M4, Our assembly observations and optimizations

A friend and I finally were able to get together and start our build process yesterday and hope to complete it today. So I wanted to start a short thread on our observations and ways we’ve optimized and improved the process.

  1. Loctite brand is so well known that most thread locker is called loctite. With the super glue having large brand name, Loctite, on the package, we figured the unmarked small tube was the superglue even though it wasn’t clear. We figured it out after we’d put the thread locker on the belts/gear assemblies and the magnets. Might be helpful for those of use who’ve used Loctite thread locker for years to have a sticker on the bag or bottle of threadlocker which says, “Not SuperGlue”. LOL or just “thread locker”.

  2. the 3 screws holding down the belt guide do not extend into the nylon locking portion of the nylock nuts and could work their way out. These screws and nuts would rattle inside the belt arm housing and likely jam in the gearing. I put a dot of thread locker on the tips of these three screws on each of the 4 belt arms to help keep them from eventually damaging the belt arms.

  3. when assembling the 2 halves of the belt arms the 6 nylock nuts on each arm are recessed enough that it can be tough getting the screw to bite and start threading. I used one loose nut placed on top of the nut/screw I was working on so that my finger and the extra nut hold the nylock in place enough to get the screw to bite every time. I just move that loose nut to each screw hole as I work around the circle of 6 screws. The 2 nuts under the encoder boards will just have to remain a PIA to get to start the threads.


16mm bolts work better for most of the locations. I plan to check if 16mm will
work everywhere when I put together the one for the local makerspace.

David Lang


I know exactly what you are talking about. I call thread locker “loctite” all the time and then get it confused. I love their super glue so much, but it for sure adds a layer of confusion.

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Luckily there were two of us and while we both made the error to start as we were laying out the parts, it was something after the 2nd application which caused me to ponder the situation and notice the “Super Glue” label on the Loctite packaging. It was a running joke the rest of the day.

That might even be enough for the 24 screws in the belt arm cases so that finger pressure on the nut holes causes pressure on the nut against the longer screw so it grabs the threads.

But it is so very nice that most everything uses the same length and size screw and single type of nut.

Doug LaRue wrote:

But it is so very nice that most everything uses the same length and size
screw and single type of nut.

I very much agree, I just wonder if they can all use 16mm bolts instead of 12mm

David Lang

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The other builder stayed with the stock v0.76 firmware and got things going and even has motion on his frame. He found out that his floor anchors are situated where at the extremes there is belt interference with things like the rollers of his CNC machine and legs on the shelving unit but that can be fixed by moving his floor anchors.

My machine took some effort to get up and running after v0.78 left it in an odd place and worst, downgrading to v0.77 firmware but still having v0.78 index.html.gz/fs data and maslow.yaml/config) left me with a forever loading white webpage. Read about that here:

But I got past that by figuring out how to hack the windows release data into the posix install system to put the v0.77 fs data on there which got me a working maslow.local web page and then I uploaded the v0.77 config/maslow.yaml file.

First thing I did was try retract all but only 3 motors moved. So to troubleshoot I powered off, swapped the encoder wires to the left of the router power cord, powered up and tried retract-all again and this time I saw that one motor move an inch. I stopped it, powered down, swapped the encoder wires back and after power up the retract-all started pulling in that 4th motor/belt.
But it kept stopping after moving only 1 inch or so but I kept pushing retract-all a half dozen more times and got it locked in place like the other 3.

Moving Z down to the base worked also.

With quite some force I was able to get the belts to release and then retract again. So things are looking good.

I also noticed this when assembling. I turned the nuts upside down to avoid them from loosening. I also noticed that they shouldn’t be tightened so much that the belt guide starts to bend. As both of the arm-parts are the same, the bottom part also has a recess. Whereas the screws for the motor need this, the beltguide does not. The belt guide supports starts to get skewed as one side goes down in the recess if they get tightened too much. I thought about putting in a spacer under the three supports, but I didn’t have any.

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