end mill problems

G

G.Scaffe

Joined
Dec 9, 2000
Messages
174
Yesterday I was trying to mill some slots for guards and the end mill bits
keep curving to the right. I changed bits and speed ,but this keeps on
happening. Anyone know what may be causing this?
Thanks
Gene
 
Check for backlash.

Make sure you're not climb milling ( unless you have a backlash eliminator on your mill.

Make sure the gibs in the ways are snugged up tight.

I'm just a student, but I can hear my instructors voice saying these things to me when I ask the question of myself.

Check your setup with the dial indicator...

Make sure everything is zipped up tight!

You probably already did all this stuff, but that's where I'd start I guess.
 
If you're cutting in the "x" direction, do you have the "y" direction locked so it can't move? You may also be making too much of a cut.
 
Something is bad wrong when a non CNC mill is cutting arcs...

If you're plowing (material on three sides of the cutter) there is a tendency for the cutter to walk to the left. The answer is lighter cuts.

Your cutter should be smaller than the slot you're cutting so there is room to take a finishing pass on both sides of the slot after you rough it out. .010 is a good finish cut.

And what the other guy said about tight gibs, you're sure your vice isn't moving etc...
 
I asume you are using high speed steel, probally 1/8 or 1/4". Invest in a few 4-flute square end CARBIDE endmills. Find a local dealer, you can usually get 1/4" standard length carbide endmills for under $10. If you're cutting with a 1/4" endmill, try taking off no more than .025" at a time. If all else fails, rotate your work 90 degrees and try again, this will tell you if it is your mill.
 
I've been lurking here for some time now absorbing info. Finally a question I can help with ! It's very common for the slot to arc if you are cutting on 3 out of 4 sides. The cure is to make your slot with a series of plunge cuts , about .025 max. at a time, then you can mill your way back to the starting point or re-cut in one pass to clean it up a bit. Not a perfect finish but a whole lot better than you got trying to do it in one pass. A clean-up cut of .002-.005 down each side will usually clean it up pretty nice, but you might rather fit it with a file instead. Remember most steels prefer ( nicer finish) to be conventional cut, that is with the cutting edge of the mill pushing it's chip ahead of the cutter towards the uncut material. Softer materials like alum. like climb cutting, throwing the chip into the void behind the cutter.
 
Do you have a bench top model mill? If so I had the same trouble once. I was removing too much metal and forcing the mill in the X direction. The head wasnt tight enough and was turning. Be sure yours clamps down very tight and go with light passes, carbide mills with coolant.
 
I use spotting drills, to remove the bulk of the metal from the entended slot, then just mill out the webbing. And finish with a .002 for finish. Mike
 
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