Slot milling general rules

Greenworks · Feb 14, 2017

Hi all,
I've been mostly turning stuff, but my lathe has live tool capabilities. I've got turning somewhat down for a self taught novice, but I've got some questions about milling. I know this topic has probably been covered half a million times on this forum, and I tried search with little success. What are some rules of thumb for slot milling? I've got an open ended slot that I'm needing to make with a 0.0625" ball nose endmill with a final depth of 0.225". the slot width is .0625". Material is 6061 T6 aluminum. What is the DOC for stepping down into a slot based on? Percentage of the tool width probably? Feeds and speeds would all stay the same right? For regular milling what percentage of the tool width axially would you use for a regular cut that's full depth? I know nothings hard and fast, but there has to be guidelines. The Machinist's Handbook laid it all out perfectly in engineer gibberish that was completely unintelligible without a for dummies translation.
Thanks all in advance

michiganbuck · Feb 14, 2017

QT; [with a 0.0625" ball nose endmill] you are likely to cut wide.. best to run a test piece to see if the results are in spec..end mill would have to run perfect to run a little over width.

Limy Sami · Feb 14, 2017

IME the problem with ball EMs is the cutting speed at the centre is ZERO but unlike an angled EM a BN has to cut at the centre to create the radius.

If I had the live tools I'd run a 90deg EM to a depth leaving the rad of the BN EM + a few 000ths '' to clean up.

onecut · Feb 14, 2017

Dont what face your slot is going in.It could be an open end slot bit like a k/way but using a ball nose.Slot has a .0625 wide(Tolerance?)the tolerance will dictate how you do it.But the tool is 1/16th ins?Normally recomended half diameter of tool=Depth of cut.If it was a thro slot I would stand them up and use a saw with a radius on then it would be the full depth-

Greenworks · Feb 14, 2017

The tolerance isn't tight. It's a guide for a throttle cable. I think I might just use a standard square EM, but a BN is preferable. 90° is a good call. You alled just run it in one pass full depth, then clean up with the ball nose? Edit- The slot has to be .0625 wide for the throttle cable to fit in. I don't have prints or nuthin. I just make stuff..

Limy Sami · Feb 14, 2017

No way at full depth, 1/16 EMs are fragile , std ROT for DOC slotting is 50% D in you case 30 odd thou

Greenworks · Feb 14, 2017

I didn't figure it would be full depth. My eyebrow was definitely raised

The slot has a 90° turn, or I'd consider using some sort of wheel. It's the hole and slot to hold the ball for a motorcycle throttle. Face drilled 2 .25 holes and the slots come in in Z to about -.15 then turn 90° with the C axis rotating around.

Danny VanVoorn · Feb 14, 2017

Probably the only rule I follow is if a slot can be made with a slotting cutter then use one. If you have to use an end mill the slot location is going to walk so leave material for finishing width after getting to the depth.
Dan

Noah Katz · Feb 23, 2017

Why not just turn the groove full circle in the lathe?

You'd have a free-standing island between the ends of the two cables, but there's no load on that so I don't see the harm.

Spirit Tool · Feb 23, 2017

Spirit Tool Arbor System

Greenworks said:
I didn't figure it would be full depth. My eyebrow was definitely raised

The slot has a 90° turn, or I'd consider using some sort of wheel. It's the hole and slot to hold the ball for a motorcycle throttle. Face drilled 2 .25 holes and the slots come in in Z to about -.15 then turn 90° with the C axis rotating around.

View attachment 191194

View attachment 191195

If you plan to use a slotting cutter consider using a Spirit Tool Arbor. Our stub arbor will handle cutters from .020" to .500" in thickness. Our arbors are hardened and precision ground to .0002" in all critical areas. ***We are the only stub arbors on the market with a KEY!*** Straight Shank or R8 Taper. Made in the USA since 1970. www.spirittool.com
Good Milling!

TeachMePlease · Feb 23, 2017

Spirit Tool said:
If you plan to use a slotting cutter consider using a Spirit Tool Arbor. Our stub arbor will handle cutters from .020" to .500" in thickness. Our arbors are hardened and precision ground to .0002" in all critical areas. ***We are the only stub arbors on the market with a KEY!*** Straight Shank or R8 Taper. Made in the USA since 1970. www.spirittool.com
Good Milling!

Just FYI, posting only to spam your business/product without contributing any sort of knowledge or assistance to the forum is a very quick trip to Ban-ville, population: You.

Study posts by people like Frank from Maritool, Curtis - Exkenna, Sol - Orange Vise, and even the new guy, Shop Supply Guru. They all have businesses related to what we all do, they all occasionally plug a product, but they also contribute much more in the way of information. Be like them, or be gone. Your choice. (This isn't a threat: I'm not a moderator. But I've been here awhile, and I've seen how the moderators, and other forum members react to such. )

deadlykitten · Feb 24, 2017

milling on a lathe is like using mini-3axis-mill, with rotary table and angular heads

it is pretty versatile, but not so rigid

so, be gentle

DMF_TomB · Feb 24, 2017

length of tool stickout from tool holder and tool length of flutes has 10x effect on most things and often people have trouble trying to use too long a small diameter end mill
.
if you use end mill with 2 times flute length it will deflect 2x2x2 or 8 times more. many a small dia end mill had broken with very little noise.
.
and tool runout of even .002 has a bigger effect on small tool where it goes unnoticed on larger dia tools

Noah Katz · Feb 24, 2017

deadlykitten said:
milling on a lathe is like using mini-3axis-mill, with rotary table and angular heads

If that's in reply to me, I said turn, not mill.

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