Bob Howard Posted January 9, 2009 Share Posted January 9, 2009 Some time ago (2 - 3 years) an article in RCM&E contained details of a DIY power supply for use with a bow for cutting foam wing blanks. I feel sure that it was a letter on the "All Write" page.The power supply was built from various bit from the electical department of B&Q, including a dimmer switch and a transformer intended for domestic halogen spotlights.I would like to have a go at making the power supply (or having one made by a qualified sparky) & cutting some wings. I already have the cutting bow, but I have lost the magazine with the article in it. Does anybody have the magazine article,or any details of what items were used, and how they were wired up? Thanks Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted January 9, 2009 Share Posted January 9, 2009 I just power mine from a 12V car battery. Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 9, 2009 Share Posted January 9, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Bob Howard Posted January 10, 2009 Author Share Posted January 10, 2009 Phil,My bow also just over 1m long, Dural tube handle with nichrome wire attached to insulated springs. I have a feeling that MFA made something very similar some years ago, but I have no idea if it is the same one.What dimmer & transfromer do you use? Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 10, 2009 Share Posted January 10, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Bob Howard Posted January 11, 2009 Author Share Posted January 11, 2009 Many thanks. Quote Link to comment Share on other sites More sharing options...
Bert Posted January 11, 2009 Share Posted January 11, 2009 Bob You could use an electric flight nicad pack with a brushed ESC and a servo tester to adjust the current flow, as I know a lot of people do.The pack can be fastened to the cutting bow to save having trailing wires, if you want.HTH Bert Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 11, 2009 Share Posted January 11, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 11, 2009 Share Posted January 11, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 12, 2009 Share Posted January 12, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Simon Milburn Posted January 13, 2009 Share Posted January 13, 2009 Hi , this is all new to me, you cut you own wings from foam? how hard is it? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted January 13, 2009 Share Posted January 13, 2009 Well it certainly requires practice, and two people is best . Root and tip end templates of hard wood or lithoplate or similar are pinned to the foam core at root and tip, marked with counting numbers, and evenly spaced to ensure the bow wire is moved across the whole chord at the same speed. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted January 19, 2009 Share Posted January 19, 2009 Hi , Iam starting the foam cutting lark and found this site that may be of use , foam cutting say no more Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted January 25, 2009 Share Posted January 25, 2009 Bob, You could try an old AT computer power supply, as there are still some knocking about for free. I fitted mine with 4mm power posts on the 12 and 5 volt side so it makes a handy general purpose power supply for the shed. I know there is a thread on one of the forums for converting an old ATX power supply which will do the same job. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted January 25, 2009 Share Posted January 25, 2009 Bob, I've found the thread for the power supply. http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply Maplins do some 25 and 50 watt wire wound resistors, you could use to control the power. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Clark Ross Posted February 2, 2009 Share Posted February 2, 2009 i use a variac it came out of a arc welder . there is a whole bank of them in a welder and when a welder goes bad they usualy throw all of them out and rebuild with new ones. if you know of a welder supply place you might pick a used one reasonably. they have more power than you will ever use. and they have there own voltage control about cutting i hang mine from a steel rod with a linaer bearing to give a smooth ride, you don't want any thing to wiggle while your cutting. the bow is pulled thru the foam and over the end templates by hand using two insulated wire hooks. the bow has two weights that are positioned to put upword or downword force against the cutting wire depending on whitch you are cutting the top or bottom of the wing. the rod is supporeted above the table from both ends. it requires only one person to operate it. clark Quote Link to comment Share on other sites More sharing options...
Paul Course Posted February 7, 2009 Share Posted February 7, 2009 What sort of foam are you using and where do you get it from? I remeber some years ago reading that roacell was good or builders blue foam from diy stores. Never tried it myself but reading about it might have a go. I intend building from a plan that specifies ribs le and te are parallel so could i just use root and tip ribs as a template or is it more complex than that Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 8, 2009 Share Posted February 8, 2009 I use an old laptop power supply - 15V and capable of supplying 3A Quote Link to comment Share on other sites More sharing options...
Bert Posted February 8, 2009 Share Posted February 8, 2009 I would advise against using a variac on the mains supply, there is no isolation with one of these variable transformers. If the cutting wire breaks or is disconnected while connected to the mains, the voltage will float up to that of the mains supply with possibly tragic results. Bert Quote Link to comment Share on other sites More sharing options...
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