Squaring the Column of Your Mill

[BobWarfield]

I did this a few weekends ago but only got the pix off the camera this evening.

Before attempting to square the column, you will want to level the mill table. I measured the column squareness before and after leveling, and there was a substantial difference, as much as 10 thou in one direction!



I used a Starret machinist's level for the job.

The idea behind squaring (which is different than tramming) is to get the column ways square to the table so that when the mill spindle moves up and down in Z, there is no change in the X, Y coordinate of the cutter tip. It just moves exactly perpendicular to the table. As you can imagine, this makes a difference!

The easiest way to check squareness is to use a cylindrical square, though many other references will do. I first checked for "nod" to make sure the column wasn't leaning forward or backward:



Put the DTI in the spindle and the cylindrical square directly behind the spindle and then sweep by moving the head up and down. You don't want your needle to move!

Next you need to measure the left/right leaning of the column:



Same drill, sweep the head up and down.

I was pretty close after leveling, and I used shim stock under the column base edges to bring it to within the couple tenths I could measure. I needed 3 thou for the "nod" direction and 1 thou for left/right. It won't stay accurate to tenths like that, but it should stay well under a thou.

For good measure, tram the head too right after.

Here is an alternate approach if you don't have a cylindrical square I saw someone else use:



Got a few other posts to make as I get the pictures processed!

Cheers,

BW

[Kipper]

Looks like a bit of Bill Todd's work...He's not a daft lad!

So did you make the tube on a lathe or buy it...... I'd hope you made it and not bought one to set a single mill up....

[EvanVH]

Yea that cylindrical square sure makes checking the perpindicularity easy.





Evan

[BobWarfield]

Kipper, it's a Brown & Sharpe I believe. eBay is my friend, LOL! $69, if I recall.

I don't hesitate to acquire metrology related items even if seldom used. I have eventually used all of them more than once. In this case, the cylinder is my master squareness reference, so it is dragged out more often than a lot of things.

Cheers,

BW