RC Crawler Bumper Mount Kit

thingiverse

There are a lot of ways to mount stuff: 3D builder in Windows 10 is an easy way to make basic mods to a file if you aren't happy with my options (add holes, stretch parts etc.). This is a generic mount kit for my RC crawler bumper projects. It's here to simplify management of files, mostly. Check back here for improvements. My goal is to avoid changing the bumpers, so cross your fingers. So far, the plan seems to be working. The install illustrations don't show the chassis rails but otherwise, I think they get the point across. You'll need some M2.5 screws, typically about 8mm for mounting and 25mm+ for strengthening the posts. Strengthening the posts is optional but worth it in my opinion. If you print out of TPU and run a screw through for stiffness, the durability is very good. Even PLA without those long screws works pretty well, but a hard crash can break the posts. The tough mounts are another option that is more durable, and they mount right to the chassis rails. You'll need to either edit the STL files to add screw holes in the posts or drill holes after printing (My pref is drilling after printing). I left out the holes because a bunch of extra holes you don't use make the posts a lot weaker. I think most people won't want to use just the posts with the bumpers because that means you have to leave exposed screw heads on the outside, so I didn't add any holes to bumpers for those, you'll have to do it. Attaching the bumper to the mount is about choosing for strength or the point of failure. If you glue and screw the bumper to the mount, it will be very solid but breakage will be more hassle to deal with. If you go with the post style mount with no screw down the middle for strength, the post will almost certainly be the point of failure (the other being screws pulled out of the bumper). Posts breaking isn't that bad because you can either glue them back together or print a new one. If you build the whole thing for strength, who knows what will break? One of my chassis bumper mounts broke after several hard crashes, but all it did was kinda break the screw hole so glue got it back to usable. My only other breakages have been posts and even posts hold up pretty well as long as you print them laying down. About durability: The most likely breakage is the posts so I've made some tweaks. - The "Tough_Mount" style is a bolt to the frame mount that provides maximum strength. - The generic post can be screwed to any of the bumpers but that results in weakness at the screw point, so it is not ideal (The screw makes the post strong but can tear out a hole in the bumper). - The post with plate style is a compromise that is supposed to result in breakage to the mount but not the bumper. No matter what you do, something is going to be the weakest link. TPU makes good mounts because it is flexible and strong but it doesn't hold screws very well because it resists threads being cut into it too well. PLA makes good bumpers because it is strong and solid but any lack of beef makes a weak spot that will break during really hard bashing. My preference is a TPU mount with screws stiffening the bendy part as needed, then glue the bumper to the mount using something like B-7000 glue that can be released with mild heat. That way, if the mount breaks you can re-use the bumper and vice versa. That being said, the "Tough_Mount" approach works pretty well in PLA and will hold up to some pretty heavy hits. I use PLA only setups a lot when I'm feeling lazy and I haven't broken much, but I favor treating it like I care about wear and tear. Notes about features: - an optional hole down the center for M2.5 screws to add strength. - a separate post if that's how you want to roll. - guide nubs so you can drill your own anchor hole instead of having a bunch that weaken the part - TRX-4 and generic SCX10 clone cross member for easy install - Axial clone cross members should work but I included it because I have it - Redcat stock cross member works, so no Redcat version - the offset posts version of the mount lets you shift the mount posts up or down 4mm. - the "3" in the file name refers to the thickness of the base plate - the long version has 50mm posts, the other have 35mm posts - the long posts will break for sure without a screw down the middle Print with a heat where stringing has just started for max strength TPU will give good strength but you'll probably need a screw for stiffness (huh, huh, screw) - you can use a longer cross member and the flex in the post will be less of an issue Use at your own risk. Wrench to drive or drive to wrench?