Using long reach end mills

[Jake2465]

In a few weeks I plan to post pictures and also some video of a miniature crankshaft on a 4th axis setup. The most challenging area will be when I will need to do live 4th axis finishing between the counterweights so I can get to the back sides of the connecting rod journals. This will require a 3/8" end mill will a 2-1/4" stick out to reach all the way to the journal.

I thought about just using the same end mill for the whole run so I don't need to change tools. I figured that I could start with something like a .001" chipload and .050" width of cut with a .500" depth of cut. But, I am not really sure because I don't ever really mill with a stick out like that.

I plan to use a solid carbide 4 flute.

Any suggestions?

 

[JimDawson]

A 0.500 DOC sounds a bit high, I suspect you will get a lot of chatter. Maybe start out with 0.050 DOC. I've never run that skinny of an end mill with that much stick out. Should be exciting

 

[Jake2465]

Should be exciting

That's what I am afraid of . When it gets too exciting, I hit the deck and start low crawling.

 

[4GSR]

If you don't need to cut with that much flute, get a extended shank carbide end mill.

If you are just cutting the side of a surface, taking full length or .500 at a time should not be a problem with carbide end mill. I've cut some deep slots with 3/8" end mills, not one that deep. Be interested how you make out.

 

[Ulma Doctor]

i recently had a brain fart and broke a 1/2" x 3" endmill- i lost track of the DOC in a manual mill and snapped er' clean off
i hope you have better luck

 

[spumco]

In a few weeks I plan to post pictures and also some video of a miniature crankshaft on a 4th axis setup. The most challenging area will be when I will need to do live 4th axis finishing between the counterweights so I can get to the back sides of the connecting rod journals. This will require a 3/8" end mill will a 2-1/4" stick out to reach all the way to the journal.

I thought about just using the same end mill for the whole run so I don't need to change tools. I figured that I could start with something like a .001" chipload and .050" width of cut with a .500" depth of cut. But, I am not really sure because I don't ever really mill with a stick out like that.

I plan to use a solid carbide 4 flute.

Any suggestions?

Reduced neck endmill is your friend here. They have solid shanks, short flute length, and are way stiffer than a regular long or extra-long endmill. Plenty of vendors sell them these days. Try Amazon - CGC Tools has a pretty good selection and they're really cheap if you're buying the last one in stock. If you don't mind spending money, Harvey Tools has just what you need.

Search for "Necked" or "Neck Relieved" or "Reduced Neck" when you're looking for a tool.

Take light chip loads (0.0015 or so) but don't rub, and 1/2D to 1D DOC, depending on the flute length. Do a 2nd finishing pass because everything flexes - even these things.

Meet your new best friend.

 

[EmilioG]

You also have end mills with reinforced, larger shanks. e.g. 3/8" endmill with a 1/2" shank.
Guhring makes some really nice cutters. Guhring RF100 Diver and the new RF100 A 90° for sharp corners., no radius.

 

[Jake2465]

Search for "Necked" or "Neck Relieved" or "Reduced Neck" when you're looking for a tool.

Thanks for the tips. The ideal end mill that would work out just dandy for me would be the reduced shank end mill. This way the flutes do not have to span the cut depth of the whole cycle.

Harvey tool sells these and they would be ideal, but look at that price . The 3/8" one is $130.

http://www.harveytool.com/prod/Squa...255/End-Mills---Square-Reduced-Shank_244.aspx

eBay sells something similar, but the shank is not reduced and the flute length is longer. It is not as optimized for what I want to do, but at one fourth the cost, I will likely try that first.

 

[Jake2465]

i lost track of the DOC in a manual mill and snapped er' clean off

Ouch! And that also snapped a few bills out of the ole wallet .

 

[Jake2465]

You also have end mills with reinforced, larger shanks. e.g. 3/8" endmill with a 1/2" shank.

I wish I could do that. The issue is that those counter weights basically make the end mill have to operate as if it was in a 2" deep pocket. Just having a regular long shank with the same diameter as the flutes will likely cause chip rubbing against the shank and the inner walls.