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.

8 comments:

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

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  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.

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  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.

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

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  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.

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

    Search: variable frequency drive bridgeport.

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  7. "and room to put it"

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

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