3D Printing
So, basically 3D printers are about additive manufacturing - building components up from the ground up rather than tearing a block of raw materials up into a final shape. Should be less wasteful and capable of producing much more complex components quicker. I'm going to concentrate here almost exclusively on the use of home based kit that is reasonably priced. I just want to try out the technology - from 3D CAD design to final component - but it should allow me to produce useful bits of kit and replace components that break on other things. Time will tell.
So, with those caveats, what is available and how does it work?
Essentially, the process starts with a 3D geometric model of something. This could be a parametric model of a machine component ,say, or a mesh based model of a statue or figurine. There are a load of computer apps that can be used to produce the model. From expensive commercial programs to free, open source, ones and I'll touch on these later. This model is turned into a solid reality by building it up from it's base a thin layer at a time - a bit like an old fashioned TV (or FAX machine if you remember them) built up a 2D picture line my line. To facilitate this the 3D model has to be 'sliced' into virtual layers by some form of technical wizardry. Some of the 3D apps can do this directly but it's probably more normal to use another computer program. Once again there are a number of these around (see later). The output from these programs is some form of code which is then sent to the actual 3D printer which uses it to build up the physical model my depositing it slice by slice - simple really! ????
There are a number of basic printing technologies available to build up the final solid object. Looking at the more important ones this might include (caveat - highly simplified descriptions comping up):
* Laser sintering: a thin layer of basic material (plastic powder with SLS but metal is also possible) is spread across a base and a laser scans across this layer fusing together the powder where it illuminates it. The last builds up a 'picture' of the initial layer. More powder is added and the next layer is formed. Continue until finished. Obviously heavier metals needs a lot more power than plastic but can be done using a laser (Direct Metal Laser Sintering, DMLS), or an electron beam (Electron Beam Melting, EBM).
* Fused Deposition Modelling (FDM): Similar to above but the material used is (usually) a melted plastic fed to a glorified hot glue gun which is moved across a surface to deposit an initial layer. The surface is dropped a bit (or the glue gun raised a bit) and a second layer is formed …
* Photopolymerisation: This builds the model out of liquid polymer that can be cured or hardened by the application of light. In many ways it's similar to laser sintering but with a fine light beam scanning the surface of a bath of polymer, hardening the material where it 'touches' to form each layer. The layer is pulled up a bit (or dropped a bit) and the next layer is done. Other systems use a single projected image to form a layer in a single 'flash'. Terms you might hear are; Stereolithography (SLA), Continuous Liquid Interface Production (CLIP) and Digital Light Production (DLP). Interestingly, arguably the first 3D printer used SLA back in 1983.
The vast majority of home 3D printers use FDM but there are a few SLA machines out there that won't break the bank. I'll concentrate on FDM from here on in.
There are basically 2 configurations of FDM printers:
The first, and most common, moves the 'glue gun' extruder (often called the 'note end') in the XY plane by using an arrangement of a carrier system on orthogonal rails across a flat bed. Movement in the Z direction is either by moving the bed up and down or moving the whole XY carrier up and down. This form originated as an open source project aimed at producing a self-replicating machine (the 3D printer prints components for other 3D printers). This goes under the name of 'RepRap' . One of the most popular and successful designs borne of this ideal is the 'Original' Prusa i3 (3rd iteration of the original design) and there are loads of relatively cheap clones (often built in China) using this basic morphology.
The second major form is called a 'Delta' or 'Kossel' design. This is a tri-cornered form that has the hot end suspended from 3 rods, each controlled from a separate stepper motor that runs in one of three vertical columns around the bed. By moving the three motors carefully it is possible to scan the extruder in a plane parallel to the bed and hence build up the succesive layers. Once again either the bed or the motors can be moved in the Z plane. The advantage of this design is the extruder mechanism and carrier is lighter and can be moved more quickly and hence print more quickly. The downside seems to be that it is harder to get accuracy.
So, with those caveats, what is available and how does it work?
Essentially, the process starts with a 3D geometric model of something. This could be a parametric model of a machine component ,say, or a mesh based model of a statue or figurine. There are a load of computer apps that can be used to produce the model. From expensive commercial programs to free, open source, ones and I'll touch on these later. This model is turned into a solid reality by building it up from it's base a thin layer at a time - a bit like an old fashioned TV (or FAX machine if you remember them) built up a 2D picture line my line. To facilitate this the 3D model has to be 'sliced' into virtual layers by some form of technical wizardry. Some of the 3D apps can do this directly but it's probably more normal to use another computer program. Once again there are a number of these around (see later). The output from these programs is some form of code which is then sent to the actual 3D printer which uses it to build up the physical model my depositing it slice by slice - simple really! ????
There are a number of basic printing technologies available to build up the final solid object. Looking at the more important ones this might include (caveat - highly simplified descriptions comping up):
* Laser sintering: a thin layer of basic material (plastic powder with SLS but metal is also possible) is spread across a base and a laser scans across this layer fusing together the powder where it illuminates it. The last builds up a 'picture' of the initial layer. More powder is added and the next layer is formed. Continue until finished. Obviously heavier metals needs a lot more power than plastic but can be done using a laser (Direct Metal Laser Sintering, DMLS), or an electron beam (Electron Beam Melting, EBM).
* Fused Deposition Modelling (FDM): Similar to above but the material used is (usually) a melted plastic fed to a glorified hot glue gun which is moved across a surface to deposit an initial layer. The surface is dropped a bit (or the glue gun raised a bit) and a second layer is formed …
* Photopolymerisation: This builds the model out of liquid polymer that can be cured or hardened by the application of light. In many ways it's similar to laser sintering but with a fine light beam scanning the surface of a bath of polymer, hardening the material where it 'touches' to form each layer. The layer is pulled up a bit (or dropped a bit) and the next layer is done. Other systems use a single projected image to form a layer in a single 'flash'. Terms you might hear are; Stereolithography (SLA), Continuous Liquid Interface Production (CLIP) and Digital Light Production (DLP). Interestingly, arguably the first 3D printer used SLA back in 1983.
The vast majority of home 3D printers use FDM but there are a few SLA machines out there that won't break the bank. I'll concentrate on FDM from here on in.
There are basically 2 configurations of FDM printers:
The first, and most common, moves the 'glue gun' extruder (often called the 'note end') in the XY plane by using an arrangement of a carrier system on orthogonal rails across a flat bed. Movement in the Z direction is either by moving the bed up and down or moving the whole XY carrier up and down. This form originated as an open source project aimed at producing a self-replicating machine (the 3D printer prints components for other 3D printers). This goes under the name of 'RepRap' . One of the most popular and successful designs borne of this ideal is the 'Original' Prusa i3 (3rd iteration of the original design) and there are loads of relatively cheap clones (often built in China) using this basic morphology.
The second major form is called a 'Delta' or 'Kossel' design. This is a tri-cornered form that has the hot end suspended from 3 rods, each controlled from a separate stepper motor that runs in one of three vertical columns around the bed. By moving the three motors carefully it is possible to scan the extruder in a plane parallel to the bed and hence build up the succesive layers. Once again either the bed or the motors can be moved in the Z plane. The advantage of this design is the extruder mechanism and carrier is lighter and can be moved more quickly and hence print more quickly. The downside seems to be that it is harder to get accuracy.
