Starting Point: Milling a 1/4 Inch Wide Slot in 1/4 Thick Steel Plate

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dansawyer

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The machine is a Bridgeport CNC with a 2 HP 2J2 head. The project is to mill a lathe spanner wrench for a L-0 lathe spindle. The raw material is 1/4 x 4 x12 hot rolled plate. I can writh the J code to do the milling. My question is what should I set the mill head rpm, cut depth, and cutting speed, IPM. The cutter is a 1/4 inch end mill.
 
Here is a place to play with numbers etc. on the left side choose mill speed and feed.
Pierre

Turning Speed and Feed Calculator

The cutting speed calculator calculates the speed, feed, and cut time for the machining operation turning.
www.custompartnet.com
 
pdentrem said:
Here is a place to play with numbers etc. on the left side choose mill speed and feed.
Pierre

Turning Speed and Feed Calculator

The cutting speed calculator calculates the speed, feed, and cut time for the machining operation turning.
www.custompartnet.com
Click to expand...
Thank you. The calculator indicates 2 IPM at 500 RPM. I will plan to take lighter cuts of about .050 inches to test.
 
Plan on at least .0006 to .0010 metal removal per tooth to avoid rubbing the cutter to death. More after you're comfortable with it.
 
Am I thinking of this correctly? 500 RPM times 4 flutes times .001 per tooth equals 2 inches per minute. These values were the output from the calculator. I will plan to take cuts of a depth of 50 thousandts. Thanks for providing a 'rule of thumb' for cuts. It makes it much easier to understand the values.
 
Curious about that turning calculator. It's set up for lathes, not mills (?). If I use a 1/4" 4-flute end mill vs. a 1-flute end mill, shouldn't I be able to increase the feed rate by a factor of 4 to keep the IPR at the same number? I popped in "0.25" for my cut diameter, 100 for SFM and got a spindle RPM of 1528 (close to my usual of "400 / cutter diameter" for steel or 1600 for a 1/4" end mill). That gave a cutting feed (IPR) of 0.0013, spindle at 1528 RPM gave a feed rate of 2 IPM.

I'm thinking (?) the diagram shows a lathe with a single cutter (like a 1-flute end mill). With a 4-flute would I get the same chip load with a feed rate 4-times greater or 8 IPM? I've been feeding WAY too fast according to this calculator. I usually got 4 - 6 IPM at 1600 RPM with a 4-flute.

Bruce
 
Bruce, on the left side there are selections to make. Hope this helps.
Pierre
 
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