Rough edges when milling steel

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turningwheels

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Ok, total N00b here. I have a brand new Grizzly G0619 with a max RPM of 1800. When trying to end mill using a .25" end mill HSS TiN, I get all sorts of rough edges. This particular cut was .002 deep at about 5.5 inches per minute. According to my handy (but I am not so sure I believe it) app that shows my feed and speed rate according to the max RPM my machine is capable of. So, what is happening here and why? I am practicing using my new DRO and even the rectangle needed to be shaved of rough burrs. Frustrating to say the least.IMG_20200521_181357.jpg
 

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Try slowing your feed rate. Maybe start at 1-3/4” per min and work from there.Is your end mill sharp?
Cheers
Martin
 
My 1+1/2 HP mill G0730 is limited to about 1" end mills and with 1" end mill I use a speed closer to 230 RPMs and use my hand on the travel dial to determine speed of cut, I also look at the surface. I almost always use lubricant--steel=cutting fluid, Al=WD-40.

But, if the ragged edges are from the second cut on that part, the first cut more than likely dulled the cutting edges.
 
Liljoebrshooter said:
Looks like a dull cutter. What brand is it? 1.4" in diameter end mill?

Joe
Click to expand...
1/4" inch. I can't type. Grizzly set of end mills. I am starting to see why people spend good money on end mills. I'll try a new end mill that hasn't seen any action yet and report back.
 
I went up to a NEW 3/8" end mill. taking max .01 inch cut on what I assume is mild steel. There are so many variables to this hobby, it's making my head spin.
However, it's still making ragged edges at 1800 rpm or 850 rpm.
If I do the calculation using the chart from here: https://www.the-carbide-end-mill-store.com/Feeds-and-Speeds.html
420x3.82/.375 = 4277 RPM If this is true, then how do I machine steel with an 1800 rpm limit?
 
Throw your chart out. Those speeds and feeds are for production machines that might weigh 10000lbs or more and spindle speeds of 10k or higher.
Most of the manual machines are not rigid enough to do this. Slow and steady usually does better for the equipment most of us have.
Joe
 
Also in the first picture you can see the chips don't look like nice chips. They look like they are from grinding. Another sign of a dull cutter.
Also the grade of steel might not be the best for clean easy machining.

Joe
 
Liljoebrshooter said:
Throw your chart out. Those speeds and feeds are for production machines that might weigh 10000lbs or more and spindle speeds of 10k or higher.
Most of the manual machines are not rigid enough to do this. Slow and steady usually does better for the equipment most of us have.
Joe
Click to expand...
Ok. It's in the garbage. What is slow and steady for us regular Joe's? Thanks for answering my questions! I know that not knowing what kind of steel I am using has a big impact.
 
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