Bed Height Adjustment

As I noted in the Adjustable Z End Stop mod, I divided the problem of leveling the bed on my Ender 3 into two independent procedures:
  1. I use the modification to the extruder fans, on which to moutn a dial indicator to level the bed without needing to reference Z-home.
  2. I use the Bed Height Adjustment modification in tandem with the Adjustable Z End Stop modification to set the Z-home bed elevation.

A video tutorial of both procedures is available here.

The Bed Height Adjustment is comprised of two printed designs:

  • Bracket
  • Arm
f3d

 

You'll need a metric dial indicator and some harware for this modification.

I purchased the dial indicator from Amazon. It is relatively inexpensive and has performed as needed.
Dial Indicator, 0 - 0.8mm range, 0.01 mm resolution
https://www.amazon.com/gp/product/B0781LY1H5/ref=oh_aui_detailpage_o01_s02?ie=UTF8&psc=1

The other hardware you'll need:

Quan Desc
2 M5x12 fastener
2 M5 T-nut
1 M4x20 fastener
1 M4 hex nut
1 M3x16 fastener
1 M3 hex nut
1 ~20 mm x ~10 mm dia compression spring

 

Bracket

The bracket has a pair of guides on the bottom surface which keep it aligned with the T-slot in the left 4040 extrusion (next to the controller box). it is fastened to the extrusion by a pair of M5x12 fasteners and T-nuts.

Note that I provided a small boss for ech of the two M5 fasteners to accommodate 12 mm length. I've noticed that in the ubiquitous metric hardware kits available on Amazon, the 10 mm long fastener is not included (which would be a much better length). So, rather than having to buy M5x10 mm fasteners, I just add to the thickness of the bracket to ensure that the 12 mm screw does not bottom-out in the extrusion T-slot.

If you have 10 mm and prefer to use them, you'll need to change the source model (which is included with the STL file download).

Arm

The arm is mounted on the bracket by means of an M4x12 fastener and nut (the fastener also serves as the pivot point). The purpose of the arm is two-fold:

  1. It holds the metric dial indicator in the correct position relative to the adjustable Z end stop.
  2. It is vertically adjustable to accommodate the range of the dial indicator. An M4x20 fastener, nut, and compression spring are used to enable very precise up and down motion.

The range of the dial indicator is 0.8 mm. Relative to the adjustment resolution we need to bring the bed elevation into spec, this is more than enough travel. However, the dial indicator needle is moveable on its pivot point; so, the procedure is first to move the needle into close position, then use the M4x20 fastener to "fine-tune" its vertical position. Once the bed has been brought to the correct Z-home elevation, it is not likely you'll need to move it very often.

This is shown in the tutorial video here.

 

Download Bracket and Arm STL models and Fusion 360 Archive as a single zip file. 

 

3D view each model:

Bracket
Arm


20181030 114145Fig. 1

A view of all the hardware needed for this modification:

Quan Desc
2 M5x12 fastener
2 M5 T-nut
1 M4x20 fastener
1 M4 hex nut
1 M3x16 fastener
1 M3 hex nut
1 ~20 mm x ~10 mm dia compression spring
 

20181030 114217 Fig. 2

Shown here is the Arm (top) and Bracket (bottom). Note the short bosses on the bracket to accommodate the M5x12 fasteners.

 

20181030 114229Fig. 3

Another view of the arm and bracket. Note the M3 nut mounted in the arm c-clamp used to secure the dial indicator.

 

20181030 114319Fig. 4

Bracket with M5 fasteners and T-nuts.

 

20181030 114440Fig. 5

Left-side view of the assembled bracket and arm. Note the M4x20 fastener as the arm pivot point and the M5x20 fastener and compression spring used for precise vertical adjustments.

 

20181030 114450Fig. 6

Right-side view of the assembled bracket and arm.

 

20181030 114547Fig. 7

Top view of the dial indicator mounted in the arm.

 

20181030 114540Fig. 8

Right-side view of the dial indicator mounted in the arm.

 

20181030 114606Fig. 9

Left-side view of the dial indicator mounted in the arm.

 

20181030 114859Fig. 10

Top view of the Bed Height Adjustment mounted on the 4040 exrusion.

 

20181030 114829Fig. 11

Left-side view of the Bed Height Adjustment mounted on the 4040 exrusion.

 

20181030 114926Fig. 12

User's view of the Bed Height Adjustment mounted on the 4040 exrusion.