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How do I CNC cut a foam fuze from cross-section drawings?

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Old 12-10-2012, 01:46 AM
  #1
BJ64
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Default How do I CNC cut a foam fuze from cross-section drawings?

I am interested in using a CNC Hotwire to cut foam sections of a fuselage with the aim of creating a full fuze to either modify and fly, or make a plug with to ultimately pull moulds from.

I have a set of accurate cross-sections and a 1/2 plan and elevation drawings that show me where each cross-section needs to be placed to create the full fuselage.

While I could probably get the result I need by cutting and filing the cross-sections out of 3mm ply etc, then using these as templates to hand hotwire each individual fuze section, I'm interested in using a CAD/CAM solution to run a 4 Axis CNC Hotwire cutter instead. I figure if I can get it to work, it should save heaps of time in the long run. As well as produce a really good quality cut fuze to either modify and balsa sheet/glass etc. to fly as is, or take the next step and produce moulds from for a full carbon/glass ship.

The added advantage is that once I get the hang of it, the possibilities are almost limitless as far as quickly producing different aircraft would be concerned.

My biggest dilemma so far is: what software to use?

There are so many CAD and/or CAM applications out there. 2D. 3D. Fuselage-specialist software. CNC capable... the list is almost endless.

And while there's a few threads around in RCU and elsewhere that broach the subject, a lot of them are fairly old and out of date with what's out there these days.

I've had a look at DevFus, DevFus Foam, DevCad, TurboCad, AutoCad and a few others. Both 2D and 3D.

The closest one to my needs so far seems to be DevFus Foam, which will generate a 3D sectioned model. The software can then export the cutting instructions for each section to something like Mach3, which will in turn run the CNC Hotwire to perform the cutting.

The only problem is, the software is going at it from the other direction i.e. start with a 3-view and end up with cross-sections.

I already have the cross-sections. I just need to load them into something that will allow me to orient them correctly and then arrange them at the spacing they need to be in order to create the final fuselage to scale. Each pair of cross-sections representing one cuttable fuselage block.

I'm hoping that there is someone out there who has already done this (or something similar) and who can point me in the right direction regarding what software I need to get to do the job.

Some of this CAD/CAM can be quite pricey, and often requires a steep learning curve before you actually start producing results. I don't need the massive power of something like AutoCad where I can design a whole football stadium down to the last nut and bolt. Just something reasonably priced with the capability of going from cross-sections to finished fuselage would be ideal.

I've thought of trying Profili2 - but using my own templates instead of it's vast list of airfoil choices. The principle would still be the same - a suitable aligned template at each end to cut a chunk of foam from.

Any recommendations, discussion, or advice would be most appreciated.

BJ
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Old 12-10-2012, 01:02 PM
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Default RE: How do I CNC cut a foam fuze from cross-section drawings?

One way I have done it is just like you said.
First draw in any software the section you like, making it a closed loop then save as dxf.
For this task you can use a program called solid edge which is a 2d and is free.
Then import the dxf into profil2 and create a profile for each side. You can make it wing with one rib
And then export a foam cut file. I don't remember the exact file extension but its something like . Bat .
For my cutter I use a Jedi cut program which is free but the machine set up takes some time .
I have mine set up so pm me if you get to this part and need help.
After set up of machine just import your 2 side profiles and the wizard will take you into set up of wire length, distance from section to section ect.
Have been using this method for some time now and it works good once you determine some of the details of wire speed.....
Let me know if you have any other questions
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Old 12-11-2012, 09:17 PM
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Default RE: How do I CNC cut a foam fuze from cross-section drawings?

Thanks for your reply, Haikt.

I'll give Solid Edge 2D a try.

Does it have a 'trace' function? i.e. can I trace my cross-sections into SE 2D from jpg scans I have aleady done, or do I have to draw them from scratch?

BJ
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Old 12-18-2012, 02:46 PM
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Default RE: How do I CNC cut a foam fuze from cross-section drawings?

I too was interested in CNC for my project and decided to do a more manual approach to save time and money. I started with the fuselage templates also. You can see my approach at my web site:
http://www.sidgates.us/HOBBIES/F-94C/F94C%20PROJECT.htm

A lot depends on the shape of your project as to whether my method will work for you.
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Old 12-18-2012, 06:05 PM
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Default RE: How do I CNC cut a foam fuze from cross-section drawings?

Thanks for your reply, Sid.

That's the route I started to go down (for the 3rd) time, but I managed to score a CNC Hotwire for a reasonable price.

I'm soooo sick of cutting/filing 'templates' and mouting them on a rod, then hotwiring around them.

The CNC Hotwire should do away with all that manual template cutting etc.

Just got to get the right software to do the job

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Old 12-24-2012, 06:22 AM
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Default RE: How do I CNC cut a foam fuze from cross-section drawings?

Merry Christmas.

And keep the good info flowing

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