patrickrio
Well-Known Member
- Joined
- Aug 15, 2020
- Messages
- 365
So, I have custom designed and built a few 3D printers and also helped redesign and change operating hardware and software for laser cutters. I am currently thinking of an inexpensive CNC construct that can cut continuously variable airfoil D tube female molds relatively cheaply. The same machine could likely do continuously variable rear wing skins too, as well as flaps and ailerons.
The system I am thinking of would use inexpensive Chinese stepper motors and Cheap Chinese Linear rails. Since the simple steppers and controller would not have smart error recovery like positive feedback DC motors of the style used in modern inkjet printers and CNCs, it is best to cut molds in pieces, so if the steppers jump catastrophically you only wreck a smallish piece of the mold.
Example of the cheapish linear rails here: Chinese MGN Linear Guides
Example of the steppers here: 0.9 degree steppers (x3)
I already own a suitable controller with stepper drivers as well as a power supply
I think I can get rail metal pieces MGN15 up to 2 meters in length, which should let me cut 6 feet of mold length at a time. In addition, the easiest cnc construct would require that the Dtube mold be cut in two halves, bottom and top. so a wing pair that was 24 feet in length together would require 8 separate cuts.... 4 6 foot lengths top and bottom.
The mold pieces would have to be easily indexed to each other for top and bottom pieces as well as the length pieces so wings could be molded accurately. so I think you would need to build a metal frame for each mold cut that would allow the pieces to quickly and accurately index to each other as well as index to the CNC cutter.
I think that using half of BoKu's mold cradle technique on kerfed material with cradles every foot or two held in a metal indexing frame would give you the rough, before CNC shape. Then the CNC would be programmed to cut just the necessary bits away.
BoKu's Cradles:
Kerfed MDF:
Once the kerfed material was in the frame, the cracks would be bondoed and then the complex curve cut with CNC.
The system I am thinking of would use inexpensive Chinese stepper motors and Cheap Chinese Linear rails. Since the simple steppers and controller would not have smart error recovery like positive feedback DC motors of the style used in modern inkjet printers and CNCs, it is best to cut molds in pieces, so if the steppers jump catastrophically you only wreck a smallish piece of the mold.
Example of the cheapish linear rails here: Chinese MGN Linear Guides
Example of the steppers here: 0.9 degree steppers (x3)
I already own a suitable controller with stepper drivers as well as a power supply
I think I can get rail metal pieces MGN15 up to 2 meters in length, which should let me cut 6 feet of mold length at a time. In addition, the easiest cnc construct would require that the Dtube mold be cut in two halves, bottom and top. so a wing pair that was 24 feet in length together would require 8 separate cuts.... 4 6 foot lengths top and bottom.
The mold pieces would have to be easily indexed to each other for top and bottom pieces as well as the length pieces so wings could be molded accurately. so I think you would need to build a metal frame for each mold cut that would allow the pieces to quickly and accurately index to each other as well as index to the CNC cutter.
I think that using half of BoKu's mold cradle technique on kerfed material with cradles every foot or two held in a metal indexing frame would give you the rough, before CNC shape. Then the CNC would be programmed to cut just the necessary bits away.
BoKu's Cradles:
Kerfed MDF:
Once the kerfed material was in the frame, the cracks would be bondoed and then the complex curve cut with CNC.
