Hot Foam cutter for RC aircraft

Hi

This is the start of my build after spending a lot of time researching the internet I've taken the plunge. Had some real good advice from this site as well.

My motivation for building a cnc hot wire foam cutter is for two reasons.
1. I'm currently building a Radio controlled Vickers Super VC10 (http://www.rckeith.co.uk/vc10) made from 3 types of foam and the biggest pain with all this is cutting templates out. I'm getting better at it now and have just cut the wings but I'd like to have something that's more accurate and removes the need for all those templates.

2. I recently visited Mike Black who's also buidling a VC10 he runs Green Air Designs and uses CNC both foam and laser cutting and got inspired by his equipment. http://www.greenairdesigns.com/lab/i...d=6&Itemid=112

I've purchased the plan from http://www.drayconstruction.com/foamstuffs/ and have all the MDF cut out. Today I also purchased the motors and electronics from ebay http://cgi.ebay.co.uk/CNC-Kit-4-Axis...item2a0900f6ee

Will get some pictures up soon.

Oh dear,don't want to dampen your expectations on that HongKong kit but I read somewhere about the driver boards are not up to scratch ie the chips pop at high peaks,it just miht of been a one off? but the uy who tested one seemed to know what he was doing.

I'll look for the source and you can judge for yourself,might of even been on here?.

http://www.mad-professor.co.uk/Misc/...AHQ%20Chip.jpg

This is not the site I'm lookin for but the info is the same ie popping chips.
http://www.cnczone.com/forums/archiv...p/t-93048.html

I had a very quick read through that cnczone thread, so much background noise. It appears the boards may be fine up to about 24v, above that the ice beneath you feet starts to thin.

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Originally Posted by GeorgeD

Oh dear,don't want to dampen your expectations on that HongKong kit but I read somewhere about the driver boards are not up to scratch ie the chips pop at high peaks,it just miht of been a one off? but the uy who tested one seemed to know what he was doing.

I'll look for the source and you can judge for yourself,might of even been on here?.

http://www.mad-professor.co.uk/Misc/...AHQ%20Chip.jpg

This is not the site I'm lookin for but the info is the same ie popping chips.
http://www.cnczone.com/forums/archiv...p/t-93048.html

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Can we please not send this thread off topic... if you'd used the search facility here you'd have seen the extensive discussions on this subject here and here. Please keep discussions on the OP's original topic - if the subject is important enough then start a new thread in the appropriate section.

Hi rckeith

Nice little machine. If the author of the plan is on iteration 3 is can't be too bad.

What sort of shapes are you looking to cut - foam core wings, 2D formers etc. ? I guess with any 2D work it's fiddly if you want lightening holes, but maybe with foam/depron you don't need them.

Do the towers move apart to handle bigger jobs?

Not into EDF myself, but looking forward to seeing the m/c in action, plus the finished aircraft.

Barry

Hi Barry

I'm looking to wings and fuselages. I have a Priory Models Lancaster which is made of white foam and then covered in balsa. On my website as well http://www.rckeith.co.uk/lanc showing the build. I'm sure I can make a fuselage without too much complication. Unfortunately she's in pieces had a speed controller failure but I have new parts to rebuild her.

This video on youtube shows the same foam cutter in action http://www.youtube.com/watch?v=hV79pjFDdRY and as you can see the towers can be moved to any desired width.

Keith

Here is the start of my machine.

The wood is MDF with a veneer. Some desk were being dumped from my work place and it seemed a same to see them burnt so I saved them for a better life as a cnc machine. All parts are cut to size.

Keith

thats going to be a posh machine then ;)

whats the material you are bulding the VC10 from? I look at the website and the video.... it looks strange stuff....

Hi Keith

I have this feelin that the width of this machine can be narrower unless I'm missin somethin that dictates it needs to be wide?

Hi Irving2008

VC10 is built with 3 type of foam Depron which comes in various widths 3 and 6mm being the most popular. Its mainly used for underfloor heating insulation. XPS is the pink/orange looking foam and is similar to blue foam used a lot in RC flying. This stuff is mainly used for wall insulation and I get mine from B&Q. The wings are the usual polystyrene foam which acts as a core and strengthened with a spar ( carbon rod or spruce) and a balsa leading edge. its then covered in brown parcel paper which is glued on with thinned PVA, a bit like wall papering. Amazingly strong once dry.

Keith

Hi GeorgeD

Yes the width can be adjusted to suit. The only thing between the towers is the hot wire,

Keith

How do Keith.

You do well to put the towers on a sliding base for differing widths apart.

ie use some T channel aluminium rack and rebate the T track in 25mm baseboard and then space the towers when ever you feel the need to widen them?or just have them permanently affixed to a base board because there's no stability in that design ie a gust of wind will blow em over :heehee: and thats not good for the motors//mechanics if you want to avoid damage.

Hi George

The towers will be clamped/screwed down on a base. The tension on the hot wire would certainly pull them over. The main reason I chose this design is that I have quite a small workshop so when not in use I can store them away. Once I've built this one I'd like to do a cnc router but I'll really need to work that one out, with the space I have. Problem I have is that a lot of space is taken up by 10 radio controlled planes of different sizes and I have 2 kits that I haven't even started yet.

