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Endmill set screw specs?

Mud

Diamond
Joined
May 20, 2002
Location
South Central PA
ISTR this posted here long ago, but can't find anything about it. Are there industry standard specs for the chamfer dimensions on the bottom of the set screws that retain endmills in side lock holders? I know they touch the sides of the notch before they contact the bottom, but by how much?
Many holder manufacturers offer replacement screws, but at an exorbitant price and special order from the factory only which is a PITA.
Used holders even in good condition often have oddball or hand shortened setscrews in them, and it's such an easy thing to fix if you know what to do.
Alternatively, does anyone have the notch specs?
 
The Weldon flat is much wider than the set screw so it contacts the flat and not the sides. Nothing special other than the exact size for balance reasons. They are just standard set screws as far as I know, based on the screws in my Maritool holders.
 
The Weldon flat is much wider than the set screw so it contacts the flat and not the sides. Nothing special other than the exact size for balance reasons. They are just standard set screws as far as I know, based on the screws in my Maritool holders.

The proper screws are not standard set screw, they have a larger chamfer which does fit neatly into the slot.I will post a page from the Weldon catalogue that gives the details later.
 
The time or two I've needed flat point set screws, I've taken regular cup point ones and chucked up in the lathe gently and flatten the cup point. Yeah, I realized they are not fully hard, but it worked.
 
The proper screws are not standard set screw, they have a larger chamfer which does fit neatly into the slot.I will post a page from the Weldon catalogue that gives the details later.
Just pulled a screw out of my Maritool holder and checked it against a 3/8" mill with a Weldon flat. There is about .05" of extra width to the flat and the chamfer angle on the screw does not match that of the Weldon flat. It has been a few years but when I looked up Weldon flats, perhaps in my Machinerys Handbook, I was amazed at how loose the tolerances were.
 
Thanks Lex. Looks like I'll continue to make them to suit each tool, I've seen too much variation from tool to tool recently. Once upon a time I could depend on the set screw to just touch the chamfers before bottoming in the notch, at least on larger tools, lately I've seen all sorts of fits. I even have one 1.25" endmill holder that has the threaded holes too close together to use both screws without takeing away the wall between the notches.
 








 
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