to drill rocker shafts (1/8). got a carbide drill bit ($5) & just started on it for a minute & the bit wants to skid off of the curved surface so I may have to file a very small flat to get it started but I'm wondering if it is going to be hard enough to do the job. your thoughts please.

Was it from an industrial store? or from a homedepot/lowes? A true tungsten carbide bit will be hard enough, a plated one may not. You may need a starter bit to get you going.
https://en.wikipedia.org/wiki/Drill_bit#/media/File:CenterDrills123456.jpg

I'm thinking it was an "Irwin" in a yellow blister pack from a true value hardware store. there is a graingers close by if need be. EDIT tomorrow I will try a mini bit to get a hole started if it will start the hole

Beriliaum(sp) bit.. super hard... hope you doing
it in a mill... also a small center bit

mini drill press/drill press vise/shaft wrapped/clamped in a rag

The shafts are probably nothing special, just thicker for strength. Chrome moly - no big deal to drill through. But you do have to get it dead nuts centered on the shaft.

That's what I needed to hear!

Mcmaster Carr will have what you need in about 3 days....put the Irwin back so you have it for your dishwasher...

McMaster-Carr, the toy store for men.

Center punching where you wan to drill is a REALLY good idea on round material. When I drill round I center punch then I let the vice float on the drill press bed in case I'm off a fraction - the vice will move so the bit is centered into the punch.

Use a good solid clamp, and Hanson bit, and who ever is making the MAC bits are great.

Also since a rocker shaft is harder than typical steel use slow speeds and cutting oil, but you probably already know that.

The rag isn't helping, use alum spacer blocks, if marking the steel rocker shafts is your concern.

Use V blocks if you have or can get them, center drill first, then good cobalt drill & use oil/coolant.

Ive had great luck in the past using a smaller piece of angle iron welded to a heavy flat that you can vice into the bed of the drill press, then you can use another clamp and hold the shaft into the valley. once you get one hole drilled you can drill through and put a bolt in that hole to keep the shaft the same.

I'm gonna get after it today. this is the last fabbing needed on this 360. thanks guys!

Have you tried centerpunching it to get a location and prevent the bit from skidding around? That's a good way of getting an idea of hardness. If you can't get a centerpunch mark in it, you may have a tough time getting a drill bit through it. Is the shaft hard chromed?

I had to go to 3/8 from 5/16 on a set once and couldn't touch them with a bit, Needed to go to a machine shop and drop a 25/64' end mill through them then chamfer with a die grinder.

Cobalt from Grainger item# 1G865

Carbide is the chit. careful on 'breakthrough'!

A nice carbide ball endmill is great if you happen to have a boss like mine?

Colbalt probably wont do too well, carbide to get through the hardened outer surface.