Question Streifen im Endergebnis

Ich lese Deutsch, ich spreche (ein wenig) Deutsch, aber ich kann kein Deutsch schreiben.
And I write here because it is *much* more active than other language forum groups.

I am playing with F-Engrave to do some inlay work, testing on some scrap bits of plywood first.
The end results have stripes on the top. (This is not new for me, I have seen it in other results too, but now I want to remove it as much as possible.)



The lines are mainly visible, you can `just' feel it.
In the photo I lightly sanded the surface and used some mineral oil on it.
I do not want to use sandpaper to take it all away. It feels counter productive for the fine inlay details, that will get sanded too.

I can inmagine several causes for this like:
- The bit is not 100% aligned with the Z-axis (possible).
- The stock is not riggidly fixed to the machine, the same argument goes for the spillboard (possible).
- The machine (420+performance kit for double Y-axis drive) is not 100% stiff and rigid, there is some flexing. (How to check?)
- Some backlash in the machine (How to check?)

Does anybody recognise this problem?
What is the best way to improve on this?

Kind regards.

You don't tell us which size your work-piece and which diameter your planing tool had, but I think "just feel" is the problem. ;o)

Most likely the problem is, that the tool is not 100% perpendicular to the surface in one or both axes (X and/or Y). When milling one line the tool goes slightly deeper into the material than on the opposite side. With the next line the high and low side sit next to each other, which is much more visible than it can be felt - at least in wood.

As you also did not say anything about the way how it's been milled (do the lines go X or Y direction? How big was the overlap? ), here is some wild guess-work.
possible causes:
Endmill is not sitting perfectly straight in the Motor.
Motor is not sitting perfectly straight in the tool-holder, where one side lifts up a bit. (Might happen due to thicker paint) Recently there was another thread which complained about a tool adapter which was not sitting straight in the tool-holder.
Portal is not parallel to the table (right side just a bit lower/higher than the left side).
The machine table cover layer (?spillboard?-dictionary did not find a translation) has not been planed.

So, if you have a square, you can start checking perpendicularity starting from table/endmill in both directions (X/Y) and then track it down to the root cause.

PS: Backlash is not the problem for that kind of lines, but having a closer look at the circle ... there might be a backlash problem on top. If things are not fixed well enough, I'd expect not to see any straight line being milled.

MagIO2 wrote: You don't tell us which size your work-piece and which diameter your planing tool had, but I think "just feel" is the problem. ;o)

The object in the image is 120 by 60 mm, the inlay in the middle is 80 by 20 mm.
About the `feeling', on the left side it is smooth and I can feel nothing, on the right side,where the stipes are more visible, I can just feel it. measuring the difference between a low and a high at the right side gives me an indication of about 30 micrometer difference (just a quick measurement).

MagIO2 wrote: As you also did not say anything about the way how it's been milled (do the lines go X or Y direction? How big was the overlap? ), here is some wild guess-work....

Your remarks are very much appreciated and I will follow it up.

Milling was done with a 10 mm endmill at roughly 13.000 rpm (at the #2 setting of the MM-1000).
The path was from left to right to left again in a zig-zag mode with 50% overlap.

MagIO2 wrote: possible causes:
Motor is not sitting perfectly straight in the tool-holder, where one side lifts up a bit. (Might happen due to thicker paint) Recently there was another thread which complained about a tool adapter which was not sitting straight in the tool-holder.

I know for certain that the motor is not always in the same position after replacing it. I have seen it before and since then I'm carefull in checking that the motor makes good contact with the plate it rests in but there is no guarantee that it is level.

MagIO2 wrote: Endmill is not sitting perfectly straight in the Motor.
Portal is not parallel to the table (right side just a bit lower/higher than the left side).

Good points, didn't think of that yet.

MagIO2 wrote: The machine table cover layer (?spillboard?-dictionary did not find a translation) has not been planed.

It was planed,... some time ago. Another point to check.

MagIO2 wrote: ...
PS: Backlash is not the problem for that kind of lines, but having a closer look at the circle ... there might be a backlash problem on top. If things are not fixed well enough, I'd expect not to see any straight line being milled.

I did some cleaning afterwards and where the circle meets the rectangualr some cleaning was required and the depts were very shallow. Also, the inlay part had some tiny breakout at that point. So, what you notice might be introduced manualy by me.

Also, I run a Square-Diamond-Circle test at regular intervals, just to monitor general behaviour and to notice when (unexpected) changes appear. And this problem does not show up there.

One more ... the portal could be tilted just a little bit. If the lines are higher in the front- and lower on the back-side it means that the portal is tilted upside backwards.
That's the problem with the fact that all parts have tolerances. Tolerances make things cheaper, but you have to be more careful when assembling the parts.

In the end the big endmills make the problem more visible, than a smaller endmill would do.

If X- and Y- are perpendicular, you could mill a big square or a parallel to check that the portal is adjusted correctly in relation to the machine-bed.

MagIO2 wrote: One more ...

In the end the big endmills make the problem more visible, than a smaller endmill would do.

Again, thanks for the advise.
The way I see it now is that the end of the bid must be paralel to the bed and also must travel paralel to the bed. There are at least five different items to check.

About tollerance:
This will be game maker. It is not possible to take that out or to reduce it. (Other than buying a professional machine with far better tollerance, which is way out of my budged).

First I will have to measure what the actual allignment is and then see what I can do about it.
After I have done something I still must measure if it has the desired effect but also if it is stable over time.

I will report results (and problems on the way) here but it might take some time.

Kind regards, André.

Hallo,

sieh Dir mal dieses Thema an.

www.stepcraft-systems.com/forum/zubehoer/6524-problem-mit-dem-20mm-adapter-schiefe-achse#59081

Vielleicht könnte das die Ursache sein.

Gruß
Achim