Transition to linkage kit

I also struggled with the offset problem for several weeks after going from the basic sled to the round sled with the triangular linkage kit. Bar told me to go to the advanced setting under Maslow setting. After changing the default rotation radius of 100 to 260 the sled moved up to within 1.5" of the x axis. I then increased the value to 285 and the sled is very close to the center. I don’t understand the math behind the rotational radius, but it certainly has a big impact on the Y axis position. I hope there will be some changes made to the software to prevent this problem.
Thanks Bar, for your help in resolving the problem.


I have limited programming experience myself, so what has been helping me the most is actually just reviewing the code that we have in place. This was my first time using Kivy, so there was a learning curve there for me as well. I would say if you’re interested, start looking at the Python/Kivy code and how it interacts!



If you have a spare PC then you could dive into Python if not I’d suggest a Raspberry Pi3. The Pi is designed to for programing education. There is a ton of Python out there.

Thank you

1 Like

the rotation radius is the distance from the center of the bit to the chain. This will vary depending on which trangulation kit you have (the wood kit is ~260mm)

you should have this approximately right before you start calibration, and the calibration figures out what your actual measurement is.

If the result is not putting the center in the right place, DO NOT tweak the rotation radius to fix that. Report the problem and we will work to fix it. In the meantime, just adjust where 0,0 is when you are doing you CAM work


@knorrisster: Definitely make sure you run the calibration routine, this dials in both the rotation radius and the chain sag modifier. Both of these will give you a more accurate machine.

If you’re having trouble centering the machine, the motor height variable might be wrong. I always like to check the machine dimensions against a tape measure (or some other manual measuring device).

That is good advice! I’ve been able to look through some of the Arduino code and have at least a general idea of what little I’ve seen. I mostly know G-Code, and I’ve done some VBA scripting in Excel. I wasn’t sure how complicated a lot of the firmware and Ground Control is. I’m a more than a little worried I’d get in the way though :upside_down_face:

Thank you for that link! That looks like a great place to get started. I’ll admit I’m a little nervous diving in. :fearful: Probably just got to start playing around with it!

Sorry for the tangent!

Start with an introductory C/C++ book for the firmware, Python for GC and work through it. I’m not familiar with the current references, having started with K&R when I already had several years full time programming experience. I’m avoiding snake labeled languages, seems too much like work these days.

There was a Humble Bundle of intro programming books sort of recently, maybe poke around on their site.

Like 3D printing and CNC there’s a learning curve and potential initial frustrations…


Thanks for the pointers! I just did a little googling for some of the reference material you mentioned. The only programming books I saw on Humble Bundle were for mobile app development. Maybe I could make GC into a mobile app :stuck_out_tongue:

Also found a couple of books on C/C++, I should probably pull the trigger on them and start familiarizing myself with the syntax.

I’m completely anticipating to have slamming my head on my desk level hang-ups! Such things happen when pushing yourself beyond your comfort zone :wink:

1 Like

Use the walls for head slamming, easier to fix drywall and you can clean and paint over the bloodstains :grinning:

The Humble bundles come and go but include some great looking bargains; they’re in my RSS feed.

For Windows the free version of Visual Studio is a good IDE. The ones I used for Linux are long dead and gone, but I hear Eclipse might be decent. Or there’s always vim with syntax coloring, but that’s a bit hardcore and not the easiest place to start.

Good Luck!


I definitely had some of these when I was completing some PRs recently. Don’t hesitate to ask questions also! Chances are that someone has already encountered the same confusing aspect and would be happy to help you detour around it.


I have another random question. After I’ve reattached the sled with the linkage kit it does not sit flat on the workspace (there’s a gap at the top of the sled). I’ve ensured the chain feeds true (I.e. the space from the linkage to the work piece is the same as the work piece and the motor sprocket). Almost as if the CG of the sled is way out of wack. Just looking for advice before I jump down any rabbit holes. Thanks! I’m

Sounds like a CG issue. The weight of the router puts the CG further outward (greater) than the distance from sprocket to workpiece. So the linkage needs to be higher to compensate. Of course, the CG changes as you move the Z-Axis in and out… so you have to find a happy median.


Makes perfect sense! Thanks

1 Like

I agree it’s a CG issue, which kit are you using and how high did you mount it
(with what router)

Currently I’m thinking that you want to err on the high side, as that will help
keep the sled from tipping as you go off the side.

David Lang

1 Like

Good to know. I actually erroneously was thinking I should mount it level with the motors to avoid the linkage from binding, but I could see my error in regards to the CG. I will post when I find what works best with my setup, I’m using the @pillageTHENburn linkage

you should mount the motors level with where the linkage ends up. So you were
correct about keeping them level with each other, just wrong about which end
controls the level.


Well put @dlang, I ended up mounting the linkage 2.5” off the sled (using the R22002 router). I also put a dab of Johnson’s paste wax on all the wood-wood contact points at the joints and mounts. That made all the difference in the world. I now need to extend my motor mounts 1.5” … but that will be for a different day. Thanks again for the help…it’s amazing how much standing back, taking a deep breath, swallowing the pride, then hitting the forums makes :smile:


Hi, I just discovered this topic searching for “gap between the sled and the surface” and instead of starting a new post, perhaps I can share my situation here. I couldn’t get the original Maslow CNC kit, so I ordered various bits form multiple sources and I got this linkage kit:

When I attached the chains, I noticed a 4cm gap at the top of the sled, which doesn’t look right to me. The router I have: AEG Router MF 1400 KE. And the frame is the default frame as described here:

This is how everything looks:

I haven’t tried cutting anything yet only, only tested the basic movement. Also this is a temp sled as described in these instructions:, but I guess I would have the same issue with the normal - round sled.

@brewed_over, as I understand you mounted by linkage kit not in the center, but 2.5" above it? Maybe you could post a photo of how it looks? Also any advices / comments from other are very welcome too.

I think your center of gravity is a bit out of whack. Can you try raising the linkage kit in the z-axis (i.e. make the pillars supporting the kit taller.)


The linkage kit (or any triangulation kit for that matter) relies upon the kit being as close to perfectly centered around the router bit as possible. Raising the linkage kit upwards on sled (i.e., vertically in the y-axis) would be detrimental.

1 Like

Ah! I see what you mean, I noticed these spaces here in the photo:

Perhaps my mistake was that I used the four middle nylon bushings as spacers. Well actually I inserted them in the linkage kits holes, then removed (now realising, I shouldn’t have done so) them and used as spacers.

Looking at the instructions again, I see that I missed / misunderstood, this bit:

“Once you have tested your spacer blocks and are happy with the balance they should be glued securely to your sled.”

Thanks a lot for a quick response!

1 Like