Mini mill thrown off

D

davidm

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I was cutting a groove in aluminum and while moving the table along the x axis I noticed the groove was way off course. I stopped the mill and its showing it went off by 2+ mms. The whole head is now cutting crooked diagonally and is "north" 2 mms from where I started.

I have dro sensors on all the axes and none of them show anything having changed.

I trammed the head and its not off much. I know I was pushing it but without tearing the whole thing apart for nothing what could have happened?
 
The head bolts seemingly came loose from the forces or the column shifted, and the dro would not see that; it doesn't know where the head is
with respect to the table
Usually it's a good idea to replace the head and column fasteners on these machines with stronger bolts than the factory provides, and tighten the P!$$
out of them
 
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It sounds like maybe the vise moved on the table or the part moved in the vise.

X-Y squareness is machined into the saddle and very hard to mess up. The head on a mini-mill also doesn’t move in Y or rotate around X (front to back).
 
jaek said:
It sounds like maybe the vise moved on the table or the part moved in the vise.

X-Y squareness is machined into the saddle and very hard to mess up. The head on a mini-mill also doesn’t move in Y or rotate around X (front to back).
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I thought the same thing but I can't find any looseness in the vice and the mill is reproducing the crooked cut on new pieces. I also cant find any gaps or noticeable misalignment in the head assembly. I saw somewhere that there are "pads" that the head is on but the posts didn't elaborate much.

I was machining far from the vice and piece so there was excess vibration that appears to have shaken something loose or out of original setting.
 
Check the gib screws. Some may have vibrated loose.
 
davidm said:
I was cutting a groove in aluminum and while moving the table along the x axis I noticed the groove was way off course. I stopped the mill and its showing it went off by 2+ mms. The whole head is now cutting crooked diagonally and is "north" 2 mms from where I started.

I have dro sensors on all the axes and none of them show anything having changed.

I trammed the head and its not off much. I know I was pushing it but without tearing the whole thing apart for nothing what could have happened?
Click to expand...
The best way is first use next size smaller end mill. Then come back and finish with correct size . Use table lock to keep the table tight as you mill just a little.

Dave
 
Was it tracking true prior to cutting the slot?

Tom
 
davidm said:
I thought the same thing but I can't find any looseness in the vice and the mill is reproducing the crooked cut on new pieces.
Click to expand...
Can you describe the crooked cut you are seeing in more detail?

If you lock the Y axis and feed the part along the X axis do you get a straight slot?
 
Welcome to the rabbit hole. You know what the real solution is. We all start out small ;)
 
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