A foam cutter

There is already plenty of descriptions of cutting bows (for foam, Depron or other similar materials) especially on Internet ! However, I will try to put my own modest contribution to it with a design as simple as possible and a bow which can be easily adjusted to any size depending on your needs.

List of material:


I think the drawing and the pictures below will give you all the details. The junction boxes are used for fixing and securing the branches(6 mm music wires) on the back of the bow and for connection of the power cord as well. The other two junction boxes used for the attachment of the cutting wire on the branches have got a groove (machined with a drilling machine or a lathe and a rat-tailed file) in order to avoid any constraint on the cutting wire where it is attached. The length of the cutting wire is adjusted to get the proper tension.
With this design, you can easily change the diameter of the cutting wire on the same bow. As far as I am concerned, I use either a 6/10 mm piano wire (feed with about 10 V - 6 A) or a Graupner Ni-Cr 3/10 mm wire, reference 849 (feed with about 12 V - 1,2 A).

See the drawing

16 and 25 mm2 junction boxes.

Machined junction box for cutting wire attachment.

Connection of the power cord and setting of the branch on the back of bow.

Attachment of the cutting wire.


Machining of the junction box used for cutting wire attachment. Watch your fingers !

Power supply:

It depends on the cutting wire you will use. A regulated DC power supply adjustable from 0 to 15 V - 10 A (DC) is suitable for the cutting wires mentioned above. With the dimensions of the cutter given above and the Graupner wire (ref. 849 - consumption 12 V - 1,2 A), even a single 12 V battery will do it. Another idea is to use a battery (12 V for example) associated with an ESC for electric motor (the one you use in your planes) ; you will adjust the current using a servo tester (or even your transmitter and your receiver - throttle channel !).


You will find on the following sites examples and advice to make use of cutting bows :

On the SeaGull's site, You will also find a simple foam calculator for cutting trapezoidal wings.

Caution !

The fumes emitted while cutting are extremely toxic. Do not inhale them and work only in a well ventilated room.

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