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

[Michael S.]

4 months break isn't that bad. The main thing is that you're feeling well again and having fun in the workshop.
I'm looking forward to more pictures of the progress.

Greetings Michael

[Kim]

Glad to see you're feeling up to doing some work out in the shop!  Hope you continue on the upward trajectory! 

The cam box covers are coming along beautifully!  And I can't believe that you program all your tool paths yourself!  That is quite a feat on its own right there.  Nicely done! 

Kim

[Admiral_dk]

As already mentioned by others - Great progress as usual Mike 

One of my immediate thoughts - didn't I come across a DOS G-Code Editor years ago that had a function that could Mirror an existing Tool-Path .... 
That could potentially have saved you quite a bit of work ....

Looking forward to the next instalment from Vixens Den 

Per         

[Laurentic]

Wow! 

The thought processes you went through to achieve that are worth a bucket load of wows on their own, never mind getting out there and doing it, producing a wonderful set of results, whilst feeling a bit crook all the while.

Await the next installment in eager anticipation.

Chris 

[fumopuc]

Hi Mike,
very good to see fresh swarf at your mill again.
Virtual work or CAM preparation is one thing, but to hear the roaring spindle again is another one.

[Vixen]

Thank you all for calling in and providing that much needed boost and encouragement. I must admit that is the one thing I missed during my summer long lay-off.   

Per, that DOS CAM program you mentioned, which produced mirrored tool paths would have saved a lot of time. There is nothing much wrong with ancient DOS programs. They all needed to be well structured to work with the minimum of computer resources. No space for Mr Microsoft's bloatware. I can still run legacy DOS software on my Win XP machines. Actually, one of the main reasons for creating all those tool path programs by hand, was a mental exercise for the mind and help drive out that dreaded brain fog.

Back to the cam box covers. Before I could make a start on the outer surfaces, I needed to make up a jig plate on which I could position and secure the individual cam box covers. The jig plate was secured in the machine vice, on parallels as before. I used the top left corner as my X0, Y0 datum, so that I could easily reestablish my machining Datum whenever needed.

The 6dia 2R corner radius cutter has very limited chip clearance space between the flutes, which governs the material removal rate and feedrate. If you are too aggressive with the feedrate, the small chip clearance space clogs with compacted chips and the job grinds to a halt. As there was a fair amount of material to remove from the stock bar I decided to rough out the outer shape to within 1mm of the finished size with a two flute 9mm dia end mill. The clearance space in a two flute cutter is huge by comparison, so I was able to indulge in some MMR (Massive Metal Removal). 5000 RPM 240 mm/min feedrate and 40% step-over. As Achim says, there is nothing like hearing the roaring spindle and watching that rooster tail of chips flying away. Look how high the chip pile in the corner as become, I had to remove a bucket full of chips before proceeding






Below you can see a 3D representation of my stack of 2D contours for machining the outer surfaces. This is from the tool path display on my Linux CNC controller. The DRO display indicates the actual tool position. I had endeavored to make each of the 27 facets identical in width (appox 0.8mm) so the contour depth increments were very small at the top and much larger on the sides.




Here you can see the first four covers after machining the outer surfaces. You can see the jig plate secured in the vice and how the bottom flange profile and the cover bolt holes are sudden revealed. The wall thickness of the shell is now only 1.5mm so I was very relieved when there were no unwanted holes or breakthroughs. You have to learn to trust yourself and your drawings. See how evenly spaced the surface facets are. They are very shallow and will be removed with a fine tooth file and wet-n-dry paper before being polished at a later date. But that can wait.






Hopefully I will be able to add the concluding installment tomorrow.

Stay Tuned

Mike   

[Kim]

That's a long haul to carve out all 8 of those!  You are coming along nicely though, Mike! 

Kim

[RReid]

Hi Mike,

It's clear that you put your enforced "quiet time" to some very good use. I can well imagine all the thought, planning, and coding that lies behind those nice pictures and your interesting description of the process. Even unfinished the cam box covers are lovely to look at!

[Art K]

Mike,
I am glad to hear that you are feeling better! You are also back to your usual high standard of work.
Art

[Vixen]

The basic machining of all eight cam box covers is now complete. I am pleased with the way they turned out, although there is still a lot of handwork required to smooth the outer surface. That will be a good indoors job during the cold of winter. I need to work out a way to do the end flanges. The cam box covers are too tall to stand vertically under the milling machine spindle. So, I may need to think about hand filing the outline shape to a steel template, the template could be accurately machined on the mill.

Below, you can see the details of both ends of a typical cam box cover. Each machined facet is approx 0.8mm wide. You can also see how each of the cover mounting holes has been spot faced.







Here you can see the 8 cam box covers on parade after they had been parted off from the stock. The thickness of the shell is a mere 1.5mm and all eight covers weigh in at 345grams. 345 grams from a starting point of 3.5kg of stock: wow, that's a lot of chips. I had considered other ways to make them. 3D metal printing perhaps, or 3D plastic printing of casting patterns?  Casting would have required four different  patterns, finding a paying for a foundry followed by post machining. On balance, machining from solid was probably the quickest, least expensive and most accurate option.




A final sanity check. Yes I have two pairs of mirror imaged long covers and two pairs on short covers.        Time to pipe 'Up spirits'




This is how the cam box covers will look when all the work is completed.




Thank you all for your company on this part of a very long journey.

Cheers   

Mike

[wagnmkr]

That is a wonderful result. Detail to the nth degree. These two engines will be a total work of art when they are done.

 

Tom

[Admiral_dk]

Even unfinished - they look amazing 

If it ends up being a 'Hand-Job' doing that - I'm sure you are up to the task Mike ....
It will just take time 

Per     

[Roger B]

Excellent     

[Laurentic]

 Beautiful work Mike, absolutely!

Chris   

[Jasonb]

Looking good Mike and good to know you are getting to use the Sorotec fluid.

Are the end flanges much as the marker pen on the ends? I would have thought they could be done in the same way as the other profiles with a series of toolpaths. I know it will be longer for you than just a contour if they were stood on end but it would get you as close as you are with the rest of the covers? Apart from the two lugs it looks to be just a larger version of a cross section through the covers.

You could do with a 90degree spindle adaptor then the CNC could do them like a horizontal borer moving mostly in X and Z around the profile.