Author Topic: Mercedes-Benz W165 Grand Prix engine in 1:3 scale  (Read 58056 times)

Offline Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #150 on: July 22, 2017, 08:51:55 AM »
Good morning Sven

Welcome to the MEM forum. We are a very friendly group from all over the world who share a common passion for making model engines. There is a special section for new members to introduce themselves and tell us about their interests and projects.
Making the crankshaft will be interesting. I have ideas to make a press together crankshaft and to use commercial ball races.

Regards

Mike
It is the journey that matters, not the destination

Offline Sven

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #151 on: July 22, 2017, 11:35:21 AM »
Ok Mike
I will introduce myself soon on right place here
Best
Sven

Offline michelko

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #152 on: July 22, 2017, 10:07:37 PM »
Very impressive  :praise2:

Offline fumopuc

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #153 on: July 23, 2017, 06:50:11 AM »
Hi Mike, thanks for showing the way you did it. I will following along and try to learn.
Kind Regards
Achim

Offline Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #154 on: July 29, 2017, 02:09:37 PM »
Part 9C   Crankcase:  Starting to finish the outside surfaces

Thanks to all of you who have posted comments, you provide the encouragement for me to keep posting this build log

In the previous installment, I described how the crankcase billets were roughed out to remove surplus material and provide a basis for the finishing cuts. I will now describe the slow process of refining the external shape of the crankcase in a number of stages. As you can imagine it was a long slow process requiring many set-ups. Each set-up provided plenty of potential opportunities for false cuts and cock-ups. The problem being compounded by machining  away of all the initial datum faces during the roughing stages.

I made a start with the auxiliary drive enclosures at the front of the engine. These enclosures house two bevel gears, driven off the crankshaft, with the added complication of being inclined downward at 30 degrees on both sides of the crankcase. They will eventually drive the coolant water pump, the fuel pump and yet another oil scavenge pump.

I made up two 30 degree angle plates, to bolt under my jig plate. I find it much more convenient to use precisely machined angle plates than to fuss about with sine bars and shim blocks etc. The angled jig plate is bolted  to the mill table and indicated into the correct position. The crankcase halves are then attached, in turn, to the jig plate which provides good position repeat-ability during the machining stages. The rod sticking out at the front is located precisely at the apex of the bevel gears and is used as the new datum for all machining relating to the bevel gears.






The differences between the roughed and semi finished auxiliary drives can be seen in the next three photos. There is a limit to the amount of machining possible with my equipment, I do not have the software to do complex 3D machining. I am limited to 2.5D machining ( pockets and contours at differing depths) which leaves plenty of hand finishing with the Dremel and files to get to the final shape.









There are two prominent extensions on either side of the rear crankcase which form the rear engine bearers. I made these up as two separate pieces which bolt on to either side of the crankcase. The securing bolts are hidden inside the crankcase and are buried in the crankcase side walls. The large hole in the left side engine mounting block was there to allow the steering rods to pass through,






Next, I cut the semi circular profile of the lower sidewalls. The left and right sides of the case are different. The right hand side is a continuous curved profile interrupted by the oil inlet pipe flange, The other side has that large bulge for the oil pumps. I used a 8mm ball nosed cutter, making repeated passes at 0.010" separation at different depths (Z axis) to produce the curved surfaces. Even at ten thou separation, the curved surfaces are not completely smooth, but that is easily sorted later with files and abrasive papers. You will notice I had to machine around the curved roots of the engine mounts. The engine mounting blocks had to be temporarily removed to allow access for the cutters





Finishing the outside surfaces was a long, slow process. I hope to conclude the rest of the machining operations in the next installment from Vixen' Den.

Stay tuned.

Mike
It is the journey that matters, not the destination

Offline Plani

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #155 on: July 29, 2017, 03:55:19 PM »
I'm following your build too. That's some truly inspiring machining  :praise2: :praise2: :praise2:
And very interesting set ups  :ThumbsUp: :ThumbsUp: :ThumbsUp:

Plani

Offline Hugh Currin

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #156 on: July 30, 2017, 12:32:02 AM »
There is a limit to the amount of machining possible with my equipment, I do not have the software to do complex 3D machining. I am limited to 2.5D machining ( pockets and contours at differing depths) which leaves plenty of hand finishing with the Dremel and files to get to the final shape.

