First attempt at laser cutting

[Steven B]

After reading many of the threads here (and elsewhere) I thought I'd dip my toe into the world of laser cutting.

 

With a fellow member of the N Gauge Society's Yorkshire Area Group I'm working on a 3d printed APT-P. I want to model the 14 car version of the train but this will leave me with around 200 window shaped holes to fill. The thought of cutting and shaping these individually filled me with dread! Instead, inspired by the modelling here and on the N Gauge Forum I decided to see if laser cut acrylic would be the answer. It turns out that it is!

 

This is my first attempt at anything CAD related since for over ten years. Following the example of others here I chose Inkscape to produce my artwork. I found it worked well (although it often crashes when printing). It doesn't have a fillet tool which makes drawing some shapes a little more complicated than they need to be. Some shapes had to be draw from basic objects and then combined/subtracted to get the required window sizes needed.

 

 

After a bit of extra advice from the laser cutters (4d Model Shop) I submitted my art-work, paid the invoice and waited. I didn't need to wait long - a sheet of laser cut 1mm thick clear acrylic/perspex arrived in the post the next day:

 

I'd taken two approaches. One was to lay the windows out like a etch with the parts connected to a fret (top of artwork above). I assumed that the laser cutters wouldn't want dozens of small windows floating around their machine. The guy at 3D Model Shop suggested I just laid them out in a grid and that they'd be able to tape them together. I tried this - hence the grid of windows in the bottom left. This worked really well and is the approach I'll take when I get the full set of windows produced. It saves on material and make more efficient use of laser time (both reducing the final price by a quid or three). It also means that I don't have to spend time cutting and filing parts from the fret.

 

 

I was really pleased with how the windows turned out. The edges were quite sharp; I'd expected the laser to have melted them a little more than they have (especially given the 1mm thickness). I'd laid out my cut lines to match the openings in the body shells. The cut width of the laser means that there's a small gap around the edge. In hindsight I should have also included windows that were 0.1mm - 0.3mm bigger as a test. Given I need space for paint and glue the difference in size shouldn't cause any problems. The pictures below show the windows fitted to the DTS of the APT:

 

 

 

 

 

 

Inspired by the success of this project I'll be using it to help with some other projects involving the conversion of some Farish coaches (test parts included in the cut shown above - answers on a post card if you can guess what it is); I'm also rather tempted to get some etching done too as I can draw CAD lines straighter than I can cut them!

 

Happy modelling.

 

Steven B.

[oldun]

I use a table plasma cutter, and we use a part of the program called "nesting" what it does is move or interlock the pieces together to reduce the number of cuts the cutter makes, so parts like your apt (jigsaw pieces), would be offset from each other and nested together as you have done with the windows, and only one line separating them, this also saves material so more parts can be cut from a sheet maximizing the yield, and saving cutter time, you dont really need a program to do it, it just takes a bit of imagination and thought but basically put all your parts as close together as you can (remembering the curf) thickness of the cuts, ours is about 3mm on steel. hope this helps.