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Author Topic: BIG MISTAKE! What an idiot i am!  (Read 8195 times)

BigAde

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BIG MISTAKE! What an idiot i am!
« on: February 13, 2010, 12:02:17 AM »

Hello all,

Today I bought a 70mm brass prop for a new tug that I am building from my local model shop! The problem I have is that the prop is exactly 70mm and now I need a kortz nozzle for it. I was planning on making my own out of some plastic pipe but I cannot fine some 70+mm pipe in B&Q and also the Kortz MMM sell are exactly 70mm so they will not fit!

does anyone know where I might be able to buy some 74mm pipe to fit my prop that I should of checked if I could get the pipe first! B&Q sell 68mm and I looked at all their differnt fittings but the prop will not fit, I tried!

Can anyone help??

Cheers

Adrian
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HS93 (RIP)

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Re: BIG MISTAKE! What an idiot i am!
« Reply #1 on: February 13, 2010, 12:08:22 AM »

do you know anyone with a lath who can spin it up and fatten the tips to fit a commercial Kort.its only 2mm off the tips so very little loss off drive

Peter
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BigAde

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Re: BIG MISTAKE! What an idiot i am!
« Reply #2 on: February 13, 2010, 12:20:28 AM »

do you know anyone with a lath who can spin it up and fatten the tips to fit a commercial Kort.its only 2mm off the tips so very little loss off drive

Peter

Thats a good idea! I would need to take off 4mm to fit a 68mm pipe! I never thought about spinning maybe even in a drill! at least then it will look more like a kotrz prop instead of the usual round normal prop!
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toesupwa

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Re: BIG MISTAKE! What an idiot i am!
« Reply #3 on: February 13, 2010, 12:27:42 AM »

Thats a good idea! I would need to take off 4mm to fit a 68mm pipe! I never thought about spinning maybe even in a drill! at least then it will look more like a kotrz prop instead of the usual round normal prop!

I wouldnt spin a prop in a drill and try to remove some material off the tips of the blades.. if i were you!... blades have a habit of coming off the 'boss' at speed when you are trying to machine them...  :embarrassed:
Unless you can hold them in a lathe and GENTLY (0.02" per cut) remove material, you would be better off making the kort to fit the prop...

My 'how to' make a kort on RC Groups..
http://www.rcgroups.com/forums/showthread.php?t=1025555
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BigAde

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Re: BIG MISTAKE! What an idiot i am!
« Reply #4 on: February 13, 2010, 12:35:49 AM »

I wouldnt spin a prop in a drill and try to remove some material off the tips of the blades.. if i were you!... blades have a habit of coming off the 'boss' at speed when you are trying to machine them...  :embarrassed:
Unless you can hold them in a lathe and GENTLY (0.02" per cut) remove material, you would be better off making the kort to fit the prop...

My 'how to' make a kort on RC Groups..
http://www.rcgroups.com/forums/showthread.php?t=1025555

Wow that is an ace tutorial but I do not have the tools to make my own like that hence using some simple plastic tube to the correct diameter.
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sinjon

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Re: BIG MISTAKE! What an idiot i am!
« Reply #5 on: February 13, 2010, 06:47:07 AM »

Would it not be possible to build up a tube to the right diameter, then lay up fibre glass ?

Colin
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Colin

FullLeatherJacket

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Re: BIG MISTAKE! What an idiot i am!
« Reply #6 on: February 13, 2010, 07:43:31 AM »

Idiot's contribution - what about cutting a slot lengthwise along a piece of 68mm tube and inserting a 19mm-wide sliver of the same material to increase the diameter out to 74mm? It won't be exactly round then but the difference won't be noticeable. You can buy a suitable adhesive for plastic drain pipe from the same source.
Suit yourself.
FLJ
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funtimefrankie

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Re: BIG MISTAKE! What an idiot i am!
« Reply #7 on: February 13, 2010, 08:43:20 AM »

that's about 3 inches, What about a paint tin or large soup tin,  shaped with filler...or even a small bucket :-))
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Tom@Crewe

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Re: BIG MISTAKE! What an idiot i am!
« Reply #8 on: February 13, 2010, 08:46:27 AM »

Spray can top. They come in all shapes and sizes, take your ruler when you help wife with the shopping.
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Airsparks

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Re: BIG MISTAKE! What an idiot i am!
« Reply #9 on: February 13, 2010, 09:21:28 AM »

 Have you tried brass tube from a plumbers merchant.

My korts are 50mm brass tube supplied by Mobile Marine Models. If all else fails ask Brian at MMM

    Alastair
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Colin Bishop

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Re: BIG MISTAKE! What an idiot i am!
« Reply #10 on: February 13, 2010, 10:46:01 AM »

If you can find a round former of the right size you could try laminating the nozzle with layers of thin styrene sheet. Once you have built it up to a decent thickness and it has fully dried it should be pretty tough.

Colin
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norry

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Re: BIG MISTAKE! What an idiot i am!
« Reply #11 on: February 13, 2010, 12:03:18 PM »

...Hi Guys...

Measure a Sooup Tin...Its about 75mm Just Right for a 70mm Prop...

If you use the Medium size Bean Tins, Then you have the correct length as well...Just build the outside up with P38...

But Remember... Beanz Meanz Heinz...Norry...

