Struggling with DXF and Lasercut 5.3

[Howard Smith]

Hi

I'm just going to throw this out there in the hope someone has come across it before.  

I'm a newbie and looking to use the laser cutter to produce sets of wing ribs in balsa, thus removing the need to cut ribs individually.  I've done the induction and produced lots of rabbits in plywood.  It's brilliant.  I've also cut a hackspace logo or two using balsa and the accuracy is phenomenal.  

I use software called Profili Pro 2 to computer generate sets of ribs with all the slots for spars and lightening holes etc.  This output to a DXF file which sounded perfect.  However on the induction evening, importing a DXF file of one rib into Lasercut 5.3 did not render the lined image onto the blue bed screen.  

I've loaded Lasercut onto my home computer and started to experiment.  The Profili forum suggests the DXF it produces is in 3D and Lasercut is perhaps not converting that to 2D for cutting; but they know nothing of Lasercut.  I've downloaded DoubleCAD XT which does import the Profili XT without issue.  However saving using the multitude of different DXF formats does not bring the file into Lasercut with any lines.  

I'm at the stage where there is no such thing as a silly suggestion (apart from give up).  It could be me just doing something really stupid.

Attached is an example file.  Any help gratefully received.

All the best

Howard

[Kirsty]

Could it be worth running the file through something like 123D Make? http://www.123dapp.com/make

[Owen]

When I try and open your DXF with Inkscape I get the following message (maybe this will be helpful?):

78 ENTITIES of type POLYLINE encountered and ignored. Please try to convert to Release 13 format using QCad.

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[Matthew Gates]

DXF has lots of versions, and different programs seem to support
different versions more or less well. In your CAD program you might
have an export or save as option which allows you to specify which DXF
version you are exporting in. This might also be in the program
settings - you'll have to have a hunt around or google it to know.

Inkscape's save as DXF v14 seems to work OK with the laser cutter,
although you still have to do things like convert objects to paths and
try to remove duplicate vertices to make it work properly.

If you do find out what settings are needed with your software, please
do write it your workflow and put it on the wiki - it's really helpful
to others to know what workflows are good.

Mouse

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[Martin Farraway]

Hi Howard

Try this

Blue is cut and magenta is etch

Martin

[Howard Smith]

Thanks for the advice Kirsty.  I'll add that to the list.

[Howard Smith]

Thanks Owen,

I've now downloaded Inkscape; wow what a fantastic piece of free software.  Have imported the file and got the same message as you.  Consistency is always good.  Have now downloaded QCad, opened the file in that and exported it into Lasercut.  The ribs now appear so we are moving forward.  

However when I click on calculate, it reports the error 'Overlapping data found, please check data and output!'  

I'll have a dig around to see if anyone else has had the same problem.

Thanks again 

Howard

[Howard Smith]

Thanks Mouse,

I'm learning loads.  It certainly looks like DXF is a standard of many different standards.  I'm with you, it is certainly a versioning issue.  Some feedback from the Profili forum (the software that produced the original DXF) states their software generates a 3D DXF file.  

Thanks

Howard

[Howard Smith]

Thanks Martin,

That looks good.  How did you do it though?

All the best

Howard

[Martin Farraway]

Hi

I opened it in cad, when I selected a line the whole part become selected.
I learned this the hard way when I did the same sort of thing with arrays.
If you select something and thing is selected it is an object, so I selected all and exploded all objects into individual components.
Lazercut will not recognise objects but once broken-down into plane, line etc it's all good and Lazercut is happy again.
Also Lazercut don't recognise layers so just colour each layer a different colour. Thus way Lazercut will separate the colour giving your layers back for different functions (cut, etch etc).

Hope this makes sense.

Martin

[Howard Smith]

Hi Martin,

Some of that makes sense.  I probably need to do some more reading.  When you say you opened it in cad, which cad package was it?

