3DP linear bearing (recirculating) and DIY linear rail (old version) by Baltojikale

Last crawled date: 3 years, 3 months ago

Update https://www.thingiverse.com/thing:4671314
3DP linear bearing and DIY linear rail
Introduction
Been searching cheap alternative which can be 3d printable (partially) and made from easily acquirable materials from home depo or similar home improvement shops. Main challenge was to innovate linear rail design which could have mounting holes to flat surface. There are few recirculating linear bearing designs on thingiverse or other depositories. Most of them designed to be used with 3dp rails or V or T aluminum profiles. T or V slot aluminum profiles ware out of question as their not that accessible locally. Thus simple profiles were used to produce linear rail. For linear bearing prototype was made with 3mm steel ball bearings. Resent ones aren’t that available but one could try to find store which specializes in bearings they often sell have bb in packs.
Design
Linear rail
Rail was produced from rectangular 15x2 mm aluminum beam and from 10x10 mm aluminum square tube. Two pieces were center drilled and riveted to acquire shape which can provide rolling surface for BB’s. Making rail involves printing alignment jig (or jigs). For hole drilling best to use calipers and pointy punch to mark drilling holes.
Linear bearing
Design was improved upon few iterations. Design required to incorporate tensioning mechanics towards linear rail. Thus bearing is made up from 5 parts. Size is kept as small as possible but also leaving some thick zones for sturdiness.
Contact points
This rail and bearing design incorporates at least 6 points of contact between rail and BB.
Printing
Used Pla with 25-35% infill, for dimensional accuracy printed outer walls first and very slowly (~5mm/s) 0.4mm nozzle. Printer slicing profile should be calibrated, at least for inner holes. For my set up I scale up models by 0.5% to compensate for part shrinking. Used 3mm BB thus model has incorporated 3.3mm diameter BB guide grooves.
Tensioning system
Current model has spacer parts which should be adjusted with file/sandpaper or before printing. Also there is 45 degree angle incorporated to horizontal tensioning. There are 2 surfaces which can be grinded off to ensure either horizontal or vertical tensioning. For tensioning inner parts have oval shaped holes thus M3 screws have space for sideways movement.
Short demonstrationhttps://youtu.be/ryh3pSujLEY
Further development
would be nice to have community help to improve design. Design improvements involve other shape rail testing, adaptation for 6mm airsoft BB’s(bullets) and more clever designs thus less parts are needed to print. This design has at least one problem: tensioning mechanism is same as mounting mechanism thus one cannot over tighten mounting screw as they can possible deform part and interfere with BB circulation.