Routing and building RC models

Hello,

Back a few years ago, I was a lot into RC model airplanes. Over the years I've kept all my electronics (motors, batteries, radio, etc.). I've got everything to build a nice plane. Plus, I've got a CNC now, so why not use it to make my own model :)

I think @routercnc does some RC planes with his CNC, but maybe other here do. I would like to know how you go about cutting them. Some may use balsa, some foam. When using foam, I guess the workflow is pretty simple: you download a model of the plane you want from a site like GrabCAD, then rescale it to fit your needs and then just program the CAM. But, what about working with balsa ? I've found some great plans, generally in PDF format, and would like to insert them into my CAD software in order to scale them and be able to program the CAM. I use SolidWorks and I know it's possible to import images, then draw sketches over the lines of the drawings, which afterwards would allow me to make every piece in 3d and assemble it nicely to make sur it fits together. But honestly, that would take me more than 40 hours of work, so I'm not too sure this is the easiest way.

How do you do it generally ?

Thanks a lot for sharing your experience :)

All the best,
G.

Eurikain,

Take a look at the Profili software. I believe this covers what you want.

No association with it, just came across it a while back when Googling.

http://www.profili2.com/eng/default.asp

Regards

Sean

I'm afraid I use the 40 hours+ method. To me this is part of the enjoyment, plus I like to make sure it is all going to fit and it can be modified to suit my needs.

I may download 3 views (front, top, side) of a plane to give the basic outline, which can be brought into the CAD software and scaled to suit. Then the formers and all the parts have to be drawn in the CAD software to build up the skeleton underneath. You can make it suit your needs and fit the hardware you want / the way you want to build and assemble it.

Or sometimes 2D drawings have been made of the formers (e.g. from a paper based plan) which can be traced around in software, or used as they are to create 3D extruded components. These can then be assembled in 3D space to make sure they all fit together. I might then change things to suit servos I have, or if it was drawn for IC engine then to suit electric motor and lipo batteries etc.

Chances are you will need to tidy things up a lot because you are now cutting things out precisely, whereas the paper drawing would be cut / fretted out by hand and then sanded to fit. You can also add lightening features which would be impractical by hand, which in turn means you could use Liteply instead of balsa because it can be cut away to approach balsa weight but be much nicer to work with. Balsa is not very nice to CNC cut and leaves a fuzzy edge and can break if you try to lighten it. Liteply is a joy to work with, can hold a clean edge, is more stable, and you can cut material away to get the weight out.

40+ hours soon becomes 30+ then 20+ 10+ as you become more used to modeling and develop techniques. I remember when I first swithced to Solid works thinking WTF.!! have I done I'll never be able to get to grips with this.!
Now I can knock quite complex parts up in no time. When you get into SW and I'm sure other softwares will have simliair options you save time because Each part can have different configurations depending on application. For instance I build router which as Gantry sides with same design but with 4 different heights and thickness. I don't need to draw 4 different parts I just have 3 different configurations of the first part with in the same model file and make any relavant changes to suit. Ie thickness or dimensions changes

This means when I assemble all these parts in 3D space to build the full machine I can load one part. Choose the Configuration for the size needed.
The end result being I can quickly model any of the 4 sizes of machine I build. If want to Mix n match then it's a simple click of configuration.

Then when want to machine that part at that size then can easily load into Cam. Infact It actually gets better than that.? Because If I've already Cammed up the part at that size before. Then want the same part but at larger size I don't need to Re-cam I just select the Configuration for the size I need and the Software nows this and Re-calculates the toolpaths.

So my point is don't think of the time it initialy takes because you'll get faster and then the power of 3D will truely kick in and save loads of time down the line when changes or adaptions are needed.

Hi all, and thank you very much for the time you take to write these answers :)

@MetalMagus
Thanks a lot, I'll have a look at that software.

