Poor surface surface finish milling steel

[Dave HalfordParticipant @davehalford22513]

Isn't side milling supposed to be approx. the radius of the cutter in depth so for the 6mm dia cutter three passes would be required for 10mm thick work.

[s dParticipant @sd79178]

Posted by Martin Connelly on 05/07/2023 11:42:30:

Anything that can be done to stiffen the process will help so if all the none moving axes are locked and the stick out of both the spindle in the head and the tool in the collet is reduced to the minimum then the next question is are you tightening the tool in the collet sufficiently to reduce flex. If you are not using a ball bearing ER nut and suitable wrenches to put high torque on the nut and therefore high pressure on the tool shank then the tool position may flex slightly in the collet holder.

Martin C

Two wrenches as as much as I can tighten it. Could it be the er32 collet holder itself? The machine came with an mt3 keyless chuck…. I could try that instead, or is that a terrible idea 😂. Running out of things to try.

Edited By s d on 05/07/2023 12:51:34

[s dParticipant @sd79178]

Posted by John Doe 2 on 05/07/2023 12:32:37:

Ah, fair enough.

Do we know then, if the milling bit is true and regular ? – is it possible to check each flute "diameter" with a DTI? – perhaps one is slightly proud compared to the others.

In the same vein; does a DTI show any bend in the driving shaft, as measured against the side of the cutter as it is rotated through 360°.

.

Edited By John Doe 2 on 05/07/2023 12:33:28

Runout on the spindle is very good but there is more in the collet holder. Used multiple tools and get similar result difficult to isolate as I only have a keyless chuck alternative. There is flex in the column too.

[JasonBModerator @jasonb]

Posted by Dave Halford on 05/07/2023 12:35:41:

Isn't side milling supposed to be approx. the radius of the cutter in depth so for the 6mm dia cutter three passes would be required for 10mm thick work.

Most makers that publish cutting data tend to show 1D to 1.5D on their 4-flute cutters so two passes at the most when also using the usually published 0.1D stepover.

It is possible to use more Ap (vertical) depth if the Ae (sideways) stepover is less particularly for the 5 or 6 flute finishing cutters.

Don't try the drill chuck

The irregular pattern would seem to suggest flexing somewhere rather than a regular pattern that could be attributed to runout.

Edited By JasonB on 05/07/2023 13:10:58

Edited By JasonB on 05/07/2023 13:14:19

[s dParticipant @sd79178]

Posted by JasonB on 05/07/2023 13:08:50:

Posted by Dave Halford on 05/07/2023 12:35:41:

Isn't side milling supposed to be approx. the radius of the cutter in depth so for the 6mm dia cutter three passes would be required for 10mm thick work.

Most makers that publish cutting data tend to show 1D to 1.5D on their 4-flute cutters so two passes at the most when also using the usually published 0.1D stepover.

It is possible to use more Ap (vertical) depth if the Ae (sideways) stepover is less particularly for the 5 or 6 flute finishing cutters.

Don't try the drill chuck

The irregular pattern would seem to suggest flexing somewhere rather than a regular pattern that could be attributed to runout.

Edited By JasonB on 05/07/2023 13:10:58

The pic with the face milling on the same side has a section that was side milled and is 6.5mm deep. It was done either with the 10mm or 6mm tool. I think it probably does get worse with deeper cuts but it's always there.

Just measured the flex again between the table and the tool, its about 0.015" (my indicator is imperial) easily with 1 hand levering against he vice, with two hands its 0.003"/0.076mm in x. About the same or a little more in y.

Similar reading from table to spindle and pulling on the top of the column maybe abut 0.004. No lose column bolts, all are very tight and there are no cracks in the paint between the column and base (nice that they painted it after it was assembled, including the allen bolts!).

I only get a tiny deflection if I try to man-handle the table in this setup.

IDK if this is significant or totally normal but the spindle-to-head flex is barely measurable so don't think its bearings. Or course there's a lot of leverage on the column.

Don't know what else to do.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by s d on 05/07/2023 13:55:42:

[…[

Just measured the flex again between the table and the tool, its about 0.015" (my indicator is imperial) easily with 1 hand levering against he vice, with two hands its 0.003"/0.076mm in x. About the same or a little more in y.

.

0.015” sounds WAY TOO MUCH … is that a typo ?

MichaelG.

[s dParticipant @sd79178]

Posted by Michael Gilligan on 05/07/2023 14:26:00:

Posted by s d on 05/07/2023 13:55:42:

[…[

Just measured the flex again between the table and the tool, its about 0.015" (my indicator is imperial) easily with 1 hand levering against he vice, with two hands its 0.003"/0.076mm in x. About the same or a little more in y.

.

0.015” sounds WAY TOO MUCH … is that a typo ?

MichaelG.

Yes it is… thanks! Will edit it.  Can no longer edit.

Should read 0.0015", sorry.

Edited By s d on 05/07/2023 14:28:21

[Michael GilliganParticipant @michaelgilligan61133]

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