Bugs in Slingshot / overall workflow

Yesterday I had a bad experience with Goliath CNC again (after some good ones).

I tried milling on a thin piece of poplar plywood (1 cm), but before the actual cut started (and failed, but I’ll leave that to another post), I experienced at least 4 bugs with the software. Before I started I updated the software on Goliath and Slingshot.

When I cut a test rectangle, one of the towers has suddenly gone away, and I had to quit the job as it didn’t reconnect when I powered it on again. This happened never before and actually should not happen! In my case, as it was only a test cut it was luckily not a big problem. However, I’ve got no idea how to deal with this problem other than hoping that it will never occur again! The towers were both fully charged, I then connected them to power and changed the Wifi channels.

After that first unsuccessful cut, I tried milling the actual project.

I had to restart all devices including Slingshot, loaded the project and did the panel detection.
Heres a list of bugs that occurred:

  • After the Slingshot update, all my custom bits where gone
  • When I added a custom bit and selected it for milling, GCode could not be generated (random error message, no hints given), so I had to stick with the standard 6mm bit (probably doesn’t make a difference anyway, but still annoying).
  • While using manual jog mode, after a while Slingshot was really lagging behind, and could not update the current position of Goliath

However, after dealing with all these annoying bugs and errors, I somehow was able to push GCode to Goliath. I wanted to start the tool measurement process, pressed the yellow button, but Goliath did nothing no matter how often I pressed the button.

So again, I had to restart everything and start from the beginning.

As I already knew the bugs of the previous session, I was able to start the milling process, which failed after 2 minutes of milling - but I’ll leave that to another post!

So overall, I wasted about 2 hours working with Goliath to end up with a failed project once again.
During that process, I had to restart Slingshot and the hardware at least 4 times.

In my opinion, this is unacceptable - Slingshot suffers from countless bugs, I can’t see any improvement when versions are released, actually, I think it’s getting worse with every new release.

In addition to the bugs, no real features are added to the software. We still have to go through the daunting process of panel detection, even if a milling process is successful!

For example during milling, it would be crucial to stop Goliath for maintenance tasks, for example cleaning the suction unit when it gets clogged. It would also be nice to change the speed of Goliath during milling.

Is there any chance that Slingshot gets the improvements it dearly needs in the future? Or that it gets released under open source license that the users can build their own version and help fixing bugs?



Hi Christian
I empathise with you. Yes the robot has lot of bugs but you learn a lot trouble shooting. Your comprehensive document should help the tech team at springa.
Goliath is a superb piece of invention as a novice I could use it comfortably.
I found the remidy is to reboot often till you get the correct result.
We complain all the time and feel that tech team is not noticing - but in fact a constructive criticism like yours will always help.
Did you look at your log file to get some info, probably the tech team would like to view them.
I understand that you do not need to upgrade your tower sensors unless asked for- check William post “Tower bricked during update”

I am going to update the firmware and slingshot this evening. Yes I have to reload my bit info as it will be wiped out and get gcode errors. This is what happened last time.

I am learning a lot from the forum and hope by new year I can be more comfortable with goliath.
I wish someone could make a wikihow page for goliath and put the forum suggestions on it for newbies.


Hi christianpro90,
thank you for your feedback.
We really appreciate them.

It would be extremely useful, to understand what happened to you and improve our product and software, if you could share with us the LOG files you can find in this path ‘C:\Springa\Slingshot\Log’ or at the path you have chosen during the Slingshot setup. Please ensure that you share with us all files with the same date on which you experienced the problems.

I will try to answer the things you wrote, provide some insights about what we think has happened to you, and at least give you some tips on how to deal with it.

When a Tower turn off during a cut, it could happen under two circumstances:

  • When the battery of the Tower gets to 0%
  • When the Tower loses the radio communication with Goliath

The first condition can be verified by looking at the LED below the USB port of the Tower Sensor.
If the LED is red it means that the battery is under 10%, if it’s yellow it’s under 20%.
I suggest checking it every time you encounter a problem with a Tower Sensor.
This is the most reliable way to check the battery status. Slingshot might show the wrong percentage due to a communication problem.

The second circumstance has happened to us several times.
It is difficult to replicate it, we have investigated it and will do it more for sure.
It can happen due to some radio interference. So my suggestion is to try different channels as you have already done.

