Milling bit question

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Avolow

Active Member
Hey all,

Couldn't find a better spot for this question, so here it is.



I have been looking over milling machine bits most of the morning and cant seem to find one that I think will do what I am looking to do.

33FX52_AW01[1].jpg

I want to make the lightsaber control boxes and "T" track for the grips on some of my projects out of different materials. Brass, copper, aluminum, plastic, etc. Milling the "T" is simple enough, I have the required bits for that. What I am looking for is some type of ball end bit that will leave a rounded cut in the base of it to conform to the 1 1/2 inch hilts I will be attaching it to. The largest shank my machine will handle is a half inch. Does anyone here know what I am looking for? What specifications am I looking at for the cut I want? I guess I am missing something when I look at the Technical Specs.

Example specs of the one I copied the picture above from.


  • Length of Cut3/4" = Am I understanding this as more or less the depth of cut? The distance from the tip to the point up the shaft were the cutting edge stops?
  • Overall Length2-1/4" = Pretty sure I got this one. :p
  • Number of Flutes2 = I get this one too.
  • Cutting Type - Center = I get this one too.
  • Cutting Direction - Right Hand = I get this one too.
  • Helix Angle35 Degrees = This is the one I am confused on. Is this the one I am looking for? The arc of cut on he ball end? If this is, what would the correct degree be to leave the cut I am looking for?

Avolow.
 

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SmilingOtter

Master Member
Everything you posted sounds right.

Standard end mills are offered with helix angles as low as 15° to as high as 60° angles. General-purpose end mills are generally around 30°. Any increase in the helix angle increases the effective shearing action thus reducing cutting forces and the amount of heat generated during the milling process. Chip ejection is also improved. Lower helix angle end mills are used on more difficult to machine materials where maximum edge strength and rigidity are important. With straight flutes the load builds up almost instantaneously, making the end mills prone to self excited chatter. With helix angles, chip load is applied to the entire flute length in a progressive siding action similar to that of a snowplow with its blade angled off to one side. This makes the cutting forces much more constant with less chance for chatter. End mills with a higher helix also tend to produce much better work piece finishes. The 50° and higher helix angles significantly reduce side loading on the mill making it possible to periphery mill thin wall sections with much less deflection.
 

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