Which tool to countersink groove?

[Sportandmiah]

I'm looking to cut a countersunk groove, 1/2 inch in length. The goal is for a 2-56 flathead screw to do two things: be flush when screwed in, and when loosened, be able to travel the length of the 1/2 inch for adjustment purposes. I tried a ball endmill but the screws, although sat flush, didn't sit well due to the ball curve of the cutter. Which type of end mill should I use? Is there a certain term for this type of cutter? Here's a couple pics of my first attempt with ball end cutter:

[websterz]

A 60* countersink would do a good job in light material. I have done it before with good results. Take a light cut and feed slowly, make 2 or 3 passes if you need to.

Where did you get the scale in your pics? I would love to have one like that!!

[dp]

A 60* countersink would do a good job in light material. I have done it before with good results. Take a light cut and feed slowly, make 2 or 3 passes if you need to.

Where did you get the scale in your pics? I would love to have one like that!!

Agree on the countersink, and google Incra Marking Rules.

[Lew Hartswick]

I think (THINK) they do make 82deg V milling cutters. OR use a
90 deg one and buy 90 deg flat head screws.
...lew...

[lane]

After you cut the slot ,Just cut the angle for the screw head with a standard 82؛ single flute counter sink. A counter sink will mill too in case you did not know.

[Patch]

I'm looking to cut a countersunk groove, 1/2 inch in length. The goal is for a 2-56 flathead screw to do two things: be flush when screwed in, and when loosened, be able to travel the length of the 1/2 inch for adjustment purposes. I tried a ball endmill but the screws, although sat flush, didn't sit well due to the ball curve of the cutter. Which type of end mill should I use? Is there a certain term for this type of cutter? Here's a couple pics of my first attempt with ball end cutter:

I suppose you're probably working with what you have on-hand (slotted screw).

Have you given any thought to using 2-56 flat pan screws?

http://ecx.images-amazon.com/images/I/21TkGX1wrXL._SL500_AA249_PIcountsize-10,TopRight,0,0_AA249_SH20_.jpg

They be slotted heads that could be face cut to desired thickness.
Use a standard end mill the dia. of the head(screw) and mill in the small recess needed to the length of your slot.
Better holding and securing characteristics while still giving you dimensional adjustment.

[Sportandmiah]

A 60* countersink would do a good job in light material. I have done it before with good results. Take a light cut and feed slowly, make 2 or 3 passes if you need to.

Where did you get the scale in your pics? I would love to have one like that!!

I bought it at a local Sears Hardware store for $12.00, it's in their small machinist section.

[Sportandmiah]

Thanks for the responses guys. I bought some better screws, still flathead but hex and phillips head, the other day from smallparts.com. I will try the pan screws as well...good idea! I attempted another set of cuts with a countersink/starter drill, but had terrible results. I'll purchase the proper end mill this week. Does the amount of flutes matter? Would I be better off with 0 flutes or 1-4 flutes?

[JoeFin]

Looks like aluminum - I would be using a 2 flute champher mill or 90 deg spot drill to champher the relief you are looking for

[JMS6449]

Just Use A 82 Degree Countersink Which Is The Correct Included Angle To Match Screw Head. Countersinks Cut Rotary, They Will Slot With No Problems, If Correct Speed And Feed Are Used.

[The Fixer]

Hmmmmm using a countersink to countersink..........Who'da thunk it!!!
Sorry guys, sometimes the rocket science that gets offered up here for simple tasks is a bit over the top. I'm a big fan of the KISS principle ....keep it simple silly! So for me using a 82 degree countersink to countersink your piece seems pretty simple....
Just my .02

[JMS6449]

That was the point of my post

[Sportandmiah]

Hmmmmm using a countersink to countersink..........Who'da thunk it!!!
Sorry guys, sometimes the rocket science that gets offered up here for simple tasks is a bit over the top. I'm a big fan of the KISS principle ....keep it simple silly! So for me using a 82 degree countersink to countersink your piece seems pretty simple....
Just my .02

Ummm...what?

To everyone else, thank you for your help.