Monday, August 31, 2015

Milling A Piece of Aluminum to 2.686"

In a proper shop, I would use a metal bandsaw to cut down to 2.75" and then machine to 2.686", but metal bandsaws are really expensive.  Instead I wrote a program where you tell it the height and width of the workpiece, and what height of finished part you want, along with millling rate, amount to remove on each pass, and away it goes.  The left side is a little uneven because of first cutting experiments.  I may also need to square the mill.  The mill is moving faster than it appears, because of 30 fps video synchronizing with spindle speed.


video

More lessons learned: The mill get knocking the workpiece out of the oddball vise above, so I went back to the Sherline mill vise.  Did not fix the problem.  As the center of gravity (or is it center of pressure?) rises above the vise jaws, it gets harder and harder to hold theworkpiece in the jaws.  So I have reduced feedrate to 2 in/min and 0.005" removed per pass.  This makes it even slower.  When I get into production for this part, Iwill find avendor who can give me a 2 3/4" wide workpiece.

By the way, feed rate and depth of cut are inversely related.  At 1 in/min, you can cut much deeper than at 3 in/min.  I need one of these.

2 comments:

Will said...

Time to upgrade to a machinist vise.

One of the potential problems with mounting a vise that size is cantilevered weight. Have you measured how much deflection there is in the table's "levelness" when you mount it?

Clayton Cramer said...

I need to square the mill first. The weight does not seem a problem so far with deflection.