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GantryCNC

by cgapeart, published

GantryCNC by cgapeart Mar 23, 2013

Description

CNC or 3D printing - the final tool head is not set in stone yet.

Updated to make the SCAD/MCAD Library usage more standard.

Now with Customizer Support!

Added cutouts for the motor mounts, and cleaned up a few spots. Also, started work on a 2d projection for export to dxf for making diagrams for actually building it.

Recent Comments

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I did some construction trials but found that the rails were not reliable enough for mounting a tool on. I don't recommend building this. I am not planning to update it further, as I have moved on to other projects. I sure learned my way around OpenSCAD in the meanwhile.
Well, I tried, but no luck. It doesn't create anything that is compatible with STL - something about it not being 2-manifold.

The updated version has the layout for making a DXF, for most of the parts, but its still a work in progress.

Freecad looks interesting, but I am really struggling with the UI still. Any tutorials you would recommend to get me past the initial learning curve? I need something the explains some of the ideas about how it works behind the scenes.
Sure thing. When I upload it next, I will include an alternate format - but STL isn't really the right format for this here, unless I break it down into seperate parts. I have also been working on adding a 2-d projection that I can export to DXF format so I can use a cad program to dimension the drawings for actual construction

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Instructions

The base design idea for the drive elements and linear rails/bearings came from: http://letsmakerobots.com/node/9006

This is an early design, and has not been built yet. I want to post it early to make it easy to share with friends and I am opening seeking comments from people who have built something like this and might be able to see some pitfalls a newbie would miss.

The OpenSCAD file is fully parameterized, to easily adjust the dimensions of the final machine. The default values I am working with create a working volume of appoximatley 10.5 inches wide, 17 inches long, and 6.5 inches high. I also have it set up the design to 'control' the device so that it is easy to visually observe the range of movement and check for areas where parts might collide.

The design is missing any kind of end-stop at the moment, and I haven't drafted in the connections between the drive rods and the axes.

The main construction material is 3/4" MDF. The current plans are based on the lumber being actually 3/4" - I haven't adjusted that for the actual dimensions yet, but thanks to OpenSCAD, that is just one variable (BaseBoardThickness) to change.

The bearings are 608 rollerblade bearings, and the motors are set as NEMA14's. I am planning on using 8mm ACME threaded leadscrews if I can get them, otherwise I will go with standard 8mm metric threaded rods.

My biggest worry so far is that I built in routed out shapes on each of the axes to make is easy to keep the drive rod in close to the axis of movement and keep the off-axis torque down. Will the wood still be strong enough? I am hoping that the slots for the T-Slot rails can be cut into the machine mostly by itself.

An Arduino with any one of the available drive software packages and motor drivers will be used to control it.

The MCAD Motors library is required for the stepper motor. The library set is available from http://github.com/elmom/MCAD . You can adjust the path in the include statement at the top of the file based on where you install it.

I did some construction trials but found that the rails were not reliable enough for mounting a tool on. I don't recommend building this. I am not planning to update it further, as I have moved on to other projects. I sure learned my way around OpenSCAD in the meanwhile.
Great work. I could open the CAD file in OpenSCAD. Could you make an export in STL so we can use FreeCAD as well? Kind regards, Kellogs.
Well, I tried, but no luck. It doesn't create anything that is compatible with STL - something about it not being 2-manifold.

The updated version has the layout for making a DXF, for most of the parts, but its still a work in progress.

Freecad looks interesting, but I am really struggling with the UI still. Any tutorials you would recommend to get me past the initial learning curve? I need something the explains some of the ideas about how it works behind the scenes.
Sure thing. When I upload it next, I will include an alternate format - but STL isn't really the right format for this here, unless I break it down into seperate parts. I have also been working on adding a 2-d projection that I can export to DXF format so I can use a cad program to dimension the drawings for actual construction
I think the tslots are mostly wasted: a sacrificial board will have to ride on top, and you would never want the cutting tool to hit the slots.
The base design is unchanged, but I have set up the openscad file to use only the standard MCAD libraries, and added customizer comments so that you can play with the parameters.
I should probably note that to render this, you do need some of the libraries linked from the openscad project page. Check the includes at the top of the file--i will add the links in later.
I have just updated the full instructions with details. The file needs the MCAD motors library, and there is an additional section of code that is needed to get the NEMA 14 size out of that library. Apparently, I make everything more complicated than it needs to be.
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