Weed eater engine conversion

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

  1. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    More info

    No time to get up into the attic and measure the skeg and I am not home for the next few days. I would guess it is around 1/8" thick. The only purpose of the skeg is to protect the prop and to enable steering. Ran one motor once during design without a skeg and was very surprised when I couldn't turn around. Luckily I had a paddle along for security.

    As far as welding - distortion is the issue. On the Duropower motor the aluminum tub was very thin and not the best alloy. It will bend if I step on it. With this motor I welded the skeg prior to having any of the internals installed and it made it difficult to insert the bushings and seals.

    There is another opition as well. You can always make a sleeve that goes over the prop end of the driveshaft. You could then weld the skeg to this sleeve. You could also design this sleeve to act as the seal as well. Something to consider.

    Mark W
     
  2. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Skeg

    Hi Mark,

    I found a piece of aluminum plate that is about .080 and is very rigid. I think it will work. I am also going to weld a small bracket to the top of the tube with a couple of 1/4 X 20 Tapped holes in it in case I want to install a top cover plate for the prop.

    I drilled and tapped 1/4 X 28 holes for the zerk fittings where each of the 3 bronze bushings are mounted in the driveshaft tube. I drilled holes through the bronze bushings that will capture the ends of the zerk fittings and keep the bronze bushings from rotating inside the drive shaft tube.

    I also made the delrin bushing that fits on the end of the tube where the prop mounts.

    Making a little progress. Ha Ha

    I have taken some pictures and will post them later today.

    John
     
  3. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    Caution

    On the "top plate" or cavitation plate, be very careful that is is rigid enough and far enough away from the prop. If not, weeds will get caught between the prop and cav plate, bend the plate towards the prop, putting a gouge in the cav plate and wear down your propeller. And you can bet the prop will not get worn evenly thus causing an unbalanced prop and bad vibrations which are never a good thing for something spinning at 7,000 rpm's.

    Don't ask how I know this.

    Mark
     
  4. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Cav Plate

    Hi Mark,

    Thanks for the tip.

    I know what you mean. I have had many of those. Ha Ha

    Well it's lunch time. Grab a bit to eat and then back to the project.

    John
     
  5. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Progress on my GX35 Build

    Hi,

    I have attached some pictures of my progress on Tuesday.

    I went by my friends house to have him weld the cav plate mount and skeg plate but he was not home. Maybe today I will have better luck.

    Made pretty good progress but still have a ways to go.

    I chamfered both ends of the bronze bushings and cross drilled them with a letter D bit so that the zerk fittings would extend through the hole in the drive shaft tube housing into the bushings to hold them in place during operation. The zerk fittings will also allow for addition lubrication as needed. I turned down some locking collars for this build and others I plan in the near future. Drilled and tapped 1/4 X 28 holes in the drive shaft tube housing for installation of the zerk fittings. Machined a piece of delrin for the lower drive shaft exit on the drive shaft tube housing. Cut out a skeg plate from .080 6061T6 aluminum plate that will be welded to the bottom of the drive shaft housing. Fabricated a cav mounting plate with 2 each 1/4 X 20 holes that will be welding to the top of the drive shaft housing.

    As you can see it was a pretty busy day. Ha Ha

    After the welding is done I am going to work on the installing the drive shaft seals and locking collar, pinning the Young's T-10 Prop, transom mount and associated tilt mechanism, tiller and associated throttle and kill switch installation,

    John
     

    Attached Files:

    Last edited: May 23, 2012
  6. American_Yankee
    Joined: Apr 2012
    Posts: 44
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    Location: Middle Tennessee

    American_Yankee Junior Member

    Thanks John, some good pics and a good looking "long-tail" build. Did you buy the bushing between the prop and the end of the shaft, or turn it out on your lathe? Is it secured with a set screw in the shaft, or just free floating? You got lots of stuff done today! Good job.
     
  7. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Delrin Prop Bushing

    Hi Chuck,

    I turned the lower black delrin bushing on my metal lathe that goes into the drive shaft housing next to the prop from some raw material I had at my shop. Currently it is free floating with a slight press fit but I may put a set screw in it to keep it from rotating.

