Hello all......

From some info I found on the scale ships forum, I decided to try my hand at making a replacement impeller for the jet boat. Luckily I found brass at my hardware store. The threads involving people making props from brass, really didn't apply to this application, since an impeller has such a high pitch, so I had to make each blade individually.

Mind you, this impeller was a test run, just to learn the basic technique, it's not perfect and not the way I wanted it, but I think its pretty decent for 3 hours of work.

So the I used brass piping, first I took my old impeller and covered the blade in tape to make a template. I had to guesstimate how much more blade area I had to add, since the hub is so much smaller in diameter. I transfered this template to the brass plate etched it and cut it out with my dremel, giving myself some extra material to work with.

Then using a propane torch, I soldered the first blade and then the second using silver solder. Tip here; cool the brass immediately with water to reduce softening of the metal.

After this, it really was more like art then engineering. I just used some vise grips and pliers and bent and shaped the blade, then using a micrometer I cut down the blades to a uniform radius. Overall the impeller is 31mm, instead of the originals 29mm, but I just finished and honestly enough work for the night, so I'll have to cut down some more tomorrow.

For the jet boats guys here. The benefits of this impeller over the plastic one are numerous. I plan to make the real one with 3 blades, which will load the motor more and reduce slippage. Secondly the reduced hub diameter dramatically increases blade area further improving thrust. And lastly using metal the impeller will not flex as much. You may think the brass is soft after all this torching and it being soldered on, but its actually quite hard to bend.

Question and comments are appreciated as well as any words of wisdom when it comes to shaping props.

~QS

the rest of the pics (all are in order of construction

You get an A++++ for effort. That looks like alot of work.
Didn't you mean "Propeller"?

Now that's gettin' your hands dirty! You da "jet"man!!!!!!

You referring to me calling it an impeller? If so, thats what a propeller in a jet drive is called. Technically it is a propeller, but in pump lingo it's an impeller.

thank you both for the compliments. The hardest part of the project was doing it all on my living room floor, I've got a small apartment and unfortunately I let someone move into my workshop room, so using a torch on right on my rug was interesting, that and kinda hurts the back after a while.

I know what an impeller is. I have changed the one in my life size outboard motor cooling system many times. But I didn't read the part where you were making that for your jet drive. sorry.

Prop Sharpening and balancing.
well that prop looks a little uneven in lots of spots and it looks about the same size as your real impeller. once you balance and sharpen it it is be smaller then your impeller and there for make lots more slippage.
i would suggest if you make another then make it a little but bigger.
and when you bend your brass. use your hands . its more a even curve.

eyekandy, well as I said this was a practice run. Being in the beginning I had no idea what I was doing, I didnt expect success on the first try. didnt come out smooth, mainly imo because there was too much solder which doesnt bend. For some reason I forgot the old days of doing plumbing and that I couldnt possibly do this with a soldering iron. So I spent probably an hour doing that till I brought out the torch. Also my blades arent long enough. That probably the toughest part, is cutting out a proper blade, but after sitting in bed thinking about it, I think I know what to do.
Hopefully today, I'll try another one, but unfortunately I sprained my wrist or something as typing this is killing me.

its was a good first try and i hope it turn out for you.
I have made my own boat props and used on my Fe boats. with success. its fun and you really get to know what your doing once you have done a few.

well, I've got my blades cut and notched, but I'm having trouble getting them at 33 degree angles to each other, I had two blades on, I was going for the third and one of the other blades fell off. Pretty tough doing this three blade thing, it's not too hard keeping one blade cool while torching, but two is proving hard, I've got the rig suspended over water now, so the blades already on, stay in the water.....gotta take a break though, gets frustrating and my wrist hurts

. Thanks for the support, without a forum like this, I probably wouldn't finish half the things I start. Gives me just enough pressure to finish, otherwise no one would even know I was doing it, besides the wifey.

it is fun though once the blades are on.

well ,after another 8 hours of welding, it broke again. Making this the fourth time one blade broke off the 3 blade impeller. In hope of help, I explain how I did it the 4th time. First I sanded the parts and tried to keep touching them to a minimum. I coated all the parts in flux and let that dry. Then I set my part in this rig I made. It makes it possible to weld are three blades on at once, in their proper finished position. Okay, so I this time I thought, was it. I carefully put everything in the jig, all metal touching, all fluxed. I heat the whole rig evenly with my propane torch for maybe 30 seconds, till the solder would melt on a blade and the shaft. I get all three done cool it down immediately with water and it seems fine, I started by trying to rip the blades off, sounds bad, but it the weld is good, it's obvious. they all pass the test. So I radiused, the impeller balanced, and then ............... then I'm sharpening the blades and this one blade bends while aparpening it with the grinding wheel(holding with hand).

Ok, lets see if there a problem I put it in water first then try to bend that blade carefully by hand. Immediately it breaks off......and honestly at this point 18 hours of fabrication time, I gave up I just had too, the other two blades are solid and they were the ones that have been solid. I 'm very confused, it's not like it bends bends and breaks, one bend and it breaks. btw I had even made a new blade. In case my rambling is unclear I have had this one blade fall off 4 times, the other always cooled with a good weld even after 4 times, since all the blades come off when I heat the impeller. I've changed the blades, the shaft and still these two original blades always hold and the third breaks. The solder tends to look aerated, like a cold weld, but it wasnt a cold weld. I'm only describing it ridiculouslly in hopes someone knows what I'm doing wrong.

Any ideas?
I'm going nuts. I'll add pics off this rig I made and the 4th gen impeller that was ready to install when it broke.
If you need the pic, theyll be up in like 30min.

ok the pics came out horrid or at least the important ones, in your mind combine the first pic and second to get the idea of the rig, the other pics are various stages of development after the ill fated welds.




okay that horrid, the first pic show the rig being held down by a clamp in pool of water, since the one thing I had at 120 degree angles was made of plastic, so a body of water was needed( it melted the first time). The close up shot, shows each blade being clamped to a somewhat L shaped piece of brass, to hold the pitch of the blades. I used those stationary clamps, hopefully now you understand what your looking at



I added a professional pic by me, since I failed miserably on these pics, gotta make it up somehow.

After not too much deliberation, just dont look at the pics, its just showing that soldered all three blades at once
Does anyone know, is there a better way, maybe solder all the blades and then insert the shaft? I either meed to stop trying or get some great advice, I'd really prefer the latter

okay, so I broke down and called hobby-lobby yet again. Last time I was told to call back, because there was a guy who knew about the drives.

This time, the guy says "jet drive, I'm not sure I know what your talking about."

I say, "well you sell jet drives for boats and I need a new impeller."

"Well, graupner doesnt sell parts for them."

"Why I guess they figure they wont break."

"So no one knows about these drives,"

"well we used to have a guy but he left the comapny about 8 months ago"
.......silence....
maybe call back after new years and there will be more sales reps available."


Okay so this company doesnt have techs, nor sales reps that even know they sell jet drives. Later he lied and said he had tried to get parts before for them, but couldnt, but 30 seconds earlier he didnt know what a jet drive was. I'm at a loss, I really thought that hobby-lobby had good customer service, but this was ridiculous. I'm sorry, but I just had to rant. A lot of people ask me why I have a graupner drive and not a swash drive, but swash drives are only for zenoah motors. So it looks like I either have to buy several "spare"" jet drives, or give up and start making a gas powered swashdrive boat.

All in all, I think this guy just did some harm to his comapny, I mean I'm going to have to recommend to people not buy these now and I feel bad for those that did. For those that did, DONT SUCK UP A ROCK, EVER or you'll have to buy a whole new drive. Even though its' just a propeller!

[>:]