please help an aluminum noob

[mike.b]

i am a woodworker doing some aluminum projects for the first time. so far they have all gone well but i am having problems countersinking 6060 aluminum plate with this 1.25 countersink.

i am cutting really lightly at .01 depths, 5000 rpm. the first two went smoothly (right)but the second two (left)chattered even after a brand new cutter. can anyone recommened a better tool, feeds, speeds? thanks

 

 

[rboucher]

Can you clamp it down on the left hand side to?

[mike.b]

it was clamped on the left when i was cutting

[john316]

.

 

Start at about 500 to 1000 rpm and 10 ipm. increase your feed and speed until you can see some ripples and then back off a little bit.

 

.

[Rick Henrickson The Boeing Co.]

don't peck, run about 500 sfm .008 per rev feed

[Kannon]

the 5000 rpm sounds very high to me.. I like john316's plan of attack.

 

Good luck!

[Rick Henrickson The Boeing Co.]

kannon, that was 500 sfm. I wasnt sure what dia he was countersinking to.

[Kannon]

sorry Rick.. I replied without seeing your recommendation. I was replying to Mike b.'s spindle speed he was running.

[chris m]

WAAAAAAAAAAAAAAAY too much RPM. Maybe 2000 and feed the **** out of it

 

Is the tool supposed to be counterboring the hole? Is another tool doing that? I wouldn't use a c'sink beyond the angle because you really have no clearance once you get around the corner

[Hardmill]

quote:

---

WAAAAAAAAAAAAAAAY too much RPM.

---

 

 

PEACE

[Charlie Pierson]

Weldon type c'sink , 800rpm , 8.0ipm

all in one go or leave .02 for 2nd and final peck.

 

cp

[Tim Johnson]

Use a one flute c-sink. multi flute c-sinks and alum don't seem to play well together. 350sfm .006 ipt. no peck Dwell 1.5 revolutions. If you must use a multi flute, 150-200 sfm .003 ipt. no dwell

[90rsgnuguy42]

The excesive chatter is caused by the multi flute c-sink. That actually looks like a Severence C-sink which is made for hand chamfering holes. Either find a c-sink with less flutes or drop the rpm's way down.

[Kannon]

all in favor spindle speed is 4x faster then it should be say I

[gms1]

We use 3 flute c-sink tools, 600rpm 10ipm and we use a dwell at the bottom of each. Our c-sink tools have pilots though so that may take out the chatter for us.

[Hardmill]

quote:

---

say I

---

:SMACK: :EYE GOUGE:

 

PEACE

[TS53]

Are you using any coolant? I have much better looking parts with flood.

[jeff]

Don't dwell, that will cause chatter also.

As stated above, 5,000 rpm is way too fast.

try 100 sfpm and 10 ipm...no peck either.

HTH

[Jimic]

For Alum. I usaully use 3/4" dia spot drill with 90 deg Incl. Run at S3000 F12 with G82.

[mike.b]

thanks for all the responses guys this is such a great forum!

i tried 600 rpm 10 inch per minute and the chatter is gone but it stops the spindle and leaves me with what you see in the picture. seems really hard on the machine. i am using coolant.

seems like a different tool is my next step. one flute?

[Müřlıń®]

Run that tool there @ 250 RPM 5 IPM, no dwell, no peck.

 

Multiflutes chatter like heck even in steel..

 

I would run that @ 50 RPM in steel @ 3 IPM.

 

Better slow it down , 10 IPM stalls your spindle? woah....

 

On second thought better use a dwell....but no peck

 

Different machines use the same tool differently...

 

250/5 ought to be about the right ratio to start with, now just override feed to get the desired results.

 

Might want to start feed @ about 3 since you are buring the corners.

[mike.b]

i will give that a try murlin

im scared now

[Müřlıń®]

You push those hard and it won't chatter, but stalling is another issue entirely.

 

That adds a wrench in there.

[?Mark]

It's not a router you're running this on is it?

It could be too weak to handle this at lower rpm.

Keep tha rpm high at 600 but slow the speed down to 2 ipm

[mike.b]

tried that and the spindle is still stalling. too many flutes?