Alternative Solutions and Rational

Solution 1:

Concept:
The material bed chosen is a solid bed. This structure consists of either metal or wood and is the table that supports the entire the device. The linear rails, drivers, and the gantry are on top. This design optimized for backlash because the devices are installed directly into the bed rather than placed on top and more material is used as support. The bed is the table that allows the machine to fit any size requirement because suitable tables are required for beds that contain just the rails.

A moving gantry covers the most surface area of the desired cutting material. The gantry moves on the XYZ planes of motion. The gantry attaches to the table by the X-axis rails. The Y and Z-axis rails attach to the gantry. The system minimizes rail usage.

Linear rails and bearings direct the motion of the router. Round linear rails have a lower load capacity compared to profile rails but the rails work. These rails operate at higher speeds due to less friction. Warped structures the rails attach to do not cause the bearings to become unmovable. The X, Y, and Z-axis use these.

Liner drivers attach to motors and linear rails. The motors cause the drivers to move which cause the rails to move. Rack and pinion drivers allow splicing for larger axes. Low torque motors work with rack and pinion drivers and create high efficiency. Larger CNC routers use them for the X and Y-axis. ACME screws are efficient for smaller axes. They are more accurate than rack and pinions but the difference is negligible in larger units. ACME screws are slower than rack and pinions. Larger CNC routers use them for the Z-axis. 

For this design, a solid bed is chosen for stability. The moving gantry allows for more coverage of the router. The round liner rails allow for slight warping of wood. The liner drivers allow for both longer and shorter axes and the efficient use of different types of drivers.

Why:

Solution 1 contains all elements necessary for the specifications.

Solution 2:

Concept:
The material bed chosen is a bed that consists of the linear rails and drivers and gantry. This type of bed allows for minimal building materials and can be supported on any table but the size makes transporting the device difficult without disassembling the machine. The lack of extra materials also makes the machine unsteady as extra metal or wood applied to the frame and gantry reduces backlash from the router. This style of bed suits a smaller CNC router rather than a larger one.

A moving gantry covers the most surface area of the desired cutting material. The gantry moves on the XYZ planes of motion. The gantry attaches to the table by the X-axis rails. The Y and Z-axis rails attach to the gantry. The system minimizes rail usage.

Linear rails and bearings direct the motion of the router. Profile linear rails have a higher load capacity and are ridged. These rails operate at lower speeds due to more friction. Warped structures the rails attach to cause the bearings to become unmovable. The X, Y, and Z-axis use these.

Liner drivers attach to motors and linear rails. The motors cause the drivers to move which cause the rails to move. Rack and pinion drivers allow splicing for larger axes. Low torque motors work with rack and pinion drivers and create high efficiency. Larger CNC routers use them for the X and Y-axis. ACME screws are efficient for smaller axes. They are more accurate than rack and pinions but the difference is negligible in larger units. ACME screws are slower than rack and pinions. Larger CNC routers use them for the Z-axis. 

For this design, a rail only bed is chosen for the use of fewer materials. The moving gantry allows for more coverage of the router. The profile liner rails allow for high load. The liner drivers allow for both longer and shorter axes and the efficient use of different types of drivers.

Why:

Solution 2 meets most criteria but falls behind in the specification regarding efficient parts.

Solution 3:

Concept:
The material bed chosen is a solid bed. This structure consists of either metal or wood and is the table that supports the entire the device. The linear rails, drivers, and the gantry are on top. This design optimized for backlash because the devices are installed directly into the bed rather than placed on top and more material is used as support. The bed is the table that allows the machine to fit any size requirement because suitable tables are required for beds that contain just the rails.

A static gantry is used when the material moves on the rails. This design contains a hybrid design. The router attached to the gantry moves on the X and Y-axis. The gantry is layered to incorporate the two different moving axes. The Y-axis is doubled  to incorporate the size of the cutting material. A static gantry has less interference with wires.

Linear rails and bearings direct the motion of the router. Round linear rails have a lower load capacity compared to profile rails but the rails work. These rails operate at higher speeds due to less friction. Warped structures the rails attach to do not cause the bearings to become unmovable. The X and Z-axis use these. The Y-axis uses drawer slides. Smaller machines use drawer slides because the slide has to move in and out of the slide casing in order to move which causes the machine to displace more space. Slides are not equipped with the ability to use linear drivers. The slides are common and can carry large loads.

