Squaring the end of a 25mm sq bar.

[Alexander Gavin 1Participant @alexandergavin1]

Hello, I am struggling to square off the end of a 25mm bar on my small milling machine. The work is held parallel to the table in an engineers vice.

i have used the largest mill I have and taking cuts of about 3mm on each pass dropping the cutter for the next pass to eventually complete the 25mm depth of the work. I keep ending up with steps rather than one flat surface. Any help?

I have wondered about using a grinding wheel in place of a cutter but that has problems with grit.

 

 

 

[JasonBModerator @jasonb]

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.

 

[Alexander Gavin 1Participant @alexandergavin1]

Thanks for getting back to me. Looking at the video and what you said it looks like my spindle speed was way too low. I will give it a try.

Thanks again

Alex

[Bill PhinnParticipant @billphinn90025]

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?

 

[Howard LewisParticipant @howardlewis46836]

Since the workpiece seems to to be too long to be held vertically in the vice, tghe technique has to be, using an End Mill in a vertical millinbg machine:

Machine first flat to the required dimensions.

Rotate bar until the new face is vertical -check with a square.

Machine second flat.

Repeat, to produce a side parallel to the first.

Repeat to produce fourth side parallel to the second.

Deburr and job’s a good ‘un

Howard

[Howard Lewis]

On 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.

[Alexander Gavin 1Participant @alexandergavin1]

Hello all and thanks for your help, I’m going to try out your ideas when I next get a chance. Sorry if my description confused anyone.

I have a length of 25mm square bar, not rod, and want each end square, that is 90degrees to its length.

again for the help.

Alex

[JasonBModerator @jasonb]

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”

[Martin ConnellyParticipant @martinconnelly55370]

It sounds to me like the OP has his bar laid down in his vice and is cutting the end in 3mm steps from above down to the thickness (or diameter) of the bar. If you have a long bar and your cutters do not have a flute length of 25mm or more then this could be the origin of the problem. I think the best solution is a cutter with a flute length that can do the full 25mm in a single pass. A cutter that can only do this in 3mm steps seems unlikely but I am not ruling it out. I am sure Jason’s video above milling the end of a workpiece beyond the sides of the vice is what is needed.

Martin C

[mgnbukParticipant @mgnbuk]

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.

[Perko7Participant @perko7]

Depending how long it is, and assuming you have a sufficient size hollow spindle on your lathe, why nut chuck it in a 4-jaw and face off the end?

[Mark RandParticipant @markrand96270]

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

[noel shelleyParticipant @noelshelley55608]

Mark has one answer ! Another would be to centre drill,  3 or 4 Jaw, use a half centre in the tailstock and simply face it, then reverse and do the other end ? That the centre is not true will matter little. Noel

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