the exact internal diameter of the tube you're bending?  And what shape is it on the end?  Does one assume its 'bullet' shaped since that's the name of the rod?

I would have thought the 'bullet' needed to go in the end of the jig that turns, so the bullet could stay tangent to the part of the tub that is bending.  But in your jig, it looks like it is in the stationary part of the tube.  Is this right?  Or maybe I'm not following it very well?

Thanks,
Kim

PS - Sorry, moved my question over to your 'tool' cross post of the bender.  Seems like a better place to ask the question!

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #377 on: May 18, 2021, 04:20:27 PM »
As Kim intimated, the pipe bender discussion and it's operation has been moved to https://www.modelenginemaker.com/index.php/topic,10352.msg236219/topicseen.html#new    where it is receiving a lot of interest from both Steam and i/c engine builders.

In the mean time, I have pressed ahead and attempted the 'snake pit' of plumbing inside the dry sump of the first W165 engine. I all went reasonably well, however most bits of pipe had to be attempted several times as I experimented to get the perfect distance between consecutive bends. I quickly discovered that because of local work hardening, it was virtually impossible to correct a slightly misplaced bend. Better to start again with a new length of annealed copper pipe. Lots of copper pipe was consumed in the process and the scrap bin is a lot fuller as a result.

I became so carried way that I completely forgot the camera and so only have the completed work to show you.

The first picture shows an overview of the bottom of the engine and the dry sump cover. Note the horizontal baffle plate around part of the dry sump, it was there to prevent the waste oil slopping arround during tight cornering, acceleration and braking





This close up shows the pipework in more detail. The larger 5.0 mm pipes handle (on the left) the fresh oil coming from the external supply tank, (on the right) the scavenged oil outgoing to the oil cooler and filters and (in the centre) the drain pipe from the front scavenge pick up (not yet made). You can also see the smaller 2.3 mm pipes which feed oil from the oil pump to each of the five main bearings. The bend radius of the 2.3 mm pipe are large compared to the pipe diameter and were formed by bending the pipe around the outside of a 16 mm diameter bar.





The battery of oil pumps have already been described, a long time ago, in section 10, which started at reply #191. You will recall, there are a number of pumps, both pressure and scavenge pumps mounted together 'en block' onto the rear main bearing cap. The bronze block on the left of the pump block, together with the first thin aluminium section act as a manifold to direct the oil flows to the various individual pump sections. The first wide section is the pressure pump which provides pressure fed oil to the five main bearing caps. The next slightly thinner pump section provides pressure oil to the four overhead cam shafts. After that is a slightly wider pump section which scavenges used oil from the front of the dry sump. That is followed by the rear sump scavenge pump section with an integral pick up strainer. At the extreme right are the pressure and scavenge pipe connections to the four overhead camshafts. This pipework will be added later in the build.





The next two photos compare the 1/3 scale model with the full size engine. It realy is a 'snake pit' of pipes and snake oil. There is evidence in the full size engine of numerous repairs to the pipes, possibly as a result of vibration and metal fatigue.




                                                                                                                                           This image, is courtesy of Daimler Benz.



Now I have to repeat all of that on the second engine

Mike

« Last Edit: May 18, 2021, 05:29:28 PM by Vixen »
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Offline tvoght

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #378 on: May 18, 2021, 04:59:49 PM »
Absolutely fascniating. And beautiful work.   --Tim

Offline Roger B

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #379 on: May 18, 2021, 05:01:36 PM »
A plumber's nightmare  ::) Crack a critical pipe and goodbye engine  :toilet_claw:

Excellent work  :ThumbsUp: The second one will be much easier  :Lol:
Best regards

Roger

Online Kim

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #380 on: May 18, 2021, 05:37:06 PM »
Wow!  That's just amazing work!  Not just the pipe, but the whole build...

Kim

Offline ddmckee54

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #381 on: May 18, 2021, 07:10:19 PM »
Having had to deal with bending tubing for hydraulic test stands all I've got to say is...  Them's some nice bends there Bubba!

Don

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #382 on: May 18, 2021, 11:21:01 PM »
A plumber's nightmare  ::) Crack a critical pipe and goodbye engine  :toilet_claw:

Thanks everyone for calling in.

Complexity and reliability never go together well and the W165 was an extremely complex little race car. In that far off era, Grand Prix races were much longer than today's. They pushed the machinary to their limits and sometimes beyond, mechanical reliability suffered. It was not unusual for 25% or more of the entrants to retire early, due to mechanical ailments. Mercedes and Auto Union would often field a team of three, four or even five cars in the hope that one would survive as the winner.

Mike
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Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #383 on: May 24, 2021, 03:34:25 PM »
One more piece of the jigsaw completed. Many more still to do.

I have completed? the oil pump pipework for both engines and also added the front suction pickup funnels. There are two discs of fine brass mesh to go under the course honeycomb strainers.
Need to think of some way to cut the brass mesh perfectly circular.   :headscratch:



Mike
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Sometimes, it can be a long and winding road

Online crueby

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #384 on: May 24, 2021, 03:50:26 PM »
Stunning work!
For cutting thin sheet stock, I'll usually clamp it between two sheets of wood then cut through the lot with a bandsaw or jig saw. Could that work for the mesh? Maybe leave the last little bit uncut in a couple places, then trim those seperately, in case things shift when making the last bit of the circle.  Or, depending on the thickness of the stock, I'll press the sandwich of wood and metal between the faceplate and tailstock center on the lathe and trim with the lathe cutter.

Offline tvoght

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #385 on: May 24, 2021, 04:10:00 PM »
They probably wouldn't be available with your exact dimensional requirement, but it's worth checking into pre-cut circular "pipe screens" for smoking pipes.  They are available in brass and stainless steel. I have looked into the stainless steel ones for use in Stirling engine regenerators.   --Tim

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #386 on: May 24, 2021, 05:14:57 PM »
Hello Chris. Tim

Thanks for the suggestions. I am tempted to try turning the mesh disks sandwiched between two sheets of wood but I am a bit worried about the mesh being pulled apart at the edges by a saw or lathe tool. I will give it a try and see what happens. I suspect the mesh needs to be stamped or sheared (scissors)
The pre-cut "pipe screens" would be ideal if they came in my size; 23 mm dia. Must be a different type of smoking pipe to my old Peterson's tobacco pipe.  :vomit:



Mike
« Last Edit: May 24, 2021, 06:00:52 PM by Vixen »
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Offline ddmckee54

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #387 on: May 24, 2021, 06:00:19 PM »
I'd be a lot more work, but what about soldering the brass screen where you intend to cut it?  (Or even super glue.)  That would keep the small bits of the mesh from coming apart as you handle it.

Online Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #388 on: May 24, 2021, 06:14:25 PM »
I'd be a lot more work, but what about soldering the brass screen where you intend to cut it?  (Or even super glue.) That would keep the small bits of the mesh from coming apart as you handle it.

Jeez Don,

Have you seen me with super glue? I still get my fingers stuck together and also to the hand tools and everything.

But you are right, it should stop the edges from fraying. Dissolve the glue with acetone afterwards?

Mike
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Sometimes, it can be a long and winding road

Offline petertha

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #389 on: May 24, 2021, 06:31:23 PM »
Mike, these superglue tips are dirt cheap & work wonders for precise applications. Unfortunately there are no standards when it comes to the tapered stems of typical CA glue bottles & the wide end of the tip could benefit by being a little more flexible to conform IMO. But they seal & work well once on. I've used them on thin through thick CA with no issues, so could probably be extended to Loctite, light oils & such.  Check prices they vary all over the map but generically seem the same. My guess is their real purpose is lab or pharma use but someone got the bright idea that hobbyists could benefit too.

 

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