Re-engaging with Maslow, Returned to Web Control and Holey Calibration. What the heck?!

I had to step away from my Maslow about 1.5 years ago because life got in the way. I’m getting back into it again and I come back to a new form of control and calibration. I barely got my maslow to the point where it could cut basic shapes using Ground Control and the standard calibration method. I’m pretty much starting from square one again as I have forgotten a lot of what I learned and probably need a fresh start anyway. I’m even building a new frame and chain tensioning via counterweights.

Do I continue with my setup as is or do I change to web control and holey calibration?
Where should someone who is just getting started/re-starting go to get the information they need (i.e. basic set upand calibration) for either of the methods?

My current setup:
Standard motors WITHOUT the upgraded gears
Standard sled with ring and standard Z-axis drive
Arduino with original Maslow motor shield

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simply download webcontrol, import your groundcontrol.ini file and you are good to go. There are a bunch of quick videos on how to do a few things, but if you just want to do triangular calibration and use webcontrol that works too. Webcontrol makes it so you can use your phone in front of the machine without having to carry a laptop tethered by USB around.


Orob started a Maslow Manual here, which is quite nice, and covers installing WebControl.


I’m a bit confused. From what I’ve been reading in the forums it sounded as though if I wanted to go the web control route I would need to upgrade the Arduino to a RasPi. However, it now appears that is only the case if I am using the RasPi as the control computer, correct?

You still use the Arduino. It can get loaded with the normal firmware.
You can run web control on a windows laptop and connect to the arduino via USB like normal. If you want to use holey calibration, you upload holey firmware to the arduino directly from web control.
If you have WiFi router near your Maslow you can use a phone to access the webpage offered up by the laptop running webcontrol, especially handy if you are on a ladder aligning sprockets. It’s second nature now for me to interface to the Maslow webpage on the phone. The webpage on the phone is the same one on the laptop.
If you are cheap like me, I just bought a cheap raspberry pi 3b+ and it runs web control, and acts as a WiFi router, although in my instance, I don’t have internet. The RPI allows me to control Maslow by phone, or I’ll bring out a laptop usually if I have multiple files to copy to the RPI.

Ok, that clears up alot for me. So I can migrate from GC to WC by creating a web control server on whatever will run the web control/server (laptop, box, Pi, etc) and still use the standard maslow firmware for the Arduino.

I can switch to Holey calibration by first migrating to web control (doesnt sound like Holey can be used with GC) and then updating the arduino firmware via the WC interface.


  1. Does that mean the Holey firmware updates/changes are going to be handled with updates to the WC software?

  2. Is the Holey firmware for the Arduino available seperately external from WC as a standalone file, similar to how the standard Arduino firmware is now?

  3. What are the Pro’s/Con’s of Holey over existing calibration methods and why would someone opt for it?

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  1. Yes, when you update web control, that comes with holey firmware. Also comes with standard, and I believe test firmware for the author’s use. I have switched between standard firmware and holey firmware in testing, all done from WC.

  2. Good question, I’ve only seen it come with web control. Holey calibration was a separate thing initially (my understanding is limited here), but as ground control hasn’t been updated as much, it was incorporated into web control by the author.

  3. I’m really not qualified to answer this one (there are long threads on this), but as a user it only partially drills six small holes into the plywood. As I calibrated on my MDF back board I could tolerate small holes.

Thank you very much, your input has been very helpfull. At the very least ill probably update to WC and wait on switching to Holey untilI learn more.

Holey calibration works on a fork of ground control that just never seemed to make it into the main line… For whatever reason. I took the holey calibration firmware and made a very slight adjustment so webcontrol can detect it as being holey instead of the stock. That version is in my firmware repo under the holey branch. When I build new webcontrol releases I rebuild both stock and holey firmwares and embed them into the release so they can be updated directly from webcontrol. The version in my repo will not work with stock gc or the holey calibration gc fork due to the small change i had to make.

a quick note on holey calibration: I took a challenge to make a video of it, but had never used it and like you thought I’d wait until I learned more. Seriously, I tried it for the first time for the video IN the video and it worked. If you need high accuracy calibration, then Holey is the way to go. There is a video on it in the link to the videos above.

