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

[RReid]

Some of that metal is coming off really hot and flying everywhere; you need long sleeves, otherwise it stings.

Sometimes stink too, when they land in your mustache right under your nose and burn the whiskers. But that's better than when they get caught between your safety glasses and the bridge of your nose. That leads to a "branding".

[crueby]

Some of that metal is coming off really hot and flying everywhere; you need long sleeves, otherwise it stings.

Sometimes stink too, when they land in your mustache right under your nose and burn the whiskers. But that's better than when they get caught between your safety glasses and the bridge of your nose. That leads to a "branding".

This afternoon, after playing in the shop, I had gone outside and sat on the porch. A few minutes later, it felt like a bug was rappelling down from my glasses onto my face - quick swat at it, managed not to destroy my glasses in the ICK response, and found out it was a long thin spiral of shavings from the lathe that had been sitting in my hair and dislodged by the wind! 
 

[kvom]

Long sleeves while operating a lathe?  Not me.

[Vixen]

Long sleeves while operating a lathe?  Not me.

Hi kvom,

That's an interesting comment.

Those of us who live in more northern latitudes can expect to wear long sleeved clothing for nine, maybe ten months of the year. In wintertime, multiple layers of clothing, including over the arms, is quite normal in the workshop. Most of us still have the ten digits we were born with.

Mike

[Admiral_dk]

I thought we where Born with Twenty Digits    though I suppose that you have to drop something heavy or very sharp to loose some off the Lower Ones 

Per

[john mills]

not wearing long sleeves at the lathe seams a bit strange i have usually worn a boiler suit in a machine shop long sleeves would have been a must i did a lot of milling and you would have a lot of burnt arms  i usually put my hands behind my back to avoid hot chips i had a job
in more recently   with heavy turning it only took a few minutes to work out you needed leather gloves to cover your hands or your hands got burnt. larger hot swarf would land on your hands and would burn but normally don't need to wear gloves.they only trap swarf on your wrists.
  factories often now have signs saying do not wear gloves at machines usually by people how have not actually done machining.
john

[Vixen]

It's cool enough, in the morning, to wear long sleeves again. So much nicer than getting hot swarf burns on the arms.

I'm making steady progress with machining of the built-up crankshaft segments. Fourteen of the sixteen are now complete. Should be finished with that opp by the weekend. Then, it's profiling the outside of all the balance weights and drilling holes for the location dowels.

The next two photos show the crankshaft segments in loose formation with the crank pins positioned in-line with each other. When the crank pins are eventually be pinned and bolted together, there will be 90 degree intervals between the crank pins.






Each crankshaft segment was bolted to the faceplate by a single, central, M5 bolt and so, is reliant on friction. The M5 bolt is pulled up real tight. As you see, the big end journal has a significant offset from the centre of the disc (main bearing). There is plenty of interrupted cuts at the beginning of each pass, before the big end journal is reached. The interrupted cut, together with the single point mounting dictates relatively shallow depths of cut, but the feeds and speeds can still be acceptably high. It is far better to be conservative with the depth of cut, even though it takes longer, than to risk a 'dig-in' or dislodging the crankshaft segment. My Colchester Chipmaster is quite capable of some really heroic, monster, cuts and fast metal removal, but not this time round.




I started with a new box of 10 lathe tips, in anticipation of a high usage rate due to the interrupted cut. The first couple of tips did not last long before they chipped. The third tip from the same box of 10, lasted and lasted; with little sign of wear or chipping. I cannot explain why, the feeds and speeds and DOC were identical for all the segments and the tips all came out of the same box. Different batches perhaps? or uncertain Chinese quality control?

Mike

[steamer]

It's certainly getting there!   Keep digging Mike, the end is in site!

I found at this point, that the lathe fixture is delicate.   Any bump, and the face will run out,    Keep checking it for face runout, and don't be afraid to take the thinnest of facing cuts to true it up between parts...


Dave

[Admiral_dk]

Great progress Mike - you can really start to see where this (Crank) is going 

I do not see any through hole in the 'Pin Area' - will this be a later addition, with another setup or ..?

Per

[Vixen]

Dave and Per, thanks for calling in, a little encouragement is always welcome.

Dave, that's a very good idea to re-face the faceplate before mounting the next part; that would eliminate any anxieties about run-out, etc. I wish I had been doing that earlier.   

Per, the threaded half of the segments are threaded blind and do not show, only the socket head in the opposite half shows, but will be hidden from view by the roller bearings and the con rods. The holes for the alignment pins (dowels) are yet to be drilled. I cannot do that on the lathe set-up. The crankshaft segments will be coordinate drilled on the mill. I will only drill one side, the two halves of each crankshaft joint will then be jig aligned, the central bolt tightened, before the alignment pin holes are drilled through and reamed to achieve the final size for the pin/dowel.

I am not sure if I explained that very clearly. I should reveal itself later

Cheers

Mike

[steamer]

What I did was check the face of the fixture before and after I cut a part...and I skimmed it if it needed it... ( I wanted less than 0.0005" run out)

As long as the zero repeats that the least run out I was going to obtain....that's all she wrote...and it was pushing my SB to the limit...I have a plain bearing headstock and while spindle float is small, it's far from zero and dances around .0005" axial.   Radially, if I can get at least 100 rpm it lifts about .0007" but stays put.      A ball/roller  bearing headstock shouldn't do that....

Dave

[Vixen]

Hello Dave,

Sounds like you know SB better than the back of your hand.

They say the accuracy of any part depends on the intrinsic accuracy of the machine, multiplied by the skill of the machinist. Skill can go some way to make up for some of the machines deficiencies.

You also need to allow for the fact that lathes rarely turn truly flat flat faces, they are most often ever so slightly dished.

You can only do your best with the equipment to hand.

Enjoy your week off

Mike

[steamer]

"You also need to allow for the fact that lathes rarely turn truly flat flat faces, they are most often ever so slightly dished.".004


.0004" at 6" diameter....concave of course.....

Funny thing is....this year marks 10 years since the rebuild, so I did some alignment checks to see where things have gone.....far as I can tell....they haven't budged a bit!

[Vixen]

Hello Dave,

So, how do you measure 0.0004" at 6 inches.
 Concave... of course.
If you stamp your feet down hard you can get bigger readings than that. 

Mike

[Admiral_dk]

Concave... of course.

I needed to think a bit about that statement ....
I suppose that the reason is that the Holder for cutting Edge isn't so easily Deflected closer to the Centre, as further away .... 

Per