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Thread: Aquarama

  1. #46
    Join Date
    Dec 2011
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    Harrington, NSW
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    119

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    I have decided to purchase 3.5mm X 1meter half rounds in brass from England for the rubbing rails. The freight will probably kill me. I will get them chromed and then drill the mounting holes 1mm. I placed some styrene strips 3.5mm half round against the hull and regardless of scale etc - it just looks the right size. Scale seems to do funny things visually as you go down.


    Work on the motor mount bracket. This is still rough and I have to find a way to fix it to the floor. The motors have water jackets that slide over them so I have to allow for their thickness. I might make a huon pine block and fix it to the floor and to the two 20mm logs. Tricky, I have to meet the floor at the V in the hull angle and come up vertical to have a top surface at 18 deg to line up with the prop tubes. Might try to get some thread inserts to make the whole thing removable. Lots to do there I think.

    140.jpg

    Finally made the prop tubes permanent now I have a good alignment with the motors. Fixed in place with high strength Araldite.

    147.jpg

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  3. #47
    Join Date
    Feb 2009
    Location
    Adelaide - outer south
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    67
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    They must be the smallest uni joints I've ever seen . It's looking great, keep up the good work.
    Cheers, Bob the labrat

    Measure once and.... the phone rings!

  4. #48
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    May 2019
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    Sydney
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    45
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    Suggest you chrome them after drilling and cutting to make sure you don't affect/damage finish and have everything covered. Also talk to chrome guys about best preparation of the surface.

  5. #49
    Join Date
    Dec 2011
    Location
    Harrington, NSW
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    If if drill the rubbing strips prior to chroming I may have a problem?

    I want to set the strips into their final curvature shape against the hull and one around the spray rail below. I agree I need to do this before chroming as I don't want to bend them after that as I may damage the finish.

    Might have to make a jig to hold the strips in place at each station - hole. Would not like the drill to run off the crown of the half round!

    Problem. If I predrill the holes in the strip first I fear that while bending them they will bend first at the drill sites causing a not smooth curve, more like a straight line between each hole?

    Problem. Also if I pre drill the holes I think the chroming process may partially of fully close over the holes. I saw that in a mates car parts he had chromed, he had to re drill all of the mount holes. Easy at 10mm not so easy at 1.5mm into hard chrome.

    Every time I solve a problem with this build I come up with another. At least it's not boring for me.

  6. #50
    Join Date
    Jul 2011
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    In between houses
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    Just as an aside, be VERY careful when charging the LiPo batteries, lots of info around snd pictures of burnt benches/garages/sheds after they have caught fire during charging. My friend who is into r.c. boats puts his in a special brick enclosure with a sand bag roof to charge them and if there is any heat or flame, the plastic bag full of sand melts and sand dumps on the battery extinguishing it. He’s working on designing a charger which senses voltage and shuts off power when needed. Worth looking into.

  7. #51
    Join Date
    May 2019
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    Sydney
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    45
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    I can only share the experience I had where pre drilling did not cause your problem and the strip did not bend at the drill holes and formed along the length of the boat fine.
    But I was working at a completely different scale and there were no sharp curves or significant force applied to the strip.
    Perhaps, after you cut your lengths you could use some of the left over material to test pre drilling and bending on your sharpest curvesfirst.

  8. #52
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    Jul 2011
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    Hi duke I’m wondering if you even need to screw them at all? Being a model it won’t spend time rubbing against wharf piles like a real boat , maybe just key the back of it well and sikaflex them on? Just thinking outside the square a bit ��

  9. #53
    Join Date
    Dec 2011
    Location
    Harrington, NSW
    Posts
    119

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    Thanks for the tips guys.

    I am pretty new to this RC LiPo battery stuff so I will heed the safety tips. Had a test charge and monitored them, they seemed to go ok at 2Amps. Did not get much heat involved and they were down to .6amp pretty quickly so I guess they came pretty well charged out of the box. Can't test them on the motors yet as I am waiting for a connector type.

    Seen some horror vids after I read thatabout LiPos. Pretty dangerous batteries - was a big problem with commercial aircraft apparently. The aircraft investigation show showed one plane catching on fire from those batteries, lost everyone on board. They did not change the battery type after loosing aircraft as the batteries were just too good. They put them in a double shielded metal box in the front of the plane under the pilots! Still using them today, think of that next time you fly.

