Coolant flow into tight pockets

trochoidalpath · Jun 9, 2020

I have been cutting some pockets with a high ratio of depth:area, like 1.5" square by 0.950" deep. I have been doing these with a 3/8" 1" LOC end mill in either a sidelock or short gage length collet chuck; just helixing down and then blowing out the pocket.

Done this way, it is proving difficult for coolant or air to get into the pocket to clear chips.

I know TSC is probably the right answer, but I'd like to find a solution that is less expensive for now. Better to use a longer reach end mill or try to find a slim-nose toolholder? (Too bad the MST Monocurves don't come in inch sizes, they look great for this!) Some other approach I'm missing? Thanks!

ChipSplitter · Jun 9, 2020

Set up an air blast gun using Locline coolant hose.
Mount it close to the holder and angled down.

Also, you could try an endmill with chipbreakers.
The chips are much smaller and easy to blast out.

Helical Tool

trochoidalpath · Jun 9, 2020

ChipSplitter said:
Set up an air blast gun using Locline coolant hose.
Mount it close to the holder and angled down.

Also, you could try an endmill with chipbreakers.
The chips are much smaller and easy to blast out.

Helical Tool

The air blast just doesn't work out. I've tried playing with the angle and position, but it's not unusual for me to have around 50 thou of clearance between the toolholder nut and the top of the pocket. It's just pretty tightly shielded.

I usually use chipbreaker roughers for this -- it helps, for sure.

ChipSplitter · Jun 9, 2020

trochoidalpath said:
The air blast just doesn't work out. I've tried playing with the angle and position, but it's not unusual for me to have around 50 thou of clearance between the toolholder nut and the top of the pocket. It's just pretty tightly shielded.

I usually use chipbreaker roughers for this -- it helps, for sure.

I assume you don't have through spindle air blast. Sometimes a hefty blast of air across the part face will deflect off the nut and still clear chips....

What about these:

CAT40 3/8 END MILL TOOL HOLDER 2.5 gage length - Made in USA MariTool

Techniks CNC Machine Tooling | CAT 40 ER Holders - Mini Nut

Mike1974 · Jun 9, 2020

trochoidalpath said:
The air blast just doesn't work out. I've tried playing with the angle and position, but it's not unusual for me to have around 50 thou of clearance between the toolholder nut and the top of the pocket. It's just pretty tightly shielded.

I usually use chipbreaker roughers for this -- it helps, for sure.

Wait. You said sidelock in first post, but now "toolholder nut"... so using one for roughing and one for finishing, or..??

ER32 is about the worst for coolant (well, not as bad as ER40..). If you are using 3/8" tools you could go to an ER16 with the "slim" nuts that are around 3/4" diameter or so. something like this
https://www.mscdirect.com/product/details/06495188

Or Slim-Fits (but they only go up to 1/4"
Techniks CNC Machine Tooling | CAT 40/50 Holders - SlimPRO

And spendy!! I think one collet is around $60 (or was last time I used them)

trochoidalpath · Jun 9, 2020

ChipSplitter said:
I assume you don't have through spindle air blast. Sometimes a hefty blast of air across the part face will deflect off the nut and still clear chips....

Nope, no through-spindle anything. I don't know if you can run through-spindle air on a Speedio...?

ChipSplitter · Jun 9, 2020

trochoidalpath said:
Nope, no through-spindle anything. I don't know if you can run through-spindle air on a Speedio...?

If you have a Speedio you'll have fun with this tool. I personally know the guy that invented it. It has a high feed bottom with variable index chip splitting flutes. you could use a 1/2" version and flat out fly to the bottom and then come back with a 3/8 x1.25 EM for the floor and corners.

https://www.iscar.com/eCatalog/item.aspx?cat=5680943&fnum=3083&mapp=ML&app=71&GFSTYP=I&isoD=1

ChipSplitter · Jun 9, 2020

Here's a video of him testing it:
If the link doesn't work search: Rick Steinard demo in a box

YouTube

trochoidalpath · Jun 9, 2020

Mike1974 said:
Wait. You said sidelock in first post, but now "toolholder nut"... so using one for roughing and one for finishing, or..??

ER32 is about the worst for coolant (well, not as bad as ER40..). If you are using 3/8" tools you could go to an ER16 with the "slim" nuts that are around 3/4" diameter or so. something like this
https://www.mscdirect.com/product/details/06495188

Or Slim-Fits (but they only go up to 1/4"
Techniks CNC Machine Tooling | CAT 40/50 Holders - SlimPRO

And spendy!! I think one collet is around $60 (or was last time I used them)

Sorry -- I use both.

Usually I rough with a 1.1" gage length Maritool sidelock, and finish with a collet chuck (Kaiser NBC with an on-size collet, if it matters). The nut diameter on those is 0.984", so kind of between ER16 regular and ER16 mini-nuts.

Hardplates · Jun 9, 2020

Ditch the endmill and rough it out with a high feed mill. I don't have TSC either and do pockets 1.6" deep every day that are around 1 1/2" by 2". I've had the best luck with Kyocera. I have carbide shank Kennametal/Stellram ones but run the steel body Kyocera's the most cause the inserts hold up better, especial in SS, 4 parts vs 1.

The chips are easy to wash out of the pocket if you have any kind of volume and a bit of pressure behind your coolant. Air works well for steel but not so much for SS. That's been my experience anyway.

D.D.Machine · Jun 9, 2020

I do a pocket about the same and blow 5 holes in it as big as I can and it gets 75% of the material out in a few seconds ,,, its shocking how hard you can feed a 1/2" screw machine drill ,, I use the GY1 tin coated ones and they last for months at 7K and .030 feed.. its a full 1/2" dia of material being removed at 210 IPM and no peck ,, If you weld up a drill up the feed rate or lower the RPM ,,,

grind a flat on the drill and use a side lock holder ,, yes the drill shank is a couple thousands under 1/2" but your not trying to make a nice pretty hole ,,

Delw · Jun 9, 2020

since its a small area, i would mount some coolant lines on your table pointing to the part, Ive done this in the past use like 1/4 and 3/8 push loc tubing and fittings off a T connected to the pump. works great.

got a job I am setting up that is a 7x9x2" hog out I am going to do this way if it will work lots of chips coming out.

BROTHERFRANK · Jun 10, 2020

Machining Aluminum? Something like this works well, the reduced neck helps with clearing chips and getting coolant in:
https://www.iscar.com/eCatalog/item.aspx?cat=5622047&fnum=1942&mapp=ML&app=57&GFSTYP=I&isoD=1

Here is a 1.25" deep pocket being roughed on a Brother in one shot with a Hanita TC6A0R13005 1/2" rougher:
YouTube

Maybe you can try splitting the loc lines with Ys and smaller nozzles to get the coolant where you want it. I like to shorten up the loc line some with solid pipe and a 45 degree fitting. Makes them more stable.

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