Drilling rocker spindles.

Has anyone drilled the current replacement Andover Norton rocker spindles ? (To eliminate the overhead rocker oil line)
I don't mind a challenge but these seem hard all the way, even a ARTU drill failed starting down the drilled bore (it wouldn't start) as did a cobalt drill.

A test on an old spindle starting down the bore worked fine with a basic HSS drill.
Admit defeat before even starting ?

I even watched the JC video again but even with that fresh charge of optimism, not a microscopic swarf to be seen.
Spark eroding them seems a little over the top.

I think I just answered my own query by trying another 40 plus year old spindle.
Immediate swarf so only externally case hardened.

I it was discussed is using a stone to soften the center of the spindle end?

accessnorton.com/NortonCommando/drilling-a-rocker-shaft.21023/

I found the Venhill cross over hose (I might be needing it)

The problem here (it seems) is the spindle end is ground (or a carbide milling cutter in the JC video) to get below the case hardening for when the drill gets to that area.
These are hard even at the base of the bore where the drilling operation starts, even if you were to start from the outer end (and it is surface hardening) you would have to get through that area at the bottom of the oil passage/bore risking a drill breakage. .

The HSS drill that would not even start on the new spindle had no problem on the old and there is no easy way to get to that area with carbide.
The fact that a ARTU/USA drill failed was a surprise, that is what I used to drill the hard all the way Moto Guzzi crankshaft.

Send The Man a pm, I am sure he has solved this one.

I put that one to bed after smoking another ARTU. http://www.artu.com/
The bad juju is the now detached tip is in the new spindle bore (Lucky I have 8)

I will fit as is new spindles and look at getting those ones done via EDM later.

I have used the masonry (Artu) drills in similar cases, but I had to relieve the back angle a bit and make a better point to get it to bite.
Carbide should work, it's harder than any case hardening I've seen.

Jaydee

Even with the old spindles you need to grind through approx 1/16" thickness of hardening on the end. If you grind a groove so the groove only cuts into the tapered sides you don't lose any effective length of the spindle. Start your drill from the outside of the spindle (not the inside).

Its a new day, I gave up on that but thanks for the replies.

The reason JC starts the drilling (video) in the already drilled oil passage is the bottom is soft (It also guides the drill) where you start, even a cheap HSS hardware store drill had no problem (as per the picture up the page)
The only hard material part (case hardened exterior) is when you get close to the end.

Even a mighty ARTU drill would not start down the hole of these new spindles, (Not a ARTU / HSS / Cobalt) it is like the whole spindle is hardened (surface or otherwise unlike the original spindles which are only hard where you see externally)

I even used a carbide ball end to put a crater in the new spindle end and nothing I have would start at the bottom of that crater drilling wise.
The catch perhaps is even if you could drill from the outer end you still have to get through the section breaking through into the oil passage which seems to be very hard also.

I might have one more go at them then give up (so I can finish the head and get the engine etc back in the frame)
I will set up a stone and mill grind the outer end this time to see if I can find softer material.

Here is a stock 40+ year old spindle which I managed to drill from the inside out without grinding the end.
I guess it does not pay to count the eggs before you have drilled the actual chicken.

jseng1 said:

Even with the old spindles you need to grind through approx 1/16" thickness of hardening on the end. If you grind a groove so the groove only cuts into the tapered sides you don't lose any effective length of the spindle. Start your drill from the outside of the spindle (not the inside).

Click to expand...

I couldn't let it beat me so rode the 140 km return trip to the city for solid carbide cutters and drilled from the outside.

1.3 mm deep with the cutter was enough to get a start (centre drill) and the drilling from there was easier than the old part, it was hard breaking through to the existing drilling though and took two drills to do so. (Maybe I hit part of the broken off ARTU tip doing so)

To drill through hard steel you could use a mason master drill. You'll need a green grinding wheel to sharped the carbide tip from negative to positive. You'll find it'll go through almost anything and remember to use a good cutting fluid/grease.
Dave

cash said:

To drill through hard steel you could use a mason master drill. You'll need a green grinding wheel to sharped the carbide tip from negative to positive. You'll find it'll go through almost anything and remember to use a good cutting fluid/grease.
Dave

Click to expand...

Thanks for the reply DT.
I got two drilled and they are now in this engine, the next pair I did went fine drilling easily with a HSS drill through the core but stopped dead once it got to the hard area in the middle of the pin (the transition into the existing oil passage)
I can not (or am afraid) to use a tipped drill that might detach inside the pin (as the purpose made ARTU drill did)

Next time I am in the city I will get/look for a carbide 1/8" slot drill/milling cutter as I used to get through the case hardening and use that to get through the last mm's.

The old pins (as a test) were a doodle compared to these modern versions (which are softer internally than the 1970's pins/spindles)
I will start on another (or two) engine/s next week.

Maybe just me but this seems like an awful lot of trouble to eliminate one small oil line for cosmetic reasons?

Tornado said:

Maybe just me but this seems like an awful lot of trouble to eliminate one small oil line for cosmetic reasons?

Click to expand...

Its an easy job but these new spindles are hard at the base of the bore unlike the originals and simply wondered if anyone had drilled these new spindles (not the original type which are a doodle)
It was a 5 minute job to do an old spindle and that was with a hardware store HSS drill.

The reason for doing it in my case is it allows an uncluttered take off point for an oil pressure gauge., maybe using the Venhill cross over hose.

The machined gauge mount will attach under the top triple clamp and the oil will flow through the mount itself to get to the gauge.