Keith

Not to big...hmmm! how about this size? fits neatley on the workbench and has a static z axis,could easily be made to the size of your requirements. :cool:

http://www.cooperman.talktalk.net/tweakie2.jpg

http://www.cooperman.talktalk.net/

Hi George

Phew! what a website. Very impressive certainly an inspiration to us all. I'll have a good read of it later certainly some real good information. Have you any recommnedations for lead screws at a reasonable cost. I've seen foam cutters done with threaded rod but most peope seem to recommended a ACME screw thread.

Keith

I'm making my own lead screws from Derlin.

I could make you some at a reasonable price,send me a PM if interested?

For your foam cutter,M12 threaded rod will suffice.

oops! make that....

Making my own ball nuts from Derlin. lol:redface:

That is a good machine, cant go wrong with linear rails, metal construction and fixed gantry

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oops! make that....

Making my own ball nuts from Derlin. lol:redface:

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Or even Leadscrew nuts???

Hi Keith, how is your hot wire cnc progressing? Just joined to learn more about cnc routing and hopefully build one in the future but have already built a foam cutter from the same plans you are using. I used hobbycnc foampro board and stepper kit and running it with GMFC, it is a simple machine, works reasonably well but quite slow compared to more complicated but smoother running builds, cuts great cores that are so much better that anything possible with a drop arm set up and no more template cutting which for me is the best bit of all. I would recommend using a bow for the hot wire though, the spring set up in the plans puts tension on the towers and the drawer sliders need all the help they can get. Like your website by the way, you may find mine interesting also http://valegliders.com

Mark

Hi mark

Foam cutter is on hold for a few months. I have all the parts and just need some time. I'm concentrating on my VC10 build which is a 2 year project that I'm coming close to finishing. The VC10 was the inspiration for a cnc foam cutter, so many templates. I hope to use the cnc foam cutter for fuselages as well. I'm aiming to make a Lancaster with it. I already have a Priory Models Lancaster, in a a bit of mess after a crash but I would like to be able build one a lot lighter. Thanks for king comments on the website, your looks slick as well. I'm hoping to start back on the foam cutter after Christmas this year. Good advice on the bow, I wondered if the spring on the wire would cause some issues with the towers.

Keith

Keith

Been a while since I've posted here but due to other RC projects foam cutter had to take a back seat. Well I'm glad to say I've finished building and it works!! Just jogging the motors at the moment with Mach3 but all seems good. Calibrated the motors today now I need to get some 4 axis gcode generated. Posted some new pics on my website http://www.rckeith.co.uk/cncfc.html scroll to the bottom. Next bit is deciding which software to use to generate the gcode. Currently playing with a demo version of FoamWorks with a 30 day license.

Keith

Looks like a nice project. My 3D printer uses M8 threaded rod, it works surprisingly well considering the price. I have always had doubts about the accuracy, but when printing at a resolution of around 0.1 mm it is not critical. The bigger problem I have is "wobble", although I think that is more of a design issue with the printer frame.

Unfortunately, the price hike to leadscrew is pretty steep. I priced up 4 sets of 10mm leadscrew and it was way too much. I would be better putting it towards a new machine.

A couple of questions: how is the wire tensioned? Presumably it has some stretch to allow for change in distance while it is cutting a profile?

Is there anything special in the software setup to handle the fact you effectively have two X,Y coordinates? My understanding of the GCode machine model is that all axes in a G1 move are synchronised and coordinated, so it does not matter how or where the axes are.

Hi Bobc

Wire will be tensioned by spring to allow for the x axis on both towers to move interdependently for cutting tapered wings. I'm testing out different software but profili2 pro has 4 axis for foam cutters and foamworks generates the gcode as well.

post some more pics up soon when I have it cutting some foam

Keith

It works
http://youtu.be/uQk3urqLs5Y

Hi Guys

Few more updates. I've added home/limit switches and run some test cuts. Its starting to become a bit easier now. Here's a link on my website CNC Config Mach3 and TB6560 with some sample cuts and setup.
I've documented the configuration so anyone else using the same set up can save a bit of time and head scratching.
The biggest learning curve I think is getting all the software to work, but I use Mach3 and profili2 which do good job. I'm also looking at InkScape as there is a gcode extension for it. Might use this to cut fuselages.

Keith

This video show the flying wing I made with the cnc foma cutter its on my video page RC Video's - rcKeith | Projects

It was a quick test to see how it could cut wings and what a fantastic flyer its is. Its my favorite flyer now. Goes like stink and can fly at snails pace as well.
Have now purchase DevFus software to make fuselages which I going to test on a 50 inch wing span Hurricane.

Keith

I've added a lot of details to my build including plans, instructions and parts/cutting lists all at my website www.rckeith.co.uk . I've have a video almost ready that should be up in a few days on using Profili Pro 2 for cutting foam wings which I'll then follow up with one on Dev Fus Foam. I've used these to produce a 50 inch Wing span Hawker Hurricane. A few images below. Not finished yet because of other stuff getting in the way. I'm now looking to build a CNC router probably a Openbuilds OX but also may try and build Mark Carew's Phlatprinter this seem ideal for producing foam models. I like the fact its fairly compact and can produce large parts.

http://www.mycncuk.com/attachment.ph...id=15864&stc=1
http://www.mycncuk.com/attachment.ph...id=15865&stc=1
http://www.mycncuk.com/attachment.ph...id=15866&stc=1