    Yes, yesterday was pretty busy.

    I borrowed my brother-in-law's conduit bender and intend to make a prototype tiller arm. I am sure that I make a couple of these prior to getting one I will like. It will attach to the black plastic fitting that is shown in the pictures just below the GX35 power head. Also have to figure out a control handle and appropriate throttle cable. These items will go a lot slower as they will take more thought based on the items I currently have at my disposal. I will try to use something I currently have. It they don't do what I need, Mark Wo had given me some suggestions.

    John
     
  8. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    Looking good John

    Wow, I think I thought about what kind of set screw to use for a longer period of time than it has taken you to get to where you are. As far as the handle/tiller, I have a bunch of part numbers I'll send your way. Wish I could post them here but am unable to.

    Couple of points on the handle. How ever you make it, it will not be right when you get the motor on the boat. It will take lots of tweaking. My suggestion is to buy lots of conduit and practice different configurations with the cheap stuff prior to making the real tiller out of aluminum. While the conduit is cheap, it has too much flex, my opinion, to make a great tiller arm. Aluminum is so much better. You can buy a 8-10' section of tubing from Home Depot or Lowes for under $15.

    It is also nice to make the tiller removable or foldable. Depending upon how you intend to transport, these motors get quite long. Folding/rotating the tiller back onto itself or making it remove easily makes the transport of the motor much easier.

    Kill switches near the throttle are nice to have. Having to reach back to the motor to kill it are mjore difficult to use.

    I'll send the various options for the tiller attachement to the motor/driveshaft in a email.

    Mark
     
  9. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Many Thanks!

    Hi Mark,

    I really appreciate your sharing your building techniques. That is what made my build go so fast.

    I just got back from my friends house that welded on the skeg and cav plate bracket. Now I can install the seals and drive shaft locking collar.

    I think I am going to look at the throttle linkage and see if I can figure something out on that issue today. I have an extended cable that I purchased for a Shindiawa trimmer that may work. It has the correct end on it for the Honda GX35. I need to find an adjustable throttle cable end that will mount on the Honda GX35 engine. The one I have on the Shindiawa trimmer may work. It is a piece of threaded rod with a hole in it with 2 adjusting nuts that allows you to move it back and forth for adjustment.

    Speaking of tiller arms what diameter and wall thickness of aluminum did you use to get the rigidity necessary to lift the tail drive shaft without any issues. I know what you mean about making the tiller arm removable so that it can be reversed for transport and my final design will incorporate that feature.

    You already sent me some diagrams and part numbers for various throttle control setups for my evaluation. Tiller attachment options and the one you liked best would be appreciated.

    John
     
  10. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    RC airplanes

    Hey John -

    You should know this stuff. I used R/C push rod connectors to connect the throttle linkage to both the motor and the throttle. They worked real well. I tried different methods and all had their plusses and minuses.

    The one that worked the best for me on the motor end were these (pictured below). On the throttle end I got some "z" connectors that I soldered onto the end of the throttle linkage. The low profile of these connectors worked best in the throttle housing.

    Mark
     

    Attached Files:

  11. HelicopterJohn
    Joined: May 2012
    Posts: 80
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    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Look Familiar

    Hi Mark,

    Yes, I have plenty of those kinds of connectors and also have the uni ball connectors we use on the R/C Helicopters. I have a temporary hookup that will work for now and I will refine it once I take the unit on it shake down cruise.

    I had a few other things that keep me busy today and I did some thinking about the tilt mechanism and tiller arm.

    I have enclosed a few pictures for your amusement.

    Tilt Mechanism:

    I found a piece in my miracle box that may work nicely for the tilt mechanism. It rocks back and forth and it has a bolt and associated locking nut on each end. Depending how deep you screw in the bolt will set the maximum depth of the tiller. It has a bolt on the opposite side that can control how high the drive shaft can be lifted out of the water. I may need to make a new bottom plate and get rid of the arc that was used for a different application.