Thanks again

Howard

[Martin Farraway]

Auto desk Autocad

[Owen]

Have you used the 'unite lines' tool in laser cut?

Inkscape is pretty cool once you get used to it.

It's definitely worth adding this to the wiki for future reference. :-)

[Howard Smith]

Thanks Martin,

Looks like I have done the same thing with QCAD.  Time to get down to the Hackspace and try some tentative cutting.

Thanks

Howard

On Friday, July 1, 2016 at 11:10:43 PM UTC+1, Martin Farraway wrote:

Auto desk  Autocad

[Howard Smith]

Can I just give a huge thank you for all the help provided by members of this group.  I'll add some closing notes in case anyone treads this path in the future.  

Profili Pro airfoil generation program uses ProfDev to render and export wing ribs.  I never got to the bottom of which version of DXF it produces but was told it is 3D.  The solution used (others will be available) was to load the file into QCAD. The free version of QCAD requires you to restart every 15 minutes but this is ample time.  You select the ribs and on the tool bar to the left, click on the Modifications Tool button, followed by the explode button.  Save the file as DXF R14 (others may work, perhaps better) and ignore the message.  Import the file into Lasercut but don't bother calculating because it will throw an error message.  On the menu bar use tools, unify lines (thanks Owen) and accept the default. 

If through Profili you included rib numbers, then you will have a problem because the unification makes the letters go wrong and it won't calculate.  Either delete the rib numbers through Lasercut or don't bother to generate them in the first place.  Add rib numbers using Lasercut and the 'A' button.  Don't forget to assign these a different colour (layer) so they can be engraved.

It should now calculate and you are ready to go.  There is probably a better way to do all of this; I'll keep exploring.

If, like me, it is the first time to use the cutter there are a few gotcha's worthy of mention.  I uploaded the file to Lasercut and it positioned the ribs way outside the on screen bed grid.  Being unfamiliar I failed to spot this and it generated a 'soft stop' error when loaded to the cutter as it was outside of the cutting bed.  Simple fix once you know, drag the ribs onto the screen bed grid and download (upload) it again to the cutter.  

It's always worth doing a test to prove the cutter is going to work on the area you are expecting and you don't have the wrong file downloaded.  For me the box it drew suggested the plane being built was full sized rather than a model.  It fitted on the sheet so having checked the correct file had been downloaded I decided to cut with it.  The ribs were the correct size but after cutting them it then started to cut a perfect box around the perimeter of my balsa.  Ironically one of the perfect ribs had been flipped over by the pulse of air and subsequently got cut in two as it fell into the path of this box.  After some head scratching it turns out that Dev Prof draws a notional line to represent the size of sheet you stated.  It's an easy fix, back in Lasercut, click on this box (you may need to zoom out) and press delete (download again).  What this did highlight was the importance of keeping an eye on the job and being ready to pause the job if a piece does get blown out into the cutting path of another part.  It allows you to lift the hood, carefully remove the offending part and resume (with the hood down).  

I have to admit my engraving did not come out as expected.  On that layer you have to specify the power and speed, and not knowing, I made them the same as cutting.  Well it cut the writing out rather than etched it, and although not the required result, it does look awesome.  There are sheets of wood and perspex to the left of the computer which gives examples of power settings for engraving.  

What was the end result like?  With a low power setting (18) on 3/32" light quarter grain balsa it came out perfectly with no burn marks and it was 100% accurate.  Much better than hours spent squinting over a scalpel and cutting mat.  

Thanks again for all your help

Howard

[Owen]

Awesome!

When you get a chance adding this to the wiki (https://wiki.nottinghack.org.uk/wiki/Laser_cutter#Other) would be excellent for future reference (people often get pointed to the Wiki instead of the Google Group as a source of information like this).

Another trick to stop the "scorching" of the underside is to "line" it with masking tape (or lying the object being cut on a "bed" of masking tape).  The tape gets the scorching and pulls off leaving a clean cut behind.