Hello, I have a question regarding mounting of the XY motors in my setup. I have 2 positions available for them, more clearly exemplified in the following picture:



The first option, with the motor under the flat plate would be best but I don't see how I could easily enclose the printer having to crochet the enclosure around the perimeter or having to completely offset the back panel. Although I could do that, I want to explore my options of mounting the motors inside the perimeter defined by the frame and the only option I have here is a top mount using spacers.

The needed distance is about 20mm, which is about the same length as the M5 Hex coupler I measured. I haven't seen M3 Hex Couplers in the stores I've checked but online info suggests they are 18mm in length. I could manage to squeeze the GT2 pulley between the plate and the motor 2 more mm but my question is: Is this setup too flimsy? Should I design a 3D printed spacer block that I can bolt to the plate with more bolts covering a larger area? Something like this Thing:704675 maybe...

What other spacer options are out there that can avoid the printed part and ensure the stability of the mounts?

Thank you.

Edited 1 time(s). Last edit at 03/01/2016 05:05PM by realthor.

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RepRap Lander concept on Concept Forge
RepRap Lander concept on RepRap Forums
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If you are going to enclose the printer.. are you also going to print ABS? Then if it is a heated enclosure you should probably keep motors outside.

I do not see a reason not to use printed parts for motor mounts. Just make them extra thick: 10mm walls with atleast 2mm of printed perimeter and high infill number. If you are paranoid about part's stiffness then go crazy thick and print thick parts with 100% infill.

The aluminium plate in your image looks just a few millimeters thick and without any bracing. Is it really going to be all that stiff as you imagine it to be?

That is a steel plate 2-2.5mm thick and about all the forces go along it so it doesn't need much thickness.
I don't plan to print ABS but one never knows, I might in future, if proper filtration and ventilation would become available.

I intuitively know that a 3d printed part would take the flimsiness from the 4 legs as I showed them in the picture but would it be too unreliable with the setup only consisting of the 18mm hex couplers and the stepper motor bolts themselves? Are there any other non-printed options I can use (say, common, off-the-shelf maybe).

PS: I incline towards keeping the motors out of the enclosure.

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RepRap Lander concept on Concept Forge
RepRap Lander concept on RepRap Forums
My Things, mostly experimental stuff

You could also flip the pulley upside down and drill a hole in the middle of your plate for the pulley to go through. Then you would not need such a long hex couplers.

I guess that 18mm long M3 coupler is a actually a brass stand-off for electronics boards. I do not think think that they are suitable for this. I have bent way to many similar length M3 stainless steels bolts just with my fingers.

Long nuts usually come 3 times longer than a diameter. So that would be 9mm for an M3 thread. However I think that smallest size is actually M5.

What about a metal mounting plate straight to the motor and then using long M5 nuts to mount this plate to the frame of the printer? That should be stiff.

I am pretty much stuck with using off-the-shelf parts for this one so I either do the first option, the flipped-under or the on-top with spacers and a 3D printed helper mount that the spacers will be hot-inserted in.

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RepRap Lander concept on Concept Forge
RepRap Lander concept on RepRap Forums
My Things, mostly experimental stuff