Mike:

It sure looks good, no matter how much hand finishing is needed. Amazing!

But how do you rough/finish these shapes? George builds a "step off sheet" and does the passes manually. (I don't know how he does, my mind would go numb leading to an error.) Do you pull points off the CAD drawing and hand code? Somehow fool the 2 1/2 D CAM into following the surface? Other? Following your build I thought you were using 3D profiling. Even more amazing if you are using 2 1/2D software.

Thanks.

Hugh
Hugh

Offline Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #157 on: July 30, 2017, 11:58:41 AM »
But how do you rough/finish these shapes? George builds a "step off sheet" and does the passes manually.

How do I produce those shapes? Hugh, That's a bit like starting off with the 64 dollar question, with no gentle build up.

Well some folks enjoy the intellectual challenge of the Times Crossword, I enjoy the challenge of sculpturing aluminium blocks to produce miniature replica engines. Both require a lot of thought and concentration

I am totally committed digital machining in my workshop. All my machines have been converted to CNC and all are now controlled by LinuxCNC. The only 'manual' input I have is the tail-stock hand wheels on my two lathes; and of course the door handle and lighting switches.

I am a long time user of AutoCAD. I do all my drawings in 2D, plan, side and end elevations and numerous cross sections. My 2 1/2D CAM software complements the 2D CAD drawings. There are now some excellent 3D CAD drawing packages and 3D CAM packages available. The are good, very good, but they are expensive; way above my pay scale and ability. Besides I don't think I have enough years left on this planet to become proficient in their use. I will stick with what I have and know how to use.

Consider the CNC lathe or CNC Mill to be a machine with a high accuracy built-in DRO and controlled via a keypad rather than hand wheels, or automatically via the computer. You control the slides and tool position either by manual keyboard input or by computer control. About 60% of my CNC lathe work is by manual input; just like a normal lathe. I jog the tool position from the keyboard rather than turning hand-wheels. The DRO tells me where I am and I can also observe the cutting action. With the CNC Mill only about 10% is manually controlled, the computer is the prime controller.

A 2 1/2D CAM tool-path generating program will produce a 3D shape, however it is limited to creating prismatic shapes i.e. shapes with vertical sides and flat bottoms. This process will be much like George's 'step-off sheet' of instructions. The two most important functions within a 2 1/2D CAM program being contour profiling and pocketing, one simply follows a given contour shape while the other also removes the material from inside the shape. Complex pseudo 3D shapes can be created by machining a successive series of contours or pockets. These tool-paths can be created from a series of drawing inputs or by manual editing (cut and paste) of previous lines of tool-path code.  The 45 degree stepped slope for the cylinder block faces were produced by editing, increasing steps of 0.1" in the Z axis while deducting 0.1" from the X or Y axes.

The CAD drawing is the prime input to the CAM tool-path generating program. The required shape of the pocket or contour is created on the CAD drawing usually by copying part of the drawing and erasing unwanted lines to leave only the desire outline  The outline shape drawing is then transferred to the CAM program which produces the tool-path instructions to machine that shape. The CAM program needs to know the tool diameter, depth and width of cut and the required feed rate. It is normal to add (edit) together several sets of tool-path instructions to create more complex shapes. Manual editing is often required to remove time wasting moves which only machine fresh air.

Wherever possible, I will position the work-piece so that the machining is normal to the face. I use accurate angle plates to alter the angular position of my jig plate to achieve this vertical alignment.

Curved surfaces are much more difficult to produce than prismatic pockets or contours. A ball nose cutter is generally used to produce the smoothest surface. The ball cutter is commanded to move in a series of close spaced contours, like the height contours on a map. Obviously the closer the contour line spacing, the smoother the surface. I aim for ten thou (0.01") separation which requires an enormous amount of contours to be created and then machined. The contour information comes from carefully constructed CAD drawing, the individual contours are processed by the CAM and added (edited) together.  Curved surfaces are very CAD drawing intensive and also require great concentration during the subsequent editing. The potential for small errors is high, so it is always a good idea to do a machining test on a scrap piece of material before you commit to your precious engine. I like to use a block of coloured perpex, plexiglass, or acrylic for the testing. Creating a curved surface tool-path is slow and time consuming, but sometimes this is the only way to produce a part or surface. This is one area where a good 3D drawing package with a STL file output would make life a lot easier.

