Wrapping 4th axel does not work - HELP

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Wrapping 4th axel does not work - HELP

Postby Idefixer » Tue Apr 30, 2019 6:05 pm

Hi.

I am using Vcarve Desctop and i have tried hundreds of ways to engrave with laser on a wooden cylinder mounted om a 4th axel.
I have set the drawing to Round working piece and set the diameter.
I then use a postscript for WINPC-NC and then I try to engrave on my GOCNC.
But every symbol or letter is wrongly engraved. A cirkel does not appear engraved as a cirkel. But if I instead use a flat surface and use a postscript for flat working piece, all symbols are engraved nicely.

So I wonder what can be wrong.

Anyone who has a clue?

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Re: Wrapping 4th axel does not work - HELP

Postby IslaWW » Tue Apr 30, 2019 6:55 pm

I do not believe that the Desktop versions support 4th axis rotary
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Re: Wrapping 4th axel does not work - HELP

Postby Rcnewcomb » Tue Apr 30, 2019 7:30 pm

Rotary is supported on VCarve Desktop. ->Link

You need to select a rotary post-processor. For you machine you will probably wan to use the "WinPC-NC ATC Rotary mm (*.nc)" post processor.
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Tue Apr 30, 2019 7:35 pm

Yes, I have done that but as the work is processed the engravings are missaligned and not correct engraved. First I thought that it had to do with non-straight lines, i.e. curves. But as I tried to engrave stars, they where missformed.
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Tue Apr 30, 2019 7:42 pm

I have both used the postscript that comes with Vcarve and I have edited it and saved this edited version as a local postscript. But neither of this postscripts gives me good result.

I have set my stepmotor to 1/2 step and with 400 steps the gear-mechanism turns 144 deg. So I have set 400 step per revolution and 144 deg as how much one revolution turns the axel. After testing 14400 deg turning, it stops allmost at the startingpoint.
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Re: Wrapping 4th axel does not work - HELP

Postby Rcnewcomb » Tue Apr 30, 2019 7:44 pm

and 144 deg as how much one revolution turns the axel

One revolution should be 360 degrees.
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Tue Apr 30, 2019 7:55 pm

yes, one revolution on the steppmotor is 360 deg but the gearbox has a 2.5x exchange so that the axel does not move more than 144 deg. So 1000 steps is one revolution on the axel and 2.5x360 deg on the stepmotor
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Re: Wrapping 4th axel does not work - HELP

Postby Rcnewcomb » Tue Apr 30, 2019 11:31 pm

If you give your machine a command of
Code: Select all
G1 A360

what does it do? Does it rotate the material 1 revolution?
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Wed May 01, 2019 11:01 am

Yes it turns the axel 1 revolution 360 degrees
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Re: Wrapping 4th axel does not work - HELP

Postby TReischl » Wed May 01, 2019 1:00 pm

So, what does "wrongly engraved" look like?

What are you expecting things to look like?

This is a circle in rotary:

Capture.JPG


Sure does not look like a circle.
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Wed May 01, 2019 1:55 pm

IMG_1018.JPG

IMG_1019.JPG

IMG_1017.JPG


This is picture of the engraving in ´Vectriv Desktop, both the drawing and the preview.
And then the engraving on a wooden stick.

This example can be much worse. For instance a circle can more look like an "e".
And a star can have one leg totally miss-engraved.

And it looks like if I want to engrave a line of letters, they most likely will not be engraved on a straight line.
A very enoying thing :-(

IMG_1021.JPG

IMG_1020.JPG


I have filled the engraving with a pencil to make it more clear where the engraving took place.

Can I have problem with my 4th axel/stepmotor so that it misses steps? I have pulled down the feed but can I do some test to see if that is the problem?
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Wed May 01, 2019 1:59 pm

One more thing.

When I do jobs on a flat surface, and restart a job, the milling/engraving is very exact and hits the same track´on the working piece.

But when I do the same with a rotating axel, the restarted job never hits the same track again. So If I do 4 exactly same engravings, they will all be separated.
On a flat surface this would not happend.

Any ideas?
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Re: Wrapping 4th axel does not work - HELP

Postby ger21 » Wed May 01, 2019 2:39 pm

Looks like your rotary axis is losing position.
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Re: Wrapping 4th axel does not work - HELP

Postby Idefixer » Wed May 01, 2019 3:00 pm

Is this something correctable in software or is it mechanical and can not be fixed?

It looks like the smaller circular movements the greater loss. If I only engrave squares, they are fine but if I put some figure together with them, all starts to be missplaced.
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Re: Wrapping 4th axel does not work - HELP

Postby Rcnewcomb » Wed May 01, 2019 5:04 pm

is it mechanical

This seems like a mechanical issue. You need to get your machine to behave in a repeatable fashion.
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