Plunge countersink for cast iron. Need tool suggestion.

[Ray C]

All,

I need to make a 5/8 dia. flat countersink into CI about 3/8" deep. A HSS 5/8 endmill would work fine if I were working with steel but CI will kill it in a heartbeat. All the carbide endmills I have will not face cut. Looked around at the usual sources and can't find the right tool... Any suggestions?

Thanks

Ray

 

[OldMachinist]

Re: Plunge countersinke for cast iron. Need tool suggestion.

Unless it's a piece of junk cast iron with lots of sand in it a high speed end mill should work fine as long it run the right surface speed. I've put many counterbores in lathe chuck backing plates with a end mill.

 

[Ray C]

Re: Plunge countersinke for cast iron. Need tool suggestion.

Hmmm... It's good quality CI -very clean. I tried 2 & 4 flute endmills in good condition and it didn't feel right. Tried a couple speeds too and quit before I end-up with a dead bit. Any ideas on speed? BTW: I'm cutting dry.


Ray

Unless it's a piece of junk cast iron with lots of sand in it a high speed end mill should work fine as long it run the right surface speed. I've put many counterbores in lathe chuck backing plates with a end mill.

 

[OldMachinist]

60-80 fpm is about right for most cast iron so (12 times 60) divided by (3.1415 times .625) equals 366 rpm's or for 80 fpm it would be 488 rpm's. I always cut cast iron dry.

 

[Jeff in Pa]

60-80 fpm is about right for most cast iron so (12 times 60) divided by (3.1415 times .625) equals 366 rpm's or for 80 fpm it would be 488 rpm's. I always cut cast iron dry.

I work with castings a lot at work and I run a bit slower ( 40-60 sfm) but our castings are a bit complex and can have hard spots.

I agree with cutting dry.

 

[Ray C]

OK guys, thanks. I'll try later this evening. BTW: I converted a couple threaded chuck backs to D1-4. Nailed the geometry on the head, knocked-out the studs, drilled/tapped all the holes in the plates and when came time to countersink to fit the studs, it just seemed weird. -Not too experienced with milling CI so I hung it up till after dinner.

I'll let you know how it goes...

Thanks
Ray

 

[Jeff in Pa]

No "lolly gagging" in the hole ( don't dwell/rub, cut). Don't jam it in but a controlled cut should work best.

 

[Ray C]

No lolly-gag'n here boss -despite the 20min nap after dinner...

Perfect! Just finished the 1st hole at 540RPM. Nice, easy, clean -firm & steady.

Thanks to both you guys... Appreciate it.

Will post a few follow-up pics in the thread about D1 Measurement when I'm done.


Ray