There are other tricks you can employ. I will sometimes input the wrong tool diameter to subtly alter the size of a hole or pocket produced. If you declare the tool is say 2 thou smaller than it actually is, you will produce a slightly larger diameter hole, ideal when you want to fit a round peg into a round hole with a controlled clearance fit.

As I say in my signature: "It is the journey that matters, not the destination" and for me the challenge of tool-path programming is an important part of that journey.

Mike





« Last Edit: July 30, 2017, 04:59:09 PM by Vixen »
It is the journey that matters, not the destination

Offline Nick_G

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #158 on: July 30, 2017, 12:18:23 PM »
.
These parts and this whole build are beyond awesomely-awesomeness.  :ThumbsUp:  :)

Nick

Offline Stuart

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #159 on: July 30, 2017, 12:20:42 PM »
Mike have you had a look at fusion 360 its free for hobby users and you get the top end package

And yes it's a steep leaning curve it does support Linux CNC

It's a combined cad cam parametric job

Boy that engine is a work of art
My aim is for a accurate part with a good finish

Online steamer

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #160 on: July 30, 2017, 01:41:00 PM »
Great right up Mike!    Love those parts!

Dave
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Damned ijjit!

Offline Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #161 on: July 30, 2017, 04:51:12 PM »
Thanks everybody,

Stuart, I have had a quick look at Fusion 360. I know it is free to students and hobby users. However I decided the 'costs' would be too high.

Firstly I would need to invest in another computer with the latest Windoz OS and all the problems that now brings. Such a move would put me back into the clutches of brother Bill Gates, I prefer to be in control of my own data and my own destiny. Secondly, the learning curve, I would need to dedicate a considerable amount of  time to become proficient in a completely new CAD/CAM system and methodology. In the end, I decided my remaining time would be best spent building engines rather than studying and learning new software. So I will stick with what I already have and have plenty of experience using; it does work after all. Maybe ten years ago, but today it is perhaps too late to restart.

Mike
It is the journey that matters, not the destination

Offline Stuart

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #162 on: July 30, 2017, 05:25:44 PM »
Mike

Ok I forgot you are Linux man , I fully understand , I hate having a windoze pc for the mill but as I wanted to use a smoothsteper and mach4 ( I needed more IO than a parallel port can offer )

But its had so much of the Billy G nanny removed all it will do now is control the mill , so it's not a pic it's a Cnc controller

My fusion 360 runs on a 27 iMac but it's taken me a while to get to grips with it ,but now I can get the part into cad then to cam ok and produce the part I need

You may have Mercedes heritage after the engine when done for display

I am sure it's been asked before but will this be a fully operational engine when completed?

My aim is for a accurate part with a good finish

Offline Vixen

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #163 on: July 30, 2017, 05:46:03 PM »
Stuart,

I sincerely hope the engines will capable of running after all the time spent building them. 

I propose to run the engine on straight Methanol without the nitro-benzine, petroleum ether and acetone additives that the Mercedes chemists mixed up for their racing fuel. I see the two stage supercharger as being a hindrance. Who needs 2.6 bar of boost on a model engine running on the bench? I have consciously increased the clearance gaps in the two Roots blowers to make them less efficient. I am also thinking about breaking in the new engine without a supercharger fitted, just a single carb connected to the inlet pipes. When the engine is running sweetly, then I can add the complication of the blowers. Someone once said ' try only one new idea at a time'

Just thinking aloud

Mike
« Last Edit: July 30, 2017, 06:12:38 PM by Vixen »
It is the journey that matters, not the destination

Offline Stuart

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Re: Mercedes-Benz W165 Grand Prix engine in 1:3 scale
« Reply #164 on: July 30, 2017, 06:35:45 PM »
Thanks Mike for the update
My aim is for a accurate part with a good finish