@routercnc
I've got some cutting plans scanned as an HD PDF. It looks great and you've got all the skeleton, I could start with that in SW. But I was also thinking that I could use a ready made model from GrabCAD, shell it in SW and build the skeleton from there (may be getting inspiration from the cutting plan I've got, because I don't have much experience in making structures for RC models, I always use to buy the kits). But the workflow as you describe it is obviously the best (and I knew that, but I just hoped there was a quicker way). SW lets you assemble the model and make sure it fits right and is custom made for your batteries and servos.

Your advice on using lite ply instead of balsa is excellent. I will have a look at where I can provide the material locally. I am sure I will be able to get the weight almost to what I'd get out of balsa, but with much more strength. I think I'll post a build thread on here when I start this build.

@JAZZCNC
You don't have to convince me :D I love SW, I am used to it, and pretty quick at it as well. I haven't used much of the configuration features because I have never needed it so far, but I think it's one of the best features of the software. I am a bit disappointed that configurations are discrete (i.e. you have to configure them in the configuration table) where as it would be nicer to have a part you can just generate by giving it dimensions. I think there is such a feature is SW (aren't they called smart components or something like that ?), but I'm not too sure anymore.

Now, coming to the CAM part, I would be very interested in knowing how you do it for the software to automatically recalculate the toolpath. I've been struggling with this over the past few weeks: sometimes when I am programming the CAM in MasterCAM, I realise I have to make little adjustments to my model, so I go back in SW, change the model, and then have to restart the hole toolpath all over again, and it's driving me nuts. I also seem to struggle in finding where you're suppose to tell the software to automatically add G91.1 in the Gcode header. I looked in my post processor file for Mach3 but couldn't find the line to do this.

All the best,
G.

I download plans from sites like aerofred, outerzone, rcgroups etc and then online convert them to jpg's and import them into Draftsight as reference images. I then trace over them, nest the parts and cut them out of balsa and lite ply. I've currently got 4 gliders and planes on the building board.

Ply does cut better than balsa but if you have a sharp cutter (single flute) and get speeds and feeds correct then it cuts OK.

What sort of planes are you looking to make?

I am looking at a P51-D Mustang :) I have found these plans that look really nice
Attachment 18225

There seems to be great models already made. I really think there is something to get out of the models already made. But this time I might try to do this in Fusion 360. It works on my mac and I'd like to see if I can get it to work properly, thought I honestly like SW much better.

I've got an old Graupner MX 12 412MHz receiver, and a brushless motor from my old parkmaster from Multiplex. Got all metal bearing/gear servos as well. Very light but really nice electronics pack. Probably should buy a more recent radio lol, 2.4GHz :)

Quote:

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Originally Posted by eurikain

@JAZZCNC
I haven't used much of the configuration features because I have never needed it so far, but I think it's one of the best features of the software. I am a bit disappointed that configurations are discrete (i.e. you have to configure them in the configuration table) where as it would be nicer to have a part you can just generate by giving it dimensions. I think there is such a feature is SW (aren't they called smart components or something like that ?), but I'm not too sure anymore.

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Not sure what your meaning because you can do this and more. Such as using Equations to drive models from other components. Advanced but still do-able.

Quote:

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Originally Posted by eurikain

Now, coming to the CAD part, I would be very interested in knowing how you do it for the software to automatically recalculate the toolpath. I've been struggling with this over the past few weeks: sometimes when I am programming the CAM in MasterCAM, I realise I have to make little adjustments to my model, so I go back in SW, change the model, and then have to restart the hole toolpath all over again, and it's driving me nuts.

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Well It's down to the Cam software being integrated with SW so can take advantage of being fully Parameteric. If MasterCam is stand alone then probably can't do that.

Quote:

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Originally Posted by eurikain

I also seem to struggle in finding where you're suppose to tell the software to automatically add G91.1 in the Gcode header. I looked in my Mach3.post file but couldn't find the line to do this.

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You will need to add this to the Post Processor. Often the post will have Procedure called "Start of Program" or "Start_Program". It's here you add the G91.1.

Yes, sorry I meant CAM, not CAD :) I see, I think there is a MasterCAM plugin for SW, have to try it out. What do you use ?