It is believed to have more accurate kinematics model (chain elongation and catenary formula) and the calibration routine, with more meausrements across the board, results in better values for that model. I don’t know if anyone has officially run a comparison though.

there is a fork of GC that supports holey calibration, but there has not been a
new release of GC or the firmware since the beginning of LAST year.

in theory, the holey calibration should get merged into the main firmware so you
have an option of using either mode.

If you are going to be switching to holey calibration, there’s less value in
importing your old groundcontrol.ini as most of it won’t matter.

as noted, many people run webcontrol on a Pi that they connect with a short USB
calbe to the arduino. This helps reduce the ‘USB connection lost’ problem but
you can run WC on a Windows, Linux, OS/X, or Pi computer. The key thing is that
it replaces the GUI with a browser (it’s getting harder to run the older GUI
software on new machines)

WC is also being maintained (accepting patches, making releases) where GC isn’t,
and we don’t know what needs to happen to get new GC/firmware releases started
again (we may need to fork the firmware so that WC can get the updates and
deploy them)

David Lang

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I could probably figrue this out if I went through all of the forum posts but I’m going to ask anyway:

Looking at GitHub, I see the standard firmware hasn’t been updated since 01/2019 and GC is just as old. Based on their release dates I’m ssuming they are not really being maintained anymore. New updates for the standard firmware and Holey firmware are now all happening within the construct of the WC fork. Is this correct?

Given all of the above, in order to be current with both the control platform as well as firmware updates (both standard and Holey) I will need to move to WC anyway.

Ok, just so that I am clear:

GC is no longer the preferred interface and I should switch to WC, obtained from here -

I could use WC with either the standard firmware vailable from the Maslow Github or use the standard firmware that is now embedded in WC. I could also use WC with the Holey firmware which is also embedded in WC.

Either way, it sounds as though I have two options:

  1. I could stick with using WC with the standard Maslow fw but theres no estimate on when or if any updates to it are forthcoming.

  2. I could switch to WC and possibly implement the Holey calibration both of which are being maintained by u/madgrizzle. Added benefit here is the standard firmware is also being maintained and I could continue to use it as well.

I believe it’s more maturity than obsolescence. The GroundControl / regular firmware combo still works pretty well; I’m currently using it on my 3-week old Maslow. I’m still learning the ropes, and I do many adjustments to the G-Code as I’m cutting a project, so having GC on the same computer as Fusion360 really helps.

When I find that I don’t tweak the cutting params as much, perhaps I’ll switch to WebControl. I don’t really have a spare Raspberry Pi anyway (my Pi Zero is running Octoprint for my 3D Printer, both my 3B+ are currently used as boat electronics, and my original Pi doesn’t run very well and doesn’t have WiFi), so I’ll keep this as a future upgrade for now.

If you move to wc, I suggest moving to holey calibration as well. Others are now involved with maintaining wc (thankfully) and are working on improving and fixing things. One contributor is looking to add a means to set zaxis limits to the firmware (keep the router from bottoming out or hitting the top) and it’ll be available in the holey firmware if successfully implemented.

Also note that GC is python2.7 only. Python2.7 is officially end-of-life, although there are some people trying to make a fork of it undeer the name tauthon.

Im probably going to run WC on a Linux server. Your GitHub mentions that I can just use the latest single file release and dont actualy have to install. I see headings of “RELEASE” and “EXPERIMENTALRELEASE”. Which release type should I go with?

Also, whats the difference between single file and single directory?

Good to know.

Experimental releases are ones that have newer features or changes we are testing out. If I were you, I would stick with the stable releases. It’s a bit odd how we do it, but last digit of the release indicates whether or not it’s stable or experimental. Even digits are stable, odd digits are experimental. Go with release 0.932.

Single directory versions decompress everything in the current directory so startup is quicker. Note, this decompresses directly into the directory where you are… so if you extract it in your home directory, lots of files will be dumped in that directory… so extract it into a subdirectory. Singlefile will create a temp directory when it’s run and will extract the files there. It takes longer to startup because of that…

ok, got it. Now it is all making sense.Thanks for the clarification.