Preface and Considerations
Build your Own:Linear Translation Stage
Parts needed
- 2x (Metal) Rods ⌀ 6mm, at least 55mm+ long
- 1x Micrometer Screw 13mm travel - Link
- 2x Compression Springs ⌀ 6mm+, 20mm+ long
- + some sandpaper and lubrication
Printed Parts
Baseplate
Print as is (horizontal), holes are oversized (6.65mm) to compensate for vertical printing (I had to use the 0.6mm nozzle at 0.2mm layer height)
Stage
Print with holes facing the printbed for accurate diameter, choose one, depending on the orientation you will be using it. For testing I used it rotated at 90° so I will also include that (rod holes are sized at 6.2mm)
Step 1
Baseplate
Most integral for this assembly to work well is the fit of the rods. You want to avoid any movement or play as much as possible. Measure their diameter using digital callipers to be sure they are exactly 6.0 mm, then check their fit by pushing them all the way through both holes of the baseplate. It should take force to push them in.
- If they don’t fit (at all): sand down the holes evenly, clean and try again.
- If you notice any play: size down the holes (ONLY IF FUSION FILE IS PROVIDED) or adjust print settings. I prefer using random seam positioning whenever other options are unavoidably interfering with the inner diameters of accurately sized holes, for example.
[When sanding PETG-CF or any carbon fibre filament wear at least a surgical mask, as the tiny fibres are harmful to your lungs and will most likely accumulate.]
Step 2
Stage
For the stage you will want a tight but moveable fit. Since we don’t use any linear bearings, the sanding is an optional step that might be dependent on the filament you’re using. If it feels somewhat smooth to push the rod through on both sides, it is probably fine, but this is best tested when assembled and moving on both rods of the baseplate – especially with lubrication. If you sand, don’t forget to dust it off with compressed air or a vacuum and finally clean with a wet paper towel, to remove any leftover dust.
Step 3
Assembly
Now that you have the printed parts ready, you can assemble everything. This might seem somewhat self-explanatory to some:
- Insert the micrometer head into the dedicated center opening on either side and screw on the nut that came with it to fix it in place.
- Push both rods in about 1/3 of the baseplate, inserted from the same direction.
- Now push the stage onto the rails, center hole facing forward, towards the micrometer head, so it fits snugly into the dedicated opening
- Push the rails through the stage slightly, so they protrude and you still have sufficient space.
- Add the springs, preferably slip onto the rod first and then compress and roughly align with the respective rod hole.
- Now you can push the rods all the way through, test the assembly and lubricate as needed.
Conclusion
For this design, a lot of the working range of the micrometer screw is sacrificed by pre-tensioning the springs at first, and at last, not fully compressing the springs for smooth operation. The final ideal travel range for me was around 5mm – more than sufficient for adjusting the final focusing lens. This ensured sufficient tension on the stage to precisely adjust the movement when reversing direction, but not too much, as to overly compress the spring. You will have to find a sweet spot depending on the screws and micrometer head you use, but you’ll quickly feel it. It does take a bit of force though – especially towards the end of the operating range.
This is by no means an ideal design, but it works well enough for this purpose and is cheap, simple and quick to build and replace. Similar designs – mostly without any guiding rails – are available online. Reducing friction and ensuring dimensional accuracy and stability is even more essential with those.