Anway if you have to stop the cut, I can suggest you a workaround to resume almost from where it stopped.
You should follow these steps:

  • turn off Goliath
  • leave the tower sensors where you fixed them
  • turn off the sensor by keeping down the yellow button until the LED gets red
  • close and reopen Slingshot
  • open the project you were cutting
  • delete all the tracks that have already been completely cut, but not the incomplete ones.
  • start the panel detection, but choose the option on the right, where you have to measure the size of your panel and type it when asked (this way of doing the panel detection is way faster than the one with the sensor. You can save a lot of time if have to do the panel detection more than one time)
  • start the cut

In this way, you can restart the work from the start of the path that Goliath was cutting.

We noticed that after the installation of the 1.08.00 version your bit’s library got reset. We have already fixed this and uploaded the software to our servers.
If it helps, you can find a backup of your bit’s library at this path ‘C:\Springa\Slingshot\backup’ or at the path you have chosen during the Slingshot setup. To have your bit’s lib back you simply have to copy the .ute file you find in the backup folder and overwrite the one you find in the Slingshot folder.

You also encounter a bug, which we already know and we are trying to solve.
This bug consists in the fact that if you create a new bit and assign it to a path when Slingshot calculates the Gcode it returns an error because it can’t find the bit that you have just created. The workaround here is to save the project, close Slingshot, and start it again. This time Slingshot will know the bit you have assigned to the track.

Regarding the problem encountered when starting the tool calibration procedure, we think that what might have happened is that Gcode did get transferred completely to Goliath. Do you remember if the Spindle raised up when the transfer of Gcode was completed? Anyway, we can look into this if you send us your log files.
This has happened to us also, but again we have to find a way to replicate it, so when can investigate what could be the cause.

Here is one useful tip for you.

If you need to stop the work for a moment you can do it by pressing the yellow button of Goliath one time, then you can do what you need. But you have to be extremely careful in moving the spindle cage because this might break the contact of the spindle cage. You can also move or push Goliath but be aware that if do so when the work will start again Goliath might give a “Positioning error”. Don’t worry you can click the yellow button on Goliath to resume the work.

We plan to add the feature to change the feedrates on the go while Goliath is working. We will let you know when we will be able to work on this. Thank you for sharing your idea with us anyway.

Thank you again for your feedback.
I hope you find this useful for you.


The tips above should be compiled into a wiki as mentioned by others. Then a troubleshooting link could be stickied here in the forums. :slight_smile:
I love learning all the tips and hearing how development is moving.


Hey Davide, thanks for the thorough reply!

  • the tower sensor was charged over night, so it was fully charged when I used the machine. The problem with radio interference is a problem which should be fixed immediately - have used tools to show the interferences on different Wifi channels? maybe the problem can be at least mitigated this way.

  • regarding the tool calibration problem (Goliath not doing anything at all) → Goliath did not move in any axis at all, so no the Z axis was not raised up. is there a way to work around this problems and still be able to start the cut?

thanks for the tip to interrupt the milling process when pressing the yellow button. is it possible to remove the spindle cage, clear the suction unit and then continue milling? this would be really helpful!

I will happily share my log files with you (sent an email to support@springa.tech).

As others have pointed out: it would be really cool to have some kind of wiki page for trouble shooting and tips for using the machine.

It could also have tips and experiences with different milling bits and settings for different kinds of woods (I think this part is crucial).



Hi, Goliath CNC has arrived a few days ago.
I have been reading the forum before the CNC arrived and also now that I have Goliath CNC.
Found a few post which where helpful to get started.
The QT movies are good, but there everything is running smoothly. Almost no troubleshooting info, and for so far I have read, there are still some issues to tackle.

At the forum it is not always clear of he topics has been solved. Is there a moderator who set the status of a topic to the actual status, NEW - WIP - CLOSED - … .
I read somewhere in a post that it would be handy to find information about known bugs , topics that are now “on the table” , work arounds , … . I can assume that this demand some efforts from the Goliath team, but on the other side, if we - the users - get information we known what’s in the pipeline.

A WIKI, would be very helpful to get started an d quickly find information about issues and how to solve them. WIKI should contain only information posted by Goliath team, so the user knows it is a validated.
Taking in concern that WIKI mostly has a very good search engine, which makes retrieving information quite easy.

A big BRAVO to the Goliath team, I really happy with the CNC,
but to get up and running in a efficient way will take some time.
Most of the issue I encountered are somewhere in the posts already mentioned, so I don’t think it would be helpfull to list them again.

Thank you all and a great 2022 with hopefully a WIKI :grinning:.