Overview of Standard and Alternative CNC linear guides – part I

Precision and strength of CNC machines is highly dependent upon the linear guides on which elements move. There are many many different ways CNC axis can move around. Part I is about general overview of existing linear guides and some alternatives. Part II will be about experimentation with T aluminum profile for use with small CNC machines.

Highly precise machines usually use linear motion guides like the one from HiWin. Such linear motion solutions are due to their complexity rather expensive. MGN12 model usually used in making high end Delta 3D printers can cost up from $40 for 40cm and up depending on length.

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But there are alternatives. The most known alternative is MakerSlide which started as Kickstarter project. In europe amberspyglass offers 1m lenght makerslides for £12.00.

It is good for medium sized machines but when going for small to tiny machines the where size and weight is an issue they are not that practical.

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Makerslide offers good rigidity for the price. It was aluminum profile of choice when building Shapeoko  CNC machines.

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Slightly beefed up version on makerslide is c-beam and V-slot from Openbuild. Also OpenRail is a good add on to standard aluminum profiles to make them into high end linear rails.

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Also standard aluminum profiles 1010 or 2020 are popular in making 3D printers, especially Kossel mini.

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Somewhere in between of HiWin and Makerslide are guide rods. They can be purchased from tiny to massive diameters and are used all over the place.  They are not that expensive by them self but require additional items to make them fully useful.

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Such guides offer a wide array of carriages that can ride on the rail.

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Now, all of these are more or less standard ways of making CNC machines move with precision. While making smaller or huge CNC machines such linear guides are sometimes impractical and other times prohibitively expensive. Thus I needed an alternative solutions for linear guides. While experimenting it was found that almost anything with little imagination can be used as rails for CNC machines.  Especially pipes, square, T and V aluminum profiles.

Note: I dont have images of all experiments so Im using internet images.

Some of examples are:

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V profile, good for large scale 3D printers as they have no Z axis force put on them.  Easy to acquire and fast to guild.

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Simple setup for use with medium CNC machines. Has no limiters so prone to wobbling.

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Rather robust setup for use with square or round pipes.

One of good examples of alternative guide lines is Mostly 3D printed CNC. Files and videos can be found of thingiverse.

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