ROBERT BURLACE

No need to generate a Gcode as such with Lightburn. It can talk directly to your laser using gbrl. Inkscape can save and open dxf, Dwg, svg, pdf, amongst others.

My experience with benbox lasted all of 30 seconds when I realised just how useless it probably was. It is really a program for etching rather than cutting but the UI is terrible. Lightburn is fairly intuitive and allows you to do quite a lot. I do mainly use it for running the cutting, while Inkscape helps me to draw, design, take measurements, etc. Honestly they do everything between them that I think we could wish for in doing what we do. Try the Lightburn free trial. No changes to your hardware, no. I presume you have done all the initial trouble shooting.... wire connections etc? Were your stepper cables connected and tidied away securely? Possible the laser has cut one if not?

Ahhh Ok- not sure how much of a difference it will make to your overall cutting time, but if you drop cutting speed down to something more like 120-180mm/minute it takes fewer passes.

Additional thought- the fumes from MDF are not pleasant or good for you. I would suggest a swap for a piece of softwood ply for your waste board when you get round to it. Still not great but the resin in mdf is mean stuff.

Posted by chris larkins on 25/10/2019 11:33:32: Success, I did as Robert suggested and tried again but this time raised up on 8mm rails, this time the parts dropped through once cut. Great stuff, glad it worked for your Chris. How many passes were you down to? What software are you on? If using Lightburn there is a setting in the device settings called “smax” this seems to default to 250 but can in fact be set to 1000. It controls the maximum power of your laser. The power on cut settings is relative to your smax setting. You may not be getting what you think is full power. Where did you find the plan? I do like Peter Miller’s models.

A small blower will definitely help I use a pond air pump and machine lubricant hose - the fan behind probably isn't directional enough to clear debris from the cut path. In addition, try raising your material off the cutting bed. I use 10cm long pieces of aluminium angle. Air is a better insulator than wood, so will stop some of the energy being conducted out of your cut piece. In addition it will reduce the distance from the laser to the piece, increasing the intensity of the beam (assuming you can focus it at that distance).

Thanks Allan, that’s what I thought- just nice to have confirmation. It’s easily done with the laser cutter. Rob

Hi everyone, Sorry for my inactivity for a couple of weeks, the rugby has meant I haven't done much. How are those of you who are trying it out getting on? Setup instructions are a little vague but I found youtube to be my friend. I think we're all pretty technically minded so you won't struggle with it. Take care not to crack any of the acrylic. Belt tensioning with the stock parts isn't very good....there are alternatives available for anyone with 3d printers, or ooznest.co.uk are pretty good. A bit of an update on my spitfire... I tried several ways to build the wing centre section and finally settled on this. The ribs on the plan are weak at exactly the point the undercarriage mounts. With some dense XPS and laser cut ribs I hot wire cut the centre section, which will have spars and a 2mm balsa skin. Planning to router away and install the U/C mount in the next day or so. This opens a new problem to solve around wing joining. I think I will fix the centre section in place permanently, making the work around the fairings easier. I am thinking that I will use a tube through the middle to join the outer sections - any suggestions on getting the dihedral right with this method? Bending the tube (only possible with aluminium?) or displacing the joiner holes on the ribs?

**Update** I have started cutting parts for my spitfire. Using 3 and 4mm poplar ply. The plan calls for a mix of 2 and 3mm liteply, but I hate the stuff. My spit will be slightly larger than the original plan too (1500 vs 1200mm). Most of the parts were cut out nicely but a few held on - presumably where adhesive was a little thicker. I have slowed the cutting speed down slightly for subsequent cuts which seems to have fixed the problem. Test fit on a few pieces to check that the tabs all go together - a tiny bit of sanding but that's all. They will all be cleaned up properly before the final assembly. A few of the other formers cut out and ready to go. I don't think I will set off multiple pieces on the same cut again. Some wing ribs I was cutting last night went wrong for some reason and all of the following parts were affected, wasting a big chunk of the ply. It's easy enough to set them off individually and position them to minimise waste anyway.