Haq XY

These are the kinematics for a lightweight gantry that I designed and hope to use for my next 3d printer

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A new lightweight gantry design for a 3d printer or other cnc machines

This is a gantry design that I came up with about a year ago. I figured out the kinematics and I hope to use it on my next 3d printer. I am going to call it "Haq XY" for now until I can come up with a better name.

Why this design?

If you want a lightweight gantry for your 3d printer or other cnc machine that doesn't have any motors on the gantry itself, there are a couple options. One is the H-Bot/ Core XY mechanism that you can read about here. There is also a pen plotter style mechanism like what is used on the Ultimaker. Another design is the Sli3DR made famous by RichRap. I am sure there are a couple other kinematic designs out there that I can't think of, but these are the main ones.

The reason I came up with this design is because I have built both an H-Bot and Core-XY printer and although you can get great results with them (My main printer right now is Core-XY), you still need a very rigid/solid gantry to deal with the racking forces. Although Core-XY eliminates most of those racking forces, you still need a rigid gantry to deal with the belt tension. For instance, if one of your belts is slightly tighter than the other, then it will skew the gantry out of square. To overcome this, you usually need to make the x axis very wide and rigid so that it doesn't skew out of alignment. This can increase the weight of the over gantry however.

I also wanted to do something different and add another X axis. I am not always one to re-invent the wheel, but I also don't like to do something that has been done a million times. As far as I know, this gantry design is a new "novel" design; although there is something similar. More on that in the next section.

Has anyone done something similar?

Sort of. It wasn't until a few months ago that I noticed that the Markforged 3d printer uses the same Kinematic design. The implementation of the kinematics (the gantry design) are different than mine, but mathematically the kinematics are very similar. I had to take a real close look at some still frames in a video to realize that it wasn't an H-bot like I originally thought. I did find this thread a couple months ago which talks about the kinematics of the Markforged, but I do like this novel approach over CoreXY. You can see a photo of the Markforged kinematics below.

What makes your's different then?

The big difference is that I designed mine to have 2 separate X axis compared to just a single X axis. This will allow either dual extrusion (similar to the BCN Sigma 3d printer) or better yet, 2 separate tools! Imagine having a 3d printer tool head on one, and a laser on the other, or a color inkjet printhead to color each layers perimeter (plus the top) and create full color 3d models. Another idea is to have a small brushless motor to act as a cnc router to do engraving (pcb's), or to do a finish pass along the important dimensions of the 3d printed model to make it more dimensionally accurate.

Another difference is that in my version the Y axis is designed to be constrained by a belt on both ends of the Y axis. Although the Markforged does encounter some racking forces, this design should counter-act those racking forces. It also allows me to have room for the 2nd X axis.


Although I am not building my next printer just yet, I do have a mechanical design drawn out for the gantry and belt path design. In the image above the X axis belt paths overlap, and criss cross. I did this to better show the belt path, not to show how it would actually look. In reality the belts B1 and B2 would be at separate heights, and they would not criss cross each other. The idler pulleys on the x axis would also restrict the belt path to 90 degree angles instead of the weird angle that it is in the diagram.


I was thinking about using Marlin for the firmware. Since these kinematics aren't implemented in any open source 3d printer firmware, I modified the core xy kinematics in Marlin for testing. I tested...

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  • Update

    haqnmaq04/02/2024 at 23:49 0 comments

    It's been a while since I uploaded this project. Since then these Kinematics have been implemented in a couple different firmwares including Reprap firmware and Klipper. There have also been a few printers built using using these kinematic equations (some of them with different belt paths) that I would like to list to help any future builders. The have done far more work on this than I ever have, so take a look.

    The Muldex build has a different belt layout, but operates in a similar manner. It's a great machine with fantastic documentation.

    Next is the Core IDX printer by Gilly. It's a modified take on a similar concept.

    Finally BCN3D recently announced their industrial 3D printer the Omega I60. Its an awesome looking machine that I hope to see in person one day.

    One final thing to note is that I also just updated the kinematic equations in my original posting. I did not have the correct equations for the X1 axis, so I apologize for the confusion. Once I posted this I sort of forgot about it. It wasn't until a couple das ago that I noticed my mistake.

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Alex wrote 11/01/2020 at 10:02 point

I have printer with this cinematic, can you get link to your source modification?

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hussainsail2002 wrote 12/21/2019 at 07:15 point

there will definitely be some racking forces on this type of system especially when you move the X axis alone. The markforged machine uses two linear blocks in series (these make the machine expensive) and has a very small X shaft to reduce this racking effect. This will make the build more expensive. I definitely would like to give it a shot. The racking exists similar to a h-bot and hence you will need expensive linear block. Compared to core xy this will reduce the need to perfectly tension and align both belts. Compared to a Cartesian I feel that the stationary motors are helpful. 

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Halton3D wrote 10/21/2019 at 15:12 point

Have you checked out the CraftBot 3 Motion system its similar but uses 4 steppers

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haqnmaq wrote 11/27/2019 at 12:03 point

Yeah, I have. I reached out to them to see if they would give some attribution but never got a response. I like the way they did their belt layout.

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Junghun wrote 06/19/2018 at 06:43 point

Have you finished building one? I am so interested. I've already finished build markforged type and it works really nicely.

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haqnmaq wrote 06/19/2018 at 13:06 point

Awesome! I haven't built anything using these kinematics yet, and I don't have plans too currently. I have too many other projects. How did you implement the kinematics in Marlin? Other people have asked me in the past, but I don't have a printer set up like this to test my Marlin changes.

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Alex wrote 11/01/2020 at 10:05 point

I HAVE printer with markforged, and additional stepper on X, And independent 2 extruders.

But marlin get error when i add dual x carrege option

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cscottcurrier77 wrote 05/18/2018 at 09:44 point

I'm also trying to mimic the markforged kinematics.  Can you tell me how to set that up in Marlin?

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GrayPillow wrote 05/13/2017 at 08:47 point

Impressive !!!

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