This assembly guide is based on the Steady Hand Tool DIY Part 1 video tutorial.
Estimated Time: 30 Minutes
- 2.5mm Hexball screwdriver
- 3.0mm Hexball screwdriver
Before starting, sort your bolts into two main piles based on their diameter and length:
- M3 Bolts (Thinner)
- M4 Bolts (Thicker)
These are the totals the steps below actually consume. Count them out before you start — it is much easier than discovering a shortfall at Step 12.
| Fastener | Quantity | Where it goes |
|---|---|---|
| M3 x 8 | 2 | Step 12 |
| M3 x 10 | 2 | Step 11 |
| M3 x 16 | 6 | Steps 8, 9, 10 |
| M3 x 20 | 3 | Step 8 |
| M3 nuts | 7 | Steps 9, 10, 11, 12 |
| M4 x 10 | 1 | Step 8 |
| M4 x 16 | 18 | Steps 4, 6 |
| M4 nuts | 19 | Steps 4, 6, 8 |
Buy a couple of spares of each. They are small, they cost cents, and one will find the floor.
Printed base only. The machined aluminium base is solid and reaches its mass as material — skip to Step 2.
- Media: round steel shot, 1.5 - 2.0 mm, nominal 2.0 mm. This is not a preference, and it is
bounded at both ends:
- Nothing above 2.0 mm. The shot enters through the central ⌀8 mm socket, and that socket, not anything inside the chamber, is the restriction that governs. Granular flow arches when the opening drops below roughly four particle diameters. At 2.0 mm the socket is four ball diameters wide and the shot flows; at 6.35 mm it is barely over one, the shot goes in single file, and it bridges at the mouth leaving the outer chamber empty.
- Nothing below 1.5 mm. The chamber vents are ⌀1.5 mm. Anything finer runs back out of them.
- SAE S-780 blasting shot and #9 steel reloading shot both sit in this window. If a grade publishes a screen analysis, check its tail stays above 1.5 mm.
- Fill through the ⌀8 socket in the top of the base. There is no cover and no fasteners — the socket is the fill port, and the base is finished as soon as it is at weight. A funnel helps.
- Pour in stages, tapping or vibrating the base between them. A settled fill reaches the target comfortably; one unsettled pour lands at the bottom of the tolerance or below.
- Weigh the base. Do not measure out the shot. The specification is 680 g ± 10 g for the finished base, and roughly 517 g of shot gets there — but printed shell mass varies with printer, material and infill, so the scale is the authority and 517 g is only indicative.
Learn from our mistake instead of repeating it. Our own first fill used 6.35 mm slingshot ammo. It bridged at the socket, packed to 49% where a settled fill reaches 60%, and produced a 619 g base against a 680 g spec. The chamber was never too small. The media was too big.
- Differentiate between M3 and M4 bolts to avoid mistakes in later steps.
- The video secures a base cover with 5x M4x16 bolts and 1x M4 nut. Neither base has a cover any more.
- The printed base is filled through the ⌀8 socket in Step 1 and is finished once it is at weight; the machined base is solid aluminium. Neither takes a fastener of any kind.
- The step number is kept so the guide still lines up with the video. Keep those six fasteners as spares.
- Parts: 14x M4x16 bolts and 14x M4 nuts.
- Assembly Order: Thin spacer ➡️ Metal bearing ➡️ Fat spacer.
- Repeat this for all 14 bearing sets.
- Parts: 8 prepared bearing sets.
- Insert the bearing sets into the horizontal cage housing.
- Parts: 4x M4x16 bolts and 4x M4 nuts.
- Secure the cage assembly.
- Pro Tip: In tight spots, thread a long bolt in from the far side as a temporary handle to guide a nut into its pocket and hold it there while you start the real fastener. The M3x20 bolts are not needed until Step 8, so one of those is a good size for the job.
- Parts: 6 prepared bearing sets.
- Assemble the bearing sets into the vertical cage components.
- Parts: 3x M3x16 bolts, 3x M3x20 bolts, 1x M4x10 bolt, 1x M4 nut.
- Join the vertical cage components and attach the vertical rods.
- Note: Use the single short M4x10mm bolt specifically for the rod interface.
- Parts: 2x M3x16 bolts and 2x M3 nuts.
- Assemble and slide the stop onto the horizontal rods.
- Parts: 1x M3x16 bolt and 1x M3 nut.
- Install the stop onto the vertical rod to limit the tool's travel.
- Parts: 2x M3x10 bolts and 2x M3 nuts.
- Secure the ring that interfaces with the tool head.
- Parts: 2x M3x8 bolts and 2x M3 nuts.
- Install the final interface component that will hold your specific tool.
- Install the Steady Hand Tool and halfmarble logo plates into their designated slots.
Next Step: Watch Part 2 to learn how to install the magnets for the base and interface.
Before you install any magnet, read the Magnet Polarity Standard. Orientation cannot be read from a model file, and getting it wrong is what stops one person's tool adapter from seating in another person's base.