Problems with accuracy

Hi all,

I have cut three circles with a diameter of 190 mm. All circles have an inner circle of 50 mm diameter cut into it. They should all be stacked on top of each other and align perfectly (only the circles, not the squares) .

When I try to align the outer circles, the inner circles don’t align at all, see the following image:

on the other hand, when I align the inner circles, the outer circles are completely off:

The misalignment is 4 mm which is huge for a cut of this dimension.

I used panel extensions for the cut, but all panels where tightly bolted to the martyr board.
The cut itself came out quite good.

I experienced similar inaccuracies on different projects, but the inaccuracy in this project is probably the most severe.

Has anyone had similar accuracy issues?



Weird… what did you use for your “Cut” (path) settings of the circles? Fill, Inside, Center or Outside? What happens if you select “Center”?

Main question is, who does the tool compensation (code G41 or G42)… Slingshot or Goliath? If code G41 or 42 never shows up in the G-code sent to Goliath, then it’s Slingshot who does the tool compensation.

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I did a test… it’s Slingshot who does the tool compensation (as expected).

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Hi Christian, thank you for your post, could you please email us the log and project file for the date you encountered this, so that we can check them and identify the cause of the problem? You can follow the attached instructions to download them.
How to send.pdf (415.0 KB)

Any update to these issues? I see people post an issue, and the last item is send us your logs. I worked in software, no issue saying, oops, we have an issue, it is in our backlog and will be fixed in the next couple of iterations. But it would be nice to have a bit more transparency on the backlog and if these items are being resolved. Hesitant to fire my unit up and waste expensive plywood :slight_smile:


you’re not alone feeling this pain …

I recently posted an issue and submitted my logs. They replied within 48 hours and did mention they were aware of a calculation issue that may have caused my problem. But yes I am hesitant to continue with any complex projects given the bumps that I have encountered.

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Springas explanation for the problem is Goliath having not enough room for maneuvering, therefore having to change orientation quite often and getting inaccurate. Unfortunately, this currently cannot be controlled in Slingshot :frowning_face:

Supposedly, a grouping feature for tracks belonging together will be introduced in one of the next versions, but no release date was given.

However, I will try my luck again tomorrow, maybe Goliath decides to stay in the same orientation.

The preferred orientation of Goliath is 0° which means that the router points upwards in reference to the line made by the two towers (perpendicular).

If you stay away at least 400 mm from that line made by the two towers and 200 mm from the left and right edges, Goliath will handle all your tracks in the same position.

Also, check the G-code of your project… Slingshot adds - for some unknown reason - some straight lines (G1-code) into the path of circles (G2/G3-code).


Another tip, keep a fair distance away from the “Tower-edge” as this area is less accurate for small holes.

In this area, the tower cables make only a small angle with Goliath so for small movements Goliath will be less accurate.


Ive had similar problems as well. This seriously needs to be resolved IMHO, this is a far cry from the promised 0.1 mm accuracy. Ive had differences of half a centimeter or more on very long parts.

Goliath needs a “dead flat” surface for accuracy. This applies also to the de panel extensions and the transition between the panel (sheet) you’re cutting and the extensions.

The wires of the towers are connected to Goliath on top, which makes that any dents in the cutting surface will be amplified by the height of Goliath.

I think the problem here with the concentric rings have more to do with the G-code generated by Slingshot (Mixing G1-code with G2 or G3 code, see previous post).

Oh right, that makes a lot of sense actually. Any angular rotation of the goliath will make the whole thing into a lever and throw off the positioning. Ha! That makes a lot of sense, thanks for that insight. That’ll allow me to compensate for this in the future, or in the very least check the tower height more accurately. I was working with extensions in order to get the most out of my work surface, but with this information, I will likely stay away from those…

I do not think you should “stay away from those” panel extensions. Just make sure they are the same height as your work surface. In most instances panel extensions could be made of the same material as the work material to be cut.

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As @vorrtec says, I would for sure use a panel extension of about 200 mm on the Tower-edge if this edge is the long edge of your sheet, this way the angle between the two wires is a bit smaller.

Right. Any advice for how to stabilize the whole set up? I still can’t shake the feeling that this is a bottleneck (or at least one of the bottlenecks) in the accuracy. I was using som PIR foam as a sacrificial layer, but that perhaps was not the best choice.

I use MDF as sacrificial layer in which I srewed the panel extensions and on top of both layers, my two towers.

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