Using Ball endmills

[chief]

All,

Thought I would ask what folks consider best practice. I'm going to cut some slots into drill rod with 3/8 and 1/2 inch ball endmills to about half the diameter of the drill rod. One end will be open, I'm planning to make some wood lathe chisels.

My question is, would you rough the slot with a normal straight endmill and finish with the ball endmill to get the rounded bottom, or would you just use the ball endmill alone, making multiple passes to get the proper depth?

Don't if there would be any advantage to using the straight cutter, other than "saving" the ball cutter until you reached the point where you wanted the rounded shape.
Thanks for any thoughts
Chief

[GlennW]

Hello chief,

I believe I'd rough them in as you described, only I'd use one size smaller end mill than the required ball end mill. That way you are just cleaning up and radiusing the slots with the Ball Ends. I've not machined Drill Rod, but it seems to like to make heat when drilled. Using that method, the less expensive standard end mills will do most of the work and take most of the heat, preserving the Ball End's a little.

A spray bottle of coolant wouldn't hurt either!

Glenn

[seal killer]

chief--

I know nothing about what you are trying to do.

However, a very good friend of mine was actually named "Chief." He was part Navaho. He was not a chief. That was just his given name.

He provided me endless hours of online education concerning investing. I invented a thing due to that education. Chief was one of the very first online educators in the world, although I do not think he finished high school. I believe I was the second online educator. I built my college's enrollment to over 40% online. (Then I retired at the top of my game!)

In the meantime, everything Chief taught me continued to GROW. He began teaching me in 1991. Although I am retired, I am still not old enough to withdraw anything without the ridiculous IRS penalty.

Chief not only taught me about investing, he taught me that online education was possible. As a result, my college had the largest two-year online program in the NATION. (I should have called it "Chief Online.

However, in ONE YEAR, I will celebrate my friend, Chief, who passed away many years ago. And, due to his education and my latter invention, I will celebrate Chief in a BIG WAY.

As I said, this has nothing to do with your topic and for that I apologize. However, you chose the best Internet pseudonym possible and gave me an opportunity to write about a truly great human being. (Jenny, if somehow you ever read this, "Hi!")

--Bill; aka seal killer

[replogle]

Maybe drill and bore the drill rod then split on a bandsaw?
RR

[lodcomm]

chief--

I know nothing about what you are trying to do.
said, this has nothing to do with your topic and for that I apologize. However, you chose the best Internet pseudonym possible and gave me an opportunity to write about a truly great human being. (Jenny, if somehow you ever read this, "Hi!")

--Bill; aka seal killer

Bill/Seal -

have you been drinking?

-t

[Harold_V]

Bill/Seal -

have you been drinking?

-t

A little respect, please, for a person that pays tribute to another when he was significant in one's success in life.

I, too, owe a great deal to one individual----and would expect others to respect my feelings.

Harold

[magic9r]

On topic I'd rough the slot with three passes from a smaller endmill, two passes at one third or so depth and one at two thirds to give a wide shallow slot with a deeper central one,
Regards,
Nick

[chief]

I wanted to thank everyone for their help. I sort of suspected the best way to go was to rough it out with the straight mill then finish with the ball. I just wanted to make sure I wasn't adding unnecessary steps.

Seal Killer, your friend and mentor sounds like a person we would all like to know better, it's obvious you have great respect and affection for him.

My chosing the name isn't nearly so deep, I spent a fair number of years in the US Navy and retired as a Senior Chief. Since I still work near the Navy with a lot of co-works that know my background, they all call me Chief, and it's just a habit to use it when folks use nicknames and avitars and such.
Thanks again
Chief

[Lloyd]

All,

Thought I would ask what folks consider best practice. I'm going to cut some slots into drill rod with 3/8 and 1/2 inch ball endmills to about half the diameter of the drill rod. One end will be open, I'm planning to make some wood lathe chisels.

My question is, would you rough the slot with a normal straight endmill and finish with the ball endmill to get the rounded bottom, or would you just use the ball endmill alone, making multiple passes to get the proper depth?

Don't if there would be any advantage to using the straight cutter, other than "saving" the ball cutter until you reached the point where you wanted the rounded shape.
Thanks for any thoughts
Chief

Your query suggests you are a seasoned turner and have your own thoughts on gouge profiles. While there are probably as many special 'Patented' 'Copyrighted' 'Registered' profiles as there are celebrity turners hawking their Signature Series tools, you may have your own designs ready for the profile grinders.

Big roughing gouges are fairly shallow but the trick smaller - tighter profiles are far more sensitive. So, if I were to grind any more, I would likely mount the blanks on the side of angle plates mounted on the mill, approach horizontally from the front. This will permit the use of various size convex rounding mills as in
http://www.jtsmach.com/jtswebshop/Pr_Cu ... s/C054.asp

Using a smaller radius tool and blending the overlap is fairly easy, and lends itself well to the final barbering when you are sharpening the tip. Use of a modified internal radius gauge is helpful. I used an ordinary die grinder to finish shape the inside, then polish, easy money.

If you have access to a surface grinder, then custom profiled stones can do a professional looking finish job.

Clamping a round rod for plowing out much of the longitudinal bulk requires special mounting and clearance consideration. More data if you are interested

Lloyd

[mechanicalmagic]

Chief,
One trick I've heard about, but cannot verify.

When finishing with a ball end mill, (assuming the gouge is in the X orientation). Tilt the head of the mill say 20 degrees. This way the absolute center of the tip is not cutting, (which it does poorly). You still get the proper radius, since the tip is a hemisphere.

Dave

[lodcomm]

Bill/Seal -

have you been drinking?

-t

A little respect, please, for a person that pays tribute to another when he was significant in one's success in life.

I, too, owe a great deal to one individual----and would expect others to respect my feelings.

Harold

You're right Harold -

Sorry Seal..

-t

[Michael_Moore]

When finishing with a ball end mill, (assuming the gouge is in the X orientation). Tilt the head of the mill say 20 degrees. This way the absolute center of the tip is not cutting, (which it does poorly). You still get the proper radius, since the tip is a hemisphere.

Dave, I've seen that mentioned many times and I think it is a good suggestion. It is the same thing why if there was room and it would work OK I'd use a .5" EM with a .125" corner radius to put a radius into the work instead of a .25" ball end mill. You get a much stiffer EM and it is easier to keep all of the radius area at a good SFM. With the .250 ball mill you've still got a significant dead spot right at the bottom. With the .5" with .125" CR that dead spot has a SFM significantly greater than the 0 SFM the ball mill has.

The problem is you don't always have room to put the CR EM in. Tilting the ball mill (as long as that isn't going to cause some other gouging problem) helps to deal with the 0 SFM issue.

cheers,
Michael