The Home Machinist!

Using my small milling machine, I noticed that when I mill a longer piece of stock (5" long piece of aluminum bar), the mill appears to take a deeper cut at the extreme ends of the stock. This happens as the table and stock move along the X axis. I thought maybe the mill was worn enough so the table sinks a bit as it passes over the middle of its travel. But after one pass, that same appearance of cutting more on the ends than the middle reappears. I figured if the mill cut the stock with a slight dip in it the first time, it would simply cut evenly the next time, following the dip cut on the first pass. I'll try measuring the flatness of the stock. I am just not sure what is going on here. ???

- Phil

Phil

A friend of mine had this problem on his mill/drill, turns out the gibs were loose on the x axis and due to a narrow saddle the table would tilt as it was moved off center ( when moved to the right the right end would drop) which would raise the other end where the cut was being made. Readjusting the gibs corrected the problem

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Rick

“We make a living by what we get, but we make a life by what we give." Sir Winston Leonard Spencer Churchill (1874-1965)
"Peace is that brief glorious moment in history when everybody stands around reloading". Unknown
Murphy's Law: " If it can go wrong it will"
Rick's axiom: "Murphy was entirely to optimistic"

Ckeck your part for flatness after you mill your slot. You culd be experiencing a warping condition as you remove the center of the material.

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You can buy good parts, or you can buy cheap parts, but you can't buy good cheap parts.

If you are using a collet, is the cutter held tight enough?

It could possibly be pulling out of the collet from the helix angle of the flutes.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

The condition reported with the gib is a chief suspect, but it may not be the saddle that's tilting. If your mill has a knee, check that gib, too. Definitely sounds like something is shifting.

Harold

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Wise people talk because they have something to say. Fools talk because they have to say something.

i have to agree with the gibs being loose as suspect number one
number 2 would be the bed and collum area flexing
you could also be distorting the table with your approach to clamping

a small mill doesnt tell us much as a tabletop machine has far differient concerns at 100 lbs than a 600 pound mill drill or a 2500 pound knee mill

some checking with a dial test indicator should allow you to locate the source of movement