Suggestions on milling large hole

[metalworkz]

Hi guys,
I have a 2" cube I need to machine a 1.125" dia. hole thru and was wondering what would be the best way to trap the slug to avoid binding on the tool as it cuts free. I plan on just milling a slot around the perimeter to cut down the machining time and thought maybe I can pin or trap the center slug so it won't come lose and bind on the tool? Any suggestions on a good way to do this? I figured I would just drill a hole in the center and pin the block to trap the center slug. Thanks for any advice.
Regards,

[VWSatOz]

It wont bind on the tool anyway, the lump will just sit there! The problem will be if you try to use a small cutter say 1/4" diam that the cutter will be too long & flimsy to go through 2" thick (if milling steel), you would have to flip the block & come from both sides
Its best just to use a 16mm cutter with short flute length & slightly necked down shank so it can't rub (if on a real mill that can handle a 16mm cutter)

[cam1]

Hmmm, drill first with the biggest drill you have.....then mill.

regards

[kbarratt]

I would suggest corkscrew milling. This is great for blind holes as well. Use a good Indexable Insert end mill, with the ability to ramp down, as it does circular interpolation, like a cork screw spiral. No slugs to worry about, no starting hole needed, and it works great with blind holes as well.
I use a cutter that's not more than 7/8 of the finish hole size to allow for chip vacating.
3/4" Iscar Helimill, or Multimaster wold work well, providing it has the capacity for the depth you need.

http://www.iscar.com/Ecat/item.asp/a...100402/lang/EN

[metalworkz]

Thanks for the suggestions and advice! I will probably try a variation of the methods offered here.
Regards,