Rather than coming down in small stages with the cutter use more of the side of it.

Make sure all other axis are locked and the cutter is sharp, come down say 6 to 8 mm but only have sideways cut of about 0.25mm

If your small milling machine has electronic variable speed it will also benefit from using a smaller cutter so the spindle speed can be increased Try a sharp 10mm dia HSS cutter at 1200rpm and feed at 300mm/min.

I assume mill is trammed OK, even if not a smaller cutter will help.

What milling machine are you using (i.e. how “small”)? What is the diameter of the cutter you’re using? Are its cutting flutes at least 25mm long? Is it sharp? Are you locking the table for each cut?

On 30 January 2024 at 20:09 Howard Lewis Said:

 

Repeat to produce fourth side parallel to the second.

Deburr and job’s a good ‘un

Howard

The OP says he wants to “square off the end of a…bar”, Howard. I don’t read this as him wanting to make square stock out of round stock. His bar may be square section already, for all we know.

Alex, what mill and cutters are you using as small to one person is a reasonable size to others. The SX2.7 in that video is a mid sized benchtop machine and would still be regarded as small by those with more industrial machines. If the same size as an SX2.7 than you should be able to take off more metal than I suggested and depending on cutters run an even higher spindle speed.

This is the same mill with a 10mm dia 3-flute coated HSS cutter 10mm vertical DOC and 1mm Horizontal DOC. Running at 1850rpm and feed of 120mm/min. Probably about the most I’d want to do in a single pass and right at the top of the speed, taking it down to 1500rpm and 100mm feed would be better for everyday use. Notice it produces clean long chips not a pile of dust

I’ve also altered the title as I too at first thought you wanted to create a square on the end of some bar. But did twig when I saw “25mm depth”

Is the milling machine spindle truly perpendicular to the table ?

This can be checked by swinging a DTI on an arm held in the spindle against the table top – sometimes known as a “trammel check”. Having the spindle tilted slightly will leave steps in the workpiece.

This check should be carried out after confirming that the column is perpendicular to the table.

Nigel B.

In the apprentice training school at work, this would have been an exercise for squares, scribers and files! 😀