edge finish - ripples and ridges

[dsc]

Thanks Jazz. The other issue is that the parts were suppose to be 15mm +/- 0.1mm, but are in fact 15.2mm - 15.25mm. Any chance of bringing them down to 15mm, so taking 0.2mm of the top?

The ripples are only visible on a single edge on one part, so not a biggie, but the ridge is present in more than 50% of edges.

Regards,
dsc.

[JAZZCNC]

The other issue is that the parts were suppose to be 15mm +/- 0.1mm, but are in fact 15.2mm - 15.25mm. Any chance of bringing them down to 15mm, so taking 0.2mm of the top?

If your asking me can I take material off for you then sorry no can't for reason's won't go into here.

But if your just asking if think it's possible then yes they just need skimming over with fly cutter.
To be honest if cut from rolled Alu plate then chances are it's not truly flat so would need both sides skimming and with only 0.2 to play with then would be touch and go if you'd have enough material to cleanly do both sides.

If you mean 0.1-0.2 oversize and can profile shape be machined to dimensions then yes it's possible but very difficult and timely to re-position on machine to such fine tolerance.
It would need 2 or 3 good clear reference points to work off and lot of messing around with positioning into correct place because with only 0.1-0.2mm to work with there's no room for error.!

[dsc]

Simply curious if it's possible to skim it or not, but I guess it's just not worth it at this point.

Another question I've got is slightly out of topic for this thread, but I'll go ahead and ask anyway. I have a bearing housing which seems to be the correct diameter if measured across x axis, but 0.1mm smaller when measured across y axis. What would cause such an error? runout on a lathe? it simply seems elliptical rather than round.

Regards,
dsc.

[Jonathan]

That's a clear example of trying to cut faster than the machine, or tool, is good for. The wavy lines could also be caused by severe resonance ... either way a finishing pass would have sorted it out.

I could skim the parts for you, but it's not a quick job unless they're quite small.

I have a bearing housing which seems to be the correct diameter if measured across x axis, but 0.1mm smaller when measured across y axis. What would cause such an error? runout on a lathe? it simply seems elliptical rather than round.

Backlash, or more precisely - greater backlash in one axis. Bearing housings should really be bored, not milled, since even if you have a rigid machine with zero backlash the pocket will end up something other than a circle. The bore doesn't have to be out by much for you to either just have a loose fit, or worse distort the outer ring of the bearing causing it to wear prematurely. If I'm cutting a part on the CNC Router which includes a bearing, then I generally either bore it completely on the lathe or if it's a big bearing mill the pocket to 0.5mm undersize and then bore it.

[dsc]

I would really only need skimming two parts as these are the plates where the the variable thickness adds to the overall depth of the whole construction and makes the side mounting holes move out of alignment.

As for the bearing housing, this was done on a lathe :O

Regards,
dsc.