Monday, August 17, 2015

Today's Machining Lesson

I could not take off .01" of aluminum in  one pass wit a 1/2" end mill.  At 0.001" and even 0.002", no problem.  However, my strategy of excavating a .4" deep path 1/8" wide in several passes and then another half the mill diameter next to it (even with the 1/4" end mill) did not work smoothly.  Perhaps I should take all .002" across the entire area, then come back and take the next .002" until I have excavated the area I need.  Should I be using a face mill?  Not for what they cost.

I determined the 1/2" end mill requires more power than the Sherline has. I am rewriting as above.

Also discovered a 3/8" roughing mill that seems to be doing the job.


  1. You really need a Bridgeport. You know you do.

  2. Sherline indicates in their FAC section that if the motor can't maintain the rpm's fairly close to what you set it at, you are taking too heavy a bite.

    I would imagine that the machine has to have a smaller window of capability than bigger machines. They say the DC motor is stronger than a 1/2 hp AC motor. ISTR that some of the early Bridgeports only had 1 hp, but every one I've seen has at least 1-1/2 hp, and lots had 2 hp.

    Just because a bit fits in the mill, doesn't mean it's appropriate to use. The bigger it is, the more restrictive it's operating parameters are, generally. It's a balancing act, really.

  3. Another factor is which direction you are traversing during the cut. The rotation of the cutting face versus movement direction can become a problem when going for heavier cuts. Also has a bearing on surface finish.

  4. Darrell: And room to put it, and three-phase power.

  5. I've got at least two neighbors who are running "real" mills like Bridgeports in their residential garages. For power you have to install a phase convertor. Yes I am very jealous of that. Even more for that then I would be if they had a red sportscar and a gorgeous supermodel grade girlfriend/wife.

  6. Don't need three-phase. Just a VFD.

    Search: variable frequency drive bridgeport.

  7. "and room to put it"

    Dude... that's what your garage is for!