Weed eater engine conversion

Discussion in 'DIY Marinizing' started by Ward, Jun 2, 2003.

  1. Mark F. CheneyM
    Joined: Oct 2008
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    Location: Bountiful Utah

    Mark F. CheneyM Junior Member

    Thank you gentlemen. However, I am not as comfortable with the computer as I am with a lathe. You're talking to a diansore [spelling] here. I will work on some good images in the proper sequence.

    Mark F. Cheney
     
    1 person likes this.
  2. rmenasco
    Joined: May 2010
    Posts: 40
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    Location: Florida

    rmenasco Junior Member

    Plans

    I dunno if anyone is interested, but someone sent some plans for a long-tail mud motor out of a weed eater. His plans are very detailed and tell you where to order all of the parts. In these plans, it also tells you where to get a 50cc scooter motor for cheaper than you can buy a new weed eater. If anyone is interested in these plans, please send me a PM with you email and I can forward them to you!
     
  3. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    am working on an electronic control some of you may be interested in, in the attached picture its like 2 of them driving 2 motors but 1 is even easier. both motors are idling in the picture and can be accelerated with the dials, is easier than holding a lever.

    am actually working on using one dial to accelerate both motors and the other to slow one down in order to allow steering :)
     

    Attached Files:

  4. Mark Wo
    Joined: Dec 2007
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    Location: Minnesota

    Mark Wo Senior Member

    Hey Mark Cheney

    Nice to see you post up the latest on the small mud motor build. As you know, I am excited to see what you ahve come up with. If you need help with the picture, send them to me and I'll upload here or anywhere you would like.

    I haven't been around the past couple of weeks and it was nice to see your post when I checked in. I'll send you a pm with my contact info.

    Can't wait to hear more about this.

    Mark Wo
     
  5. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    bit more progress

    have remade the throttle cables and controller again, will test this design but a few things to do, figure it'll be worth extending the horizontal motor mounts to be able to space the props a bit more, this will also allow easier steering. still need to find/make a rudder to go on the center shaft that connects to the control arm, the control arm will allow some steering without having to adjust motor speeds when criusing by manually moving the rudder when rotating the control arm. will also cut down the longer motor drive shaft to balance the motors out more.

    any suggestions as to a rudder shape and size?

    another thought, has anyone considered using a small old forward/reverse gearbox from a small ride on mower to be able to reverse a weed eaters direction?
     

    Attached Files:

  6. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    Rifraff,

    That is pretty cool what you're doing there. Integrating the servos to control your throttle so you can drive by joy stick is pretty impressive

    One thing I'm interested in hearing about after your first test run is how these dual motors track since they are both spinning the same direction. On boats with dual engines, they spin opposite each other to off set the thrust vector they both create. You may not expeariance any lop-siddedness, but then again, you might. Only testing will tell.:p

    You might take a look at kayak rudder sizes and make yours slightly larger.

    I say grab a riding lawnmower gear box and give it a try! You've already shown you have an eye for pairing up drive components :D I wonder though how much additional parasitic drag that would add to your sytem. Each new mechanical junction adds to the power loss. Riding lawnmowers don't tend to be build from precision components.

    Erich
     
  7. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    erich, yeah still working out the best values for the components, am aiming to move the accelerator cable only about 6mm over the full travel of the potentiometer, these weed eaters do not have much travel in the cable, so trying to also keep the cable as close as possible to the center of servo. will post a schematic when its working best. one motor with 1 pot to control speed is easy, and alot better than holding onto the lever the whole time and should allow a little more motor control than the standard slow or fast. the parts to make the electronics for a single motor are about $2 and can be covered in epoxy or hot glue to make them waterproof. and then you need a normal hobby servo and a basic bracket.

    the dual motor thing is just because they are there and because a single motor propells me fine so should be fun to see what 2 can do, though the current setup can be detached from the boat in about 2 minutes and is not that complex. i know what you mean about both motors going the same direction, am hoping that using a 3 blade prop on the side not being driven as hard will counteract the effect enough, and am also going to use a rudder that with be controlled using the same handle that holds the electronics, this handle also allows lifting the props from the water if need be in weeds or sticks. am gonna make the rudder from from plastic about 125mm x 150mm and 16mm thick and then grind it and curve it into some kind of aerofoil shape, then drill a hole for the 10mm aluminium rod and add a few screws to stop it spinning

    currently both motors want to rest pretty hard on the boat when not in water as the angle is about 55 degrees from vertical when idle ( the handle and control box prevent the hot motors getting in contact with the vinyl of the inflatable, though only about 30 degrees when the motors are pushing the boat, so when in river and the motors pushing should not be too hard as the setup should be pretty ballanced when the motors are working in water, will adjust motor height to get this point in the best place

    still need to make the 3 fin propellor housing and and make an extra bracket to go horizontally between the 2 motors to lock the shafts and prevent the props rotating once the optimal angle is acheived to keep the boat going forward with both props spinning the same way
     
  8. reynolddog
    Joined: Jun 2010
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    Location: fl

    reynolddog Junior Member

    When you guys try to turn do you have to do the limbo, or am I missing something?
     
  9. rmenasco
    Joined: May 2010
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    Location: Florida

    rmenasco Junior Member

    What do you mean? I am confused?
     
  10. ben2go
    Joined: Jul 2008
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    Location: Upstate, South Carolina,USA

    ben2go Boat Builder Wanna Be

    He is speaking of the left and right swing of the tiller or steering handle.
     
  11. reynolddog
    Joined: Jun 2010
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    Location: fl

    reynolddog Junior Member


    Right. How do you guys steer with these things?
     
  12. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    yes reyolddog you are missing somthing ...between the ears....
     
  13. ben2go
    Joined: Jul 2008
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    Location: Upstate, South Carolina,USA

    ben2go Boat Builder Wanna Be

    Same as a outboard motor.
     
  14. reynolddog
    Joined: Jun 2010
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    Location: fl

    reynolddog Junior Member

    I understand that, I just don't see some of these designs be comfortable at all to steer.

    Here is what I currently have. This kayak was not made for a motor...but for a rutter and his been a PITA to get this working. I have not yet tried the design as I don't have a prop.... What I'm worried about the the angle and height of the handle as it is considerably high when it's at the "running angle", and is not very comfortable... Don't laugh, I know it's not as fancy as some of your rigs. But I'm doing this as trial and error trying to save $.

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  15. ben2go
    Joined: Jul 2008
    Posts: 187
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    Location: Upstate, South Carolina,USA

    ben2go Boat Builder Wanna Be

    I have seen a brush trimmer, like yours, set up as a mini out board.That may work better that a mud motor and you could use your rudder pedals and cables to control the motor.The set up I saw used a standard trolling motor transom mount.
     
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