Well. Long time no entry.
First of all Happy New Year to everyone.
I've made a few improvements on the Hadron printer I've built. I'll try to list them in the next couple weeks, maybe you'll be able to use some of them.
One of the things I wanted to improve was the Z axis stop screw. Here is the one I've made originally.
I just used a solid aluminum block back then, and threaded an M4x0.7 screw into it, and added a nut to prevent the screw from rattling out. As robust this design is – I used it for a year – it's a pain to adjust it. You need to raise the Z axis, insert an Allen wrench, use a wrench to loosen the nut, adjust, tighten the nut and check the z height again. This was tedious. Also you'll have to have those wrenches handy every time you want to adjust it.
Why do I need to adjust it that often? I realize If I print 0.25 mm layer height or 0.1 mm layer height I’ll need to have different Z height. Sure you can do this in the slicer, but I like to manually adjust it
First I used a 3/4”x3/4” bracket made out of aluminum angle stock. I threaded it, but because the aluminum extrusion thickness in 3.175 mm only 4 threads were grabbing. This allowed the screw to wobble, thus my z height was all over the map.
Next I bored the hole out to add this rivet nut.
I pressed it in, but the result was pretty much the same.
Well, I kept researching and came across another rivet nut from McMaster Carr. This is the real deal. Here is a x-section of the assembly.
With the help of the printed lever you can fine adjust the Z-height. I usually put a strip of standard printer paper under the extruder nozzle. I then lower the Z axis all the way until the paper is pinched and hard to pull by hand. Then I start going up @0.1 mm at a time. I record how many times I raised the Z gantry, and then knowing the thread I used has a 0.7 mm pitch I can adjust the lever. This make the whole adjustment process really straightforward. If the lever hits the makerslide I can rise it, reposition and when it comes back down I can continue the adjustment.
Here are the loose parts:
After assembly:
and here it is mounted on the printer:
I print the handle without support. that is how it's designed. The bolt is M4x0.7 and 30 mm long. the Spring used is also stock. Last and most important thing - I add a dab of blue thread locker to the screw thread. this will make it rock solid, but with some prevailing torque you still can do the adjustment.
Here is the stl file for the handle:
http://www.thingiverse.com/thing:217377