First Mod - Z axis REV A

Share your hardware improvements for your HIC i3, the good and the bad!
Post Reply
User avatar
Chip Luck
Posts: 191
Joined: February 11th, 2016, 9:12 am
Location: Central Florida
3D Printer(s): HICTOP Reprap Prusa I3

First Mod - Z axis REV A

Post by Chip Luck » February 11th, 2016, 2:17 pm

I was not satisfied with the instructions, there was no mention of just how far to insert the vertical threaded shafts into the coupler.

Now, being an engineering type and consulting with my best frieind that is a master machinist that has 20+ years desining and building this type of setup, you do NOT want the shaft bottoming out on top of the motor shaft at the bottom, nor do you want the entire shaft inserted into the flex-coupler - that will defeat it's purpose.

Also of note, normally the threaded end of the shaft is turned down on a lathe so it is a round mounting point, you do NOT normally mount a threaded shaft with set screws pressing on the threads = non-precision.

Right now, living with what was supplied by the MFG I performed the following until my actual lead screws, bronze bearings, etc. arrive.

1) measured top depth of shaft that will go into the flex-coupler, insert threaded rod just down to the first 'cut' in the coupling and torque set screws
measuring rod depth into coupling
2) Mark the shaft depth:
mark rod depth
Z-axis rod properly inserted into motor coupling
3) took a drift, and gently seated the smooth Z-axis rods into the hole in the lower motor bracket rod hole.

4) took a split washer and inserted it as a pre-load/shim to put pressure on the smooth rod under the top bracket plastic retainer to keep pressure on the smooth Z-axis shaft, this 'should' maintain shaft position and it has so far. You will also see now the Z-axis threaded rod is extended PAST the top part of the upper rod holders. Do not like the design of the upper shaft retainer's, the will wallow out over time in the threaded rod hole. Some install bearings. However, proper procedure would to get perfectly standard M8 straight threaded rods (or real lead screws) and install modified top rod holders with a bearing to retain the threaded rod/lead screw.
Top view of rod holder
So far, this has worked well. Again, will be updating the z-axis assembly to a true leads screw and bearing setup in the near future.

Hope this helps, mine sure is running more smoothly - and the rods do not pop out of the bottom mounting hole and with the rod properly installed in the coupling, print quality definitely has increased.


User avatar
Posts: 745
Joined: March 25th, 2017, 8:17 am
Location: Washington
3D Printer(s): Hictop 3DP11/12

Re: First Mod - Z axis REV A

Post by Roberts_Clif » August 2nd, 2017, 12:06 pm

This is an old post, Wanted to add some newer data. Z-Axis stepper motor brackets are so thin that they would not stay in the supports.
Was searching thingiverse and came across this little jewel for the smooth rod supports.

Ratdoghippy on thingiverse modeled a pair of Z-Axis solid rod supports Here
which will provide excellent support for the Z-Axis smooth rods.


Is the support for the threaded rods actually necessary, with this much better smooth rod support would the print be deteriorated in any way if the threaded rod's were not supported.
Electronics Technician / Computer Programmer

Post Reply

Return to “Hardware Modifications”