Granite bumper sping

[schneidp20]

Are you breaking your bumper spring and tired of buying an inventory of stock replacements? 3D print your own. I'm still experimenting so I'm interested in your experience if you try this. I've managed to break both a Nylon and PC so these still aren't indestructible so be sure to make spares. I guess that's still better than breaking the shock tower. Comments and suggestions are welcome.

https://www.thingiverse.com/thing:4144767

 

[SrC]

Nice. Thanks for sharing.

 

[s_fussnecker]

Are you breaking your bumper spring and tired of buying an inventory of stock replacements? 3D print your own. I'm still experimenting so I'm interested in your experience if you try this. I've managed to break both a Nylon and PC so these still aren't indestructible so be sure to make spares. I guess that's still better than breaking the shock tower. Comments and suggestions are welcome.

https://www.thingiverse.com/thing:4144767

I'm somewhat new to 3D printing and still have not tried Nylon or PC, so I've been printing these in PETG, but they are too brittle. I've only used 2 so far, but both have shattered on me on the first use. I do bash pretty hard most of the time, but the first one I shattered was on a small RC track, not a 20 ft jump.

I don't think it's the material to blame, but the thickness of the model. If you compare them to the stock springs, they are much thicker, which does not mean better. They are supposed to be springs after all. I will eventually get around to designing my own thinner version, but I don't have access to SolidWorks, and I'm still learning Fusion 360. In the meantime, I'm playing around with the wall thickness and infill to try to make these more flexible. I actually have one printing at this moment with thinner walls. I'm hoping to try it out tomorrow, so I'll let you know if it holds up or not.

 

[schneidp20]

You are right, PETG is pretty brittle. So is PC. The best filament I found so far is nylon. However, in cold weather it too becomes brittle. Just stop hitting stuff.

 

[jondilly1974]

You are right, PETG is pretty brittle. So is PC. The best filament I found so far is nylon. However, in cold weather it too becomes brittle. Just stop hitting stuff.

Or use TPU ??‍

 

[schneidp20]

Re: Or use TPU ??‍

I tried TPU too, but it's too flexible with this design. A solid piece with say 20% fill should work. I haven't gotten around to redesigning the bumper for TPU

 

[s_fussnecker]

You are right, PETG is pretty brittle. So is PC. The best filament I found so far is nylon. However, in cold weather it too becomes brittle. Just stop hitting stuff.

I've been researching printing with Nylon, and I think my printer can handle it, so I'm going to order a spool and give it a try soon. Stop hitting stuff is not an option for me, I like to go big and often have to pay the consequences. https://www.youtube.com/channel/UC8o7kXe14q8y6TuKx_6WgrQ?view_as=subscriber

 

[GRC]

I broke 4 bumper springs on the first 4 runs with my Granite. Then I stuffed the bumper springs with foam tape. I have not broken a bumper spring since. I jump. My bumpers take hard hits, they survive bad landings from 30 foot jumps. They provide great protection and never break. The bumper springs are amazing once you stuff them with foam.

 

[parcou]

I broke 4 bumper springs on the first 4 runs with my Granite. Then I stuffed the bumper springs with foam tape. I have not broken a bumper spring since. I jump. My bumpers take hard hits, they survive bad landings from 30 foot jumps. They provide great protection and never break. The bumper springs are amazing once you stuff them with foam.

View attachment 101895

Where did you get those clean-cut foam stripes on the shock tower?

 

[s_fussnecker]

I broke 4 bumper springs on the first 4 runs with my Granite. Then I stuffed the bumper springs with foam tape. I have not broken a bumper spring since. I jump. My bumpers take hard hits, they survive bad landings from 30 foot jumps. They provide great protection and never break. The bumper springs are amazing once you stuff them with foam.

View attachment 101895

That's great! I've been thinking about trying something like that but haven't gotten around to it yet. I'm glad to know it's working for you. I'm still going to try printing new bumper springs in nylon tomorrow since my thinner walled PETG still shattered today, but the foam tape should be an improvement either way. Do you use any specific type or do you think anything will work?

Off topic, but what shocks are you running? They look nice. I've been struggling with finding good shocks. I have some Hot Racing Aluminum bleeder shock bodies coming, but I am not finding any other decent options. I bought a cheap set of aluminum shocks from ebay, but the lengths weren't an exact match and I bent one 90 degrees after a few runs. (not the shocks fault entirely, see the jump that did it here:

) The stock shocks just leaked all the oil. I also bought a rebuild kit for the original shocks since I heard they stop leaking after a rebuild, but I haven't tested it yet.

 

[GRC]

Off topic, but what shocks are you running? They look nice.

Tekno shocks TKR6021/TKR6022. I think the front may have a different number now. They are slightly longer than stock shocks. Better for landing jumps, but you may notice more rollover at first. If you want to keep the same ride height, you can use the wider shock holes on RPM arms. But after some spring adjustment, they're running great and like the extra travel/cushion. They are expensive, especially since I added emulsion aluminum caps and delrin parts. But they perform great and have been rock solid. I don't want to jinx myself, but they have never caused a problem. No bent shock rods, no broken rod ends, no leaking. I'm no longer running the bronze Tekno springs. They looked great, but weren't stiff enough for big jumps. I'm running Arrma shock springs now.