End mill holder?

H

Howardd

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I’m looking for a 7/8 inch end mill and found the following note in the section of high speed steel end mills in the McMaster catalog.
Note: For use with an R8 taper spindle, end mills with 7/8", 1", and 1 1/4" shank diameters should be secured with an end mill holder (sold separately).
How Important is the end mill holder?

I did not see this precaution in the section for carbide mills.

Thanks
Howardd
 
The load on the flutes of the "larger" end mills tends to pull them from collets. the Weldon holder (mentioned in McMaster/Carr, )uses a set screw to keep the end mill from sliding out of the holder. The true Weldon brand has the bore offset just enough to keep the tool on center when the setscrew is tightened. Non-Weldon holders may not have this feature.

Edit: fix typo
 
My largest R8 collet is 7/8, it has a step about 1-1/2" in so that would be max insertion depth. A double ended cutter would not work. Wall is getting thin too, which would say that's about the end of R8 spindle hole. I have some larger diameter cutters with reduced shanks (like 3/4), so they are fine in a collet. The holders have a set screw to hit the flat on a Weldon shank. Some have enough depth to accept a double ended cutter. Main disadvantage I see is the holders can burn up a bunch of Z travel if it becomes important and lots of stick out has its own issues. Why no warning is anyone's guess.
 
What kind of mill do you have as a 7/8" end mill may be to big. The only reason to use a holder is so the end mill doesn't slide out. The increased length will act like a lever. A rigid mill with a Cat 40 spindle would unlikely have this problem.
 
This thread comes along just as I'm looking into this. I have a HSS 1" mill with a 1/2" shank and not until my last project did I notice this pulling out of the collet. I looked into tool holders and then as a side trip while on ebay shell mills. But it seems that's also a deep subject as there's different angles? I'm not sure what that means. Seems every time I go down the rabbit hole I just end up with more questions than answers since I don't have the background in machining.

So should I go tool holder(I might have to machine a flat on my old mill) or just bypass the whole thing and go shell mill?
 
What kind of operation are you hoping to accomplish? Facing, slotting, shouldering, etc. A shell mill may be preferred for one while another tool may be better for another. I have found that smaller tools give better results rather than pushing the capacity of an R8 taper.
 
In this case I was squaring up the end of a round shaft. I was wanting to make single passes using the 1" mill instead of several passes with a smaller mill. Because I was going down to the round portion did I notice the discrepancy between what the DRO said and what I saw. On the first side I was even with the round part. At the same Z dimension on the DRO I was into the round on the next side. That's when I figured out it had pulled out of the collet. Didn't seem like cleaning the collet and mill shaft and then tightening as tight as I could get the collet could stop the creep.
 
For the Weldon style end mill holders to hold against pull out, the cutters must have the Weldon notches in the sides of the shanks to act as physical stops. Otherwise, you will still be hoping for enough friction to hold them.
 
A handy machinist could grind Weldon shank flats on their tools. I favor end mill holders for R8 spindles. Nice air tight pop! when removing tools from the holders gives me a warm whisky glow in my belly that lets me know all is right in the world.
 
pontiac428 said:
A handy machinist could grind Weldon shank flats on their tools.
Click to expand...
Absolutely. Just try to do a neat job of it, not guess and by gosh on the bench grinder...

Weldon Flat Tool | AB Tools, Inc.

Are you tired of hand ground screw flats on you your end mill and cutter shanks? Mill precise flats with our new Weldon Flat Tools. Proudly made in the USA by AB Tools, Inc.
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