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Author Topic: Brushless motor/ESC for Dumas 19" racing runabout.  (Read 8866 times)

Nige52

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #25 on: December 07, 2011, 09:48:30 AM »

lol seals bein attacked by tubs of vaseline %%


Vaseline is Petroleum Jelly. Petroleum Jelly rots rubber.....
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #26 on: December 07, 2011, 09:52:52 AM »

yeah i weighed that up. we use to use it to put rubber radiator hoses on. probably not a good idea. The hot water melted it fast though so didnt cause any problems.
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Subculture

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #27 on: December 07, 2011, 04:27:09 PM »

Depends on what rubber it is.

Nitrile rubber isn't damaged by Vaseline. Neoprene and silicone is however. Silicone rubber is also damaged by silicone grease, although that is about the only rubber that is damaged by that grease.

If you don't know what rubber the seals are made of, the safest lubricant to use is animal or vegetable fat. So a thin smear of butter, marge, lard or cooking oil will not damage the seals. Even just smear of saliva or water will probably be sufficient to get the seals to slide on.

Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #28 on: December 08, 2011, 11:32:24 AM »

Thanks to all for the great advice but, unfortunately, still no go :((.  Take the O rings out and the jacket slides on easily.  Put them in and, seen from the inside, the motor just buts up against the O rings and no amount of pushing or twisting get is over them.  I found this film on U-tube which shows the procedure with a finned motor.
http://www.youtube.com/watch?v=dB8iey86mL8
However, the Turigny is a smooth cased motor with no fins.  Has anyone fitted a water jacket to one of these and can point out the jacket which they fitted?  It may just be that the one I got on ebay will never fit.  The alternative would be to fit the jacket without O rings and seal both end with epoxy resin.  Would this work? 
I could run the motor without cooling.  Its spec is at the link below.  I would run it on the Chris Craft with a 7.2V battery, a 60 amp Turigny ESC and a 30mm prop.
http://www.hobbyking.com/hobbyking/store/__17725__XK2845_B_2000kv_Brushless_Inrunner.html
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #29 on: December 08, 2011, 01:35:53 PM »

If your struggling with the o rings then epoxying will work, as long as you make a good seal. I found when epoxying some nipples to my cooling jacket that they dont form a brilliant bond, but as long as the motor isnt bashed about too much it will stay in place. it might help to rough the surfaces a bit. Its a shame really because the cooling jacket should fit that motor.  {:-{
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ooyah/2

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #30 on: December 08, 2011, 08:06:46 PM »

Thanks to all for the great advice but, unfortunately, still no go :((.  Take the O rings out and the jacket slides on easily.  Put them in and, seen from the inside, the motor just buts up against the O rings and no amount of pushing or twisting get is over them.  I found this film on U-tube which shows the procedure with a finned motor.
http://www.youtube.com/watch?v=dB8iey86mL8
However, the Turigny is a smooth cased motor with no fins.  Has anyone fitted a water jacket to one of these and can point out the jacket which they fitted?  It may just be that the one I got on ebay will never fit.  The alternative would be to fit the jacket without O rings and seal both end with epoxy resin.  Would this work? 
I could run the motor without cooling.  Its spec is at the link below.  I would run it on the Chris Craft with a 7.2V battery, a 60 amp Turigny ESC and a 30mm prop.
http://www.hobbyking.com/hobbyking/store/__17725__XK2845_B_2000kv_Brushless_Inrunner.html

Jeremy,
Does the water jacket have enough meat on it to machine grooves to take the rings, if so send it up to me and I will machine grooves at each end for you.
George.
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #31 on: December 09, 2011, 02:35:33 PM »

George

Kind offer   :-)) but the O rings are already located in grooves at either end.  The jacket is just too small (by a tad) for a 28mm diameter motor.  Not a great expense on ebay and I'll put it down to experience.  I'll go to Astec and make sure I get something that fits.

Jeremy
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #32 on: December 09, 2011, 02:58:39 PM »

it turns out a few people having the same problem {:-{
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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #33 on: December 10, 2011, 03:02:29 PM »

Can't you just run some mastic around each end- bit less permanent than epoxy, and should remain watertight provided you're thorough.

You could use silicone or acrylic mastic.

Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #34 on: December 14, 2011, 12:55:34 PM »

I have just received a Leopard cooling jacket from Astec - fits perfectly  :-)).  I would definitely suggest avoiding the one I first purchased off ebay.  It does not do what it says on the tin.
http://www.ebay.co.uk/itm/RC-Boat-Aluminium-28mm-380-Motor-Water-Cooling-Jacket-/220778484560?pt=UK_ToysGames_RadioControlled_JN&hash=item33676c5350
Thanks to all for your advice
Jeremy
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #35 on: December 14, 2011, 03:21:57 PM »

apart from that little flop have you got the new motor installed.
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #36 on: December 15, 2011, 03:22:14 PM »

No so simple  :((!  With the Leopard jacket in place, the diameter is too big for the 360 size bracket.  I could turn the bracket round, except that it is firmly epoxied to the butterfly keel at the bottom of the hull.  Wrench it out and I could destry the boat.  I will try the ebay jacket sealed with mastic and see if that will do the job.
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #37 on: December 15, 2011, 05:24:33 PM »

lol thats just bad luck
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #38 on: December 15, 2011, 10:19:38 PM »

Mastic did not do the job!  :((.  Motor runs fine but the jacket leaks.  I'm wondering whether heating up the jacket might cause it to expand enough to allow it to be fitted with its O rings.  I'll have a go and see.  Someone must have fitted one of these.  Prestwich Model Boats sell a motor with exactly the same jacket already fitted.  I will ask Dave Marles about it.  He may know the secret!
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #39 on: December 15, 2011, 10:35:23 PM »

try this pete its a long shot though. put the motor in the freezer to make it shrink. put the seals in the jacket and put the jacket in boiling hot water, stick it on the hob in a saucepan.

DONT FOR HEAVENS SAKE BURN YOUR HANDS use gloves or something and put a big o butter on the freezing cold motor and try pushing the jacket on. makes sure your get all the old silicone off first.

have you got any pics?

Btw it seems like this jacket is a bit tight so maybe you could loosen it up a bit with a file. if you have one of course.
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nick_75au

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #40 on: December 16, 2011, 11:22:28 PM »

How about smaller diameter (cross section) O'rings they should be available from local bearing shops or similar,
Nick
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #41 on: December 17, 2011, 05:28:04 PM »

Hi Nick

Very close to the solution!  Before I read your posting, I paired down the O rings in situ using a dremel sanding drum and then, using butter and a fair amount of force, I was able to get the jacket on  :-)).  It will never come off now.  Anyway, all's well that ends well and many thanks for the various suggestions along the way.  Mad Mike suggested earlier that several others have encountered the same problem.  I hope this helps.

Jeremy
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #42 on: December 17, 2011, 05:31:13 PM »

next time we get someone asking how to put a cooling jacket on a motor you will be the man :-))
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #43 on: February 23, 2012, 05:24:57 PM »

Just to let you know that the Turnigy 2845 2000Kv motor, 25mm prop and a 7.2V battery gives the boat a great turn of speed  :-)).  It is almost silent in operation and the battery seems to last forever.  When I next get down to the lake with a camera, I will post some photos and hopefully a video.  The modified O rings clearly work to seal the water jacket - not a trace of water inside the boat.  Thanks to all for your advice :-).

Jeremy
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #44 on: March 11, 2012, 09:52:39 PM »

Link to U-tube video:
http://www.youtube.com/watch?v=cLd2vhbfe9w
She goes well :-)
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grasshopper

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #45 on: March 11, 2012, 11:14:42 PM »

You mentioned prop diameters and a pitch of around 30' - and some have mentioned smaller diameters. Are you only using X type racing props and not shallower pitch more scale like propellers?

As I remember in the Graupner range of props there were several classification dependent on pitch and  blade shape. There were three blade scale type props with shallow pitch, 2 blade 'racing props' with a high pitch and then really high pitch carbon fibre ones for surface drives - I think the designations may have been P, X and S but don't quote me...

A change to a shallower pitch prop but similar diameter with a higher revving motor might keep a decent speed, drop the current draw and run it cooler.
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #46 on: March 12, 2012, 09:41:12 AM »

Prop is Graupner sub-surface drive racing prop 32.5mm diameter.  It seems to be well suited to the set-up.  Motor runs cool and almost silent.
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