    The metal strips have to be bent on quite a curve around the spray wings across the transom and up the other side in one piece. I will as suggested try some test pieces first. Maybe I do not need the pseudo screw holes and screws but I think it would look kinda cool so I will persevere.

    It will be ages as the metal is coming for England. My better half suggested going to England to get them but I am wise to her, she just wants to go over there to snoop around her ancestors old graves etc.

  10. #54
    Join Date
    Dec 2011
    Location
    Harrington, NSW
    Posts
    119

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    Went to order the brass rubbing strakes from England. £7.50 for a piece of 1m brass whoo hoo I will have five please.

    But wait .. that will be £175.00 for freight UK to AUS. EACH! No thanks very much.

    So I still have not found a supplier for rubbing strips yet. I am getting desperate for something to use.

    Meanwhile I made some back of seat drinks trays for the little dudes that will sit in the back. The photo etch grill came from from a kit and I made the surrounds from Huon Pine and rebated using the Dremel and the Dremel router attachment. Ca glued it together, not too bad. Wouldn't mind a drink with them right now!

    149.jpg

    149.3.jpg

  11. #55
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    Jul 2011
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    I’m sure I saw half inch wide half round brass in the rack at McJings, I’ll have a look next time I am there

  12. #56
    Join Date
    Dec 2011
    Location
    Harrington, NSW
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    Yes I can get 1/2 inch half round in Aus too. I think it is too wide at 12.5mm that would scale up at 120mm for a brass rubbing rail !..

    I think about 3.5mm maybe 4mm? would be about 35mm on a real boat.

    Ideal 850mm long by 3.5 W 2mm T. I think..

    Does that sound right?

  13. #57
    Join Date
    May 2019
    Location
    Sydney
    Age
    45
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    209

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    Sad to hear freight was that bad.

    I found this which harkens back to the milling idea.
    Jig for milling Half Round Beading from round stock | Model Engineer


    My googlefu is strong today as I found this Australian Site.
    Brass Half Round - Hobby Mechanics


    Also this alternative site which agrees to free shipping for orders over $60 or somthing (UK again).
    Has a good range of beading from 1/8" to 5/32" (3.9mm).
    Search Results -> brass half round :

  14. #58
    Join Date
    Jan 2014
    Location
    Sydney Upper North Shore
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    4,464

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    A bit extra but How about something upmarket like this if your stuck?

    Sterling Silver Full 1/2 Rnd Wire 4.0x2.0mm

  15. #59
    Join Date
    Dec 2011
    Location
    Harrington, NSW
    Posts
    119

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    Thanks Bones and others,

    I had seen the Aus Hobby Mechanics web site with the 3.2mm half round but shied away as it listed 300mm lengths only. I did not think I had the skill to join the lengths neatly so I had dodged it.

    I rang a John Ruggles from the Hobby Mechanics in Queensland and he was able after some running around to supply me with a 2.7m continuous length of 1/8" half round brass. Great helpful fella, good price and not too bad for the freight. Just got the mail, should be here soon!

    That's another problem nailed down - excuse the pun.

    Duke.

  16. #60
    Join Date
    Dec 2011
    Location
    Harrington, NSW
    Posts
    119

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    Mounting the motors,

    Used some Huon Pine trimmed to the angle of the prop tubes to the hull floor. Used two thread inserts to accommodate socket head screws used later to fasten the motors. Drilled the inserts in the vice to stop splitting.

    150.1.jpg

    Resined the screw block into the hull between the logs with some similar shaped spacers either side and onto the floor.

    150.jpg

    Used some aluminum angle to make a mounting bracket. Had to allow OS holes for tuning of motor positions and of bracket to mount position. The motors were tuned to allow for minimal deviation at the universals, I hope this relieves the stress on them and the transmission of more power without binding losses.

    154.jpg

    The motor bracket was trimmed of unnecessary material to lessen weight.

    162.jpg

    Mounting bracket and motors in final position. Props seem to spin easy by hand without any binding. No connectors for the batteries delivered yet so no power test.

    The 2 ESCs were joined back to back with HD doubled sided tape to make one block. I made a noggin behind station 8 to mount the ESC block. Used 2 velcro tapes to bind the ESC block to the noggin, nice and tight can't move. The water tubes are only rough at this stage, I have number 2 son making me some SS exhaust flanges and copper exhaust pipe to go through the transom.

    162.4.jpg

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