General Objectives - FabRap

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General Objectives

Generation Two

Finally work has started on the second generation of CNC Router.  The original router has performed surprisingly well considering it was built from scrap material and that it lacked the sophistication of linear guides and proper lead screws.  It has been in use for a number of years and has accomplished all of the tasks set.  It was slow and had to have backlash compensation.

The desire to have a fully professional CNC Router with the proper Balls Screws and Linear Guides has prevailed and thus we have started on Gen Two.  One of the problems facing any enthusiast in South Africa is the cost of the components.  Local purchase is exorbitantly expensive and prohibitive.  The solution for this was to get four to five other participants to share the cost of importation of the major components.  Sharing the cost of importation and lower cost of components from China has made it a viable proposition.

In order to lower the risk of communicating our requirements to the Chinese, we have decided to use their standard products.  This allows us to place the orders precisely with a good understanding of what we will be getting.  The products to be imported are as follows:

a)  2 supported  linear rails type SBR20-300MM for the Z axis
b)  4 supported  linear rails type SBR20-1200MM for the X and Y axis
c)  12 linear ball bearings
d)  1  DFU1605-350MM balls screw with double ball nut
e)  3  DFU1605-1250MM balls screws with double ball nut
f)  4 Sets of BK/BF12 ball screw bearing blocks
g)  4 6.35 to 8 mm flexible couplings for the motors.

Having learnt to work in really confined spaces, it is important that the first part of the project to be built will be the router cabinet.  This will allow for a home for all components and partly built sections to be stored and kept in a disciplined manner.  Later when the CNC router is complete it will provide storage for all the cutting tools, work clamps and possibly materials to be stored.  I have found it an absolute necessity to have all the required tools and materials stored in a safe and organised manner.

The cabinet frame has been made from standard 50 mm Square Welded Steel Tube with the supports made from angle iron and flat bar.  Heavy duty lockable castors have been fitted to allow the cabinet to be moved easily when required.  All covering will be made from 16mm MDF sheet finished with a Poly Urethane paint.  The colours chosen were Ivory (RAL1013) with the top being Traffic Blue (RAL5017).  Poly urethane was chosen for it's ability to withstand the various oils and cutting fluids.

Once the frame was completed and painted the next stage was to finish the floor plan for the base of the cabinet.  Apologies for the pictures.  Assembly took place in my car port and I have removed the background to make it easier to see exactly how it has been constructed.  

It is our intention to use the web site as a means of communication to the other partners building similar machines.  This will make sure I update the web site as progress is made and this in turn should benefit the visitors to the site.

A hinged panel has been included for the mounting of all the electronic control components.  These will include two 36 Volt DC power supplies, four stepper motor controllers, the Planet CNC USB 4 axis controller, a separate power supply for the USB Board and solid state switches for the above components and the Spindle. A more thorough description will be included in the control section.

The panel will be hinged out for the initial wiring and testing.  The fact that all the electronic units are easily visible makes it easy to undertake the connections and to measure all points to ensure correct connections.  Later when maintenance is required the side panel can be removed and the control panel can be hinged out for easy access.  

The panel is held in the out or retracted position by two slide bolts.  For the out position the slide bolts fit into holes in the frame.  Once this is retracted the same slide bolts will fit into holes in the metal cabinet frame.  

The panel will have the Power Supplies, Motor Drivers, the Control board and all electronics mounted onto it.  For maintenance it can be fixed in the outer position and for daily use it will be returned into the Vertical position with the side of the cabinet fitted.  3 fans have been fitted to the bottom of the cabinet to ensure a good flow of cooling air for the equipment.  Filter will be added to the fans to make sure that dust is excluded from the cabinet.

The next stage was to mount the side panels onto the cabinet.  The inside panels have been deliberately shortened to ensure a free flow of air.  This should give good ventilation to the electronics and drivers.  

When running at full speed both the power supplies and the drivers can get quite hot.  The build log will eventually show all equipment fitted with the cabinet and the wiring of this section.

A drawer has been added for a lap top computer that will be used to control the machine.  The Lap Top will be connected to the Controller using an Ethernet Cable.  When not in use the Lap Top can be removed to reduce the space occupied by the machine.

Also all G-Code files can be tested prior to machine start up with the ability to simulate all code in a quite office environment. Making it more convenient to prepare for a new project.

Finally the doors have been fitted to the frame and the table top fitted.  We finally have a home ready for the CNC Router and until that has been completed all delivered parts can be safely packed away and stored below the work surface.  The only problem is that the convenience of a large work surface results in the wrong projects being undertaken on the work surface

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