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chrise

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Re: BIG MISTAKE! What an idiot i am!
« Reply #12 on: February 13, 2010, 12:20:55 PM »

...Hi Guys...


I use the Medium size Bean Tins, Then you have the correct length as well...Just build the outside up with P38...

Do you mean that your Korts are no more than a layer of P38? I would not have thought it strong enough unless very thick so how thick does it need to be & do you have a trick for getting a nice smooth outside surface? This would offer alternatives to the never ending search for plastic tube!

For your top & bottom pivots do you just use roughened brass rod or do you solder spreader plates to your rudder shaft to spread the load?
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Colin Bishop

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Re: BIG MISTAKE! What an idiot i am!
« Reply #13 on: February 13, 2010, 12:58:46 PM »

I think Norry meant to use the tin as the base and build up the shape with P38.
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Bryan Young

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Re: BIG MISTAKE! What an idiot i am!
« Reply #14 on: February 13, 2010, 03:40:31 PM »

Just in passing, fairly recently I (jokingly) suggested to the guy (Turkish?) who is making his own nozzles that for all the world the end result looked just like a Fray Bentos steak and kidney pudding tin. These tins are very robust and mor "solid" than your usual food tin.
The contents are pretty good also, so a trial may be worth the effort!. BY.
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Notes from a simple seaman

chrise

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Re: BIG MISTAKE! What an idiot i am!
« Reply #15 on: February 13, 2010, 04:50:10 PM »

I think Norry meant to use the tin as the base and build up the shape with P38.

Pity. I had hoped that Norry had found something new.
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norry

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Re: BIG MISTAKE! What an idiot i am!
« Reply #16 on: February 13, 2010, 06:04:28 PM »

...Hi Guys...
It seems that Chris E has found something new... A cheeky way of twisting words...

How to take a posting made by one member of the Forum, Change the Wording of that Posting, Then use it as a quote from the original posting...

I never stated that that I use Bean Tins to make Kort Nozzles...
I suggested that they could be used to make Korts in a Lower Budget build...
All my tugs are built for Tug-Towing and have been fitted with proper Factory Made Korts...

...Best Regards...Norry...
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andywright

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Re: BIG MISTAKE! What an idiot i am!
« Reply #17 on: February 13, 2010, 08:51:36 PM »

I would buy a MMM kort, and shape the blades to fit, it is possible to do this by hand or with a dremel, bare in mind to keep the prop balanced, it you bought the Kort you could use this as the template,
Andy
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craftysod

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Re: BIG MISTAKE! What an idiot i am!
« Reply #18 on: February 13, 2010, 09:11:16 PM »

Get a kort from MMM and just sandpaper a couple of mill out of it 
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HS93 (RIP)

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Re: BIG MISTAKE! What an idiot i am!
« Reply #19 on: February 13, 2010, 09:16:58 PM »

what make off prop is it ? and what part of the world are you in ?  ( roughley)

Peter
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captain ron

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Re: BIG MISTAKE! What an idiot i am!
« Reply #20 on: February 13, 2010, 10:11:51 PM »

What about a plastic beaker.It is tapered so you could remove a section anywhere along its length to vary the diameter.You could also use it as a mould to make your own.Tupperware also do tapered storage containers that would probably suit.

Ron
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poll

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Re: BIG MISTAKE! What an idiot i am!
« Reply #21 on: February 14, 2010, 09:14:57 AM »

You could try the sleeve that couples the 68mm pipes together.

John
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DARLEK1

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Re: BIG MISTAKE! What an idiot i am!
« Reply #22 on: February 14, 2010, 01:39:17 PM »

A plant pot? There has got to be one the right size somewhere!
 Paul... :-)
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BigAde

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Re: BIG MISTAKE! What an idiot i am!
« Reply #23 on: February 14, 2010, 02:26:01 PM »

WoW what a massive response!

Sorry I cannot reply to all of them but here goes:

I got my prop and swiftly went into my kitchen cupboards and found said bean tin and WOW they are perfect size BUT then thought on, If i cut the top and bottom off it would then be too flimsy, putting fiber glass around it would be a pain to sand to the correct shape!

I tried finding a 68mm pipe fitting which should be bigger but could not find what I needed for the job of the correct size, I might have to go to Jewsons!

I am going to look in ASDA for a plastic cup which might just well do the job!!! Excellent idea!!!!!!

I dont fancy buying a Kortz from MMM as this boat was ment to be a budget build and so far I have probably spent the best part of 150 just trying to get a running hull with no decking or super structure!

I am trying to get this boat running for the Ellesmere Port boat show in a few weeks so I have a second tug for towing!!!

Right I am off to ASDA!!! keep you all posted
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portside II

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Re: BIG MISTAKE! What an idiot i am!
« Reply #24 on: February 14, 2010, 05:01:51 PM »

Just going back to fitting the props in mmm korts , i had the same problem with a 90mm prop and a mmm kort .
There was an idea of pitting the prop in a lathe or drill and trying to machine some material off , this can be done as i did it by putting the prop on a shaft and either using a drill or a lathe if you have one , and a piece of emery/glass paper to reduce the diameter .
This is an easy job and within 5 mins of stop and starting the prop was a good fit with ablut 1mm clearance .
it worked for me.
daz
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