Welcome! Log In Create A New Profile


Prusa I3 hole sizes

Posted by interzen 
Prusa I3 hole sizes
October 13, 2014 04:46PM
Hi all,
I was wondering if anybody can help me with a quandary.

I am using my mendel max 1.0 to print parts for an I3 single plate rework (10 mm y-axis threaded rods) but I am having some sizing issues.

I started by printing a y-corner to check my machines calibration and the holes are very loose on the 10 mm threaded rods and slightly loose on the 8 mm rod. My caliper shows the 10 mm rod holes are actually about 10.75 mm and the partial hole to hold the 8mm smooth rod is about 8.4 mm. I am printing in ABS which I am less familiar with and my first thought was that I need to compensate for shrinkage or maybe I was under extruding.

My printer is working great and the part looks perfect to me other than this hole size issue. Solid infill on the top surface is very smooth which would change if I upped the extrusion rate very much. On a whim I decided to look at the STL file in netfab and measure the hole sizes. To my surprise they are very close to my physical measurements not the even 10mm and 8mm I was expecting. The outside measurement of my printed part is 17.65 instead of the 18 in the model which I think is due to shrinkage and possibly under extrusion. I have double checked my e-steps/mm and filament diameter. I seem to have near perfect solid infill at my current settings with very little to no inset between extrusion lines.

Does anybody know if the holes are deliberately over-sized?

I really want to dial in my settings and keep them the same for all the pieces so they match in dimensions. What sized hole should I actually be shooting for? I assume the smooth rods will need to be very close to 8 mm or they will move. How about the threaded rod holes. Is a little slop OK? I have heard of people having to drill parts out but I have the opposite problem.


Edited 4 time(s). Last edit at 10/13/2014 09:59PM by interzen.
Re: Prusa I3 hole sizes
October 18, 2014 06:37PM
Yes, depending on what you slice with, and your printer, holes are smaller than expected for most people. All my openscad code has wiggle variables which expand holes by a bit. Your machine and slicer combo are working too well!
Sorry, only registered users may post in this forum.

Click here to login