Final assembly and test of the spindle nose adaptor - RESULT!!

After the recent distraction caused by the 3D scanner, resurrecting the 3D printer and buggering about with the throttle bodies for my Honda S800 engine, the spindle nose adaptor has seen no action.

On the face of it, there should be little more left than to assemble the parts and test the runout. The big, big question is - is the runout remotely acceptable? I will be more than just slightly pissed off if there's any noticeable runout after all the time and care I've put into this thing. 

Last time round, I was preparing to finish machine the taper and face while mounted in place on the lathe spindle. Here's what happened.

Finish machining:

Let's go Fatty.

Phew - no cockups yet. We will leave it there:

There's a slight burr at the join of the taper and the face that fouls the register on the chuck backplate. I manually machined that off:

Now the face needs to be skimmed back, as there is still a rattle fit on the taper. How much? Plastigauge to the rescue. The taper is 7.125 degrees, so each mm of reduction in the radius of the taper will result in an 8mm needing to be removed from the axial position of the face, since Tan(7.125) = 1/8. I ensured the gap was on the Plastgauge side when squashing the backplate up against the spindle tape, so the 150um represents the total diametric gap.

With a radial gap of 150um/2 = 75um, I need to skim the face about 0.6mm axially (=75um x 8). Perhaps a bit more than I'd planned but there's not much I can do. Obvs if that gap were too big, I'd find problems getting the cams to tighten up...

How's that looking?

Really rather good!

There. Job done. Good tight fit on the taper and no cockups along the way.

What about the runout?

The next (final?) step is to do the final assembly and check the runout. Firstly, the grubs screws that hold the cams need to be ground back a little. Skimming 0.6mm off the face of the adaptor has made them stick out slightly proud of the adap[tor body so that the chuck can't sit flush. A quick spell on the belt sand does the trick

The Multisize collet chuck is probably the most accurate chuck I have, so let's use it to do a proper runout test. This is the internal taper that the collets locate against. The runout barely registers on this 10um DTI, so is of the order of 1um or so and most of this is surface roughness rather than actual runout.

And here's the proof:

I think we can call that a success. Thank fuck for that. And woohoo - I've actually finished a job for once in my life!