Hey all, Doing some pre-season work on my gear and noticed that the tiny set screw is stripped and useless on my Battlers pump. Pump spins fine, does nothing! This makes the third time since I started last fall that I've seen problems with a crappy metal set screw inset in plastic impeller. The impeller itself is in great shape, but useless without a functioning set screw which I'm not sure I'll be able to safely remove without damaging the weak plastic threads inside the impeller. Does anyone know of a source for metal replacement impellers, or at least for plastic impellers with a metal collar? I don't really want to order another cheaply made plastic one from Battlers (at $9.50 USD) and end up replacing it later due to setscrew or plastic thread failing. Or, does anyone know another source for pre-built pumps with metal impellers? P.S.- Dammit! I think I just lost/misplaced the impeller while I was working on tuning up my guns earlier. The pump is sitting there but no impeller. Mack
I have seen people try casting their impellers with a metal collar and setscrew built in, but I don't remember how that worked. Another option is to make your own, using sheet brass and a soldering torch. Until someone started making decent cast impellers, some people used "penny pumps" that were copper pennies soldered or superglued to collars and brass impeller blades. If you have a mill, you can make one out of solid aluminum. If you have a CNC mill, you can make a nice one out of solid aluminum. You could also try casting a threaded insert into your impeller, instead of a collar.
KK, thanks for the replies. I found the impeller sitting on top the servo boxes and managed to remove the old set screw and replace it with a new one. It seems to be holding so I should be good for now, just lucky I didn't damage the plastic threads. I think I will try and make my own metal impellers, using the locking collars we put on the prop shafts to lock them into place. If I can solder one of the collars to a metal plate that will give me the metal-on-metal reliability I'm looking for and give me my center anchor point for the soldered on impeller blades too. ...always more things to distract me.
I used to make pumps and tugboat has the molds. I casted in place a metal ring with the set screw in it so that the plastic did not take the load. I believe that BC also switched to that after one too many impellers crapped out due to plastic threads. If you do cast the impeller, you can use a suitably modified shaft collar of the appropriate size as the cast in insert. Simply dremel in a cris cross pattern into the sides so that the insert can neither slip nor spin (I put my inserts at one end of the impeller, hence the slipout provisions) and insert a long fully threaded screw into the collar through the side of the mold. Cast plastic. Remove screw (I hope you used ample release agent) remove impeller from mold, and put in stainless steel setscrew. -Greg
Have the same problem with the set screw for BC rudder gears they sent me a new one but it did the same thing so I just ca them in place worry about it when I have to remove them hopefully never
Set screws can be ordered from Small Parts. Choose the thread and choose the length. I bought a variety and supply the entire club.
If the plastic is thoroughly stripped, I'd drill out & tap a new hole in a larger size, TBD by how much oversize you need to drill it. I'd also switch to a longer setscrew. That will get you more holding power for a given torque. Don't over-tighten & use thread-lock, CA, etc. Don't get any into/onto the shaft, pump housing, etc. I'd be wary of casting with an embedded shaft collar. That might throw the whole assembly out of balance. JM
