Friday, November 1, 2013

R-8 End Mill Holders

In my recent raids on the scrap bin at work, I found several R-8 shank blanks.  These are for making your own custom tool holders to go in the milling machine.  Since I only bought collets to hold 3/8" and 1/2" tools for my machine, this is the perfect opportunity to make holders for the other sizes as well as other things like slitting saw arbors and boring head adapters.  No sense leaving them all sit around looking like pepper grinders.

This first one is going to be a 5/8".  I indicated it in a 4-jaw chuck because the machine shop at school didn't have the right size 5-C collet to hold the .950" diameter. 
After facing, I center drilled, pilot drilled, and then drilled it with a 9/16" drill.  I had made the mistake of drilling the set screw hole in the side beforehand, so the 9/16" drill kept wanting to wander when going through it. 
I was able to correct the drill's runout when boring the hole.  This step was important because it made the hole run true, and that will affect how true the tool runs in the milling machine.  After boring the hole to .610" I reamed it with a 5/8" reamer.
Afterwards I turned down the excess material to give it more clearance.
I then took it to the mill to re-chamfer the set screw hole, I think I overdid it a bit, but nonetheless, there is still ample thread to hold the set screw.
Here it is holding a 5/8" shank end mill in the mill.
In other news, it looks like the Covenant invaded the shop and had a lathe accident... I knew those alien bastards couldn't handle our primitive technology.  I don't know how the Elites could've turned the handles with fingers that long...
Update
I made a couple more; one for 3/4" and another for 7/8" as well as a boring head adapter.  Up next: an arbor for a massive circular saw blade.

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