Tightening up the slap on XY

Just got finished building the MPCNC and I have a few questions as I’m a Noob to just about all of this.

Question 1:

When I first put X and Y up I heard a plastic scraping sound along X. On the other hand, Y moves beautifully. I disassembled and loosened the bolts which helped correct the problem but now there seems to be a lot of slop in the X and Y. This equates to about an 8th inch of play that I really need to tighten up. See video clip. When I was building the center, all of the bolts were so tight that they seemed to be threading themselves in. Although I saw a number of people drilling these out, I felt like tight might be better and so I left them as is for the first test because you can always take more off but you can put it back on. Is it normal to need to drill the bolt holes out?

Question number two:

Question number two:

As I was testing the stepper motors I noticed that they responded intermittently to commands from the full graphic smart controller/prepare/move axis/move X/ move 10 mm/turn knob. At start up everything works as expected, but then after moving on any axis for some time there’s no response to the turn of the knob. Stop moving for a while and then it comes back but the screen reads the wrong location. I went with the Chinese knock off so that could be the problem but I wonder if this is a common thing any help with this would be appreciated greatly.

w.r.t. 2) Are you saying it sometimes misses a turn on the LCD knob, or are you saying it’s skipping steps (grinding noises)?

The axes should move smoothly when powered off, although if they rack, then can get stuck.

w.r.t. 1) I think Ryan or others might know better, but I’m going to guess the advice will be to run it for a few test projects, and then take it apart/reassemble it. Things will loosen up enough to be able to adjust them how you want. I’m not sure though, I don’t have this version of MPCNC.

Also, w.r.t. 2) If it’s skipping steps, then the microcontroller and LCD won’t know. So they would display the desired value, but the motors would be in a different location.

No plastic should be anywhere near a rail to scrape.

You went too far and need to snug them up a bit.


Tight is fine needing to drill is not common. If you printed it you might need to check your printer, if you bought it from me then a little de-burr on the shiny side usually fixes it.


Not exactly sure what is going on, I rarely move it with the knob, have you tried my crown gcode? I don’t think this is an issue.

Here’s the video

trim.330478AB-18DC-44EF-BC81-19708AB2A51F.mov (3.07 MB)

Your set screw is not on the shaft flat but I am not sure what else might be wrong from that video.

Your belts are a bit loose and the cable ties should be positioned a little differently to minimize there flex, the corner tops are backwards but I don’t think it matters much.

Thanks for the quick reply guys and Ryan, amazing piece of work thank you so much for making it open source.

Jeff: I will tighten it up first and run it for a while and see if that does it. If not I’ll disassembled, drill, reassemble and try again.

Ryan: I will load up the crown and see what I get from repetier. So far I have only jogged around because I haven’t secured any of the wiring yet. I don’t have the wiring harness and hesitate to cut the wires to go in series because I don’t have a crimp tool for the ends as of yet. i’ve built out to the 30 x 30 max that you suggested in the instructions. Will the wiring harness you supply be big enough to accommodate? I changed the motherboard setting in Marlin to ramps 14 sf to use the extruder connections for X2 Y2 so I could begin testing without cutting the wires but I imagine the extruder steps per unit could cause a disparity between X and x2. Strangely, when I did this, X2 wound up on E1 and Y2 on E0. I was flying blind because I couldn’t locate any docs describing this particular use case but I figured the new endstop firmware update might have something to that effect. If I continue as it is, should I adjust the extruder setting to 200 to match X & Y? Are there any others settings I should know about related to this tune sure of the X2 x2 steppers run at the same rate? Can you link me to the docs on x2 y2 specifics so I don’t have to bother you with more noob questions of this nature?


I remapped them myself you can see what I did on the firmware in my github. You can use the dual endstop firmware and just turn off the endstops but leave the dual axis turned on.

I’ll grab the wiring harness and hotend from your store. Tighten belts check.
Cable ties check.
Corner tops check.
New firmware check.
Setscrew on the shaft? Please elaborate.

In the video it didn’t look like your pulley set screws where located on the flat of the stepper shaft. One of the things I was looking for was your pulley slipping, it seemed fine.

Setscrew – found, fixed.

ALL METAL 3D PRINTING EXTRUDER =Sold out. How long before you are restocked?

I have the titans in stock, the other ones are waiting on different steppers, due end of the week I hope.

Copy that, I’ll work on stabilizing the CNC until you get them in. Thanks again for the assist

I’m not an expert, but it seems to me that using zipties to mount your router to the Z is not the most stable thing to do…


Agreed, just for a test or 2 to see how deep it will hang