    Tiller Arm:

    I also found a piece of 1/2 thick aluminum that I could use for attaching the tiller arm to the drive shaft housing. It will be adjustable so that it can be slid up and down the drive shaft housing tube to achieve a good balance point. I intend to bore a 1" hole in one end of the plate and slide it over the drive shaft housing tube. The other end I will bore another hole and insert a piece of aluminum bar stock that will protrude through both sides of the aluminum plate. Then I can place the tubing tiller arm on the side towards the engine for operation and remove it and place it on the other side of the bracket for transportation and storage.
     

    Attached Files:

  12. American_Yankee
    Joined: Apr 2012
    Posts: 44
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    Location: Middle Tennessee

    American_Yankee Junior Member

    Good job rmensco, looks like a good duck boat. I'm in the process of building the same setup as HelicopterJohn, but working on other things while he gives his the ole "test run" for bugs.

    Was at the local metal scrap yard this afternoon looking for outer shaft and drive shaft material. Found an old "Gamefisher" 1.7 HP outboard...mostly complete... in the aluminum scrap pile. I have taken the lower end off and it looks good. Marked the driveshaft and rotated the prop one full revolution. Looks like it's about a 2.25 to 1 lower gear ratio. It has a big beefy 3 shoe clutch that I'm trying to get off of the bottom of the engine now. Both of my gear pullers were too large to grab hold and pull it off of the crankshaft. Once I get it off, I'll check the weedeater engines I have to see if I can rig up something.

    I'm also studying the muffler system, and how they routed it down below the water line. I may experiment with it to figure out a system for my Longtail later.

    If I get something rigged up, I'll post some pics on the contraption. Hey... for thirteen bucks ($13), it's worth that much just for the amusement factor! Right? That's cheap recreation! I know, I'm easily amused.
     
  13. American_Yankee
    Joined: Apr 2012
    Posts: 44
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    Location: Middle Tennessee

    American_Yankee Junior Member

    Hey John, great job! I see you made it by your friend's that does the aluminum welding. Man! You're knocking them dead! Wish I lived in your neighborhood...with a motivator like you around... my longtail would be pushing my Otter Stealth around in no time!

    Looks like you might be ready to do those "sea trials" in a day or two!

    As stated in a previous post, I found a Gamefisher 1.7 HP outboard in the aluminum scrap bin at the local metal scrap yard. The lower unit is good... so I plan to make it stir water some way! It'll be something to keep me busy, while I'm gathering parts for the longtail.

    I'm excited to see you so far along on your build! Don't forget... make that Utube video!

    Chuck
     
  14. HelicopterJohn
    Joined: May 2012
    Posts: 80
    Likes: 3, Points: 8, Legacy Rep: 47
    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Honda GX35 Long Tail Build

    Hi Chuck,

    I have to design a couple of parts for the tiller and tilt and rotation mechanism. Also have to design a clamp for the transom for the tilt and rotation mechanism to fit in. This will take some time.

    Yesterday one of my friends showed up with 3 Echo back-pack trimmers that were not working. Spent most of the afternoon fixing them and shooting the breeze. Had to remove those EPA required plastic covers that prevent you from adjusting the carb high and low needles. Once those were removed I was able to easily adjust the carbs and now all run fine.

    Have another friend coming today that needs some machine work done so that will also slow progress somewhat. I have to treat him right because he is my video guy. Ha Ha

    We will get they finally, just trying to get it as near correct as possible on the first try.

    John
     

  15. HelicopterJohn
    Joined: May 2012
    Posts: 80
    Likes: 3, Points: 8, Legacy Rep: 47
    Location: Seffner, Florida

    HelicopterJohn HelicopterJohn

    Honda GX35 Drive Shaft Tilt Assembly

    Hi,

    Made a few parts for my friend today for his camera but was able to work in a few pieces for the Drive Shaft Tilt Mechanism. The bolts in the front and back of the swivel mechanism allow you to set mechanical stops in both the up and down direction of the drive shaft assembly. I still need to a little trimming of material from the top of the Drive Shaft Tilt Mechanism.

    I still have to make another attachment arm for the tiller and throttle control and kill switch that will attach to the Drive Shaft. With any luck I may get that done tomorrow.

    John
     
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