Liner drivers attach to motors and linear rails. The motors cause the drivers to move which cause the rails to move. Rack and pinion drivers allow splicing for larger axes. Low torque motors work with rack and pinion drivers and create high efficiency. Larger CNC routers use them for the X and Y-axis. ACME screws are efficient for smaller axes. They are more accurate than rack and pinions but the difference is negligible in larger units. ACME screws are slower than rack and pinions. Larger CNC routers use them for the Z-axis. 

For this design, a solid bed is chosen for stability. The hybrid gantry allows for more coverage on the Y-Axis and less wires. Drawer slides carry larger loads. The round liner rails allow for slight warping of wood. The liner drivers allow for both longer and shorter axes and the efficient use of different types of drivers.

Why:

Solution 3 does not meet most criteria. The solution falls behind in the support of desired cutting material, efficient use of parts, and size of machine.

Solution 4:

Concept:
The material bed chosen is a solid bed. This structure consists of either metal or wood and is the table that supports the entire the device. The linear rails, drivers, and the gantry are on top. This design optimized for backlash because the devices are installed directly into the bed rather than placed on top and more material is used as support. The bed is the table that allows the machine to fit any size requirement because suitable tables are required for beds that contain just the rails.

A static gantry is used when the material moves on the rails. This design contains a generic static gantry where the router attached only moves on the Z-axis. The material bed is attached to rails that move the material on the X and Y-axis. This design reduces the size a CNC router can support because the machine size is doubled to cover the entire size of one particular piece of cutting material. The material bed is layered because one layer is attached to the x-axis rails and the other layer is attached to the Y-axis rails. A static gantry has less interference with wires.

Linear rails and bearings direct the motion of the router. Drawer slides are used for smaller machines because the slide has to move in and out of the slide casing in order to move which causes the machine to displace more space. Slides are not equipped with the ability to use linear drivers. The slides are common and can carry large loads. These slides are used for the X and Y-axis. A profile linear rail is used for the Z-axis. Profile linear rails have a higher load capacity and are ridged. These rails operate at lower speeds due to more friction. Warped structures the rails attach to cause the bearings to become unmovable.

Liner drivers attach to motors and linear rails. The motors cause the drivers to move which cause the rails to move. Rack and pinion drivers allow splicing for larger axes. Low torque motors work with rack and pinion drivers and create high efficiency. Larger CNC routers use them for the X and Y-axis. ACME screws are efficient for smaller axes. They are more accurate than rack and pinions but the difference is negligible in larger units. ACME screws are slower than rack and pinions. Larger CNC routers use them for the Z-axis. 

For this design, a solid bed is chosen for stability. The static gantry eliminates wire interference. Drawer slides carry larger loads. Profile linear rails are rigid and allow high loads. The liner drivers allow for both longer and shorter axes and the efficient use of different types of drivers.
Why:

Solution 4 does not meet most criteria. The solution falls behind in the support of desired cutting material, efficient use of parts, and size of machine. 

Specification Grid:

Specification Grid
Specifications	Solution 1	Solution 2	Solution 3	Solution 4
The CNC router must be able to cut desired material precisely.	+ The machine is designed to cut wood.	+ The machine is designed to cut wood.	+ The machine is designed to cut wood.	+ The machine is designed to cut wood.
The machine must be able to support 2’x4’ pieces of plywood	+ The machine can support the load and size of the piece of wood.	+ The machine can support the load and size of the piece of wood.	- The machine can support the load but not the size of the piece of wood.	- The machine can support the load but not the size of the piece of wood.
The machine should use the most efficient parts.	+ The solid bed allows for stability. The moving gantry allows surface coverage. The linear rails allow for warping of wood and load. The linear drivers allow for larger and small axes.	- The rail bed does not allow stability. The moving gantry allows surface coverage.	- The solid bed allows for stability. The hybrid gantry does not allow for coverage of surface area. The linear drivers allow for larger and small axes.	- The solid bed allows for stability. The static gantry does not allow for coverage of surface area. The linear drivers allow for larger and small axes.
The machine should be of the smallest size possible to cut a 2’x4’ piece of plywood.	+ The machine is just large enough for 2’x4’ pieces of wood.	+ The machine is just large enough for 2’x4’ pieces of wood.	- The machine is too small for 2’x4’ pieces of wood.	- The machine is too small for 2’x4’ pieces of wood.
Tally of Ratings	4+	3+	1+	1+

Final Solution

I intend to develop solution 1. The solution meets all specifications. The solid material bed allows for stability. The moving gantry allows greater surface area coverage. The only down fall is that the wiring is longer. The linear rails allow wood to settle over time. Since the machine will be in an environment that is close to the ocean, the wood may warp. These rails are not affected by warping and are made from materials that do not rust. The combination of rack and pinion and ACME screws allow for different sized rails.