Little Monster - None 3D Parts to Make
It was my goal to have this project 100% 3D printable. But some things just cant be made strong enough out of plastic.
The following simple parts need to be made out of Alu round stock and can be made with a hack saw, drills and taps
Drills needed: 3mm 4.5mm, 6mm, 8mm
Taps Required: 5mm & 6mm.
Parts to manufacture Little Monster Mower:
Step files for these metal parts are on the GITHUB Site
Wheel Axel Adapters
Wheel axle adapters (15mm outer diameter). Converts the short 6mm motor shaft to a 15mm diameter motor axel shaft. The adapter is clamped to the 6mm motor shaft with a 6mm screw or set screw and fits through the 15mm bearing in the wheel arch. The wheel is then fixed to the axle adapter with an M4 bolt which goes through the diameter of the wheel hub into the axle adapter.
Make sure to loktite the threads on the M6 set screw. Otherwise at some point it will back off and be loose.
Little Monster Mower Axle
The wheel axle assembly is as follows.
An M4 bolt is screwed through the rear wheel into the rear axle to lock the wheel
Drill Templates Axle Adapters
To aid the manufacture of the wheel axles I created these templates which can be downloaded from my GITHUB site here.
There are 2 types of templates.
1. For a drill press (recommended)
2. For a Hand Drill (longer template to help the drill keep straight)
End 6mm hole to fit over the motor axle.
First print the templates and cut the 15mm Alu round stock to the right length. Make sure that the cuts are as straight as possible (best of all using a chop saw)
1. Put the 3mm drill template on the axle.
2. Drill the axle (best with a basic drill press) with a 3mm pilot hole using the template hole to center the hole in the axle. You may need to tap down the template onto the axle with a rubber hammer to ensure the template is sitting correctly on the axle.
3. Once the 3mm pilot hole is drilled. Remove the 3mm template and replace it with the 6mm template. Again ensure the template is correctly sitting on the axle. Drill the hole again with a 6mm drill.
4. The axle should now be drilled with a 6mm drill with a very well centered hole.
6mm Set Screw Template.
Using the same method as above take the square shaped templates and use them to drill first a 3mm pilot hole, then a 5.5mm hole. Finish by tapping a 6mm screw thread into the axle. The templates will ensure that the hole is centered on the dameter of the axle perfectly.
Using this method its possible to get very repeatable results.
Push the axles into the 3D printed rear wheel. Using a long wire through the axle hole mark the position of the wheel screw. Using that mark drill a 3.5mm hole and tap it to 4mm to accept the wheel locking screw.
Mower Motor to Blade Disc Adapter.
Aluminium round section (ca. 28-30mm diameter x 15mm height) with an 8mm through hole to fit the mower motor shaft.
2x 5mm threaded holes to accept M5 bolts from the blade disc.
Drill Templates Blade Adapter
To aid the manufacture of the motor blade adapters I created these templates which can be downloaded from my GITHUB site here.
Use them in the same way as the axle templates above.
- Start with 3mm pilot holes for all 3 holes
- Expand the holes to 4.5mm
- Continue to expand the center hole to 6mm then 7mm then 8mm
Using the templates produces really nice results. Disc in the video is the one I manufactured above in the photo montage: