Are End Mills Tapered?

Thanks guys!
  • Yes, this is with my Atlas MFC.
  • I did take a spring cut.... no difference.
  • The tip and the shank (beyond the flutes) both mic at .624. In between is about the same, although it is more difficult to position the mic.
  • I checked movement in the X and Y directions with a dial indicator with its magnetic base stuck onto the head. X and Y are not bad: better than +/- .001 over about 3 inches of travel.
  • Rolling the end mill on a counter top and sighting the edge, it does not appear to be bent. But this is not much of a test.
  • I still need to check the Z movement. It might be that the jaws of my vise are not perpendicular to its base. It is a cheapo import from Little Machine Shop, but it fits the MFC nicely. Or it might be that the head casting is somehow misaligned.
  • I do have some old American-made end mills. I will run one of those for comparison.
I'll figure it out from here. When I first noticed the problem I thought I was being an idiot and that end mills might be tapered by design for some reason.
 
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Definitely sounds like an alignment issue to me. Since there is no change with a spring pass I would bet something is a bit skewed in either the vise kicking the part up, or head not trammed in to the table.
 
Can you help us all get on the same page. Since you have a horizontal mill, things are a bit different.
We could really use a pic of your set up.

It would be nice to have no confusion about where the problem might be.
 
My Bridgeport M head bearings are shot, so on heavy cuts I get quite a bit of spindle deflection that leads to a tapered surface.
 
Well.... I changed to another end mill and now I am getting good results. But I changed some other things too, so I don't know for sure that it was the end mill. This is approximately the setup I was using. At any rate, I'm happy now. Thanks for all the good ideas!

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It's always easy enough to toss the end mill back in later & run a test cut to see if it is still there. Now that you got it true is get done with making the more pressing chips then you can come back to the test piece when you have a slow moment.
 
I see I spy a...
Tool holder...

Tool holders are great when you absolutely must have your cutter run off center.
Is using a tool holder the only option for using an end mill in your machine?
 
With the vise I have, oriented the way it is shown, a collet and end mill will not reach far enough. But I agree, I would prefer not to use the tool holder. A better option might have been to set up the arbor and use a horizontal cutter.
 
JPMacG said:
With the vise I have, oriented the way it is shown, a collet and end mill will not reach far enough. But I agree, I would prefer not to use the tool holder. A better option might have been to set up the arbor and use a horizontal cutter.
Click to expand...

Better to have your set up than no mill at all :)

Dunno if you have run into it or not, but you might come across "imperial" mills that are actually metric. It will cause problems with your tool holder. Might not hurt to put a caliper on your HF mill and make sure it really is the right size for your holder.
 
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