Greetings fellow cockpit builders!
A few of our members who own CNC machines have asked me to describe the process of how I have been creating my backlighting panels. Rather than repeating myself, I thought I would put a short tutorial together. First of all, I must state that I have only had the CNC machine a short time and I am still learning how to drive the beasty myself! Having said that, I think getting your head around a CNC machine and the software is not that difficult and great results can be achieved relatively quickly. My only regret is that I didn’t buy one of these toys years ago! They are a must for any hobbyist I think!
When I think of the labour time that went into the first A320TQ I built and how many parts the CNC could have cut out for me now – sigh! In November 09, I commenced building the A340TQ for a customer before I had received the CNC but I finished it with many CNC cut parts. It makes it so much easier and components are so much more accurate. I have gone back over the A340TQ and drawn all the components I had already made in AutoCAD so the next A340 TQ should be a lot quicker to produce. Before anyone asks, I’m afraid I won’t be sharing the files I produce for building simulator components, a business must have some trade secrets or there will be no business! I can only describe the processes that I have found work for me. They may not be the most efficient methods but as I mentioned before, and I am still quite new to the CNC machine!
I like to use the router for cutting out pieces but I find that engraving is better using the Dremel tool as shown in figure 1, it’s much quieter too. My machine has a workable area of 350mm x 220mm so it can quite easily handle any panel or throttle quadrant part.
Hardware - Do I mention a CNC machine here or is that too obvious? I think you will really need one of those! A vertical bandsaw, table saw or jigsaw to cut out the raw materials required. A 3mm endmill and a 3mm 25 degree 0.5mm tip engraving tool. The material I use is 4.5mm thick Opal Acrylic sheeting, a 2.4m x 1.2m sheet cost me about AUD$130.00 so it is relatively cheap. To our U.S. friends, I’m sorry but I don’t do imperial measurements, I think my great grandfather did, I’ll let you calculate and perilously add your fractions!
I highly recommend Vectric’s VCarvePro5.5, I have found it very easy to learn and it is a lot simpler to use than AutoCad and it quickly generates the G Code to drive the CNC machine. I use Mach 3 software with my machine and this is probably the most popular software for the hobbyist. I have made a few good AutoCad drawings but I have found it quite a slow slog for the beginner, I plan to increase my skills in AutoCad as I believe it is still a very useful tool for the CNC machinist. You will also need reference photos of the panels you wish to reproduce and I have used many screenshots from the B737 operations manual to produce my MIP set panels. I have used an epoxy enamel spray paint to paint the panels, it has a drying time of 6 hours but the tough high gloss finish is well worth the wait. I have used “White Knight” ‘machinery grey’, available at Bunnings for the local Aussies at $15.00 a can! It might not be Boeing RAL accurate but for this engineer with a purple/grey colour deficiency, it is definitely close enough!
I will describe the process I use with VCarvePro software to produce an autobrake panel, the same process was used for each of my MIP panels.
Step 1 – Capture a screenshot of the Autobrake panel from the Boeing manual or other reference as per Fig 2. I have opened this file in Photoshop 6 and resized it to 145mm wide. A true size bitmap or Jpeg is required prior to opening in VCarvePro (The black pointers were just arrow markers from the manual). It is now ready to work with in VCarvePro
Step 2 Open VCarve and create a new file which is large enough to draw the autobrake panel on, I usually make the file about 10mm larger in width and height to accommodate the drawing. Use the bottom left hand corner of the panel for zero reference of the X & Y axis so when the Jpeg has been imported to VCarve, move it to align with the bottom left hand corner.
Note – VCarve has a really good image trace function that will create vectors but it can be messy, I prefer to hand draw the rectangles and plot the holes for creating toolpaths.
Step 3 Using the circle tool from the palette, choose the hole diameter you will need for your switches and click on the picture in the centre of the knobs to plot the drilling toolpath. I used the Polyline tool to draw around the picture in the correct shape, straight lines are ok to start with. Then I use the fillet tool to put the round corners where they need to be and use the rectangle tool to draw boxes around the “Auto brake disarm” annunciator and MFD box. See Fig. 4
Step 4 – Next we need some toolpath lines around the three rotary switches. This is easy with the Polyline tool, when hovering near the centre of a circle the polyline snaps to the centre and you click and drag the line away. The lines snap to major angles so it is easy to draw at 45 degrees. See Fig.5
I then use the scissor tool to cut away the lines inside the circles as they are not required.
Step 5 – Applying the text. Applying text in VCarve is simple and very similar to other programs. I am told that the Boeing font is ‘Futura MDBT’ so I will use it in this tutorial. I used 4.5mm text for the main words and 3.5mm text for the smaller words. See Fig. 6
Step 6 – Remove the jpeg and create the toolpaths – see Fig. 7. Vectric’s website has great videos showing how to create toolpaths, see www.vectric.com they explain it better than I can, it’s not hard!
The panel first needs to be drilled, the rectangles cut and then the outside of the panel cut out, you can see I’ve smoothed the corners with a 2mm radius using the fillet tool again. The engraving comes after the painting. I will create tool paths for this operation with a 3mm endmill cutter. The result of the first toolpath generation is shown in Fig.8 VCarve gives brilliant previews of what your CNC
Step 7 – The fun bit, engraving the text and lines to bring the piece to life! First I will engrave the lines with a 1.5mm diameter endmill – See Fig. 9 VCarve has a button for deleting the waste material but it only deletes the outer waste.
Step 8 – The text – I have been having good success with text using a 3mm diameter, 25 degree engraving tool with a 0.5mm tip. Figure 10 shows the preview image of the text engraved. The small triangle on the SPD REF knob had to be a separate toolpath from the text but used the same tool.
I think it’s always a good idea to run the CNC machine around the outside of the work piece without actually cutting anything to make sure you can cut the material without hitting the hold down clamps or running off the edge of the workpiece etc. I’ve come unstuck a few times with errors like this and I think it is worth doing a ‘dummy run’ to reduce the possibility of breaking cutters and wasting materials!
CNC machining has become a new hobby in itself and I’m looking forward to doing a lot more projects with my machine. It certainly is good fun and quite rewarding. I hope you find elements of this tutorial useful! I wish you the best of luck with your projects!