Ok so looking to take some old molds I got and drill them out a bit to make them plain based instead of gas checked. Basically it's just going form a narrow hole to a wide one. Saw some pics online about using a drill press but curious about how you should go about making sure you got you bit perfectly centered so you don't have a cockeyed hole. Tips ? Tricks ? Thanks

If you had a go plug or drill the size of the mold you could chuck it and center it that way, without doing a bunch of math hope your bit is ground center and use it to align.

Hmmm that's makes sense, was also thinking a pin gauge might work too

Yup, actually that’s what I was thinking of and all I could come up with was the go plug.

if you don't have a perfectly sized pin or bit to align it, you could put a tapered center punch in the chuck and lower until the taper guides the mold into place.

On a different topic: Your pictures reminded me of another trick I've done. When I have a sticky mold, I take a few bullets from that mold and coat them with car polish. Then put them in the mold and drill a small pilot hole into the lead. Put a drywall screw into the pilot hole. When the screw gets tight, it will spin the bullet. A phillips bit in a drill press works great for holding it straight and maintaing a small amount of down pressure so the bit doesn't skip in the screw.

You got to hold your mouth just right.....

Lazer works great.

When you think its all lined up, lower the bit slowly, not running. When it contacts what you are drilling, look for any side to side deflection in the bit, from various angles. This might not be as obvious with larger bits. Its a trick we use when drilling the pin holes for barrel pins in flintlocks.

Like said above, something the same dia, then chuck that. Then replace with bit.

Gotta stick your tongue out JUST far enough.....

A quick and easy way to center up an existing hole in the press or mill is to machine grind a cone shape point on a hardened dowel or something similar, chuck that up in the press, and just drop it on the hole, then clamp the part down. I hope you can visualize what I'm saying. Big Bob

Put an old t shirt on it to fill the void that is in fact there, drill not running, push into hole and start the motor, the shirt will spin so better just use a piece of it.