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Cut too heavy or not?

Dave K2

Stainless
Joined
Apr 18, 2007
Location
Hertfordshire, England
Hi all,

can someone verify a machine setup for me. I'm cutting cast iron on a bridgeport with BR2J head. Its an interrupted cut, probably 45 degrees of a circle 13" diameter. I'm using a 3" boring head with 3/4" brazed carbide tooling, side mounted.

I have set these figures:-
depth of cut=0.25mm
feed rate=0.15mm/rev (.006")
speed=90rpm (300fpm)

does that sound ok or too heavy in one way or another?

i'm only asking as its a long job and i have two to do.

results so far seem ok but i dont want to kill the tool or machine.

thanks in advance

dave
 
Dave, it sounds good to me and if it is working the only thing would be to experiment with DOC or spindle speed to get the job done faster. If faster is not a problem then don't change it if it's working.
 
If the length of the cut is excessive, (more than 2 inches???) I would be concerned about trashing the quill. I, myself, prefer to feed the knee and keep the quill sucked up and clamped all the way for more rigidity. There is a lot of spindle load developed by the 6 1/2 inch radial cut + the interrupted cut. Just my .02

Keith
 
Heres the setup,

DSCN0958.jpg


As its too far to make in one pass. i'm doing it in two sections, working with maximum quill retraction of course, so its two cuts of about 3" each.

Dave
 
If that is all you have to work with, then so be it. That tool will start talking to you when it is dull. I would perform that job on my lathe using a chuck mounted line boring type of bar centered in the tailstock on a live center and mount the work piece to my carriage. Then you could just feed the carriage and work longitudinally via the feed screw. Adjust the tool bit using a magnetic base and Dial indicator.
 
If that is all you have to work with, then so be it. That tool will start talking to you when it is dull. I would perform that job on my lathe using a chuck mounted line boring type of bar centered in the tailstock on a live center and mount the work piece to my carriage. Then you could just feed the carriage and work longitudinally via the feed screw. Adjust the tool bit using a magnetic base and Dial indicator.

I had thought of that but lathe will only swing 12" (just) so the mill it had to be.

The first one is done now with excellent results so thats good.

thanks all
DAve
 
Glad that it is working out for you. There have been times like that for me also. At least you were able to develope a plan of attack and get good results. After all, "It's All In Your Head."

Regards, Keith
 
Must be one bad @$$ boring head and bar cause I would consider that extreme for my machine. I've learned you can argue with theory and Machinerys handbook, but not results.
 
This is why I come here

Great example of getting a job done. The ideas that surface here are the reason I love PM. Thanks for sharing.
Joe
 
Must be one bad @$$ boring head and bar cause I would consider that extreme for my machine. I've learned you can argue with theory and Machinerys handbook, but not results.

Its the biggest cut diameter i've made to date and i was definately impressed with the finish, there was a slight 'ripple' effect on the section following the hole in the middle, it could be seen but not felt by hand. I'm guessing its the bar springing a bit?

in the top and bottom 'full length' cuts, the surface was perfect.

Anyways the jobs done now with excellent results and i'm glad i bought the big boring head.

Dave
 








 
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