They were a piece of piss to fit. The only vague challenge was removing the large internal circlip ("snap ring" to our Mercan cousins). My only proper internal circlip pliers are too small, so I used a pair of long nosed ("snipe nosed"?) pliers with a ground end to prevent the jaws slipping off the compressed circlip.
What you can't see unless you look closely is that I've tapped the 3 fixing holes in the cast bearing housing. The holes were M8 clear and I've tapped them M10. That way I can extract them from above by screwing three M10 bolts into the holes. As noted previously, they are almost impossible to remove unless you knock them up from below. Good thing I did this, as I needed to countersink one of the holes not long after I'd pushed it home the first time....
Before:
After:
The sensors also arrived today - from CPC. Pretty much as expected, physically speaking. No chance (or point) testing them quite yet, so I will only find out if the whole plan will work once they are mounted and powered up.
The Stupid Fat Bloke appeared in the workshop at this point, like a bad penny. He's been in before quite a few times and almost without exception he comes up with really stupid ideas that don't work and simply cost time and sorely try your patience. This time he suggested drilling out the two top holes (for the M6 screws) and simply fitting a couple of captive "clinchnut" inserts. Sure enough, I have loads of these including some in M6 size. You just drill out the hole to 9.5mm dia and rivet the insert in place. Or if you don't have the correct setting tool, you can just squash it in using the vise.
So I drilled out the holes just as The Stupid Fat Bloke suggested. It all looked pretty simple and straightforward until I pointed out that the insert would have to be on the wrong side of the bracket. I want to be able to adjust the position of the sensors from outside, through the access hole. Duh. Obviously at this point I told The Stupid Fat Bloke to fuck off out of my workshop but I know he'll be back before long.
Now I was stuck with a couple of oversized holes. The CNC Gods smiled at me at this point as I spotted that the metal inserts in the sensors were 7mm ID, so could possibly be tapped M8 if I was careful. Sure enough, after 10 minutes or so buggering about with some M8 hand taps, I had a result.
As mentioned above, I twigged at this point that I'd need to remove the gear assembly and replace the LH of the three screws with a countersunk one, to prevent the bolt head from interfering with the sensors. So in with three M10 bolts to drive the assembly up and out of the quill bore. A bit fiddly but a lot easier than the first time.
I only have a 1/2" (12.5mm) dia countersink tool and the std M10 CSK head is a fair bit bigger than that, so I had to turn down a CSK bolt. Easy enough in the lathe. The photo is upside down but you can make out the "CCET" insert I used. Gave a superb finish - better than the mystery stainless steel I used for the ISO40 toolholder extension last week.
Job done - just the ticket:
So now the output gear assembly is refitted finally. New bearings and countersunk fixing bolt:
Next, drill and tap the 2 fixings for the bracket. First drill, then vacuum up the swarf:
I generally tap using a cordless drill driver but there's not enough room to get the chuck in there and drill / tap a hole that is remotely perpendicular to the surface. So it was manual tapping here (M5, with a slightly oversize 4mm tapping drill):
There you are. Sensors mounted on bracket, bracket mounted on head. The sensors appear to be roughly where they should be, with room to adjust both the angle and the gap.
That'll do for now. Next - dig out a PSU and scope and see if they actually behave themselves. That'll be the moment of truth....
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