precision tuning

[David Grubmair]

Hello guys!

At first I'd like to thank you for your hard work and the joy it was to build this thing!

I have built a reprap cylone and it took quite a long time since i'm on a low budget as student. My build version is v0.9.7. Now that everythings finished i don't seem to get good results, and i don't really know what i'm doing wrong..

As one of my first projects i tried to mill out a pic programmer available on http://www.obddiag.net/picprog.html. Autoleveling works fine but when i try to mill, the traces seem to be to thin. Because the bit is "jumping" inside the other trace. It seems to have something to do with stability or feedrate?

The Feedrate is set to 80 mm/min and the milling depth is 0.8 mm with a 60 degree, 1mm bit. 

I'm using this spindle: ebay powered by 44V 2A supply. Maybe I'l need a better supply?

I have seen other who were milling smt traces, so why isn't that working? (I'm a little bit jealous.. :D)

Thanks in advance and keep on working on that great project!

David

[David Grubmair]

Oh and I forgot to introduce myself.. ;)

My name is David and I'm an electrical engineering student from Austria. I am tight on budget, but i managed to build v0.9.7 up and running.. :) Thanks for this great project!

[Steve]

David,

 

Your cuts look pretty deep in the pictures I am not sure of the specs on your cutter

But I use 60 degree V-bits with a .2mm flat. I would try a cutting depth of -0.35 to -0.40

That would give you a cut width between 0.035 to 0.046. On other thing is watch you

Captive nut on the z=axis to make sure its staying captive I found that my print caused

This nut to be loose in the space for it, in my case I glued it in with some abs slurry so

It cannot move.

 

The thickness of you copper layer depends on the board itself this is a chart taken

I think from a forum post that shows copper thickness based on copper weight.

 

0z/ft2    mm        in            mil

0.5         0.0175   0.0007   0.7

0.75       0.0255   0.0010   1.0

1             0.035     0.0014   1.4

2             0.071     0.0028   2.8

3             0.105     0.0042   4.2

 

 

Also from the forum is this chart showing cut width against cutting depth. If you are using a 1 oz copper board and cutting at 0.035 then the cutting width for

Your 60 degree bit should be around 0.035 mm.

 

I would also suggest cutting back your feed rate to maybe 40 mm/min to start out until you know how your machine does then start bumping up the speed

As you get familiar with it.

 

Hope this helps

 

Regards,

Steve

 

73 de ve3sjk

 

 

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[Samuel Kranz]

Hi David, 

As ve3sjk said you're milling very deep. I used to mill with a depth of 0.15-0.2 mm (30° bit). Since you're powering your spindle with "only" ~100W I would also suggest to reduce the feedrate, seems your spindle has trouble milling that deep (you can see this in the middle of your pcb - the wavy part - I suppose these should be round).

good luck :D

[David Grubmair]

Thanks for the good advice, i really think that could help.. :)

It seems the whole process is a lot like try and error. 

I'l try it after my courses today and then hopefully get good results.

[David Grubmair]

Hello again.. =)

I have now double checked the parameter which i have adjusted.

And I have seen something strange: the milling depth is set to only 0.08 mm in pcb2gcode?

​

Then it must have something to do with the autolevel settings. I double checked them also, but I didn't find something wrong:

So there must be be a Offset added anywhere, which i don't know.. :/

Oh and i have to mention that i have no endstops installed, could that be a problem?

I'm simply "homing" to (0,0,0).

I have already ordered mine, but they take a long time from china.. ;)

Thanks in advance! =)

David

​

[Carlos García]

Hi David, do you start the probing routine with the tool at Z=0? If that's the case try to move it higher before running the probing.
Normally I home XY and leave Z high, it is corrected when probing or with the "zero tool" button

Cheers,
Carlos

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[David Grubmair]

Hello again! =)

Thanks for the responses, and after the last exams i now have some time to work on the cyclone again. I have now installed the chinese endstops and after some fiddling,

they work great. I also made a wooden enclosure because my neighbours have complained. :D

@Carlos

Before I start my probing routine, i always home X,Y and Z Axis. Below is a picture of my probing results.

​

To me, these values seem to be to far away, because there is about 0.4 mm difference, is that normal?

If I set the milling depth in pcb-gcode to about +3 mm, the milling depth is only touching the surface. This means that i have an offset somewhere, I don't know about??

Thanks for the great help and the ongoing work.. =)

Cheer's

David

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[David Grubmair]

Hey guys!

It's me again.. :) Thousand thanks to you Carlos!! 

I did exactly the same as everytime, except that I don't home the Z axis before the milling and the probing process!

And it works, I can't believe it.. =)

Could you explain to me, why I don't have to home the Z Axis?

Anyway thanks to all of you who helped me here.. :)

Cheer's from Austria

David

[Carlos García]

Oh I am very sorry for not replying on time. Great that you could fix it!

Basically the Z axis is homed (Z=0) at the top of the material. This is done automatically when pressing "auto-level", at the bottom-left corner.

But if you do it previously (manually) it will confuse the system, as the tip will already be in contact with the material. It can only home Z if the tool is lifted above the material initially.

Cheers and sorry again for the delay!

Carlos

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