The "Hitchhiker's Guide" to the Maxi-Stream mod

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Correct, the whole assembly pulles out a bit then kicks back in to start the correct way. The prop itself actually pulls out the magnet / impeller assembly when it spins the incorrect direction which causes it to hit the stopper.

:fish1::hammer:
 
cool, finished mine.

my opinions. the 2nd "better" prop, I think it was dumas? the black one, not the one pictured. the hub isnt as thick as the white one appears to be. though it worked, I needed to use a drill press and steps of bit sizes to not go off center and destroy it.

also I didnt put a stopper in, and it seems to fix itself anyway... I assume the prop is making contact with the bar even though its not stepped down.

1 idea I had though, you could probably drill through the PVC shroud, and insert a length of the ridgid airline. drill through that in the middle and pass the shaft though. instead of using the acrylic bar, since that might not be as available to some people.
 
So are you thinking the 2nd prop is better? Better flow??

Also, I got a chance to test my question about whether the MJ900 and MJ1200 were the same except for the impeller assembly. They answer.... they apparently are not. I took the impeller assy from a MJ1200 and put it in a MJ900 body and it would not start. I swapped out the rubber impeller part and it worked fine. So it looks like the magnet part is the same but the rubber piece is too large for a MJ900 to run.

I tend to agree with dhnguyen on using the the MJ1200. If you are going to do it you need to find a larger prop to make it worthwhile. Otherwise you should just use the 900 and save some energy.
 
never used the white one to compare. by the numbers its a harder pitch and the pump can turn it... so Id assume its more flow.

I wonder if reducing the diameter of the pipe around the prop would act as a cowling and increase flow further. I know it works for air, but I also know they dont do it on boats but that might be because its drag would offset its benefit. not the same for us, might help.
 
<a href=showthread.php?s=&postid=6363865#post6363865 target=_blank>Originally posted</a> by areze
...
I wonder if reducing the diameter of the pipe around the prop would act as a cowling and increase flow further. I know it works for air, but I also know they dont do it on boats but that might be because its drag would offset its benefit. not the same for us, might help.
Click to expand...


Already tried it and nope you won't get any better flow out of it by using a smaller diameter pipe. In fact the flow is better if the pipe is larger.

The key to getting the maximum amount of flow is to have as much inlet holes or slots in your PVC shroud as possible.


D.
 
Im already there heh, I crisscrossed the fancy slots at 90degree offsets and it starts to get kinda flexable with all those slots in it. donno how many more you could put without it becoming an issue.

more RPMs would be good. the propellor really isnt spinning all that fast, not sure exactly what it is at, but I bet that is all of the difference between a tunze and these.
 
Hey incidentally, I used a cheapo Lifetech AP1500 powerhead (made by JEBO) for one of these mods and it is A LOT stronger than the MJ900 or MJ1200. The AP1500 although only rated for 275GPH is a much larger motor and magnet and has more torque as well. I was able to use a 1.75" propeller on this pump easily and the flow is very impressive.

Might be worth while to check into as the AP1500 pumps you can get for like $10 brand new.

You would have to use a 2" PVC pipe to make the shroud though but that too will allow for larger propellers to be used.


D.
 
Well, I finally got mine all together and well, it sure packs a punch thats for sure.. heck the thing was dooing loops in my bathtub when I tested it. BUT ... there is a constant buzzing sound comming from it. It changes pitch louder and softer but doesn't seem to ever go away completely. Any ideas what could be causing this.. I can't keep in the tank as is. Thanks for any advise.

Chris
 
I think the issue that you are having with the buzzing is that the impeller is not balanced properly. I had the same issues with mine and no matter how much I tried to balance it, noise would eventually develop over time. I did end up cheating and went the seio route which appears to have somewhat less flow, but for the price, I couldn't refuse - I got them dirt cheap. I am still looking at pursuing this mod in the future, but am somewhat preoccupied with raising some baby Clarkii's. If anyone has the parts and time, I would suggest possibly attaching the props closer to the magnet and shortening the housing. In looking at the Tunze's, the prop assembly is at the base, rather than extended down the housing. I would assume that this would reduce the necessity for balancing as the issue I was having was over time, the plastic impeller extension that the prop was glued to would groove from the friction of the shaft. As the housing grooved, it would become more and more unbalanced until it finally made this annoying humming noise constantly.

:fish1::hammer:
 
ok I guess what I'll do is remove the cross member installed, and cut a new one that fits tight without glue. move it around till i'm rid of the buzz and then mark and glue. Thanks for the info.
 
dhnguyen-
Did you mount the impellers at the very end of the rigid tubing or are they part way down the tubing?I see both pics in this thread.
 
Before I glue my new cross brase in let me ask this... With the original mj impeller it would be self centering from the magnet correct? And because of the length of and torque of the propellers, the mod is no longer sef centering? And thus, I will have to try and center the shaft into the cross brase so its not resting against the magnet inside.... Hmm.. if all the above is true... I might do the cross brase from the earlier version where the brace sits outside the pvc housing... this would be alot easier to try and center.. just cut a piece a little larger move around till you don't feel it touching the magnet inside... mark, cut and glue.



<a href=showthread.php?s=&postid=6381764#post6381764 target=_blank>Originally posted</a> by dhnguyen
The buzzing hum is probably caused by the whole magnet impeller being off centered (even slightly).

You need to take a good look at the PVC housing and see if this is somehow off making the shaft slightly angled causing the hum.

As far as the propeller itself, you can get a prop balancer to do this.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXDS11&P=7


D.
Click to expand...
 
Self centering is one thing, balanced is another. A centered impeller will direct the flow perpendicular to the PH body, instead of at a slight angle. It will also prevent additional friction from the magnet against the PH body as well. If the prop is not balanced properly, it will create a wobble as centrifigual force is exerted upon the prop assembly itself. This in time could lead to a variety of issues from noise to total prop failure. I have found that centering the impeller is simplistic compared to balancing it.

:fish1::hammer:
 
If the shaft is held in place down in the circular hole in the MJ and the other end is in the cross member where does the wobble come from? The whole unit spins around the shaft and the shaft is stationairy as best I see it, so as long as the shaft is straight (which it is) then there should be no wobble. Now if its off centered, then the magnet could rub the wall in the mj causing the noise. Anyhow, I've dissassembled the shaft and plan on trying one prop for the next try and see if that makes any diff.

<a href=showthread.php?s=&postid=6392549#post6392549 target=_blank>Originally posted</a> by Worldwithin
Self centering is one thing, balanced is another. A centered impeller will direct the flow perpendicular to the PH body, instead of at a slight angle. It will also prevent additional friction from the magnet against the PH body as well. If the prop is not balanced properly, it will create a wobble as centrifigual force is exerted upon the prop assembly itself. This in time could lead to a variety of issues from noise to total prop failure. I have found that centering the impeller is simplistic compared to balancing it.

:fish1::hammer:
Click to expand...
 
Dhnguyen, I'm using the black props as listed in the forum.. does it matter which end is pointing out? And if using two props, does it also matter which way they are pointing? hehe I hope this is an obviously stupid question.

<a href=showthread.php?s=&postid=6381764#post6381764 target=_blank>Originally posted</a> by dhnguyen
The buzzing hum is probably caused by the whole magnet impeller being off centered (even slightly).

You need to take a good look at the PVC housing and see if this is somehow off making the shaft slightly angled causing the hum.

As far as the propeller itself, you can get a prop balancer to do this.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXDS11&P=7


D.
Click to expand...
 
What black propeller are you using? What brand? And yes it does matter which end you point the propeller.

A photo would help

D.
 
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