Building a 3D Printer, RepRap Mendel Prusa2 by craynerd

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j45on:
Chris are you running the bearings on silver steel ?
I had trouble with my first cnc using bearings on silver steel as the bearing balls are harder than the shaft and it scored the shaft rather than running smoothy.
I now have lots of silver steel now as I had to buy hardened and ground shaft :palm:

raynerd:
Jason, I didn`t think about that...just presumed silver steel would be better than mild steel. I`m guessing I`ll have to change it to hardened rod at some point.... ohh dear, more ££££!!

Ok, we`ll in the little bits of time I pinch in the workshop, I`ve made more progress.

I`ve put the 6mm ply table on 225x225mm with the belt and motor in place for the Y motion:

I`ve gone for a double bearing rather than using the printed bearing holders... tough one as lots in the IRC said there bearing guides worked fine but a few said this method is better:

Bearings in position and belt grips shown:

The the x axis built and clipped into place:

Carriage running on linear bearings on the X axis

Lead screws for the z axis along with nuts and springs:

Turned down some little couplings for my lead screws as the printed ones wouldn`t hold. They are M8 one end and grub screw 5mm bore the other:

and currently as it stands:

Next job is to add the belt to the carriage and mount the motor and then I think I`ll be looking at assembling the extruder!

ChrisC:
The printed couplings are normally designed to have a piece of 5mm bore PVC tubing slipped onto the motor shaft before assembling. It is intended to allow a bit of flexibility to take up mis-alignments between the motor, leadscrew and the Z axis nut.

Chris

raynerd:

--- Quote ---The printed couplings are normally designed to have a piece of 5mm bore PVC tubing slipped onto the motor shaft before assembling
--- End quote ---

Yes, I believe so but unfortunately I didn`t see this in any of the assembly tutorial videos or guides. A little tube would have been useful to counter some misalignment but I`ll see how these solid ones work. I must admit, they both turn just fine but one does look at a slight angle. However, since the x axis idler is fixed in its position of the flat bar in relation to the lead screw, I don`t see how there is anything that can be done about it! I`ll have to see how it runs with the motors attached.

Chris

ChrisC:
Yes the quality of the build info is a little variable! I'm not sure how useful the PVC tube actually is. My Prusa has it fitted, but I'm building a second system at the moment and I'm trying a printed coupler without PVC tube. It will be interesting to see how the rigid couplers compare to the more flexible ones. In theory you do need some compliance here to protect the motor bearings, but the whole frame is so flexible that I doubt it actually makes a huge difference.

Your build is looking good. What electronics are you planning to use?

Chris

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