Hi guys, I have a “square-tubing frame” related question. I am designing a frame that has the same node architecture as the quadrap#quadrap-3d-printer but I want to have 2 bolts per connection instead of one.
I am designing the Drill Guide TOOL that will help me drill straight all these holes and I had the idea to use some of the bearings I will later use for the belts as temporary guides.
My issue is that those bearings have a 4mm ID so I would end up with 6 4mm holes per node. Is 4mm a too small diameter bolt for securely attaching the tubes in a node? My current design has 5mm bolts but I don’t have the bushings for it so why not keep the vitamins to a minimum and reuse something that will later be used in the build :).
I agree from the start that one bolt per tube-2-tube connection can be enough but I am thinking about drilling ease too (if the tubes will be steel drilling smaller diameter holes is easier) and also about installation time (after your first drills you just connect the tubes and you have a square corner, no rotation as you would have with one bolt, so it’s easier to move on and drill the other holes). Also being close to the walls the fastening force will not tend to buckle the surfaces the bolts go through.
4mm holes can be a tad small but after you have them straight it’s quite easy to just enlarge them with another drill bit freehand.