Got a bit of mapping and drawing done this eve,
Im making a cover for the E34 M5 diff as mentioned. The original cover wont mount to subframe, so given the price off Bmw(380euro) Ill mill my own.
Below is where I started mapping the holes for the new cover. They are pretty important that they are right in the new milled part, so that it bolts up to diff clean.
You could measure the holes with a calipers, and a divider and plot on paper, but having the cnc makes this easier, and more exact.
Ill try explain how its done incase anyone is interested, or thinking of dipping a toe into cnc land soon.
I remember being the same years ago, thinking cncs were mental, and impossible,- but they are actually pretty simple when you get to know them.
Bolted diff to table square.
Fitted a 12mm round over bit. Set mill in center of case approximately and zero'd all axis.
The pictures are a bit crap as Im just getting to know new phone.
Anyone doing this lsd conversion can skip this step and go buy an E39 M5 diff cover off Bmw like a normal person would.
Bolted to table,
All axis zero'd approx in the middle of diff,
New drawing opened, where the cursor is, where x and y lines meet, is 0,0 and since I zero'd all axis, thats now where the bit is too, on the table,
The correct number of circles(holes) are drawn in in roughly the correct position,
The mill is now moved with the jog buttons to all the hole locations on the diff and their coordinates noted, and transferred to drawing. Once you transfer, the circle moves to a new location where the actual hole is on the diff, and where the bit is sitting, this is done for all holes, 'mapping' them exactly onto the new part drawing - as below,
Bit moved to hole position,
Note coordinates, ignoring the z thats the up and down,
Over to drawing, select that circle,
Click coordinates box, and fill in the coordinates from mill screen above,
Circle moves to new position,
This is done with all holes, and all datum points I needed,
Completed hole locations, now on new drawing,
Onto finding the axle center line. Straight edge held to edge of holes, and touched off with pointer in mill,
Y position noted on mill, and then transferred to drawing,
Since the inner diameter of flange hole(!) is 100mm, taking 50mm off that measurement and drawing another line give me the center line of shafts.
There are more accurate ways of doing this with a dial gauge, but its accurate enough considering where it is,
Then more of the same, finding the other datum points, and case edges,
Thats the basic outline down now, complete with hard measurements of where it needs to bolt to.
The rest, is pretty easy, I need to yet draw in the two hanger points(see E39 diff below) And put some proper shapes and profiles on the drawing before I can mill,
You can see the complete E39 diff below(smaller that M5 diff) and also the difference in the rear covers - the E34 M5 cover is 25mm higher than my diff/cover - which is why I need to make another one!
The billet cover will look something like the one below, but taller to cover the diff I just mapped above.
Its actually easier to do all this, than describe it, LOL,
More as it happens!