Key seat cutter problems?

[Von Mikey]

I am cutting a circular groove in 6061 alum. with a 1.000 woodruff cutter on a HAAS vf3, the speed and feed calculations I get with the formulas I normally use seem on the high side. The tool has to be extended a little and I may only get one shot at this cause its a prototype part. The part is 12" long and bolted to a 10" angle plate any recomendations on who much to slow down the spindle / feed rate would be appreciated.

[Boots]

Hi,
You need to provide a little more info. How many Teeth does your cutter have? How wide is it. I know it's 1 in. in dia. that's all I know and that you are cutting alum. Are you just plunging in to cut a key seat ? Or are you cutting a long key way? If this is a prototype and you only got one shot I'd do it on a Bridgeport. If you are cutting for a woodruff key then your depth is also going to be critical.

[Von Mikey]

It's a 1.00 X 3/16 12 tooth cutter. The part is a 12.325 cyllinder with various milled
slots and holes along its sides. It came to me as an extrusion that was saw cut and than faced to print specs. It requires a 1.5 dia. groove .200 wide and a depth of .110 about .6924 from the top of the part. The Bridgeports are all tied up on other jobs and because of the lenth of the part the head would have to be turned and the part clamped to the side of the table to machine this operation. If we end up manufacturing this part for production it will most likely be done on the HAAS with a dedicated fixture and NC program.

[Boots]

Yeah you are right. My formulas show about a 30 IPM feed rate @ 1250 RPM that gives you a .002 chip load per tooth. That's not a lot for Alum. but the way you have to hold it and the groove is high up on the end I'm afraid you are going to get a lot of chatter. (Alum. Extrusion does that.) So to prevent that I would go with a heavier chip load and slower RPM by droping the RPM to 850 you'll increase the chip load by .001 (.003 total) and use cutting oil. If you are using regular water soluable oil coolent then just use the coolent full strength (without any water in it) it will smoke a little probably but will prevent any redepositing of metal and give a better finish.
You know after thinking this over a little I might be tempted to use a bore bar type cutter and just fly cut it. Grind a tool and put it into a bore bar holder. I have done this before but you must have a solid hold on it so the part does not resonate. Chatter will start and the cut will go south in a hurry. I take it this is not something that can be done in a lathe huh?
Good luck with it.

[Von Mikey]

Thanks Boots, A bridgeport opened up and I hogged it out to get it off my desk. It worked out well at 850 rpm.