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Drilling a Deep .680 Hole with Think Ouside Wall

blackwolf4278

Aluminum
Joined
Oct 1, 2020
Hi Guys, I wanted to ask if anyone might advise me on how to properly machine a ID with the following paramaters:

OD Size: DIA 0.8"
ID Size: DIA 0.68"
Depth: 3.8"
Mat'l: Aluminum 6061

So this leaves me with a thin wall and a long cut. I've tried doing it on a lathe but the finish was crap, one time it was okay the second it was horrible with no noticeable pattern, so then I tried it on a mill with better results and the part was "acceptable" - but by no means nice.

So the way i do it on the mill:

Spot Drill
Then 43/64 Drill .1 Peck at 650 RPM and 5 Feed -> Which works fine.
After I interpolate a .625" DIA Endmill in there in order to get rid of the drill point, works okay but very loud.
And finally I Ream with a .680 HSS Reamer at 260 RPM and 1.7Feed and it very loud at some point and the finish doesn't look pretty at all.

Would anyone have any suggestions?
 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
Is this a roller? Start with 1" round, drill your hole then machine OD between two centers.

Edit: I would run the reamer about 850rpm and 15-20 ipm. If it's a manual lathe, slower...
 

blackwolf4278

Aluminum
Joined
Oct 1, 2020
No there's actually more to the part.

Its as follows:

Top OD DIA 1.97" for 1.44" than OD goes to DIA .8" for another 3.82" and final OD is 1.25" DIA for another 1"

As well I do this on a Mill(you said lathe)

Part looks like this:


|***************|
|***************|
|***************| This OD is 1.97" by 1.44" long
|***************|
|***************|
|***************|

____|*******|
____|*******|
____|*******|
____|*******|
____|*******|
____|*******| This OD is .8" by 3.82" long
____|*******|
____|*******|
____|*******|
____|*******|
____|*******|

_|*************|
_|*************|
_|*************|
_|*************| This OD is 1.25" by 1" long
_|*************|
_|*************|
 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
No there's actually more to the part.

Its as follows:

Top OD DIA 1.97" for 1.44" than OD goes to DIA .8" for another 3.82" and final OD is 1.25" DIA for another 1"

As well I do this on a Mill(you said lathe)

Part looks like this:


|***************|
|***************|
|***************| This OD is 1.97" by 1.44" long
|***************|
|***************|
|***************|

____|*******|
____|*******|
____|*******|
____|*******|
____|*******|
____|*******| This OD is .8" by 3.82" long
____|*******|
____|*******|
____|*******|
____|*******|
____|*******|

_|*************|
_|*************|
_|*************|
_|*************| This OD is 1.25" by 1" long
_|*************|
_|*************|

Yeah…I don’t see a benefit to doing this on a mill. Drill a 1/4 or 5/16 hole then go to the bigger drill. Keep the part and tools cool. Ever tried to machine bubble gum?
 

hvnlymachining

Cast Iron
Joined
Jun 21, 2019
Location
St.Onge
Sounds like a chip weld problem. If you can get live coolant, that will make a lot of difference. If not, break out the squirt bottle. Give a couple different fluids a try until desired results are achieved.

Good luck.
 

blackwolf4278

Aluminum
Joined
Oct 1, 2020
Yeah…I don’t see a benefit to doing this on a mill. Drill a 1/4 or 5/16 hole then go to the bigger drill. Keep the part and tools cool. Ever tried to machine bubble gum?

I've tried it on a lathe, as I originally mentioned the finish would come out very bad once in a while and it had no pattern. Its a long hole that has to be turned with a small BB
 

blackwolf4278

Aluminum
Joined
Oct 1, 2020
Sounds like a chip weld problem. If you can get live coolant, that will make a lot of difference. If not, break out the squirt bottle. Give a couple different fluids a try until desired results are achieved.

Good luck.

That would be awesome, but none of my machines have the capability.
 








 
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