Face mill finish

[Edward]

Hi guys,

I've just bought a Glaze 50mm 90 degree face mill. I've never used a face mill before, so I don't know what finish to expect. As you can see in the photos, the tool marks are showing, but they are very fine and I can't feel them at all with the finger. Using a Scotch grey polishing pad, they completely go... to give you an idea. The "join" line of the step over is completely level around mid way, but I can just feel the tiniest of raised level at the beginning and at the end.

In other words, the narrow band is slightly higher at both 1/4 ends of the piece, but completely level in the middle. It's pretty minute anyway.

My questions are:

-Are the tool marks to be expected, as I say, I can't feel them, so I think that's pretty good, but is it possible to improve, as in...can one get a mirror finish with a 5 insert face mill, or is this as good as it gets?

-How do you explain the slightly raised level at the step over line, and only at the ends? I thought maybe to do with tramming, but then this would only be evident on one end and not both? The piece is only 60 x 60mm.

The feed was constant, 500mm/min at 1700rpm. Many thanks

Edward

[JAZZCNC]

Tool marks are to be expected to some degree but the raised edge is simply because your spindle is out of Tram. Wider the tool the more it will show how far out your spindle tram is. You've most likely not seen this before due to using smaller tooling but soon as you go wide any errors show up.!

Getting a mirror Finish is all about feeds and speeds and material along with whole load of other factors like machine ridgidty, coolant etc only thru trial and error will you find the right combination, if at all.! . . No one can give you magic numbers to achive this.

[Edward]

Tool marks are to be expected to some degree but the raised edge is simply because your spindle is out of Tram. Wider the tool the more it will show how far out your spindle tram is. You've most likely not seen this before due to using smaller tooling but soon as you go wide any errors show up.!

Getting a mirror Finish is all about feeds and speeds and material along with whole load of other factors like machine ridgidty, coolant etc only thru trial and error will you find the right combination, if at all.! . . No one can give you magic numbers to achive this.

Thank you, Dean. Off I go to tram that mill then. I am not too worried about the minute toolmarks, as you can't even feel them. But the raised edge is something I have to sort out.


Edward

[Edward]

OK, I've now trammed the column to be perpendicular to the table. I just shimmed it to one side (for the X) and slightly towards the back (for the Y). I am pleased to say that the step over raised edge when using the face mill has completely gone, so the piece is now completely flat. A pleasant achievement.

However, one problem still remains. The Sieg SX2.7 has a fixed head, it can't be rotated, unlike the X3. This means that while you can shim the column to be perpendicular to the table, the spindle may not necessarily be perpendicular as well.

In other words, it doesn't follow that both the spindle AND the column are parallel to each other and in turn that BOTH are perpendicular to the table.

So I did the typical spindle tramming, with an indicator set on a radius of 150mm and lo and behold, when measuring both sides along the X, there was a disparity (even though the column and table are perpendicular).

This probably accounts for the slight face mill circular marks, as the facemill is engaging the piece at an angle as it's not perfectly horizontal to the piece. Since the tool marks are at the trailing half of the face mill circle, this probably gives me a clue as to which way the tool (i.e. the spindle) is tilted.

This poses a new problem....how do I tilt the spindle? I am not sure if it will be possible to shim it, first I have to find out how to take the spindle out, etc...


But before I do so, and find the hard way, is there anyone with knowledge of similar machines who can tell me if there may me some slack in the spindle housing that will allow me to tilt it slightly, or any other suggestions? Or do I just have to live with it?

Edward

[Robin Hewitt]

So your Z axis is not your spindle? Tricky. How far out is it?

[Edward]

Hi Robin

This is not a router. I should've mentioned that the head is fixed.

The head cannot be tilted or rotated unlike other mills as it's a cast iron block with the dovetails machined into it. So the only thing I can think of is somehow tilting the spindle itself, but it may be tightly enclosed in its housing so that there is no room to shim it to one side.

With a 300cm diameter and the spindle as a centre, I think there is around a mm. tilt on the X. I didn't measure it precisely because I got a shock when I found this and I am still recuperating:)

Edward