Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Problem prop shaft  (Read 2819 times)

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Problem prop shaft
« on: March 18, 2007, 02:23:02 PM »

My Robbe scheutze has twin props.
I have been testing it on the bench prior to floating it.
One prop shaft runs really hot after about a minute the other is fine.
Any ideas what I have done wrong ?

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

Colin Bishop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 10,393
  • Location: SW Surrey, UK
Re: Problem prop shaft
« Reply #1 on: March 18, 2007, 02:30:34 PM »

Either the shaft or the tube could be very slightly bent. Another possibility is that there is insufficient horizontal play in the shaft causing it to bind. Do both shafts feel the same when you rotate them by and with the motors disconnected?

Another thing to try is to apply pressure to the outer end of the tube while it is running to see if it becomes less noisy - this could indicate a bent shaft/tube.

I had a similar problem with my Fishery Cruiser but it was noise rather than heat. One tube was slightly bent and adjusting the A bracket to push it out a fraction has largely solved the problem.
Logged

chromedome

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 241
  • Location: scotland
Re: Problem prop shaft
« Reply #2 on: March 18, 2007, 02:38:35 PM »

I would want to have all look at the shaft if you can still manage to slide it out the sea tube and see if there is evidence of binding.

   chromedome
Logged

HS93 (RIP)

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,949
  • I cannot spell , tough
  • Location: Rainhill UK
Re: Problem prop shaft
« Reply #3 on: March 18, 2007, 05:18:43 PM »

Just take it out if possible and roll it on a flat surface ,worktop,etc leave the prop on over the edge , you can usually see if its got any slight bends, or just remove the motor coupling and see if it spins free leave the prop on again it acts a bit like a flywheel to help it spin. it may just need a light oil and a slow run to help it bed in .  Peter
Logged

Shipmate60

  • Global Moderator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,292
  • You bark - I will bite!!!
  • Location: Fareham
Re: Problem prop shaft
« Reply #4 on: March 18, 2007, 07:41:32 PM »

have you tried running in the shafts.
Does the shaft get hot on one bearing or both?
If only one put sone toothpaste on the shaft on the end that is getting hot.
And run motor slowly, monitoring the temp, if it gets hot stop.
Only do this if the shaft is straight!!
Logged
Officially a GOG.

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Re: Problem prop shaft
« Reply #5 on: March 18, 2007, 08:04:07 PM »

Have slackened of the connections at either end of tube in case they were binding too tight. Had to wait for it to cool down so I haven't tried it yet. Will try it tomorrow.
Dont want to take out shafts too often as these Robbe ones are a bu**er to get in and out.

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Re: Problem prop shaft
« Reply #6 on: March 19, 2007, 10:51:53 AM »

Thanks chaps have had it running at half speed for last two hours. Seems fine.

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

J.beazley

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 879
  • The building never ends
  • Location: Locks Heath, Hampshire
Re: Problem prop shaft
« Reply #7 on: March 19, 2007, 01:21:44 PM »

So whens the Water trials then???
Logged
If it floats I'll  build it, if it sinks its a sub either way its in the water so I'm content.

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Re: Problem prop shaft
« Reply #8 on: March 19, 2007, 01:32:17 PM »

Got to get the electrics sorted yet.
Westbournes sold me male instead of female Tamiya connector. It might be here tomorrow, hopefully.
Hasn't been near water yet, SWIMBO had bath taken out and walk in shower put in. Cant float boat in shower.

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

Shipmate60

  • Global Moderator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,292
  • You bark - I will bite!!!
  • Location: Fareham
Re: Problem prop shaft
« Reply #9 on: March 20, 2007, 10:40:06 PM »

Richard,
I have 2 x 777 motors from Model Motors Direct on 12 volts with similar props to yours, but 4 blade.
Fastest minesweeper I have ever seen flat out!!!
I might have to fit torpedo tubes to her.

Bob
Logged
Officially a GOG.

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Re: Problem prop shaft
« Reply #10 on: March 21, 2007, 09:33:06 AM »

Hopefully I will finish this one soon if I ever get my Tamiya plug.
I have also ordered one from http://www.component-shop.co.uk/html/batteries.html
Ordered yesterday at 1400 received e-mail last night to tell me it has been despatched so am keeping fingers crossed.

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

Shipmate60

  • Global Moderator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,292
  • You bark - I will bite!!!
  • Location: Fareham
Re: Problem prop shaft
« Reply #11 on: March 27, 2007, 11:02:59 PM »

Richard,
have you put in additional supports on the inboard end of the propshafts.
Was another thread that made me think of yours.
These thin hulls can flex quite a lot, so the propshaft needs support at BOTH ends.
It can be quite noisy.

Bob
Logged
Officially a GOG.

J.beazley

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 879
  • The building never ends
  • Location: Locks Heath, Hampshire
Re: Problem prop shaft
« Reply #12 on: March 28, 2007, 07:38:11 AM »

Wise words there Bob,
i took your advice and mounted a piece of wood under the prop tubes to deal with the exact problem.
Stopped most of the vibration and has reduced flexing loads.

Jay ;D
Logged
If it floats I'll  build it, if it sinks its a sub either way its in the water so I'm content.

DickyD

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 9,497
  • www.srcmbc.org.uk
  • Location: Southampton UK
    • SRCMBC
Re: Problem prop shaft
« Reply #13 on: March 28, 2007, 07:55:09 AM »

Richard,
have you put in additional supports on the inboard end of the propshafts.
Was another thread that made me think of yours.
These thin hulls can flex quite a lot, so the propshaft needs support at BOTH ends.
It can be quite noisy.

Bob
No Bob, shall have a look at it. Thanks.

Richard ;)
Logged
Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk
Pages: [1]   Go Up