Looking to start on my pump, finally. However, one thing is in my way. How the hell do I attach a plastic printed impeller to the metal motor shaft?? I tried glue once on props/gears & they eventually just fell off & spun in place…….. what are ya’ll doing?
keep in mind that it’s only been in about 4 battles. Take it with a grain of salt. But I used really thin CA glue and the impeller still works just fine on the Lutzow
Interesting… so you had success just gluing it? I’ve been searching for some sort of aluminum/brass coupler thingamadoo.
I have my plastic ones with a set screw that would hit the flat spot on the shaft to keep it on.For my metal ones I used a bit of loctite and that worked well. Just had a pump apart today could have showed you.
What format? And what motor? I've tried a lot of printed impellers over the years. Very few survived. One had a dubro collar abs slurried into it. I've tried replicating it and haven't had good results. Pretty much everything else has the impeller disintegrating. Lol I do make my small cruiser pumps with a printed pump/impeller on a brushed 380 motor and for that the impeller is actually press fit onto the motor shaft. I haven't had any issues or heard any from others so that might be an option for you.
what I have done is the Dubro collar but like what @Beaver said unfortunately it does make the impellers a bit fragile but I have two that have stayed together so far. I also have press fit ones which are in my NJ and those impellers are metal and they run at 6s and haven’t given me any grief yet.
Ideally, dual format. Since I have both rule sets here; I’d like to swap the cannons & radio profile only. I was thinking about the dubro. Where did you get metal impellers? I’ll probably start with gluing it in place & then iterate from there...
I have used: 3d-printed ABS impellers with tapped #4-40 setscrews, no metal reinforcement, with 380-sized motors for destroyers, cruisers, and transports. One setscrew sits on a flat spot on the motor shaft, the other setscrew (on the opposite side) is there to roughly balance things out. No failures yet. 3d-printed resin impeller with tapped #4-40 setscrews, no metal reinforcement, with a 1200kV brushless motor for Big Gun. Moves LOTS of water through a 1/4" outlet. No metal reinforcements, same two-setscrew arrangement as my ABS impellers, just a bigger pump to take advantage of the power. Again, no failures yet. I have heard that some people heat-set or acetone-weld a metal collar into their 3d-printed pumps. I haven't needed to, but none of my pumps have been particularly powerful.
That seems to be the sweet spot for printed impellers, lower power pumps with less resistance. When we start getting into fast gun rpms and pressures, that's when start breaking. I've got a potentially promising low cost solution for the best fast gun pump impeller design in the hobby. I just haven't had the time to finish the prototype and test.
I've used all of the above along with a good old fashioned axial roughening of the shaft and a press fit of abs onto a 5mm shaft. Removal of impeller = destruction of impeller, so buyer beware. It all comes down to how much torque the connection must resist to stay static... which comes down to the design of the impeller. One designed for a specific pressure rise and flow running slower will by definition require more torque than exactly the same performance point running faster, and that isn't even considering the efficiency gains one usually can get raising the specific speed above where many of our pumps run.... One designed as a regen turbine impeller, for example, will also have a significantly different load profile from a centrifugal impeller....
Loctite 680 is designed to retain round things into round things. I use it for printed props on stainless shafts, metal props on shafts, foster breech sleeves on gun barrels...etc. I see no reason why it would not work for this purpose. It will require destroying the impeller to get it off the motor.
I’ll give it a try. i don’t care about destroying the impeller. If I want it off, it’s either broken or I’m upgrading the design
