Z-motor bracket

Hi all ,

Decided to build the MPCNC burly .I printed all the parts on my Velleman vertex K8800 printer .
I’m stuck with the Z-motor-F-Burly bracket and the z-lower-F-burly .Putting them on the 2 tubes (25 mm ) is very tough .I can push them on the tubes but they do not slide .I need to use 2 flat screw drivers to open the holes to push it down .Even then it is difficult …
I allready reprinted one of the 2 parts reduced filament (95%) instead of 100% .
When I measure the hole diameter it is around 24.6 mm .
Question : is it normal that these parts are that tough to put on the tubes .
All the others parts ( feet for examples ) were easy to slide on the tubes .
Any ideas ?


Could there be a little “elephant’s foot” on the side that was on the build platform making the diameter at that end smaller?

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Tom,This is not the case .The round holes have a chamfer on both sides .
I decided to convert he stl back to a solid and made a section .
It seems that the tubes are 25 mm hole designed .The hole for the bearing seems to be 22.4 .The bearing has an outside diameter of 22 mm .So we have 0.4 mm gap on the bearing but no gap on the tubes .It looks to me that it is designed this way.

I’m currently printing the 25.4 mm version of this part.Let’s see tomorrow if that slides better on the tubes as my current parts are allmost impossible to use .


What software are you using?

Mine were tight, but they weren’t THAT tight!


I’m using cura.
Just tried the 25.4 mm version and seems to be perfect.Just a light friction .When the bolts are mounted i think it will be perfect.

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Mine were very tight, I used a steel ruler to gently (well not so gently to be honest) prise the faces apart. I printed them in PETG (as that’s what I had at the time) which is quite a strong material.


Hello all,

I just did a check on the foot part for the 25 mm tube and also that hole is around 25.3 mm
So I’m still wondering if the design requires that tight fit on those parts .Maybe the egineer who designed this part can answer.


That would be @vicious1.


There should be a larger opening, maybe the conversion to a solid from the STL picked different facets.

This has not been much of an issue in the past, but as long as you can get the tubes it it will be fine.

It is not an issue .I printed the 25.4 mm version which is perfect for the 25 mm tube.
Maybe it is worth to check the diameters in the 3d model .I think the conversion is not the issue .
I checked the feet ( 25.4 mm for 25 mm) ,the bearing on the z-motor bracket (22.3 mm for 22mm ) .
When I checked the L version of the z-motor bracket it measures also 25.4 mm for 25.4 mm.Also here i see no bigger opening.Same as in the F version .
So the measurement on my solids seems to be consistent with the physical printed parts .7
Any way,I.m back on track to continue this great project.

Best regards

If you get binding it is because the lead screw in in a slightly different position.

I am not going to edit the old files, since I have not had any issues while they were current, but I will take care with the new ones.