Countersinking on a HAAS TM-1???

[ChAlKbOaRd]

This is a pretty simply question that I am sure someone out there has a definite answer to. I have a HAAS TM-1 CNC mill, so it can handle a halfway decent load in the Z. I am pulling my hair out trying to figure out some way to CS a hole .525 deep without the machine wanting to fall apart!

My setup right now is a 1-flute 82 degree countersink. I am shredding into some 6061 aluminum, so yah, this is pretty soft stuff. My feedrate is at a creeping 1.3 IPM and my spindle is at a measly 300 RPM.

Should I change the feed and RPM? Should I buy a CS with more flutes? (4 or 6 flute cutter?) I personally think I should increase the number of flutes on the CS so there isn't as much rub between the stock and the cutting edge. Do you guys have any ideas on what I should do?

Thanks for your time. 8D

[artin5]

I think your RPM and feeds are way too low. I have used the same tool to countersink on a Vf-1 with no problems. Try bumping up the RPM to 3500 and the feed to 5-6ipm. You could also try pecking it if the loads are too big. But definetly start by increasing rpm.

[Geof]

Wrong Tool!! Wrong procedure; or at least that is my diagnosis.

Countersinks do not have side clearance; they are not like milling cutters with cutting clearance on the flutes or drills which have clearance behind the lands, the sides above the cutting edeg are nearly always parallel. Once you get deeper than the 82 degree cutting edge you get serious binding added to the fact there is no chip clearance.

Drill the hole first with a drill a few thou larger than the countersink then go in and countersink the bottom.

EDIT: And of course do go much faster; for HSS the same speed as the drill for carbide as fast as the machine can go.

[artin5]

Geof,
What you are saying is true. But the original post doesn't doesn't mention the diameter of the countersink used so maybe at .5" it's still in the cutter area of the CS tool. Obviously, if there is a counterbore and the hole is countersunk you should do as Geof said and drill first.

[Geof]

Originally Posted by artin5 Geof, What you are saying is true. But the original post doesn't doesn't mention the diameter of the countersink used so maybe at .5" it's still in the cutter area of the CS tool. Obviously, if there is a counterbore and the hole is countersunk you should do as Geof said and drill first.

Yes , you are correct. For some reason I thought I had seen a diameter of 1/2" mentioned. My only excuse is that I had not drunk my morning coffee .

Now that I am thinking straighter I still think "Wrong Tool" and "Wrong procedure" could be correct.

If 0.525" deep signifies a countersink diameter of greater than 1.05" that does seem a bit large for TM to drive. Use a smaller countersink (maybe 3/8" dia.), carbide preferably, running at top speed and interpolate the countersink in three steps. A little bit of trig is needed to get the ratio between the Z depth and the radius needed but that is simple.

[cam1]

Hi:
Try this: To avoid or eliminate the chatter associated with single flute CS operations, try
placing a small rag or HD paper towel (cloth reinforced) between the cutter and the workpiece. It eliminates the chatter and vibration.I've used this method many times, in spite of the doubtful initial response.

regards

[ChAlKbOaRd]

Thanks guys! I've only been in the CNC game for a couple years and have most of the stuff down, but it seems that I finally met my match with this darn CS!!! I will go out right now and bump up the RPMs big time and increase the feed rate to about 5 IPM. I'll go see what happens and let you guys know! Thanks for all the input.